AU2004202476A1

AU2004202476A1 - Human G Protein-Coupled Receptors

Info

Publication number: AU2004202476A1
Application number: AU2004202476A
Authority: AU
Inventors: Dominic Behan; Derek T Chalmers; Ruoping Chen; Huong T Dang; Martin Gore; Karin Lehmann-Bruinsma; Chen W Liaw; I-Lin Lin; Kevin Lowitz; Carol White
Original assignee: Arena Pharmaceuticals Inc
Current assignee: Arena Pharmaceuticals Inc
Priority date: 1998-10-12
Filing date: 2004-06-03
Publication date: 2004-07-01
Also published as: AU6299199A; AU770871B2

Description

1

AUSTRALIA

Patents Act 1990 ARENA PHARMACEUTICALS, INC.

COMPLETE SPECIFICATION STANDARD PATENT Invention Title: Human G Protein-Coupled Receptors The following statement is a full description of this invention including the best method of performing it known to us:- HUMAN G PROTEIN-COUPLED RECEPTORS RELATED APPLICATION DATA This application is a divisional application of Australian Patent Application No.

62991/99 (Acceptance No. 770871) the contents of which are incorporated herein in their entirety by reference. Australian Patent Application No. 62991/99 (Acceptance No. 770871) claims priority benefit of each of the following applications, all filed with the United States Patent and Trademark Office via U. S. Express Mail on the indicated filing dates: U.S. Patent Number 6,555,339, filed with the U.S. patent and Trademark Office as USSN 09/170,496 on October 13, 1998; U.S. Serial Number 09/417,044 filed on October 12, 1999; U.S. Serial Number 09/416,760 filed on October 12, 1999; U.S.

Provisional Number 60/110,060, filed November 27, 1998; U.S. Provisional Number 60/120,416, filed February 16, 1999; U.S. Provisional Number 60/121,852, filed February 26, 1999; U.S. Provisional Number 60/109,213, filed November 20, 1998; U.S. Provisional Number 60/123,944, filed March 12, 1999; U.S. Provisional Number 60/123,945, filed March 12, 1999; U.S. Provisional Number 60/123,948, filed March 12, 1999; U.S. Provisional Number 60/123,951, filed March 12, 1999; U.S. Provisional Number 60/123,946, filed March 12, 1999; U.S. Provisional Number 60/123,949, filed March 12, 1999; U.S. Provisional Number 60/152,524, filed September 3, 1999; U.S.

Provisional Number 60/151,114, filed August 27, 1999 and U.S. Provisional Number 60/108,029, filed November 12, 1998; U.S. Provisional Number 60/136,436, filed May 28, 1999; U.S. Provisional Number 60/136,439, filed May 28, 1999; U.S. Provisional Number 60/136,567, filed May 28, 1999; U.S. Provisional Number 60/137,127, filed May 28, 1999; U.S. Provisional Number 60/137,131, filed May 28, 1999; U.S.

Provisional Number 60/141,448, filed June 29, 1999; U.S. Provisional Number 60/136,437, filed May 28, 1999; U.S. Provisional Number 60/156,633, filed September 29, 1999; U.S. Provisional Number 60/156,555, filed September 29, 1999; U.S.

Provisional Number 60/156,634, filed September 29, 1999; U.S. Provisional Number 60/156,653 filed September 29, 1999; U.S. Provisional Number 60/157,280 filed October 1, 1999; U.S. Provisional Number 60/157,281 filed October 1, 1999; U.S.

Provisional Number 60/157,282 filed October 1, 1999; U.S. Provisional Number 60/157,293 filed October 1, 1999; and U.S. Provisional Number 60/157,294 filed October 1, 1999. This application is also related to U.S. Serial Number 09/364,425, filed on July 30, 1999. Each of the foregoing applications are incorporated by reference herein in their entirety..

FIELD OF THE INVENTION The invention disclosed in this patent document relates to transmembrane receptors, and more particularly to human G protein-coupled receptors, and specifically to GPCRs that have been altered to establish or enhance constitutive activity of the receptor.

Preferably, the altered GPCRs are used for the direct identification of candidate compounds as receptor agonists, inverse agonists or partial agonists having potential applicability as therapeutic agents. More particularly, the invention relates to a mutated (non-endogenous) version of a T-cell death-associated gene receptor (TDAG8), that by virtue of the mutation is constitutively active.

BACKGROUND OF THE INVENTION General This specification contains nucleotide and amino acid sequence information prepared using Patentln Version 3.1, presented herein after the claims. Each nucleotide sequence is identified in the sequence listing by the numeric indicator <210> followed by the sequence identifier <210>1, <210>2, <210>3, etc). The length and type of sequence (DNA, protein (PRT), etc), and source organism for each nucleotide sequence, are indicated by information provided in the numeric indicator fields <211>, <212> and <213>, respectively. Nucleotide sequences referred to in the specification are defined by the term "SEQ ID followed by the sequence identifier (eg. SEQ ID NO: 1 refers to the sequence in the sequence listing designated as <400>1).

The designation of nucleotide residues referred to herein are those recommended by the IUPAC-IUB Biochemical Nomenclature Commission, wherein A represents Adenine, C represents Cytosine, G represents Guanine, T represents thymine, Y represents a pyrimidine residue, R represents a purine residue, M represents Adenine or Cytosine, K represents Guanine or Thymine, S represents Guanine or Cytosine, W represents Adenine or Thymine, H represents a nucleotide other than Guanine, B represents a nucleotide other than Adenine, V represents a nucleotide other than Thymine, D represents a nucleotide other than Cytosine and N represents any nucleotide residue.

As used herein the term "derived from" shall be taken to indicate that a specified integer may be obtained from a particular source albeit not necessarily directly from that source.

Throughout this specification, unless the context requires otherwise, the word "comprise", or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated step or element or integer or group of steps or elements or integers but not the exclusion of any other step or element or integer or group of elements or integers.

Throughout this specification, unless specifically stated otherwise or the context requires otherwise, reference to a single step, composition of matter, group of steps or group of compositions of matter shall be taken to encompass one and a plurality (i.e.

one or more) of those steps, compositions of matter, groups of steps or group of compositions of matter.

Each embodiment described herein is to be applied mutatis mutandis to each and every other embodiment unless specifically stated otherwise.

Those skilled in the art will appreciate that the invention described herein is susceptible to variations and modifications other than those specifically described. It is to be understood that the invention includes all such variations and modifications. The invention also includes all of the steps, features, compositions and compounds referred to or indicated in this specification, individually or collectively, and any and all combinations or any two or more of said steps or features.

The present invention is not to be limited in scope by the specific embodiments described herein, which are intended for the purpose of exemplification only.

Functionally-equivalent products, compositions and methods are clearly within the scope of the invention,.as described herein.

The present invention is performed without undue experimentation using, unless otherwise indicated, conventional techniques of molecular biology, microbiology, virology, recombinant DNA technology, peptide synthesis in solution, solid phase peptide synthesis, and immunology. Such procedures are described, for example, in the following texts that are incorporated by reference: Sambrook, Fritsch Maniatis, Molecular Cloning: A Laboratory Manual, Cold Spring Harbor Laboratories, New York, Second Edition (1989), whole of Vols I, II, and III; DNA Cloning: A Practical Approach, Vols. I and II N. Glover, ed., 1985), IRL Press, Oxford, whole of text; Oligonucleotide Synthesis: A Practical Approach J. Gait, ed., 1984) IRL Press, Oxford, whole of text, and particularly the papers therein by Gait, ppl-22; Atkinson et al., pp35-81; Sproat et al., pp 83-115; and Wu et al., pp 135-151; Nucleic Acid Hybridization: A Practical Approach D. Hames S. J. Higgins, eds., 1985) IRL Press, Oxford, whole of text; Animal Cell Culture: Practical Approach, Third Edition (John R.W. Masters, ed., 2000), ISBN 0199637970, whole of text; Immobilized Cells and Enzymes: A Practical Approach (1986) IRL Press, Oxford, whole of text; Perbal, A Practical Guide to Molecular Cloning (1984); and Methods In Enzymology Colowick and N. Kaplan, eds., Academic Press, Inc.), whole of series.

It is intended that each of the patents, applications, and printed publications mentioned in this patent document be hereby incorporated by reference in their entirety.

Any discussion of documents, acts, materials, devices, articles or the like which has been included in the present specification is solely for the purpose of providing a context for the present invention. It is not to be taken as an admission that any or all of these matters form part of the prior art base or were common general knowledge in the field relevant to the present invention as it existed before the priority date of each claim of this application.

As those skilled in the art will appreciate, numerous changes and modifications may be made to the preferred embodiments of the invention without departing from the spirit of the invention. It is intended that all such variations fall within the scope of the invention and the claims that follow.

Description of the related art Although a number of receptor classes exist in humans, by far the most abundant and therapeutically relevant is represented by the G protein-coupled receptor (GPCR or GPCRs) class. It is estimated that there are some 100,000 genes within the human genome, and of these, approximately or 2,000 genes, are estimated to code for GPCRs. Receptors, including GPCRs, for which the endogenous ligand has been identified are referred to as "known" receptors, while receptors for which the endogenous ligand has not been identified are referred to as "orphan" receptors.

Nucleic acid encoding the native or wild-type GPR38 receptor was first described in isolated form by McKee et al., Genomics 46(3), 426-434, 1997. GPCRs represent an important area for the development of pharmaceutical products: from approximately of the 100 known GPCRs, 60% of all prescription pharmaceuticals have been developed.

GPCRs share a common structural motif. All these receptors have seven sequences of between 22 to 24 hydrophobic amino acids that form seven alpha helices, each of which spans the membrane (each span is identified by number, transmembrane-1 transmebrane-2 etc.). The transmembrane helices are joined by strands of amino acids between transmembrane-2 and transmembrane-3, transmembrane-4 and transmembrane-5, and transmembrane-6 and transmembrane-7 on the exterior, or "extracellular" side, of the cell membrane (these are referred to as "extracellular" regions 1, 2 and 3 (EC-1, EC-2 and EC-3), respectively). The transmembrane helices are also joined by strands of amino acids between transmembrane-1 and transmembrane-2, transmembrane-3 and transmembrane-4, and and transmembrane-6 on the interior, or "intracellular" side, of the cell membrane (these are referred to as "intracellular" regions 1, 2 and 3 (IC-1, IC-2 and IC-3), respectively). The "carboxy" terminus of the receptor lies in the intracellular space within the cell, and the "amino" terminus of the receptor lies in the extracellular space outside of the cell.

Generally, when an endogenous ligand binds with the receptor (often referred to as "activation" of the receptor), there is a change in the conformation of the intracellular region that allows for coupling between the intracellular region and an intracellular "Gprotein." It has been reported that GPCRs are "promiscuous" with respect to G proteins, that a GPCR can interact with more than one G protein. See, Kenakin, 43 Life Sciences 1095 (1988). Although other G proteins exist, currently, Gq, Gs, Gi, Gz and Go are G proteins that have been identified. Endogenous ligand-activated GPCR coupling with the G-protein begins a signaling cascade process (referred to as "signal transduction"). Under normal conditions, signal transduction ultimately results in cellular activation or cellular inhibition. It is thought that the IC-3 loop as well as the carboxy terminus of the receptor interact with the G protein.

Under physiological conditions, GPCRs exist in the cell membrane in equilibrium between two different conformations: an "inactive" state and an "active" state. A receptor in an inactive state is unable to link to the intracellular signaling transduction pathway to produce a biological response. Changing the receptor conformation to the active state allows linkage to the transduction pathway (via the G-protein) and produces a biological response.

A receptor may be stabilized in an active state by an endogenous ligand or a compound such as a drug. Recent discoveries, including but not exclusively limited to modifications to the amino acid sequence of the receptor, provide means other than endogenous ligands or drugs to promote and stabilize the receptor in the active state conformation. These means effectively stabilize the receptor in an active state by simulating the effect of an endogenous ligand binding to the receptor. Stabilization by such ligand-independent means is termed "constitutive receptor activation." SUMMARY OF THE INVENTION Disclosed herein are non-endogenous versions of endogenous, human GPCRs and uses thereof.

1. GPR38 In its endogenous form, GPR38 is not constitutively active, i.e. GPR38 signaling via G protein is ligand-dependent. Thus, it is not feasible to search directly for inverse agonists of endogenous GPR38. Accordingly, the present inventors sought to employ a mutation approach to identify a constitutively activated version of GPR38 to permit screening of candidate compounds against the non-endogenous, constitutively activated version of GPR38.

One embodiment of the present invention provides an isolated polynucleotide encoding a non-endogenous, constitutively activated version of a human G protein-coupled receptor (GPCR), in particular a polynucleotide encoding a non-endogenous, constitutively activated version of the human G protein-coupled receptor designated GPR38.

Preferably, the isolated polynucleotide of the present invention comprises a nucleotide sequence selected from the group consisting of: a sequence encoding a polypeptide that comprises the amino acid sequence set forth in SEQ ID NO: 130; the sequence set forth in SEQ ID NO: 129; a sequence having at least about 80% identity to SEQ ID NO: 129 other than a sequence encoding a non-endogenous, constitutively activated version of a human G protein-coupled receptor comprising isoleucine residue at position 225 of SEQ ID NO: 130; and the sequence of wherein the constitutively activated version of a human G protein-coupled receptor comprises an amino acid sequence having a lysine residue at a position equivalent to position 297 of SEQ ID NO: 130.

Even more preferably, the isolated polynucleotide comprises a nucleotide sequence selected from the group consisting of: a sequence that is identical or substantially identical to SEQ ID NO: 129 wherein the codon at nucleotide positions 889-891 encoding lysine is unchanged or substituted with a codon that encodes an amino acid other than valine; a sequence encoding a constitutively activated version of a human G protein-coupled receptor having an amino acid sequence identical or substantially identical to SEQ ID NO:130 wherein the lysine residue at amino acid position 297 is unchanged or substituted with an amino acid other than valine; and a sequence encoding a variant of a non-endogenous, constitutively activated version of a human G protein-coupled receptor comprising the amino acid sequence set forth in SEQ ID NO: 130 in which the lysine residue at position 297 is substituted for a different amino acid other than valine.

In a particularly preferred embodiment, the isolated polynucleotide of the present invention comprises a nucleotide sequence selected from the group consisting of: a sequence encoding the amino acid sequence set forth in SEQ ID NO: 130; and the nucleotide sequence set forth in SEQ ID NO: 129.

For the purposes of nomenclature, the nucleotide and amino acid sequence set forth in SEQ ID NO: 129 and SEQ ID NO: 130, respectively, relate to the non-endogenous, constitutively activated version of the human G protein-coupled receptor designated GPR38.

A further embodiment of the present invention provides an isolated polynucleotide encoding a GPCR fusion protein, wherein said polynucleotide comprises a nucleotide sequence of an isolated polynucleotide encoding a GPCR, preferably fused to a nucleotide sequence encoding a G protein, in particular a Gs protein.

A further embodiment of the present invention provides a vector, such as an expression vector, comprising a nucleotide sequence encoding a GPCR, preferably operably linked to a promoter. In one embodiment, the nucleotide sequence encoding the GPCR is fused to a nucleotide sequence encoding a G protein, in particular a Gs protein such that a GPCR fusion protein is capable of being expressed from said expression vector.

A further embodiment of the present invention provides a recombinant host cell comprising the vector or expression vector of the present invention.

A further embodiment of the present invention provides a method of producing a nonendogenous, constitutively activated version of a human G protein-coupled receptor or a GPCR fusion protein comprising the steps of: transfecting the expression vector of the present invention into a host cell thereby producing a transfected host cell; and culturing the transfected host cell under conditions sufficient to express a nonendogenous, constitutively activated version of a human G protein-coupled receptor or GPCR fusion protein from the expression vector.

In one preferred embodiment, the method further comprises obtaining the transfected host cell and preferably, further comprises obtaining or isolating a membrane fraction from the transfected host cell.

A further embodiment of the present invention provides an isolated membrane of a transfected host cell wherein said isolated membrane comprises a non-endogenous, constitutively activated version of said human G protein-coupled receptor or a GPCR fusion protein encoded by an isolated polynucleotide of the invention.

A further embodiment of the present invention provides an isolated or recombinant non-endogenous, constitutively activated version of a human G protein-coupled receptor polypeptide comprising an amino acid sequence selected from the group consisting of: a sequence comprising the amino acid sequence set forth in SEQ ID NO: 130; a sequence having at least about 80% identity to SEQ ID NO: 130 other than a sequence comprising isoleucine residue at position 225 of SEQ ID NO: 130; and the sequence of wherein said sequence comprises a lysine residue at a position equivalent to position 297 of SEQ ID NO: 130.

Preferably, the isolated or recombinant non-endogenous, constitutively activated version of a human G protein-coupled receptor polypeptide comprises an amino acid sequence selected from the group consisting of: a sequence that is substantially identical to SEQ ID NO:130 wherein the lysine residue at amino acid position 297 is unchanged or substituted with an amino acid other than valine; and a sequence comprising the amino acid sequence set forth in SEQ ID NO: 130 in which the lysine residue at position 297 is substituted for a different amino acid other than valine.

In a particularly preferred embodiment, the isolated or recombinant non-endogenous, constitutively activated version of a human G protein-coupled receptor polypeptide comprises the amino acid sequence set forth in SEQ ID NO: 130.

A further embodiment of the present invention provides an isolated or recombinant GPCR fusion protein comprising an amino acid sequence of the isolated or recombinant non-endogenous, constitutively activated version of a human G protein-coupled receptor polypeptide. Preferably, the GPCR fusion protein comprises a G protein, in particular a Gs protein.

A further embodiment of the present invention provides a method of identifying a modulator of a G protein-coupled receptor. In one embodiment, the method comprises the steps of: contacting a candidate compound with a recombinant host cell that expresses the non-endogenous, constitutively activated version of a human G protein-coupled receptor polypeptide of the invention or an isolated membrane comprising said non-endogenous, constitutively activated version of a human G protein-coupled receptor polypeptide; and measuring the ability of the compound to inhibit or stimulate functionality of the G protein coupled receptor polypeptide wherein inhibition or stimulation of said functionality indicates that the candidate compound is a modulator of the G protein-coupled receptor polypeptide.

In an alternative embodiment, the method of identifying a modulator of a G proteincoupled receptor comprises the steps of: contacting a candidate compound with a recombinant host cell that expresses the GPCR fusion protein of the invention or an isolated membrane comprising said GPCR fusion protein; and measuring the ability of the compound to inhibit or stimulate functionality of the G protein-coupled receptor polypeptide portion of said GPCR fusion protein wherein inhibition or stimulation of said functionality indicates that the candidate compound is a modulator of the G protein-coupled receptor polypeptide.

Preferably, the method of identifying a modulator of a G protein-coupled receptor further comprises providing the host cell or membrane expressing/comprising the GPCR polypeptide or GPCR fusion protein.

In a particularly preferred embodiment, the present invention provides a method of identifying a modulator of a G protein-coupled receptor comprising the steps of: providing a recombinant host cell that expresses a GPCR fusion protein comprising the amino acid sequence set forth in SEQ ID NO: 130 and a Gs protein or an isolated membrane comprising said GPCR fusion protein; contacting a candidate compound with the recombinant host cell or isolated membrane; and measuring the ability of the compound to inhibit or stimulate functionality of the G protein-coupled receptor polypeptide portion of said GPCR fusion protein wherein inhibition or stimulation of said functionality indicates that the candidate compound is a modulator of the G protein-coupled receptor polypeptide.

2. TDAG8 TDAG8 was cloned and sequenced in 1998. Kyaw, H. et al, 17 DNA Cell Biol. 493 (1998); see Figure 1 of Kyaw for nucleic and deduced amino acid sequences. The endogenous ligand for TDAG8 is unknown. Thus, TDAG8 is an orphan GPCR having an open reading fi-ame of 1,011 bp encoding a 337 amino acid protein. TDAG8 is reported to be homologous to the mouse TDAG8 and expressed in lymphoid tissues, including peripheral blood leukocytes, spleen, lymph nodes and thymus. TDAG8 is also reported to be localized to chromosome 14q31-32.1. Id.

In its endogenous form, TDAG8 is not constitutively active, i.e. TDAG8 signaling via G protein is ligand-dependent. Thus, it is not feasible to search directly for inverse agonists of endogenous TDAG8. Accordingly, the present inventors sought to employ a mutation approach to identify a constitutively activated version of TDAG8 to permit screening of candidate compounds against the non-endogenous, constitutively activated version of TDAG8. Accordingly, one embodiment of the present invention provides an isolated polynucleotide encoding a non-endogenous, constitutively activated version of a human G protein-coupled receptor (GPCR), in particular a polynucleotide encoding a non-endogenous, constitutively activated version of the human G protein-coupled receptor designated TDAG8.

Preferably, the isolated polynucleotide of the present invention comprises a nucleotide sequence selected from the group consisting of: a sequence encoding a polypeptide that comprises the amino acid sequence set forth in SEQ ID NO: 134; the sequence set forth in SEQ ID NO: 133; a sequence having at least about 80% identity to SEQ ID NO: 133 other than a sequence encoding a non-endogenous, constitutively activated version of a human G protein-coupled receptor comprising isoleucine residue at position 225 of SEQ ID NO:.134; and the sequence of wherein the constitutively activated version of a human G protein-coupled receptor comprises an amino acid sequence having a lysine residue at a position equivalent to position 225 of SEQ ID NO: 134.

Even more preferably, the isolated polynucleotide comprises a nucleotide sequence selected from the group consisting of: a sequence that is identical or substantially identical to SEQ ID NO: 133 wherein the codon at nucleotide positions 673-675 encoding lysine is unchanged or substituted with a codon that encodes an amino acid other than isoleucine; a sequence encoding a constitutively activated version of a human G protein-coupled receptor having an amino acid sequence identical or substantially identical to SEQ ID NO: 134 wherein the lysine residue at amino acid position 225 is unchanged or substituted with an amino acid other than isoleucine; and a sequence encoding a variant of a non-endogenous, constitutively activated version of a human G protein-coupled receptor comprising the amino acid sequence set forth in SEQ ID NO: 134 in which the lysine residue at position 225 is substituted for a different amino acid other than isoleucine.

In a particularly preferred embodiment, the isolated polynucleotide of the present invention comprises a nucleotide sequence selected from the group consisting of: a sequence encoding the amino acid sequence set forth in SEQ ID NO: 134; and the nucleotide sequence set forth in SEQ ID NO: 133.

For the purposes of nomenclature, the nucleotide and amino acid sequence set forth in SEQ ID NO: 133 and SEQ ID NO: 134, respectively, relate to the non-endogenous, constitutively activated version of the human G protein-coupled receptor designated TDAG8.

A further embodiment of the present invention provides a recombinant host cell comprising the vector or expression vector of the present invention. Preferably, the host cell is a mammalian cell a mammalian cell selected from the group consisting of a COS-7 cell, a 293 cell, and a 293T cell. In another embodiment the host cell is a melanophore or CHO cell. Preferably, the method further comprises obtaining the transfected host cell. Alternatively, or in addition, the method further comprises obtaining or isolating a membrane fraction from the obtained transfected host cell.

A further embodiment of the present invention provides a method of producing a nonendogenous constitutively-activated human G protein-coupled receptor comprising introducing a mutation into the coding region of nucleic acid comprising the nucleotide sequence of SEQ ID NO: 81 at a codon corresponding to positions 673-675 of said sequence, isolating or recovering the modified nucleic acid, and expressing the modified nucleic acid to thereby produce a non-endogenous constitutively-activated human G protein-coupled receptor. Preferably, the nucleic acid is DNA, cDNA. In an alternative embodiment, the nucleic acid is RNA from lymphoid tissue, such as, for example, peripheral blood leukocytes, spleen, lymph nodes or thymus. As will be apparent from the disclosure herein, it is particularly preferred that the mutation is the substitution of isoleucine at position 225 of SEQ ID NO: 84 for lysine.

A further embodiment of the present invention provides an isolated or recombinant non-endogenous, constitutively activated version of a human G protein-coupled receptor polypeptide comprising an amino acid sequence selected from the group consisting of: a sequence comprising the amino acid sequence set forth in SEQ ID NO: 134; a sequence having at least about 80% identity to SEQ ID NO: 134 other than a sequence comprising isoleucine residue at position 225 of SEQ ID NO: 134; and the sequence of wherein said sequence comprises a lysine residue at a position equivalent to position 225 of SEQ ID NO: 134.

Preferably, the isolated or recombinant non-endogenous, constitutively activated version of a human G protein-coupled receptor polypeptide comprises an amino acid sequence selected from the group consisting of: a sequence that is substantially identical to SEQ ID NO:134 wherein the lysine residue at amino acid position 225 is unchanged or substituted with an amino acid other than isoleucine; and a sequence comprising the amino acid sequence set forth in SEQ ID NO: 134 in which the lysine residue at position 225 is substituted for a different amino acid other than isoleucine.

In a particularly preferred embodiment, the isolated or recombinant non-endogenous, constitutively activated version of a human G protein-coupled receptor polypeptide comprises the amino acid sequence set forth in SEQ ID NO: 134.

In a particularly preferred embodiment, the present invention provides a method of identifying a modulator of a G protein-coupled receptor comprising the steps of: providing a recombinant host cell that expresses a GPCR fusion protein comprising the amino acid sequence set forth in SEQ ID NO: 134 and a Gs protein or an isolated membrane comprising said GPCR fusion protein; contacting a candidate compound with the recombinant host cell or isolated membrane; and measuring the ability of the compound to inhibit or stimulate functionality of the G protein-coupled receptor polypeptide portion of said GPCR fusion protein wherein inhibition or stimulation of said functionality indicates that the candidate compound is a modulator of the G protein-coupled receptor polypeptide.

A further embodiment of the present invention provides a process for identifying a modulator of a G protein-coupled receptor (GPCR) comprising the steps of: providing a recombinant host cell that expresses a non-endogenous constitutively activated GPCR comprising an amino acid sequence selected from the group consisting of: a sequence comprising the amino acid sequence set forth in SEQ ID NO: 134; and (ii) a sequence encoding a constitutively activated variant of having an amino acid sequence identical or substantially identical to SEQ ID NO:134 wherein the lysine residue at amino acid position 225 is unchanged or substituted with an amino acid other than isoleucine; contacting a candidate compound with the recombinant host cell or isolated membrane thereof; measuring the ability of the compound to modulate activity and/or expression of the G protein-coupled receptor polypeptide portion of said GPCR polypeptide wherein modulation of activity and/or expression indicates that the candidate compound is a modulator of the G protein-coupled receptor polypeptide; optionally, determining the structure of the compound; and providing the compound or modulator or the name or structure of the compound.

In an alternative embodiment, the present invention provides a process for identifying a modulator of a G protein-coupled receptor (GPCR) comprising the steps of: providing a recombinant host cell that expresses a GPCR comprising an amino acid sequence selected from the group consisting of: a sequence comprising the amino acid sequence set forth in SEQ ID NO: 134; and (ii) a sequence encoding a constitutively activated variant of having an amino acid sequence identical or substantially identical to SEQ ID NO:134 wherein the lysine residue at amino acid position 225 is unchanged or substituted with an amino acid other than isoleucine; contacting a candidate compound with the recombinant host cell or isolated membrane; measuring the ability of the compound to modulate activity and/or expression of the G protein-coupled receptor polypeptide portion of said GPCR polypeptide wherein modulation of activity and/or expression indicates that the candidate compound is a modulator of the G protein-coupled receptor polypeptide; optionally, determining the structure of the compound; optionally, providing the name or structure of the compound; and producing or synthesizing the compound.

In a related embodiment, the present invention provides a process for modulating the activity and/or expression of a GPCR of the present invention said process comprising performing the screening method supra to thereby identify a modulator of the GPCR and then contacting a GPCR with the identified modulator or administering the identified modulator to a subject under conditions sufficient to modulate the activity and/or expression of the GPCR.

Preferred cells for use in the screening assays over express a GPCR of the present invention by virtue of having been stably transformed or transiently transfected with a nucleic acid comprising a GPCR-encoding gene of the invention. For example, 293 cells that have been stably transformed or transiently transfected with nucleic acid comprising said GPCR-encoding gene are particularly suitable for this purpose. This embodiment of the present invention clearly encompasses a preferred form comprising obtaining or producing the transformed or transfected cell.

Any class of candidate modulator described herein can be tested in the inventive screening assay.

In one embodiment, the test compound is a small molecule, such as, for example, a modulator of a receptor that shares some structural homology with a receptor of the present invention.

In an alternative embodiment, the test compound is an antibody that binds to a GPCR protein of the present invention.

Without limiting the invention, antibodies and small molecules are typically capable of modulating the activity of a target protein.

In a further embodiment, the test compound comprises siRNA or shRNA comprising a nucleotide sequence derived from the nucleotide sequence of a GPCR-encoding gene of the present invention according to standard procedures.

In an alternative embodiment, the test compound comprises antisense RNA.

As will be known to the skilled artisan. siRNA, shRNA and antisense RNA are generally capable of modulating expression of a target gene.

In an alternative embodiment, the test compound comprises a peptide of at least about 4-10 amino acids in length derived from the amino acid sequence of the GPCR protein of the present invention.

Preferably, the signal transduction mediated by a G-protein coupled receptor in the tissues(s) modulates a downstream physiological or biochemical parameter in a subject such as involved in the development or aetiology of disease or a medical condition. Accordingly, the present invention clearly contemplates prophylactic and/or therapeutic treatments wherein the level of GPCR expression and/or activity is modulated in a subject in need thereof.

A further embodiment of the present invention provides a method of treating a disorder or disease associated with expression and/or activity of a GPCR of the present invention said method comprising administering a modulator of said GPCR to a subject in need thereof for a time and under conditions sufficient to modulate GPCR expression and/or activity in said subject.

Preferably, the method comprises administering an amount of an agent that reduces GPCR activity or expression to the subject sufficient to reduce the level or activity of a GPCR protein or mRNA encoding a GPCR protein in a cell of the subject.

Accordingly, the antagonist may comprise nucleic acid, such as, for example, antisense nucleic acid, a ribozyme, or nucleic acid that forms a triple helical structure, capable of reducing GPCR expression in a cell of the individual. Antibodies, peptides or small molecules that bind a GPCR and inhibit its activity are also useful in this context. As with the other embodiments described herein, it is particularly preferred to use an agent that reduces GPCR expression comprising a small interfering RNA (siRNA) or short hairpin RNA (shRNA) molecule, or alternatively, an antibody that binds to a GPCR protein thereby inhibiting its activity. Other antagonists, dominant negative mutants, small molecules etc are not to be excluded.

Alternatively, the method comprises administering an amount of an agent that enhances or agonizes GPCR activity or expression to the subject sufficient to enhance the level or activity of a GPCR protein or mRNA encoding a GPCR protein in a cell of the subject. Accordingly, the agonist may comprise a peptide or small molecule agonist.

Such agents are able to be administered by injection or preferably, by non-invasive routes such as by oral ingestion, intranasal inhalation, intra-aural formulation, or suppository.

A further embodiment of the present invention provides for the use of a composition that modulates GPCR expression and/or activity in the preparation of one or more medicaments for treating a disease or disorder associated with expression and/or activity of a GPCR in a subject.

Preferably, the compound modulates signal transduction in lymphoid tissue, e.g., thymocyte deletion including the deletion of self-reactive T cells in the thymus, and/or peripheral T cell development and.or apoptosis of T cells. This may be confirmed, for example, by screening in a 293 cell or a 293T cell. Accordingly, in a related embodiment, the screening method and process supra identifies a compound for delaying, preventing or reducing apoptosis of T cells or a condition associated with apoptosis of T cells.

A further embodiment of the present invention provides a commercial package comprising: a composition that modulates GPCR expression and/or activity in a subject; and instructions for use of the composition and agent for treating a disease or disorder associated with expression and/or activity of the GPCR in a subject.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a representation of 8XCRE-Luc reporter plasmid (see, Example 4) FIGS. 2A and 2B are graphic representations of the results of ATP and ADP binding to endogenous TDAG8 (FIG. 2A) and comparisons in serum and serum free media (FIG.

2B).

FIG. 3 is a graphic representation of the comparative signaling results of CMV versus the GPCR Fusion Protein H9(F236K):Gsa.

FIG. 4 is a graphic representation showing a comparative analysis of endogenous GPR38 relative to non-endogenous constitutively-activated GPR38 ("V297K").

The control is designated "CMV".

FIG. 5 is a graphic representation of endogenous, constitutively activated TDAG8 ("TDAG8 WT") and non-endogenous, constitutively activated TDAG8 ("TDAG8 Mut") in a 293 cell-based cAMP assay.

FIG. 6 is a graphic representation of ATP and ADP activation of CMV (control; expression vector) and endogenous, constitutively activated TDAG8 ("TDAG8 WT") in 293 cell-based cAMP assay.

FIG. 7 is a graphic representation of ATP and ADP activation of CMV (control; expression vector) and endogenous, constitutively activated TDAG8 ("TDAG8 WT") grown in serum and serum-free media in 293 cell-based cAMP assay.

FIGS. 8A-8B is a representation of a dose response curve for endogenous, constitutively activated TDAG8 ("TDAG8 WT") in 293 cell-based cAMP assay. Figure 8A shows ATP binding to "TDAG8 WT" at an EC50 value of 139.8uM, while Figure 8B shows ADP binding to "TDAG8 WT" at an EC50 value of 120.5uM.

FIGS. 9A-9B provides graphic results of comparative analysis of endogenous TDAG8 versus non-endogenous, constitutively activated TDAG8 ("I225K") (control is designated "CMV") in 293 (FIG. 9A) and 293T (FIG. 9B) cells.

FIG. 10 is a reproduction of results of a tissue distribution of TDAG8 against various tissue-source mRNA's.

DETAILED DESCRIPTION Definitions The scientific literature that has evolved around receptors has adopted a number of terms to refer to ligands having various effects on receptors. For clarity and consistency, the following definitions will be used throughout this patent document. To the extent that these definitions conflict with other definitions for these terms, the following definitions shall control: AGONIST shall mean an agent ligand, candidate compound) that by virtue of binding to a GPCR activates the GPCR so as to elicit an intracellular response or GTP binding to membrane mediated by the GPCR.

AMINO ACID ABBREVIATIONS used herein are set out in Table 1: TABLE 1 ALANINE ALA A ARGININE ARG R ASPARAGINE ASN N ASPARTIC ACID ASP D CYSTEINE CYS C GLUTAMIC ACID GLU E GLUTAMINE GLN

Q

GLYCINE GLY G HISTIDINE HIS H ISOLEUCINE ILE I LEUCINE LEU L LYSINE LYS K METHIONINE MET M PHENYLALANINE PHE F PROLINE PRO P SERINE SER S THREONINE THR T TRYPTOPHAN TRP W TYROSINE TYR Y VALINE VAL V ANTAGONIST shall mean an agent ligand, candidate compound) that binds, and preferably binds competitively, to a GPCR at about the same site as an agonist or partial agonist but which does not activate an intracellular response initiated by the active form of the GPCR, and can thereby inhibit the intracellular response by agonist or partial agonist. An antagonist typically does not diminish the baseline intracellular response in the absence of an agonist or partial agonist.

CANDIDATE COMPOUND shall mean a molecule (for example, and not limitation, a chemical compound) which is amenable to a screening technique.

CODON shall mean a grouping of three nucleotides (or nucleotide analogues) that generally comprise a nucleoside (adenosine guanosine cytidine uridine and thymidine coupled to a phosphate group and which, when translated, encodes an amino acid.

COMPOSITION means a material comprising at least one component.

COMPOUND EFFICACY or EFFICACY shall mean the ability of a compound to inhibit or stimulate one or more GPCR functions directly or indirectly, by measurement of GTP (via [35S]GTPyS) or cAMP level in the presence or absence of a candidate compound.

CONSTITUTIVELY ACTIVATED RECEPTOR shall mean a receptor subject to constitutive receptor activation. A constitutively activated receptor can be endogenous or non-endogenous.

CONSTITUTIVE RECEPTOR ACTIVATION shall mean stabilization of a receptor in the active state by means other than binding of the receptor with its endogenous ligand or a chemical equivalent thereof.

CONTACT or CONTACTING shall mean bringing at least two moieties or compounds or compositions of matter together, whether in an in vitro system or an in vivo system.

ENDOGENOUS shall mean a material that a mammal naturally produces.

ENDOGENOUS in reference to, for example and not limited to the term "GPCR" or "receptor" shall mean that which is naturally produced by a mammal (for example, and not limitation, a human) or a virus. By contrast, the term NON-ENDOGENOUS in this context shall mean that which is not naturally produced by a mammal (for example, and not limitation, a human) or a virus.

G PROTEIN COUPLED RECEPTOR FUSION PROTEIN and GPCR FUSION PROTEIN, in the context of the invention disclosed herein, shall mean a nonendogenous protein comprising a GPCR such as an endogenous or non-endogenous, constitutively activated orphan GPCR preferably fused to at least one G protein, most preferably, the alpha subunit of such G protein that binds GTP, with the G protein preferably being of the same type as the G protein that naturally couples with endogenous orphan GPCR. In the preferred form, the G protein can be fused directly to the C-terminus of the GPCR or there may be spacers positioned between the two.

HOST CELL shall mean a cell capable of having a Plasmid and/or Vector incorporated therein. In the present context, the Plasmid or vector will typically contain nucleic acid encoding a GPCR or GPCR fusion protein in operable connection with a suitable promoter sequence to permit expression of the GPCR or GPCR fusion protein to occur.

In the preferred embodiment, the host cell is a eukaryotic cell, such as a melanophore, or a mammalian cell a spleen cell, a cell of the lymph node, a leukocyte e.g., peripheral blood leukocyte, a lymphocyte, a 293 cell, a 293T cell, a CHO cell or a COS cell.

INHIBIT or INHIBITING, in relation to the term "response" shall mean that a response is decreased or prevented in the presence of a compound as opposed to in the absence of the compound.

INVERSE AGONIST shall mean an agent ligand, candidate compound) which binds to either the endogenous form of a GPCR or to the constitutively activated form of a GPCR and which inhibits the baseline intracellular response initiated by the active form of the receptor below the normal base level of activity which is observed in the absence of an agonist or partial agonist, or decreases GTP binding to membranes.

Preferably, the baseline intracellular response is inhibited in the presence of the inverse agonist by at least 30%, more preferably by at least 50%, and most preferably by at least 75%, as compared with the baseline response in the absence of the inverse agonist.

KNOWN RECEPTOR shall mean an endogenous receptor for which an endogenous specific ligand has been identified. By contrast, an ORPHAN RECEPTOR shall mean an endogenous receptor for which an endogenous ligand specific for that receptor has not been identified or is not known.

LIGAND shall mean an endogenous, naturally occurring molecule specific for an endogenous, naturally occurring receptor.

MODULATE shall mean a variation in activity and/or expression of a GPCR such as, for example, a variation in activity and/or expression produced by a modulator.

MODULATOR shall mean and antagonist, agonist, inverse agonist or partial agonist as hereinbefore defined.

MUTANT or MUTATION in reference to an endogenous receptor's amino acid sequence shall mean one or more amino acid deletions, insertions or substitutions that produce a modified sequence of similar functionality including a constitutively activated form of an endogenous non-constitutively activated receptor. In terms of equivalents to specific sequences, a subsequent mutated form of a human receptor is considered to be equivalent to a first mutation of the human receptor if the level of constitutive activation of the subsequent mutated form of the receptor is substantially the same as that evidenced by the first mutation of the receptor. In any event, it is preferred for the percent amino acid sequence identity between a mutated form of a receptor and the non-mutated receptor is at least about 80%, more preferably at least about 90% and more preferably at least 95%. Ideally, and owing to the fact that the most preferred mutation disclosed herein for achieving constitutive activation includes a single amino acid and/or codon change between the endogenous and the nonendogenous forms of the GPCR, it is preferred for the percent sequence amino acid sequence identity with the non-mutated sequence should be at least about 98%. As will be known to the skilled artisan, a mutation in the receptor per se may be readily accomplished, for example, by introducing a mutation into the coding region of the nucleic acid encoding the receptor.

MUTANT or MUTATION in reference to nucleic acid encoding an endogenous receptor shall be taken to include any GPCR-encoding nucleic acid of the invention modified to comprise a nucleotide deletion, insertion or substitution and encoding a modified form of a receptor of the invention, including a constitutively activated form of an endogenous non-constitutively activated receptor. The term MUTANT or MUTATION shall also be taken to include any modified nucleic acid relative to a nucleotide sequence of the invention as disclosed herein that, by virtue of the degeneracy of the genetic code, encodes a receptor of the invention as disclosed herein.

It is preferred for the percent nucleotide sequence identity between a mutated form of a receptor and the non-mutated receptor is at least about 60%, preferably, at least about more preferably at least about 80%, even more preferably at least about 90% and still more preferably at least about 95% or 98%.

PARTIAL AGONIST shall mean an agent ligand, candidate compound) that by virtue of binding to a GPCR activates the GPCR so as to elicit an intracellular response or GTP binding to a membrane mediated by the GPCR, albeit to a lesser extent or degree than that observed for an agonist as hereinbefore defined.

PHARMACEUTICAL COMPOSITION shall mean a composition comprising at least one active ingredient, whereby the composition is amenable to investigation for a specified, efficacious outcome in a mammal (for example, and not limited to a human).

Those of ordinary skill in the art will understand and appreciate the techniques appropriate for determining whether an active ingredient has a desired efficacious outcome based upon the needs of the artisan.

PLASMID shall mean a circular DNA molecule of bacteria and yeasts that is capable of autonomous replication independent of chromosomal DNA, and which typically carries one or more genes encoding antibiotic resistance proteins. A preferred PLASMID is amenable to insertion of nucleic acid encoding a GPCR or GPCR fusion protein and is capable of being introduced into a Host Cell for the purposes of replication and/or expression of the inserted nucleic acid.

SMALL MOLECULE shall be taken to mean a compound having a molecular weight of less than about 10,000 grams per mole, including a peptide, peptidomimetic, amino acid, amino acid analogue, polynucleotide, polynucleotide analogue, nucleotide, nucleotide analogue, organic compound or inorganic compound including a heteroorganic compound or organometallic compound), and salts, esters and other pharmaceutically acceptable forms thereof. In certain preferred embodiments, small molecules are organic or inorganic compounds having a molecular weight of less than about 5,000 grams per mole. In certain preferred embodiments, small molecules are organic or inorganic compounds having molecular weight of less than about 1,000 grams per mole. In certain preferred embodiments, small molecules are organic or inorganic compounds having a molecular weight of less than about 500 grams per mole.

STIMULATE or STIMULATING, in relationship to the term "response" shall mean that a response is enhanced or increased in the presence of a compound as opposed to in the absence of the compound.

TRAVERSE or TRAVERSING, in reference to either a defined nucleotide sequence or a defined amino acid sequence, shall mean that the sequence comprises or is contiguous with more than one region or domain of a protein. For example, in an amino acid sequence of a GPCR comprising 10 amino acids in length wherein 3 amino acid residues of said sequence are within the TM6 region of the GPCR and the remaining 7 residues are within the IC3 region of the GPCR, the 10-residue amino acid sequence is considered to traverse the TM6 and IC3 regions of the GPCR.

VECTOR shall mean a circular DNA capable of having at least one heterologous nucleic acid a cDNA or other nucleic acid encoding a GPCR or a variant thereof or a GPCR fusion protein) inserted therein and which is capable of incorporation into a host cell. The vector may be an expression vector.

The order of the following sections is set forth for presentational efficiency and is not intended, nor should be construed, as a limitation on the disclosure or the claims to follow.

Introduction The traditional study of receptors has always proceeded from the a priori assumption (historically based) that the endogenous ligand must first be identified before discovery could proceed to find antagonists and other molecules that could affect the receptor.

Even in cases where an antagonist might have been known first, the search immediately extended to looking for the endogenous ligand. This mode of thinking has persisted in receptor research even after the discovery of constitutively activated receptors. What has not been heretofore recognized is that it is the active state of the receptor that is most useful for discovering agonists, partial agonists, and inverse agonists of the receptor. For those diseases which result from an overly active receptor or an underactive receptor, what is desired in a therapeutic drug is a compound which acts to diminish the active state of a receptor or enhance the activity of the receptor, respectively, not necessarily a drug which is an antagonist to the endogenous ligand.

This is because a compound that reduces or enhances the activity of the active receptor state need not bind at the same site as the endogenous ligand. Thus, as taught by a method of this invention, any search for therapeutic compounds should start by screening compounds against the ligand-independent active state.

Identification of Human GPCRs The efforts of the Human Genome project has led to the identification of a plethora of information regarding nucleic acid sequences located within the human genome; it has been the case in this endeavor that genetic sequence information has been made available without an understanding or recognition as to whether or not any particular genomic sequence does or may contain open-reading frame information that translate human proteins. Several methods of identifying nucleic acid sequences within the human genome are within the purview of those having ordinary skill in the art. For example, and not limitation, a variety of human GPCRs, disclosed herein, were discovered by reviewing the GenBank(TM) database, while other GPCRs were discovered by utilizing a nucleic acid sequence of a GPCR, previously sequenced, to conduct a BLAST(TM) search of the EST database. Table 2 lists several endogenous GPCRs that we have discovered, along with a GPCR's respective homologous receptor.

Receptor homology is useful in terms of gaining an appreciation of a role of the receptors within the human body. Homologies between orphan receptors, and between orphan receptors and known receptors, and patterns of receptor expression, are used to determine one or more roles and associated diseases or disorders for the receptors within the human body. Additionally, such homology can provide insight as to possible endogenous ligand that may be natural activators for orphan GPCRs and disorders associated therewith.

Receptor Screening Screening candidate compounds against a non-endogenous, constitutively activated version of the human GPCRs disclosed herein allows for the direct identification of candidate compounds which act at this cell surface receptor, without requiring use of the receptor's endogenous ligand.

Techniques have become more readily available over the past few years for endogenous-ligand identification (this, primarily, for the purpose of providing a means of conducting receptor-binding assays that require a receptor's endogenous ligand) because the traditional study of receptors has always proceeded from the a priori TABLE 2 Disclosed Accession Open Reading Per Cent Reference to Human Number Frame Homology Homologous Orphan Identified. (base Pairs) To Designated GPCR GPCRs GPCR (Accession No.) hARE-3 AL033379 1,260 bp 52.3% LPA-R U92642 bARE-4 AC006087 1,119 bp 36% P2Y5 AF000546 hARE-5 AC006255 1,104 bp 32% Oryzias D43633 latipes hGPR27 AA775870 1,128 bp hARE-i A1090920 999 bp 43% D13626 KIAA0001 hARE-2 AA359504 1,122 bp 53% GPR27 hPPRi H67224 1,053 bp 39% EBI1 L31581 hG2A AA754702 1,113 bp 31% GPR4 L36148 hRIJP3 AL035423 1,005 bp 30% 2133653 Drosophila melanogaster IIRUP4 A1307658 1,296 bp 32% pNPGPR NP_004876 28% and 29% AAC41276 Zebra fish Ya and and Yb, AAB94616 respectively AC005849 1,413 bp 25% DEZ Q99788 23% FMLPR P21462 hRUP6 AC005871 1,245 bp 48% GPR66 NP_006047 hRUP7 AC007922 1,173 bp 43% H3R AF140538 hGHN3 EST 36581 1,113 bp 53% GPR27 hCHN4 AA804531 1,077 bp 32% PAR-i 4503637 hCHN6 EST 2134670 1,503 bp 36% edg-1 NP_001391 hCHN8 EST 764455 1,029 bp 47% D13626 KIAAOOO 1 hCHN9 EST 1541536 1,077 bp 41 %LTB4R NM000752 hCHNiO EST 1365839 1,OS5bp 35% P2Y NM002563 assumption (historically based) that the endogenous ligand must first be identified before discovery could proceed to find antagonists and other molecules that could affect the receptor. Even in cases where an antagonist might have been known first, the search immediately extended to looking for the endogenous ligand. This mode of thinking has persisted in receptor research even after the discovery of constitutively activated receptors. What has not been heretofore recognized is that it is the active state of the receptor that is most useful for discovering agonists, partial agonists, and inverse agonists of the receptor. For those diseases which result from an overly active receptor or an under-active receptor, what is desired in a therapeutic drug is a compound which acts to diminish the active state of a receptor or enhance the activity of the receptor, respectively, not necessarily a drug which is an antagonist to the endogenous ligand.

As is known in the art, GPCRs can be "active" in their endogenous state even without the binding of the receptor's endogenous ligand thereto. Such naturally-active receptors can be screened for the direct identification without the need for the receptor's endogenous ligand) of, in particular, inverse agonists. Alternatively, the receptor can be "activated" via, e. mutation of the receptor to establish a non-endogenous version of the receptor that is active in the absence of the receptor's endogenous ligand.

Screening candidate compounds against an endogenous, non-constitutively activated human orphan GPCR disclosed herein can also provide for the direct identification of candidate compounds which act at this cell surface receptor, without requiring use of the receptor's endogenous ligand.

By determining areas within the body where the endogenous version of human GPCRs disclosed herein is expressed and/or over-expressed, it is possible to determine related disease/disorder states which are associated with the expression and/or over-expression of the receptor.

With respect to creation of a mutation that may evidence constitutive activation of the human GPCR disclosed herein is based upon the distance from the proline residue at which is presumed to be located within TM6 of the GPCR; this algorithmic technique is disclosed in co-pending and commonly assigned patent document U.S. Serial Number 09/170,496, incorporated herein by reference. The algorithmic technique is not predicated upon traditional sequence "alignment" but rather a specified distance from the aforementioned TM6 proline residue. By mutating the amino acid residue located 16 amino acid residues from this residue (presumably located in the IC3 region of the receptor) to, most preferably, a lysine residue, such activation may be obtained. Other amino acid residues may be useful in the mutation at this position to achieve this objective.

Disease/Disorder Identification and/or Selection As will be set forth in greater detail below, most preferably inverse agonists to the nonendogenous, constitutively activated GPCR can be identified by the methodologies of this invention. Such inverse agonists are ideal candidates as lead compounds in drug discovery programs for treating diseases related to this receptor. Because of the ability to directly identify inverse agonists to the GPCR, thereby allowing for the development of pharmaceutical compositions, a search for diseases and disorders associated with the GPCR is relevant. For example, scanning both diseased and normal tissue samples for the presence of the GPCR now becomes more than an academic exercise or one which might be pursued along the path of identifying an endogenous ligand to the specific GPCR. Tissue scans can be conducted across a broad range of healthy and diseased tissues. Such tissue scans provide a preferred first step in associating a specific receptor with a disease and/or disorder. See, for example, Australian Patent Application No.

770056 for exemplary dot-blot and RT-PCR results of several of the GPCRs disclosed herein.

Preferably, the DNA sequence of the human GPCR is used to make a probe for dotblot analysis against tissue-mRNA, and/or RT-PCR identification of the expression of the receptor in tissue samples. The presence of a receptor in a tissue source, or a diseased tissue, or the presence of the receptor at elevated concentrations in diseased tissue compared to a normal tissue, can be preferably utilized to identify a correlation with a treatment regimen, including but not limited to, a disease associated with that disease. Receptors can equally well be localized to regions of organs by this technique.

Based on the known functions of the specific tissues to which the receptor is localized, the putative functional role of the receptor can be deduced.

Based on the known functions of the specific tissues to which the TDAG8 receptor is localized, the putative functional role of the receptor is deduced. For example, TDAG8 is predominantly expressed in the lymphoid tissues, specifically the spleen, peripheral blood leukocytes and lymph nodes. Expression of TDAG8 has been reported to increase during activation of-induced death of T-cell hybridomas stimulated by glucocorticoids or anti-T-cell receptor antibodies (see, Choi J.W. et al. 168 Cell.

Immunol. 78 (1996)). This suggests that TDAG8 plays a role in immature thymocyte deletion and peripheral T-cell development. The deletion of self-reactive immature Tcells in the thymus is mediated by apoptosis upon T-cell receptor interaction. Apoptosis is characterized by a rapid collapse of the nucleus, extreme chromatin condensation, DNA fragmentation, and shrinkage of cells, and it is often dependent on the synthesis of new sets of RNA and protein. (see, Choi et al., 168 Cellular Immun. 78 (1996)).

There is a strong correlation between apoptosis and TDAGS; an increase in apoptosis results in an increase in the expression of TDAGS.

Thus, the present invention contemplates an inverse agonist to TDAG8 for the prevention of apoptosis or death of T-cells upon activation.

Screening of Candidate Compounds 1. Generic GPCR screening assay techniques When a G protein receptor becomes constitutively active active in the absence of endogenous ligand binding thereto), it binds to a G protein Gq, Gs, Gi, Go) and stimulates the binding of GTP to the G protein. The G protein then acts as a GTPase and slowly hydrolyzes the GTP to GDP, whereby the receptor, under normal conditions, becomes deactivated. However, constitutively activated receptors continue to exchange GDP to GTP. A non-hydrolyzable analog of GTP, 35 S]GTPyS, can be used to monitor enhanced binding to membranes which express constitutively activated receptors. It is reported that 35 S]GTPyS can be used to monitor G protein coupling to membranes in the absence and presence of ligand. An example of this monitoring, among other examples well-known and available to those in the art, was reported by Traynor and Nahorski in 1995. The preferred use of this assay system is for initial screening of candidate compounds because the system is generically applicable to all G protein-coupled receptors regardless of the particular G protein that interacts with the intracellular domain of the receptor.

2. Specific GPCR screening assay techniques Once candidate compounds are identified using the "generic" G protein-coupled receptor assay an assay to select compounds that are agonists, partial agonists, or inverse agonists), further screening to confirm that the compounds have interacted at the receptor site is preferred. For example, a compound identified by the "generic" assay may not bind to the receptor, but may instead merely "uncouple" the G protein from the intracellular domain.

2a. Gs and Gi.

Gs stimulates the enzyme adenylyl cyclase. Gi (and Go), on the other hand, inhibit this enzyme. Adenylyl cyclase catalyzes the conversion of ATP to cAMP; thus, constitutively activated GPCRs that couple the Gs protein are associated with increased cellular levels of cAMP. On the other hand, constitutively activated GPCRs that couple the Gi (or Go) protein are associated with decreased cellular levels of cAMP. See, generally, "Indirect Mechanisms of Synaptic Transmission,"Chpt. 8, From Neuron To Brain (3rd Ed.) Nichols, J. G. et al eds. Sinauer Associates, Inc. (1992). Thus, assays that detect cAMP can be utilized to determine if a candidate compound is, e. an inverse agonist to the receptor such a compound would decrease the levels of cAMP). A variety of approaches known in the art for measuring cAMP can be utilized; a most preferred approach relies upon the use of anti-cAMP antibodies in an ELISAbased format. Another type of assay that can be utilized is a whole cell second messenger reporter system assay. Promoters on genes drive the expression of the proteins that a particular gene encodes. Cyclic AMP drives gene expression by promoting the binding of a cAMP-responsive DNA binding protein or transcription factor (CREB) which then binds to the promoter at specific sites called cAMP response elements and drives the expression of the gene. Reporter systems can be constructed which have a promoter containing multiple cAMP response elements before the reporter gene, e. P-galactosidase or luciferase. Thus, a constitutively activated Gslinked receptor causes the accumulation of cAMP that then activates the gene and expression of the reporter protein. The reporter protein such as P-galactosidase or luciferase can then be detected using standard biochemical assays (Chen et al. 1995).

2b. Go and Gq.

Gq and Go are associated with activation of the enzyme phospholipase C, which in turn hydrolyzes the phospholipid PIP 2 releasing two intracellular messengers: diacycloglycerol (DAG) and inositol 1,4,5-triphosphate (IP 3 Increased accumulation of IP 3 is associated with activation of Gq-and Go-associated receptors. See, generally, "Indirect Mechanisms of Synaptic Transmission," Chpt. 8, From Neuron To Brain (3rd Ed.) Nichols, J. G. et al eds. Sinauer Associates, Inc. (1992). Assays that detect IP 3 accumulation can be utilized to determine if a candidate compound is, e. an inverse agonist to a Gq-or Go associated receptor such a compound would decrease the levels of IP 3 Gq-associated receptors can also been examine using an API reporter assay in that Gq-dependent phospholipase C causes activation of genes containing API elements; thus, activated Gq associated receptors will evidence an increase in the expression of such genes, whereby inverse agonists thereto will evidence a decrease in such expression, and agonists will evidence an increase in such expression.

Commercially available assays for such detection are available.

3. GPCR Fusion Protein The use of an endogenous, constitutively activate orphan GPCR, or a non-endogenous, constitutively activated orphan GPCR, for screening of candidate compounds for the direct identification of inverse agonists, agonists and partial agonists provides a unique challenge in that, by definition, the receptor is active even in the absence of an endogenous ligand bound thereto. Thus, it is often useful that an approach be utilized that can enhance the signal obtained by the activated receptor. A preferred approach is the use of a GPCR Fusion Protein.

Generally, once it is determined that a GPCR is constitutively active or has been constitutively activated, using the assay techniques set forth above (as well as others), it is possible to determine the predominant G protein that couples with the endogenous GPCR. Coupling of the G protein to the GPCR provides a signaling pathway that can be assessed. Because it is most preferred that screening take place by use of a mammalian expression system, such a system will be expected to have endogenous G protein therein. Thus, by definition, in such a system, the constitutively activated orphan GPCR will continuously signal. In this regard, it is preferred that this signal be enhanced such that in the presence of, e. an inverse agonist to the receptor, it is more likely that it will be able to more readily differentiate, particularly in the context of screening, between the receptor when it is contacted with the inverse agonist.

The GPCR Fusion Protein is intended to enhance the efficacy of G protein coupling with the GPCR. The GPCR Fusion Protein is preferred for screening with a nonendogenous. constitutively activated GPCR because such an approach increases the signal that is most preferably utilized in such screening techniques, although the GPCR Fusion Protein can also be (and preferably is) used with an endogenous, constitutively activated GPCR. This is important in facilitating a significant "signal to noise" ratio; such a significant ratio is import preferred for the screening of candidate compounds as disclosed herein.

The construction of a construct useful for expression of a GPCR Fusion Protein is within the purview of those having ordinary skill in the art. Commercially available expression vectors and systems offer variety of approaches that can fit the particular needs of an investigator.

A variety of expression vectors are available to those in the art, for purposes of utilization for both endogenous and non-endogenous human GPCRs and fusion proteins comprising same. In one embodiment, the expression vector is pCMV. This vector was deposited with the American Type Culture Collection (ATCC) on October 13,1998 (10801 University Blvd., Manassas, VA 20110-2209 USA) under the provisions of the Budapest Treaty for the International Recognition of the Deposit of Microorganisms for the Purpose of Patent Procedure. The DNA was tested by the ATCC and determined to be. The ATCC has assigned the following deposit number to pCMV: ATCC #203351.

The criteria of importance for such a GPCR Fusion Protein construct is that the GPCR sequence and the G protein sequence both be in-frame (preferably, the sequence for the GPCR is upstream of the G protein sequence) and that the "stop" codon of the GPCR must be deleted or replaced such that upon expression of the GPCR, the G protein can also be expressed. The GPCR can be linked directly to the G protein, or there can be spacer residues between the two (preferably, no more than about 12, although this number can be readily ascertained by one of ordinary skill in the art). We have a preference (based upon convenience) of use of a spacer in that some restriction sites that are not used will, effectively, upon expression, become a spacer. Most preferably, the G protein that couples to the GPCR will have been identified prior to the creation of the GPCR Fusion Protein construct. Because there are only a few G proteins that have been identified, it is preferred that a construct comprising the sequence of the G protein a universal G protein construct) be available for insertion of an endogenous GPCR sequence therein; this provides for efficiency in the context of large-scale screening of a variety of different endogenous GPCRs having different sequences.

4. cAMP Detection Assay TDAG8 has been discovered to contain a conserved motif commonly found in purinergic receptors human P2Y). Purinoceptors contain conserved residues with positively charged amino acids His and Arg) and are preferentially activated by adenosine nucleotides ATP and ADP). Communi et al., 272 Jo. of Biol. Chem.

31969 (1997). Thus, the binding of adenosine nucleotides to purinoceptors can be coupled to the stimulation of adenylyl cyclase. Although TDAG8 is not characterized as a purinoceptor, the common motif, located before the "DRY" region of a GPCR, led us to determine whether ATP and/or ADP are potential endogenous activators of TDAG8.

In the case of TDAG8, it has been determined that this receptor couples the G protein Gs. Gs is known to activate the enzyme adenylyl cyclase, which is necessary for catalyzing the conversion of ATP to cAMP. Although no known endogenous ligand has been identified for TDAG8, such that TDAG8 is considered an orphan GPCR, Figures 2 and 6 evidence that ATP and ADP bind to TDAG8, resulting in an increase in cAMP.

From these data, both of the adenosine nucleotides act as endogenous activators to TDAG8, and as endogenous activators, they increase the level of cAMP about 59% and about 55%, respectively.

Medicinal Chemistry Generally, but not always, direct identification of candidate compounds is preferably conducted in conjunction with compounds generated via combinatorial chemistry techniques, whereby thousands of compounds are randomly prepared for such analysis.

Generally, the results of such screening will be compounds having unique core structures; thereafter, these compounds are preferably subjected to additional chemical modification around a preferred core structure(s) to further enhance the medicinal properties thereof. Such techniques are known to those in the art.

Pharmaceutical Compositions Candidate compounds selected for further development can be formulated into pharmaceutical compositions using techniques well known to those in the art. Suitable pharmaceutically-acceptable carriers are available to those in the art; for example, see Remington's Pharmaceutical Sciences, 16Edition, 1980, Mack Publishing Co., (Oslo et al., eds.) Other Utility Although a preferred use of the human orphan GPCRs disclosed herein may be for the identification of candidate compounds as inverse agonists, agonists or partial agonists (preferably for use as pharmaceutical agents), these GPCRs can also be utilized in research settings. For example, in vitro and in vivo systems incorporating GPCRs can be utilized to further elucidate and understand the roles these receptors play in the human condition, both normal and diseased, as well as understanding the role of constitutive activation as it applies to understanding the signaling cascade. The value in human orphan GPCRs is that its utility as a research tool is enhanced in that by determining the location(s) of such receptors within the body, the GPCRs can be used to understand the role of these receptors in the human body before the endogenous ligand therefor is identified.

Other uses of the disclosed receptors will become apparent to those in the art based upon, inter alia, a review of this patent document.

Examples The following examples are presented for purposes of elucidation, and not limitation, of the present invention. While specific nucleic acid and amino acid sequences are disclosed herein, those of ordinary skill in the art are credited with the ability to make minor modifications to these sequences while achieving the same or substantially similar results reported below. The traditional approach to application or understanding of sequence cassettes from one sequence to another from rat receptor to human receptor or from human receptor A to human receptor B) is generally predicated upon sequence alignment techniques whereby the sequences are aligned in an effort to determine areas of commonality. The mutational approach disclosed herein does not rely upon this approach but is instead based upon an algorithmic approach and a positional distance from a conserved proline residue located within the TM6 region of human GPCRs. Once this approach is secured, those in the art are credited with the ability to make minor modifications thereto to achieve substantially the same results 43 constitutive activation) disclosed herein. Such modified approaches are considered within the purview of this disclosure.

Example 1 Endogenous Human GPCRs 1. Identification of Human GPCRs Several of the disclosed endogenous human GPCRs were identified based upon a review of the GenBank database information. While searching the database, the following cDNA clones were identified as evidenced below in Table 3.

TABLE 3 Disclosed Accession Complete DNA Open Reading Nucleic Amino Human Number Sequence Frame Acid Acid Orphan (Base Pairs) (Base Pairs) SEQ ID SEQ ID GPCRs No. No.

hARE-3 AL033379 111,389 bp 1,260 bp 1 2 hARE-4 AC006087 226,925 bp 1,119 bp 3 4 AC006255 127,605 bp 1,104 bp 5 6 hRUP3 AL035423 140,094 bp o 1,005 bp 7 8 AC005849 169,144 bp 1,413 bp 9 hRUP6 AC005871 218,807 bp 1,245 bp 11 12 hRUP7 AC007922 158,858 bp 1,173 bp 13 14 Other disclosed endogenous human GPCRs were identified by conducting a BLAST(TM) search of EST database (dbest) using the following EST clones as query sequences. The following EST clones (TABLE 4) identified were then used as a probe to screen a human genomic library.

TABLE 4 Disclosed Query EST Clone/ Open Reading Nucleic Amino Human (Sequence) Accession No. Frame Acid Acid Orphan Identified (Base Pairs) SEQ ID SEQ ID GPCRs No. No.

hGPCR27 Mouse AA775870 1,125 bp 17 18 GPCR27 hARE-1 TDAG 1689643 999 bp 19 AI090920 hARE-2 GPCR27 68530 1,122 bp 21 22 AA359504 hPPR1 Bovine 238667 1,053 bp 23 24 PPR1 H67224 hG2A Mouse See Example 1,113 bp 25 26 1179426 below hCHN3 N.A. EST 36581 1,113 bp 27 28 (full length) hCHN4 TDAG 1184934 1,077 bp 29 AA804531 hCHN6 N.A. EST 2134670 1,503 bp 31 32 (full length) hCHN8 KIAA0001 EST 764455 1,029 bp 33 34 hCHN9 1365839 EST 1541536 1,077 bp 35 36 Mouse EST Human 1365839 1,005 bp 37 38 1365839 hRUP4 N.A. AI307658 1,296 bp 39 N.A. "not applicable".

2. Full Length Cloning 2a. hG2A (Seq.Id. Nos. 25 26) Mouse EST clone 1179426 was used to obtain a human genomic clone containing all but three amino acid hG2A coding sequences. The 5' end of this coding sequence was obtained by using 5' RACE

M

and the template for PCR was Clontech's Human Spleen Marathon-Ready T cDNA. The disclosed human G2A was amplified by PCR using the G2A cDNA specific primers for the first and second round PCR as shown in SEQ ID NO: 41 and SEQ ID NO: 42 as follows: 5'-CTGTGTACAGCAGTTCGCAGAGTG-3' (SEQ ID NO: 41; 1st round PCR) 5'-GAGTGCCAGGCAGAGCAGGTAGAC-3' (SEQ ID NO: 42; second round PCR).

PCR was performed using Advantage GC Polymerase Kit (Clontech; manufacturing instructions is followed), at 94 0 C. for 30 sec followed by 5 cycles of 94°C. for 5 sec and 72 0 C. for 4 min; and 30 cycles of 94°C. for 5 sec and 700 for 4 min. An approximate 1.3 Kb PCR fragment was purified from agarose gel, digested with Hind III and Xba I and cloned into the expression vector pRC/CMV2 (Invitrogen). The cloned-insert was sequenced using the T7 Sequenase TM kit (USB Amersham; manufacturer instructions is followed) and the sequence was compared with the presented sequence. Expression of the human G2A is detected by probing an RNA dot blot (Clontech; manufacturer instructions is followed) with the P 32 -labeled fragment.

The hG2A open reading frame is also sub-cloned into pCMV for expression as described according to the general procedure described in Example 3.

b. hCHN9 (Seq.Id. Nos. 35 36) Sequencing of the EST clone 1541536 indicated that hCHN9 is a partial cDNA clone having only an initiation codon; the termination codon was missing. When hCHN9 was used to "blast" against data base the 3' sequence of hCHN9 was 100% homologous to the 5' untranslated region of the leukotriene B4 receptor cDNA, which contained a termination codon in the frame with hCHN9 coding sequence. To determine whether the 5' untranslated region of LTB4R cDNA was the 3' sequence of hCHN9, PCR was performed using primers based upon the 5' sequence flanking the initiation codon found in hCHN9 and the 3' sequence around the termination codon found in the LTB4R 5' untranslated region. The 5' primer sequence utilized was as follows: 5'-CCCGAATTCCTGCTTGCTCCCAGCTTGGCCC-3' (SEQ ID NO: 43; sense) and 5'-TGTGGATCCTGCTGTCAAAGGTCCCATTCCGG-3' (SEQ ID NO: 44; antisense).

PCR was performed using thymus cDNA as a template and rTth polymerase (Perkin Elmer) with the buffer system provided by the manufacturer, 0.25 jtM of each primer, and 0.2 mM of each 4 nucleotides. The cycle condition was 30 cycles of 94°C. for 1 min, 65 0 C. for 1 min and 72 0 C. for 1 min and 10 sec. A 1.1 kb fragment consistent with the predicted size was obtained from PCR. This PCR fragment was subcloned into pCMV for expression as described according to the general procedure described in Example 3, and for sequence analysis (see, SEQ ID NO: c. hRUP4 (Seq. Id. Nos. 39 The full length RUP4 was cloned by RT-PCR with human brain cDNA (Clontech) as templates: 5'-TCACAATGCTAGGTGTGGTC-3' (SEQ ID NO: 45; sense) and 5'-TGCATAGACAATGGGATTACAG-3' (SEQ ID NO: 46; antisense).

PCR was performed using TaqPlus T M PrecisionTM polymerase (Stratagene; manufacturing instructions followed) by the following cycles: 94 0 C for 2 min; 94°C. sec; 55 0 C. for 30 sec, 72 0 C. for 45 sec, and 72 0 C. for 10 min. Cycles 2 through 4 were repeated 30 times.

The PCR products were separated on a 1% agarose gel and a 500 bp PCR fragment was isolated and cloned into the pCRII-TOPO vector (Invitrogen) and sequenced using the T7 DNA Sequenase TM kit (Amsham) and the SP6/T7 primers (Stratagene). Sequence analysis revealed that the PCR fragment was indeed an alternatively spliced form of AI307658 having a continuous open reading frame with similarity to other GPCRs. The completed sequence of this PCR fragment was as follows:

GGCACGTGCAACAACTTGAGATCAAATATGACTTCCTATATGAAAAGGAACACAT

CTGCTGCTTAAGAGTGGACCAGCCCTGTGCACCAGAAGATCTACACCACCTTCATC

CTTGTCATCCTCTTCCTCCTGCCTCTTATGGTGATGCTTATTCTGTACGTAAAATTGG

TTATGAACTTTGGATAAAGAAAAGAGTTGGGGATGGTTCAGTGCTTCGAACTATTC

ATGGAAAAGAAATGTCCAAAATAGCCAGGAAGAAGAAACGAGCTGTCATTATGAT

GGTGACAGTGGTGGCTCTCTTTGCTGTGCTGGGCACCATTCCATGTTGTCCATATGA

TGATTGAATACAGTAATTTTGAAAAGGAATATGATGATGTCACAATCAAGATGATT

TTTGCTATCGTGCAAATTATTGGATTTTCCAACTCCATCTGTAATCCCATTGTCTAT

GCA-3' (SEQ ID NO: 47).

Based on the above sequence, two sense oligonucleotide primer sets: 5'-CTGCTTAGAAGAGTGGACCAG-3' (SEQ.ID.NO: 48; oligo 1), 5'-CTGTGCACCAGAAGATCTACAC-3' (SEQ.ID NO: 49; oligo 2) and two antisense oligonucleotide primer sets: 5'-CAAGGATGAAGGTGGTGTAGA-3' (SEQ ID NO: 50; oligo 3) 5'-GTGTAGATGTTCTGGTGCAGAGG-3' (SEQ ID NO: 51; oligo 4) were used for and 5'-RACE PCR with a human brain Marathon-Ready M cDNA (Clontech, Cat# 7400-1) as template, according to manufacture's instructions. DNA fragments generated by the RACE PCR were cloned into the pCRII-TOPO T vector (Invitrogen) and sequenced using the SP6/T7 primers (Stratagene) and some internal primers. The 3' RACE product contained a poly(A) tail and a completed open reading frame ending at a TAA stop codon. The 5' RACE product contained an incomplete end; the ATG initiation codon was not present.

Based on the new 5' sequence, oligo 3 and the following primer: (SEQ ID NO: 52; oligo were used for the second round of 5' race PCR and the PCR products were analyzed as above.

A third round of 5' race PCR was carried out utilizing antisense primers: 5'-TGGAGCATGGTGACGGGAATGCAGAAG-3' (SEQ ID NO: 53; oligo 6) and 5'-GTGATGAGCAGGTCACTGAGCGCCAAG-3' (SEQ ID NO: 54; oligo7).

The sequence of the 5' RACE PCR products revealed the presence of the initiation codon ATG, and further round of 5' race PCR did not generate any more 5' sequence.

The completed 5' sequence was confirmed by RT-PCR using sense primer 5'-GCAATGCAGGCGCTTAACATTAC-3' (SEQ ID NO: 55; oligo 8) and oligo 4 as primers and sequence analysis of the 650 bp PCR product generated from human brain and heart cDNA templates (Clontech, Cat# 7404-1). The completed 3' sequence was confirmed by RT-PCR using oligo 2 and the following antisense primer: 5'-TTGGGTTACAATCTGAAGGGCA-3' (SEQ ID NO: 56; oligo 9) and sequence analysis of the 670 bp PCR product generated from human brain and heart cDNA templates. (Clontech, Cat# 7404-1).

The hRUP4 open reading frame is also sub-cloned into pCMV for expression as described according to the general procedure described in Example 3.

d. hRUP5 (Seq. Id. Nos. 9 The full length hRUP5 was cloned by RT-PCR using a sense primer upstream from ATG, the initiation codon (SEQ ID NO: 57), and an antisense primer containing TCA as the stop codon (SEQ ID NO: 58), which had the following sequences: 5'-ACTCCGTGTCCAGCAGGACTCTG-3' (SEQ ID NO: 57) 5'-TGCGTGTTCCTGGACCCTCACGTG-3' (SEQ ID NO: 58) and human peripheral leukocyte cDNA (Clontech) as a template. Advantage cDNA polymerase (Clontech) was used for the amplification in a 50ul reaction by the following cycle with step 2 through step 4 repeated 30 times: 94 0 C. for 30 sec; 940 for sec; 690 for 40 sec; 72 0 C. for 3 min; and 72 0 C. fro 6 min. A 1.4 kb PCR fragment was isolated and cloned with the pCRII-TOPO T M vector (Invitrogen) and completely sequenced using the T7 DNA Sequenase T M kit (Amsham). See, SEQ ID NO: 9.

The hRUP5 open reading frame is also sub-cloned into pCMV for expression as described according to the general procedure described in Example 3.

e. hRUP6 (Seq. Id. Nos. 11 12) The full length hRUP6 was cloned by RT-PCR using primers: 5'-CAGGCCTTGGATTTTAATGTCAGGGATGG-3' (SEQ ID NO: 59) and 5'-GGAGAGTCAGCTCTGAAAGAATTCAGG-3' (SEQ ID NO: and human thymus Marathon-Ready m cDNA (Clontech) as a template. Advantage cDNA polymerase (Clontech, according to manufacturer's instructions) was used for the amplification in a 50ul reaction by the following cycle: 94°C for 30 sec; 94 0 C for sec; 66 0 C for 40 sec; 72 0 C for 2.5 sec and 72 0 C. for 7 min. Cycles 2 through 4 were repeated 30 times. A 1.3 Kb PCR fragment was isolated and cloned into the pCRII-

TOPO

T vector (Invitrogen) and completely sequenced (see, SEQ ID NO: 11) using the ABI Big Dye TerminatorTM kit Biosystem).

The hRUP6 open reading frame is also sub-cloned into pCMV for expression as described according to the general procedure described in Example 3.

f RUP7 (Seq. Id. Nos. 13 14) The full length RUP7 was cloned by RT-PCR using primers: 5'-TGATGTGATGCCAGATACTAATAGCAC-3' (SEQ ID NO: 61; sense) and 5'-CCTGATTCATTTAGGTGAGATTGAGAC-3' (SEQ ID NO: 62; antisense) and human peripheral leukocyte cDNA (Clontech) as a template. Advantage T M cDNA polymerase (Clontech) was used for the amplification in a 50ul reaction by the following cycle with step 2 to step 4 repeated 30 times: 94 0 C for 2 minutes; 94 0 C for seconds; 60 0 C for 20 seconds; 72 0 C for 2 minutes; 72 0 C for 10 minutes. A 1.25 Kb PCR fragment was isolated and cloned into the pCRII-TOPO T M vector (Invitrogen) and completely sequenced using the ABI Big Dye TerminatorTM kit Biosystem). See, SEQ ID NO: 13.

The hRUP7 open reading frame is also sub-cloned into pCMV for expression as described according to the general procedure described in Example 3.

g. Angiotensin II Type 1 Receptor ("AT1 Seq Id Nos. 65 and 66) The endogenous human angiotensin II type 1 receptor was obtained by PCR using genomic DNA as template and rTth polymerase (Perkin Elmer) with the buffer system provided by the manufacturer, 0.25 pM of each primer, and 0.2 mM of each 4 nucleotides. The cycle condition was 30 cycles of 94 0 C. for 1 min, 55 0 C. for 1 min and 72 0 C. for 1.5 min. The 5' PCR primer contains a HindIII site with the sequence: 5'-CCCAAGCTTCCCCAGGTGTATTTGAT-3' (SEQ. ID NO.: 63) and the 3' primer contains a BamHI site with the following sequence: 5'-GTTGGATCCACATAATGCATTTCTC-3' (SEQ. ID NO.: 64).

The resulting 1.3 kb PCR fragment was digested with HindIII and BamHI and cloned into HindIII-BamHI site of pCMV expression vector. The cDNA clone was fully sequenced. Nucleic acid (SEQ. ID NO.: 65) and amino acid (SEQ. ID NO.: 66) sequences for human AT were thereafter determined and verified.

The ATI open reading frame is also sub-cloned into pCMV for expression as described according to the general procedure described in Example 3.

h. GPR38 (Seq. Id Nos. 129 and 130) To obtain GPR38, PCR was performed by combining two PCR fragments, using human genomic cDNA as template and rTth poymerase (Perkin Elmer) with the buffer system provided by the manufacturer, 0.25 pM of each primer, and 0.2 mM of each 4 nucleotides. The cycle condition for each PCR reaction was 30 cycles of 94 0 C. for 1 min, 62 0 C. for 1 min and 72 0 C. for 2 min.

The first fragment was amplified with the 5' PCR primer that contained an end site with the following sequence: 5'-ACCATGGGCAGCCCCTGGAACGGCAGC-3' (SEQ. ID NO.:67) and a 3' primer having the following sequence: 5'-AGAACCACCACCAGCAGGACGCGGACGGTCTGCCGGTGG-3' (SEQ. ID NO.:68).

The second PCR fragment was amplified with a 5' primer having the following sequence: 5'-GTCCGCGTCCTGCTGGTGGTGGTTCTGGCATTTATAATT-3' (SEQ. ID NO.: 69) and a 3' primer that contained a BamHI site and having the following sequence: 5'-CCTGGATCCTTATCCCATCGTCTTCACGTTAGC-3' (SEQ. ID NO.: The two fragments were used as templates to amplify GPR38, using SEQ. ID NO.: 67 and SEQ. ID NO.: 70 as primers (using the above-noted cycle conditions). The resulting 1.44 kb PCR fragment (SEQ ID NO: 129) was digested with BamHI and cloned into Blunt-BamHI site of pCMV expression vector as described in Example 2.

i. MC4 (Seq. Id Nos. 73 and 74) To obtain MC4, PCR was performed using human genomic cDNA as template and rTth polymerase (Perkin Elmer) with the buffer system provided by the manufacturer, 0.25 [tM of each primer, and 0.2 mM of each 4 nucleotides. The cycle condition for each PCR reaction was 30 cycles of 94°C. for 1 min, 54°C. for 1 min and 72 0 C. for 1.5 min.

The 5' PCR primer contained an EcoRI site with the sequence: 5'-CTGGAATTCTCCTGCCAGCATGGTGA-3' (SEQ. ID NO.: 71) and the 3' primer contained a BamHI site with the sequence: 5'-GCAGGATCCTATATTGCGTGCTCTGTCCCC'-3 (SEQ. ID NO.: 72).

The 1.0 kb PCR fragment was digest with EcoRI and BamHI and cloned into EcoRI- BamHI site of pCMV expression vector. Nucleic acid (SEQ. ID NO.: 73) and amino acid (SEQ. ID NO.: 74) sequences for human MC4 were thereafter determined.

The MC4 open reading frame is also sub-cloned into pCMV for expression as described according to the general procedure described in Example 3.

j. CCKB (Seq. Id Nos. 77 and 78) To obtain CCKB, PCR was performed using human stomach cDNA as template and rTth poymerase (Perkin Elmer) with the buffer system provided by the manufacturer, 0.25 [M of each primer, and 0.2 mM of each 4 nucleotides. The cycle condition for each PCR reaction was 30 cycles of 94 0 C. for 1 min, 65 0 C for 1 min and 72 0 C for 1 min and 30 sec.

The 5' PCR primer contained a HindlII site with the sequence: 5'-CCGAAGCTTCGAGCTGAGTAAGGCGGCGGGCT-3' (SEQ. ID NO.: and the 3' primer contained an EcoRI site with the sequence: 5'-GTGGAATTCATTTGCCCTGCCTCAACCCCCA-3 (SEQ. ID NO.: 76).

The resulting 1.44 kb PCR fragment was digest with HindIII and EcoRI and cloned into HindIIl-EcoRI site of pCMV expression vector. Nucleic acid (SEQ. ID NO.: 77) and amino acid (SEQ. ID NO.: 78) sequences for human CCKB were thereafter determined.

The CCKB open reading frame is also sub-cloned into pCMV for expression as described according to the general procedure described in Example 3.

k. TDAG8 (Seq Id Nos. 81 and 82) To obtain TDAG8, PCR was performed using genomic DNA as template and rTth polymerase (Perkin Elmer) with the buffer system provided by the manufacturer, 0.25 [tM of each primer, and 0.2 mM of each 4 nucleotides. The cycle condition was cycles of 94 0 C for 1 min, 56 0 C for 1 min and 72 0 C for 1 min and 20 sec.

The 5' PCR primer contained a HindIII site with the following sequence: 5'-TGCAAGCTTAAAAAGGAAAAAATGAACAGC-3' (SEQ. ID NO.: 79) and the 3' primer contained a BamHI site with the following sequence: 5'-TAAGGATCCCTTCCCTTCAAAACATCCTTG (SEQ. ID NO.: The resulting 1.1 kb PCR fragment was digested with HindIII and BamHI and cloned into HindIII-BamHI site of pCMV expression vector. Three resulting clones sequenced contained three potential polymorphisms involving changes of amino acid 43 from Pro to Ala, amino acid 97 from Lys to Asn and amino acid 130 from Ile to Phe. Nucleic acid (SEQ. ID NO.: 81) and amino acid (SEQ. ID NO.: 82) sequences for human TDAG8 were thereafter determined.

The TDAG8 open reading frame is also sub-cloned into pCMV for expression as described according to the general procedure described in Example 3.

1. H9 (Seq Id Nos. 139 and 140) To obtain H9, PCR was performed using pituitary cDNA as template and rTth polymerase (Perkin Elmer) with the buffer system provided by the manufacturer, 0.25 gM of each primer, and 0.2 mM of each 4 nucleotides. The cycle condition was cycles of 94°C. for 1 min, 62 0 C. for 1 min and 72 0 C. for 2 min.

The 5' PCR primer contained a HindIII site with the following sequence: 5'-GGAAAGCTTAACGATCCCCAGGAGCAACAT-3' (SEQ. ID NO.: and the 3' primer contained a BamHI site with the following sequence: 5'-CTGGGATCCTACGAGAGCATTTTTCACACAG-3' (SEQ. ID NO.: 16).

The resulting 1.9 kb PCR fragment was digested with HindIII and BamHI and cloned into HindIII-BamHI site of pCMV expression vector. H9 contained three potential polymorphisms involving changes of amino acid P320S, S493N and amino acid G448A. Nucleic acid (SEQ. ID NO.: 139) and amino acid (SEQ. ID NO.: 140) sequences for human H9 were thereafter determined and verified.

The H9 open reading frame is also sub-cloned into pCMV for expression as described according to the general procedure described in Example 3.

Example 2 Preparation of Non-endogenous, Constitutively Activated GPCRs Those skilled in the art are credited with the ability to select techniques for mutation of a nucleic acid sequence. Presented below are approaches utilized to create nonendogenous versions of several of the human GPCRs disclosed above. The mutations disclosed below are based upon an algorithmic approach whereby the 16amino acid (located in the IC3 region of the GPCR) from a conserved proline residue (located in the TM6 region of the GPCR, near the TM6/IC3 interface) is mutated, most preferably to a lysine amino acid residue.

1. Transformer Site-directed(TM) Mutagenesis Preparation of non-endogenous human GPCRs may be accomplished on human GPCRs using Transformer Site-DirectedTM Mutagenesis Kit (Clontech) according to the manufacturer instructions. Two mutagenesis primers are utilized, most preferably a lysine mutagenesis oligonucleotide that creates the lysine mutation, and a selection marker oligonucleotide. For convenience, the codon mutation to be incorporated into the human GPCR is also noted, in standard form (Table TABLE Receptor Identifier Codon Mutation hARE-3 IIARE-4 hGPCR1 4 hGPCR27 hGPR38 hARE-1 hARE-2 hPPR1 hG2A hRUP3 hRUP4 hRUP6 hRUP7 hCHN4 hMC4 hCHN3 hCHN6 hCHN8 hCHN9 hCHN1O hH9 hCCKB hTDAG8 F313K V233K A240K L257K C283K V297K E232K G285K L239K K232A L224K V272K A236K N267K A302K V236K A244K S284K L352K N235K 0223K L231K F236K V332K 1225K The following GPCRs were mutated according with the above method using the designated sequence primers (Table 6).

TABLE 6 Receptor Codon Lysine Mutagenesis Selection Marker Identifier Mutation (SEQ. ID. NO.) (SEQ. ID. NO.) 5-3' orientation, mutation orientation sequence underlined hRUP4 V272K CAGGAAGAAGAAACGAGC

CACTGTCACCATCATAATG

TGTCATTATGATGGTGACA ACAGCTCGTITrCTrCT-rCC GTG (83) TG(84) hATI see below alternative approach; see below alternative approach; see below hGPR38 V297K GGCCACCGGCAGACCAAAC CTCCTrFCGGTCCTCCTATC GCGTCCTGCTG (85) G'TTGTCAGAAGT (86) IICCKB V332K alternative approach; see below alternative approach; see below hTDAG8 122 5K GGAAAAGAAGAGAATCAA CTCCTrCGGTCCTCCTATC AAAACTAC2ITGTCAGCATC GTTGTCAGAAGT (88) (87) hH9 F236K GCTGAGGTrCGCAATAAAC CTCCTrCGGTCCTCCTATC TAACCATG'1TGTG (143) GTrGTCAGAAGT (144) hMC4 A244K GCCAATATGAAGGGAAAA

CTCCTFTCGGTCCTCCTATC

ATTACCTTGACCATC (137) GTTGTCAGAAAGT (138) The non-endogenous human GPCRs were then sequenced and the derived and verified nucleic acid and amino acid sequences are listed in the accompanying "Sequence Listing" appendix to this patent document, as summarized in Table 7 below: TABLE 7 Non Endogenous Human Nucleic Acid Sequence Amino Acid Sequence GPCR (mutation) Listing Listing hRUJP4 (V272K) SEQ. ID NO.: 127 (see alternative approaches below) hAT1 hGPR38 (V297K) hCCKB (V332K) SEQ. ID NO.: 129 SEQ. ID NO.: 131 SEQ. ID NO.: 133 SEQ. ID NO.: 141 SEQ. ID NO.: 128 (see alternative approaches, below) SEQ. ID NO.: 130 SEQ. ID NO.: 132 SEQ. ID NO.: 134 SEQ. ID NO.: 142 hTDAG8 (1225K) hH9 (F236K) hMC4 (A244K) SEQ. ID NO.: 135 SEQ.TD.NO.: 136 For example, the non-endogenous, constitutively activated human TDAG8 receptor (SEQ ID No: 134) was prepared by creating a I225K mutation in the endogenous sequence set forth in SEQ ID NO: 82. Mutagenesis of nucleic acid (SEQ ID NO: 81) encoding the endogenous receptor was performed using Transformer Site-Directed T M Mutagenesis Kit (Clontech) according to manufacturer's instructions, with a lysine mutagenesis oligonucleotide (SEQ.ID NO: 87) and a selection marker oligonucleotide (SEQ.ID NO: 88), as shown in Table 6. This mutatgenesis produced the mutant nucleic acid set forth in SEQ ID NO: 133 which encodes the non-endogenous, constitutively activated human TDAG8 receptor (SEQ ID No: 134).

2. Alternative Approaches for Creation ofNon-endogenous Human GPCRs a. AT] 1. F239K Mutation Preparation of a non-endogenous, constitutively activated human ATI receptor was accomplished by creating an F239K mutation (see, SEQ. ID NO.:89 for nucleic acid sequence, and SEQ. ID NO.: 90 for amino acid sequence). Mutagenesis was performed using Transformer Site-Directed Mutagenesis(TM) Kit (Clontech) according to the to manufacturer's instructions.

Two mutagenesis primers were used, a lysine mutagenesis oligonucleotide (SEQ. ID NO.: 91) and a selection marker oligonucleotide (SEQ. ID NO.: 92), which had the following sequences: 5'-CCAAGAAATGATGATATTAAAAAGATAATTATGGC-3'(SEQ. ID. NO.: 91); and 5'-CTCCTTCGGTCCTCCTATCGTTGTCAGAAGT-3'(SEQ. ID. NO.: 92), respectively.

2. N111A Mutation Preparation of a non-endogenous human ATI receptor was also accomplished by creating an N111A mutation (see, SEQ. ID NO.:93 for nucleic acid sequence, and SEQ.

ID NO.: 94 for amino acid sequence).

Two PCR reactions were performed using pfu polymerase (Stratagene) with the buffer system provided by the manufacturer, supplemented with 10% DMSO, 0.25 pM of each primer, and 0.5 mM of each 4 nucleotides. The 5' PCR sense primer used had the following sequence: 5'-CCCAAGCTTCCCCAGGTGTATTTGAT-3' (SEQ. ID NO.: 95); and the antisense primer had the following sequence: 5'-CCTGCAGGCGAAACTGACTCTGGCTGAAG-3' (SEQ. ID NO.: 96).

The resulting 400 bp PCR fragment was digested with HindIII site and subcloned into HindIII-Smal site of pCMV vector construct). The 3' PCR sense primer used had the following sequence: 5'-CTGTACGCTAGTGTGTTTCTACTCACGTGTCTCAGCATTGAT-3' (SEQ. ID NO.: 97); and the antisense primer had the following sequence: 5'-GTTGGATCCACATAATGCATITTCTC-3' (SEQ. ID NO.: 98) The resulting 880 bp PCR fragment was digested with BamHI and inserted into Pst (blunted by T4 polymerase) and BamHI site of 5' construct to generated the full length N111 A construct. The cycle condition was 25 cycles of 94 0 C. for 1 min, 60 0 C. for 1 min and 72 0 C. for 1 min PCR) or 1.5 min PCR).

3. AT2K255IC3 Mutation Preparation of a non-endogenous, constitutively activated human ATI was accomplished by creating an AT2K255IC3 "domain swap" mutation (see, SEQ. ID NO.:99 for nucleic acid sequence, and SEQ. ID NO.: 100 for amino acid sequence).

Restriction sites flanking IC3 of AT1 were generated to facilitate replacement of the IC3 with corresponding IC3 from angiotensin II type 2 receptor (AT2). This was accomplished by performing two PCR reactions. A 5' PCR fragment (Fragment A) encoded from the 5' untranslated region to the beginning of IC3 was generated by utilizing SEQ. ID NO.: 63 as sense primer and the following sequence: 5'-TCCGAATTCCAAAATAACTTGTAAGAATGATCAGAAA-3' (SEQ. ID.NO.: 101) as antisense primer. A 3' PCR fragment (Fragment B) encoding from the end of IC3 to the 3' untranslated region was generated by using the following sequence: 5'-AGATCTTAAGAAGATAATTATGGCAATTGTGCT-3' (SEQ. ID NO.: 102) as sense primer and SEQ. ID NO.: 64 as antisense primer. The PCR condition was 30 cycles of 94°C. for 1 min, 55 0 C. for 1 min and 72 0 C. for 1.5 min using endogenous ATI cDNA clone as template and pfu polymerase (Stratagene), with the buffer systems provided by the manufacturer, supplemented with 10% DMSO, 0.25 gM of each primer, and mM of each 4 nucleotides. Fragment A (720 bp) was digested with HindIII and EcoRI and subcloned. Fragment B was digested with BamHI and subcloned into pCMV vector with an EcoRI site 5' to the cloned PCR fragment.

The DNA fragment (Fragment C) encoding IC3 of AT2 with a L255K mutation and containing an EcoRI cohesive end at 5' and a AfllI cohesive end at was generated by annealing 2 synthetic oligonucleotides having the following sequences: AACCCGTGACCAAG-3' (sense; SEQ. ID NO.: 103) AGTAAGTGTTTTCG-3' (antisense; SEQ. ID NO.: 104).

Fragment C was inserted in front of Fragment B through EcoRI and AflII site. The resulting clone was then ligated with the Fragment A through the EcoRI site to generate ATI with AT2K255IC3.

4. A243+ Mutation Preparation of a non-endogenous human ATI receptor was also accomplished by creating an A243+ mutation (see, SEQ. ID NO.: 105 for nucleic acid sequence, and SEQ. ID NO.: 106 for amino acid sequence). An A243+ mutation was constructed using the following PCR based strategy: Two PCR reactions was performed using pfu polymerase (Stratagene) with the buffer system provided by the manufacturer supplemented with 10% DMSO, 0.25 gM of each primer, and 0.5 mM of each 4 nucleotides. The 5' PCR sense primer utilized had the following sequence: 5'-CCCAAGCTTCCCCAGGTGTATTGAT-3' (SEQ. ID NO.: 107); and the antisense primer had the following sequence: 5'-AAGCACAATTGCTGCATAATTATCTTAAAAATATCATC-3' (SEQ. ID NO.: 108).

The 3' PCR sense primer utilized had the following sequence: 5'-AAGATAATTATGGCAGCAATTGTGCTTCTTTTTCT=T-3' (SEQ. ID NO.: 109) containing the Ala insertion and antisense primer: 5'-GTTGGATCCACATAATGCATTTCTC-3' (SEQ. ID NO.: 110).

The cycle condition was 25 cycles of 94 0 C. for 1 min, 54°C. for 1 min and 72 0 C. for min. An aliquot of the 5' and 3' PCR were then used as co-template to perform secondary PCR using the 5' PCR sense primer and 3' PCR antisense primer. The PCR condition was the same as primary PCR except the extention time was 2.5 min. The resulting PCR fragment was digested with HindIII and BamHI and subcloned into pCMV vector. (See, SEQ. ID NO.: 105) b. CCKB Preparation of the non-endogenous, constitutively activated human CCKB receptor was accomplished by creating a V322K mutation (see, SEQ. ID NO.: 111 for nucleic acid sequence and SEQ. ID NO.: 112 for amino acid sequence). Mutagenesis was performed by PCR via amplification using the wildtype CCKB from Example 1.

The first PCR fragment (1 kb) was amplified by using SEQ. ID NO.: 75 and an antisense primer comprising a V322K mutation: 5'-CAGCAGCATGCGCTTCACGCGCTTCTTAGCCCAG-3' (SEQ. ID NO.: 113).

The second PCR fragment (0.44 kb) was amplified by using a sense primer comprising the V322K mutation: 5'-AGAAGCGCGTGAAGCGCATGCTGCTGGTGATCGTT-3' (SEQ. ID NO.: 114) and SEQ. ID NO.: 76.

The two resulting PCR fragments were then used as template for amplifying CCKB comprising V332K, using SEQ. ID NO.: 75 and SEQ. ID NO.: 76 and the above-noted system and conditions. The resulting 1.44 kb PCR fragment containing the V332K mutation was digested with HindIlI and EcoRI and cloned into Hindlll-EcoRl site of pCMV expression vector. (See, SEQ. ID NO.: 111).

3. QuikChange (TM) Site-Directed(TM) Mutagenesis Preparation of non-endogenous human GPCRs can also be accomplished by using QuikChangem Site-Directed TM Mutagenesis Kit (Stratagene, according to manufacturer's instructions). Endogenous GPCR is preferably used as a template and two mutagenesis primers utilized, as well as, most preferably, a lysine mutagenesis oligonucleotide and a selection marker oligonucleotide (included in kit). For convenience, the codon mutation incorporated into the human GPCR and the respective oligonucleotides are noted, in standard form (Table 8): TABLE 8 Receptor Codon Lysine Mutagenesis Selection Marker Identifier Mutation (SEQ. ID. NO.) (SEQ. IID. NO.) 5T-3' orientation, mutation orientation underlined hCHN3 hCHN6 S284K L352K hCHN8 hCHN9 hCHNIO N235K G223K L23 1K

ATGGAGAAAAGAATCAAAAGAA

TGTTCTATATA (115)

CGCTCTCTGGCCTTGAAGCGCAC

GCTCAGC (117)

CCCAGGAAAAAGGTGAAAGTCA

AAGTITC (119)

GGGGCGCGGGTGAAACGGCTGG

TGAGC (12 1) CCCCTTGAAAAGCCTAAGAAC17 GGTCATC (123) TATATAGAACATrCIT= GATTCTI1CTCCAT (116)

GCTGAGCGTGCGCTTCA

AGGCCAGAGAGCG (118)

GAAAACTI=GACTICAC

CTI1LCCTGGG (120)

GCTCACCAGCCGTFITCA

CCCGCGCCCC (122)

GATGACCAAGTTCTTAG

GCTITCAAGGGG (124) Example 3 Receptor expression A variety of cells are available to the art for the expression of proteins, however the use of eukaryotic cells is preferred for the expression of GPCRs or constitutively activated variants thereof or GPCR fusion proteins.

In one embodiment, melanocytes are used to express a GPCR or constitutively activated variants thereof or GPCR fusion protein. Melanophores are skin cells found in lower vertebrates. They contain pigmented organelles termed melanosomes.

Melanophores are able to redistribute these melanosomes along a microtubule network upon G-protein coupled receptor (GPCR) activation. The result of this pigment movement is an apparent lightening or darkening of the cells. In melanophores, the decreased levels of intracellular cAMP that result from activation of a Gi-coupled receptor cause melanosomes to migrate to the center of the cell, resulting in a dramatic lightening in color. If cAMP levels are then raised, following activation of a Gscoupled receptor, the melanosomes are re-dispersed and the cells appear dark again.

The increased levels of diacylglycerol that result from activation of Gq-coupled receptors can also induce this re-dispersion. In addition, the technology is also suited to the study of certain receptor tyrosine kinases. The response of the melanophores takes place within minutes of receptor activation and results in a simple, robust color change.

The response can be easily detected using a conventional absorbance microplate reader or a modest video imaging system. Unlike other skin cells, the melanophores derive from the neural crest and appear to express a full complement of signaling proteins. In particular, the cells express an extremely wide range of G-proteins and so are able to functionally express almost all GPCRs.

Melanophores are utilized to identify compounds, including natural ligands, against GPCRs. This method can be conducted by introducing test cells of a pigment cell line capable of dispersing or aggregating their pigment in response to a specific stimulus and expressing an exogenous clone coding for the GCPR. A stimulant, melatonin, sets an initial state of pigment disposition wherein the pigment is aggregated within the test cells if activation of the GPCR induces pigment dispersion. However, stimulating the cell with a stimulant to set an initial state of pigment disposition wherein the pigment is dispersed if activation of the GPCR induces pigment aggregation. The test cells are then contacted with chemical compounds, and it is determined whether the pigment disposition in the cells changed from the initial state of pigment disposition.

Dispersion of pigments cells due to the candidate compound, including but not limited to a ligand, coupling to the GPCR will appear dark on a petri dish, while aggregation of pigments cells will appear light.

The use of melanophores to screen for modulators of GPCR activity and/or expression is in accordance with the materials and methods described in U.S. Patent Number 5,462,856 and U.S. Patent Number 6,051,386. These patent disclosures are hereby incorporated by reference in their entirety.

In particular, the melanophores are plated in e.g. 96-well plates (one receptor per plate).

48 hours post-transfection, half of the cells on each plate are treated with melatonin. Melatonin activates an endogenous Gi-coupled receptor in the melanophores and causes them to aggregate their pigment. The remaining half of the cells are transferred to serum-free medium 0.7X L-15 (Gibco). After one hour, the cells in serum-free media remain in a pigment-dispersed state while the melatonintreated cells are in a pigment-aggregated state. At this point, the cells are treated with a dose response of a test/candidate compound. If the plated GPCRs bind to the test/candidate compound, the melanophores would be expected to undergo a color change in response to the compound. If the receptor were either a Gs or Gq coupled receptor, then the melatonin-aggregated melanophores would undergo pigment dispersion. In contrast, if the receptor was a Gi-coupled receptor, then the pigmentdispersed cells would be expected to undergo a dose-dependent pigment aggregation.

In other embodiments of the invention, mammalian cells are utilized. Preferred mammalian cells include, but are not limited to CHO cells, COS-7 cells, 293 cells and 293T cells, although the specific mammalian cell utilized can be predicated upon the particular needs of the artisan and the tissue in which the GPCR is expressed in nature.

For the purposes of exemplification, the general procedure for expression of the disclosed GPCRs in 293T cells is as follows.

On day one, 1X10 7 293T cells per 150mm plate are plated out. On day two, two reaction tubes are prepared (the proportions to follow for each tube are per plate): tube A is prepared by mixing 20utg DNA pCMV vector; pCMV vector with receptor cDNA, etc.) in 1.2ml serum free DMEM (Irvine Scientific, Irvine, CA); tube B is prepared by mixing 120pl lipofectamine (Gibco BRL) in 1.2ml serum free DMEM.

Tubes A and B are admixed by inversions (several times), followed by incubation at room temperature for 30-45 min. The admixture is referred to as the "transfection mixture". Plated 293T cells are washed with 1X PBS, followed by addition of serum free DMEM. 2.4ml of the transfection mixture is then added to the cells, followed by incubation for 4 hrs at 37 0 C/5% CO 2 The transfection mixture is then removed by aspiration, followed by the addition of 25ml of DMEM/10% Fetal Bovine Serum. Cells are incubated at 37 0 C/5% CO 2 After 72hr incubation, cells are harvested and utilized for analysis.

Example 4 Assays for Determination of Constitutive Activity of Non-endogenous GPCRs A variety of approaches are available for assessment of constitutive activity of the nonendogenous human GPCRS. The following are illustrative; those of ordinary skill in the art are credited with the ability to determine those techniques that are preferentially beneficial for the needs of the artisan.

1. Membrane Binding Assays: 5 S]GTPyS Assay When a G protein-coupled receptor is in its active state, either as a result of ligand binding or constitutive activation, the receptor couples to a G protein and stimulates the release of GDP and subsequent binding of GTP to the G protein. The alpha subunit of the G protein-receptor complex acts as a GTPase and slowly hydrolyzes the GTP to GDP, at which point the receptor normally is deactivated. Constitutively activated receptors continue to exchange GDP for GTP. The non-hydrolyzable GTP analog, 35 S]GTPyS, can be utilized to demonstrate enhanced binding of 35 S]GTPyS to membranes expressing constitutively activated receptors. The advantage of using 35 S]GTPyS binding to measure constitutive activation is that: it is generically applicable to all G protein-coupled receptors; it is proximal at the membrane surface making it less likely to pick-up molecules which affect the intracellular cascade.

The assay utilizes the ability of G protein coupled receptors to stimulate 35 S]GTPyS binding to membranes expressing the relevant receptors. The assay can, therefore, be used in the direct identification method to screen candidate compounds to known, orphan and constitutively activated G protein-coupled receptors. The assay is generic and has application to drug discovery at all G protein-coupled receptors.

The 3 sS]GTPyS assay can be incubated in 20 mM HEPES and between 1 and about mM MgCl 2 (this amount can be adjusted for optimization of results, although 20 mM is preferred) pH 7.4, binding buffer with between about 0.3 and about 1.2 nM 35 S]GTPyS (this amount can be adjusted for optimization of results, although 1.2 is preferred) and 12.5 to 75 pg membrane protein COS-7 cells expressing the receptor; this amount can be adjusted for optimization, although 75 tg is preferred) and 1 tM GDP (this amount can be changed for optimization) for 1 hour. Wheatgerm agglutinin beads tl; Amersham) are then added and the mixture incubated for another 30 minutes at room temperature. The tubes are then centrifuged at 1500* g for 5 minutes at room temperature and then counted in a scintillation counter.

A less costly but equally applicable alternative has been identified which also meets the needs of large scale screening. Flash platesTM and Wallac T m scintistrips may be utilized to format a high throughput 35 S]GTPyS binding assay. Furthermore, using this technique, the assay can be utilized for known GPCRs to simultaneously monitor tritiated ligand binding to the receptor at the same time as monitoring the efficacy via 35 S]GTPyS binding. This is possible because the Wallac beta counter can switch energy windows to look at both tritium and 35 S-labeled probes. This assay may also be used to detect other types of membrane activation events resulting in receptor activation. For example, the assay may be used to monitor P phosphorylation of a variety of receptors (both G protein coupled and tyrosine kinase receptors). When the membranes are centrifuged to the bottom of the well, the bound 35 S]GTPyS or the Pphosphorylated receptor will activate the scintillant which is coated of the wells. Scinti strips (Wallac) have been used to demonstrate this principle. In addition, the assay also has utility for measuring ligand binding to receptors using radioactively labeled ligands. In a similar manner, when the radiolabeled bound ligand is centrifuged to the bottom of the well, the scintistrip label comes into proximity with the radiolabeled ligand resulting in activation and detection.

2. Adenylyl Cyclase A Flash PlateTM Adenylyl Cyclase kit (New England Nuclear; Cat. No. SMP004A) designed for cell-based assays can be modified for use with crude plasma membranes.

The Flash Plate wells contain a scintillant coating which also contains a specific antibody recognizing cAMP. The cAMP generated in the wells was quantitated by a direct competition for binding of radioactive cAMP tracer to the cAMP antibody. The following serves as a brief protocol for the measurement of changes in cAMP levels in membranes that express the receptors.

Transfected cells are harvested approximately three days after transfection. Membranes were prepared by homogenization of suspended cells in buffer containing 20 mM HEPES, pH 7.4 and 10 mM MgC12. Homogenization is performed on ice using a Brinkman Polytron(TM) for approximately 10 seconds. The resulting homogenate is centrifuged at 49,000 X g for 15 minutes at 4 0 C. The resulting pellet is then resuspended in buffer containing 20 mM HEPES, pH 7.4 and 0.1 mM EDTA, homogenized for 10 seconds, followed by centrifugation at 49,000 X g for 15 minutes at 4°C. The resulting pellet can be stored at -80 0 C. until utilized. On the day of measurement, the membrane pellet is slowly thawed at room temperature, resuspended in buffer containing 20 mM HEPES, pH 7.4 and 10 mM MgC12 (these amounts can be optimized, although the values listed herein are preferred), to yield a final protein concentration of 0.60 mg/ml (the resuspended membranes were placed on ice until use).

cAMP standards and Detection Buffer (comprising 2 VCi of tracer [1251] cAMP (100 Vl] to 11 ml Detection Buffer) are prepared and maintained in accordance with the manufacturer's instructions. Assay Buffer is prepared fresh for screening and contained mM HEPES, pH 7.4, 1 mM MgCl 2 20 mM (Sigma), 0.1 units/ml creatine phosphokinase (Sigma), 50,iM GTP (Sigma), and 0.2 mM ATP (Sigma); Assay Buffer can be stored on ice until utilized. The assay is initiated by addition of 50 ul of assay buffer followed by addition of 50 ul of membrane suspension to the NEN Flash Plate.

The resultant assay mixture is incubated for 60 minutes at room temperature followed by addition of 100 ul of detection buffer. Plates are then incubated an additional 2-4 hours followed by counting in a Wallac MicroBetaTM scintillation counter. Values of cAMP/well are extrapolated from a standard cAMP curve that is contained within each assay plate.

3. Reporter-based Assays 1. CREB Reporter Assay (Gs-associated Receptors) A method to detect Gs stimulation depends on the known property of the transcription factor CREB, which is activated in a cAMP-dependent manner. A PathDetect T M

CREB

trans-reporting System (Stratagene, Catalogue #219010) can utilized to assay for Gs coupled activity in 293 or 293T cells. Cells are transfected with the plasmids components of this above system and the indicated expression plasmid encoding endogenous or mutant receptor using a Mammalian Transfection Kit (Stratagene, Catalogue #200285) according to the manufacturer's instructions. Briefly, 400 ng pFR- Luc (luciferase reporter plasmid containing Gal4 recognition sequences), 40 ng pFA2- CREB (Gal4-CREB fusion protein containing the Gal4 DNA-binding domain), 80 ng pCMV-receptor expression plasmid (comprising the receptor) and 20 ng CMV-SEAP (secreted alkaline phosphatase expression plasmid; alkaline phosphatase activity is measured in the media of transfected cells to control for variations in transfection efficiency between samples), are combined in a calcium phosphate precipitate as per the Kit's instructions. Half of the precipitate is equally distributed over 3 wells in a 96well plate, kept on the cells overnight, and replaced with fresh medium the following morning. Forty-eight (48) hr after the start of the transfection, cells are treated and assayed for, luciferase activity 2. AP 1I Reporter Assay (Gq-associated Receptors) A method to detect Gq stimulation depends on the known property of Gq-dependent phospholipase C to cause the activation of genes containing API elements in their promoter. A PathdetectTM AP-1 cis-Reporting System (Stratagene, Catalogue #219073) can be utilized following the protocol set forth above with respect to the CREB reporter assay, except that the components of the calcium phosphate precipitate were 410 ng pAP 1-Luc, 80 ng pCMV-receptor expression plasmid, and 20 ng CMV-SEAP.

3. CRE-LUC Reporter Assay 293 and 293T cells are plated-out on 96 well plates at a density of 2 X 104 cells per well and were transfected using Lipofectamine Reagent (BRL) the following day according to manufacturer instructions. A DNA/lipid mixture is prepared for each 6well transfection as follows: 260 ng of plasmid DNA in 100 pl of DMEM were gently mixed with 2 l of lipid in 100 tl of DMEM (the 260 ng of plasmid DNA consisted of 200 ng of a 8xCRE-Luc reporter plasmid (see below and FIG. 1 for a representation of a portion of the plasmid), 50 ng of pCMV comprising endogenous receptor or nonendogenous receptor or pCMV alone, and 10 ng of a GPRS expression plasmid (GPRS in pcDNA3 (Invitrogen)). The 8XCRE-Luc reporter plasmid was prepared as follows: vector SRIF-p-gal was obtained by cloning the rat somatostatin promoter at BglV-HindIII site in the ppgal-Basic Vector (Clontech). Eight copies of cAMP response element were obtained by PCR from an adenovirus template AdpCF126CCRE8 (see, 7 Human Gene Therapy 1883 (1996)) and cloned into the SRIF-p-gal vector at the Kpn-BglV site, resulting in the 8xCRE-p-gal reporter vector.

The 8xCRE-Luc reporter plasmid was generated by replacing the beta-galactosidase gene in the 8xCRE-0-gal reporter vector with the luciferase gene obtained from the pGL3-basic vector (Promega) at the HindIII-BamHI site. Following 30 min. incubation at room temperature, the DNA/lipid mixture was diluted with 400 pl of DMEM and 100 [mu]l of the diluted mixture was added to each well. 100 tl of DMEM with FCS were added to each well after a 4 hr incubation in a cell culture incubator. The following day the transfected cells were changed with 200 pl/well of DMEM with FCS. Eight hours later, the wells were changed to 100 pl /well of DMEM without phenol red, after one wash with PBS. Luciferase activity were measured the next day using the LucLite m reporter gene assay kit (Packard) following manufacturer instructions and read on a 1450 MicroBeta T m scintillation and luminescence counter (Wallac).

To detect Gs stimulation of non-endogenous constitutively activated GPR38, a PathDetect pCRE-Luc trans-Reporting System (Stratagene, Catalogue 219075) was utilized in 293T cells. Cells were transfected with the plasmids components of this system and the indicated expression plasmid encoding endogenous or non-endogenous receptor using a Mammalian Transfection Kit (Stratagene, Catalogue #200285) according to the manufacturer's instructions. Briefly, 400 ng pCRE-Luc, 80 ng pCMV (comprising the receptor) and 20 ng CMV-SEAP (secreted alkaline phosphatase expression plasmid; alkaline phosphatase activity was measured in the media of transfected cells to control for variations in transfection efficiency between samples) were combined in a calcium phosphate precipitate as per the manufacturer's instructions. Half of the precipitate was equally distributed over 3 wells in a 96-well plate, kept on the cells overnight, and replaced with fresh medium the following day.

Forty-eight (48) hr after the start of the transfection, cells were treated and assayed for luciferase activity using a LucliteTM Kit (Packard, Cat. 6016911) and "Trilux 1450 Microbeta" liquid scintillation and luminescence counter (Wallac) as per the manufacturer's instructions. The data were analyzed using GraphPad Prism T (GraphPad Software Inc.).

Results for GPR38 Results shown in Figure 4 indicate an 83.1% increase in activity of the non-endogenous, constitutively active version of human GPR38 (V297K) (11,505 relative light units) compared with that of the endogenous GPR38 (1950 relative light units).

Results for TDAG8 Data shown in Figures 2 and 6 indicate that ATP and ADP bind to endogenous TDAG8 resulting in an increase of cAMP of about-59% and about 55% respectively. Data in Figure 7 evidence ATP and ADP binding to endogenous TDAG8 where endogenous TDAG8 was transfected and grown in serum and serum-free medium. ATP binding to endogenous TDAG8 grown in serum media evidences an increase in cAMP of about 65%, compared to the endogenous TDAG8 with no compounds; in serum-free media there was an increase of about 68%. ADP binding to endogenous TDAG8 in serum evidences about a 61% increase, while in serum-free ADP binding evidences an increase of about 62% increase. Data in Figures 8A and 8B indicate that ATP and ADP bind to endogenous TDAG8 with an EC50 value of 139.8uM and 120.5uM, respectively.

Although data presented in Figure 7 indicate substantially the same results when serum and serum-free media were compared, our choice is to use a serum based media, although a serum-free media can also be utilized.

4. SRF-Luc Reporter Assay One method to detect Gq stimulation depends on the known property of Gq-dependent phospholipase C to cause the activation of genes containing serum response factors in their promoter. A PathdetectTM SRF-Luc-Reporting System (Stratagene) can be utilized to assay for Gq coupled activity in, COS7 cells. Cells are transfected with the plasmid components of the system and the indicated expression plasmid encoding endogenous or non-endogenous GPCR using a Mammalian TransfectionTM Kit (Stratagene, Catalogue #200285) according to the manufacturer's instructions. Briefly, 410 ng SRF-Luc, 80 ng pCMV-receptor expression plasmid and 20 ng CMV-SEAP (secreted alkaline phosphatase expression plasmid; alkaline phosphatase activity is measured in the media of transfected cells to control for variations in transfection efficiency between samples) are combined in a calcium phosphate precipitate as per the manufacturer's instructions. Half of the precipitate is equally distributed over 3 wells in a 96-well plate, kept on the cells in a serum free media for 24 hours. The last 5 hours the cells are incubated with 1 pM Angiotensin, where indicated. Cells are then lysed and assayed for luciferase activity using a LucliteTM Kit (Packard, Cat. 601691 1) and "Trilux 1450 Microbeta" liquid scintillation and luminescence counter (Wallac) as per the manufacturer's instructions. The data can be analyzed using GraphPad Prism(TM) (GraphPad Software Inc.) 5. Intracellular IP3 Accumulation Assay On day 1, cells comprising the receptors (endogenous and/or non-endogenous) can be plated onto 24 well plates, usually 1XlOcells/well (although his umber can be optimized. On day 2 cells can be transfected by firstly mixing 0:25 ug DNA in 50 ul serum free DMEM/well and 2 ul lipofectamine in 50 pl serumfree DMEM/well. The solutions are gently mixed and incubated for 15-30 min at room temperature. Cells are washed with 0.5 ml PBS and 400 pl of serum free medium is mixed with the transfection media and added to the cells. The cells are then incubated for 3-4 hrs at 37 0 C in 5%C0 2 and then the transfection medium is removed and replaced with 1 ml/well of regular growth media. On day 3 the cells are labeled with 3 H-myo-inositol.

Briefly, the medium is removed and the cells are washed with 0.5 ml PBS. Then 0.5 ml inositol-free/serum free media (GIBCO BRL) is added/well with 0.25 tCi of 3 H-myoinositol/well and the cells are incubated for 16-18 hrs o/n at 37°C in 5%C0 2 On Day 4 the cells are washed with 0.5 ml PBS and 0.45 ml of assay medium is added containing inositol-free/serum free media 10 tM pargyline 10 mM lithium chloride or 0.4 ml of assay medium and 50 ul of 10X ketanserin (ket) to final concentration of 10 tM. The cells are then incubated for 30 min at 37 0 C. The cells are then washed with 0.5 ml PBS and 200 [l of fresh/icecold stop solution (lM KOH; 18 mM Na-borate; 3.8 mM EDTA) is added/well. The solution is kept on ice for 5-10 min or until cells were lysed and then neutralized by 200 tl of fresh/ice cold neutralization sol. HCL). The lysate is then transferred into 1.5 ml Eppendorf tubes and 1 ml of chloroform/methanol is added/tube. The solution is vortexed for 15 sec and the upper phase is applied to a Biorad AG1-X8TM anion exchange resin (100-200 mesh). Firstly, the resin is washed with water at 1:1.25 W/V and 0.9 ml of upper phase is loaded onto the column. The column is washed with 10 mls of 5 mM myo-inositol and 10 ml of 5 mM mM Na-formate. The inositol tris phosphates are eluted into scintillation vials containing 10 ml of scintillation cocktail with 2 ml of 0.1 M formic acid/ 1 M ammonium formate. The columns are regenerated by washing with 10 ml of 0.1 M formic acid/3M ammonium formate and rinsed twice with double-distilled water (dd

H

2 0) and stored at 4 0 C in water.

Exemplary results are presented below in Table 9 and, in the case of TDAG8, in Figures 9A (293 cells) and 9B (293T cells): 74 TABLE 9 Receptor Mutation Assay Utilized Signal Generated Endogenous Version (Relative Light Units) Signal Generated Non- Endogenous Version (Relative Light Units) Percent Difference hATi hTDAG8 hH9 hGGKB F239K AT2K255I1C3 1225K 1225K F236K V332K

SRF-LUC

CRE-LUC

(293 cells)

CRE-LUC

(293T cells)

CRE-LUC

34 34 2,715 65,681 1,887 785 137 127 14,440 185,636 6,096 3,223 300%A 270%A 430%A 1 220%A 3 Example Cell-Based Detection Assay 1. TDAG8 293 cells were plated-out on 150 mm plates at a density of 1.3x107 cells per plate, and were transfected using 12 ug of the respective DNA and 60 ul of Lipofectamine Reagent (BRL) per plate. The transfected cells were grown in media containing serum for an assay performed 24 hours post-transfection. For detection assay performed 48 hours post-transfection (assay comparing serum and serum-free media; see FIG. the initial media was changed to either serum or serum-free media. The serum-free media was comprised solely of Dulbecco's Modified Eagle's (DME) High Glucose Medium (Irvine Scientific #9024). In addition to the above DME Medium, the media with serum contained the following: 10% Fetal Bovine Serum (Hyclone #SH30071.03), 1% of 100 mM Sodium Pyruvate (Irvine Scientific #9334), 1% of 20 mM L-Glutamine (Irvine Scientific #9317), and 1% of Penicillin-Streptomycin solution (Irvine Scientific #9366).

A 96-well Adenylyl Cyclase Activation FlashplateTM was used (NEN: #SMP004A).

First, 50 ul of the standards for the assay were added to the plate, in duplicate, ranging from concentrations of 50 pmol to zero pmol cAMP per well. The standard cAMP (NEN: #SMP004A) was reconstituted in water, and serial dilutions were made using lxPBS (Irvine Scientific: #9240). Next, 50 ul of the stimulation buffer (NEN: #SMP004A) was added to all wells. In the case of using compounds to measure activation or inactivation of cAMP, 10 ul of each compound, diluted in water, was added to its respective well, in triplicate. Various final concentrations used range from 1 uM up to 1 mM. Adenosine 5'-triphosphate, ATP, (ResearchBiochemicals International: #A-141) and Adenosine 5'-diphosphate, ADP, (Sigma: #A2754) were used in the assay. Next, the 293 cells transfected with the respective cDNA (CMV or TDAG8) were harvested 24 (assay detection in serum media) or 48 hours posttransfection (assay detection comparing serum and serum-free media). The media was aspirated and the cells washed once with lxPBS. Then 5 ml of lxPBS was added to the cells along with 3 ml of cell dissociation buffer (Sigma: #C-1544). The detached cells were transferred to a centrifuge tube and centrifuged at room temperature for five minutes. The supernatant was removed and the cell pellet was resuspended in an appropriate amount of IxPBS to obtain a final concentration of 2X10 6 cells permilliliter. To the wells containing the compound, 50 ul of the cells in IxPBS (1X10 cells/well) were added. The plate was incubated on a shaker for 15 minutes at room temperature. The detection buffer containing the tracer cAMP was prepared. In 11 ml of detection buffer (NEN: #SMP004A), 50 ul (equal to 1 uCi) of [1 25 ]cAMP (NEN: #SMP004A) was added. Following incubation, 50 ul of this detection buffer containing tracer cAMP was added to each well. The plate was placed on a shaker and incubated at room temperature for two hours. Finally, the solution from the wells of the plate were aspirated and the flashplate was counted using the Wallac MicroBeta(TM) scintillation counter.

In FIG. 6A, ATP and ADP bind to endogenous TDAG8 resulting in an increase of cAMP of about 130% and about 110% respectively. FIG. 6B evidences ATP and ADP binding to endogenous TDAG8 where endogenous TDAG8 was transfected and grown in serum and serum-free medium. ATP binding to endogenous TDAG8 grown in serum media evidences an increase in cAMP of about 205%, compared to the endogenous TDAG8 with no compounds; in serum-free media there was an increase of about 220%.

ADP binding to endogenous TDAG8 in serum evidences about a 165% increase, while in serum-free ADP binding evidences an increase of about 170% increase. ATP and ADP bind to endogenous TDAG8 with an EC50 value of 500 uM and 700 uM, respectively, as shown in FIG. 8A and FIG. 8B.

Although the results presented in FIG. 6B indicate substantially the same results when serum and serum-free media were compared, our choice is to use a serum based media, although a serum-free media can also be utilized.

Example 6 GPCR Fusion Protein Preparation 1. General approach The design of the constitutively activated GPCR-G protein fusion construct was accomplished as follows: both the 5' and 3' ends of the rat G protein Gsa (long form; Itoh, H. et al., 83 PNAS 3776 (1986)) were engineered to include a HindIII AAGCTT-3') sequence thereon. Following confirmation of the correct sequence (including the flanking HindIII sequences), the entire sequence was shuttled into pcDNA3.1(-) (Invitrogen, cat. no. V795-20) by subcloning using the HindIII restriction site of that vector. The correct orientation for the Gsa sequence was determined after subcloning into pcDNA3.1(-). The modified pcDNA3.1 containing the rat Gsa gene at HindIII sequence was then verified; this vector was now available as a "universal" Gsa protein vector. The pcDNA3.1(-) vector contains a variety of well-known restriction sites upstream of the HindIII site, thus beneficially providing the ability to insert, upstream of the Gs protein, the coding sequence of an endogenous, constitutively active GPCR. This same approach can be utilized to create other "universal" G protein vectors, and, of course, other commercially available or proprietary vectors known to the artisan can be utilized-the important criteria is that the sequence for the GPCR be upstream and in-frame with that of the G protein.

TDAG8 couples via Gs, while H9 couples via Gz.

For the following exemplary GPCR Fusion Proteins, fusion to Gsa was accomplished.

2. TDAG8 A TDAG8(I225K)-Gsa Fusion Protein construct was made as follows: primers were designed as follows: 5'-gatcTCTAGAATGAACAGCACATGTATTGAAG-3' (SEQ. ID NO.: 125; sense); and 5'-ctagGGTACCCGCTCAAGGACCTCTAATFCCATAG-3' (SEQ. ID.NO.: 126; antisense), wherein nucleotides in lower caps are included as spacers in the restriction sites between the G protein and TDAG8. The sense and anti-sense primers included the restriction sites for XbaI and KpnI, respectively.

PCR was then utilized to secure the respective receptor sequences for fusion within the Gsa universal vector disclosed above, using the following protocol for each: 100 ng cDNA for TDAG8 was added to separate tubes containing 2 ul of each primer (sense and anti-sense), 3 uL of 10 mM dNTPs, 10 uL of 10XTaqPlusTM Precision buffer, 1 uL of TaqPlusTM Precision polymerase (Stratagene: #600211), and 80 uL of water.

Reaction temperatures and cycle times for TDAG8 were as follows: the initial denaturing step was done it 94°C. for five minutes, and a cycle of 94 0 C. for 30 seconds; 0 C. for 30 seconds; 72 0 C. for two minutes. A final extension time was done at 72 0

C.

for ten minutes. PCR product for was run on a 1% agarose gel and then purified (data not shown). The purified product was digested with XbaI and KpnI (New England Biolabs) and the desired inserts purified and ligated into the Gs universal vector at the respective restriction site. The positive clones was isolated following transformation and determined by restriction enzyme digest; expression using 293 cells was accomplished following the protocol set forth infra. Each positive clone for TDAG8:Gs-Fusion Protein was sequenced to verify correctness.

GPCR Fusion Proteins comprising non-endogenous, constitutively activated TDAG8(I225K) were analyzed as above and verified for constitutive activation.

3. H9 An H9(F236K)-Gsa Fusion Protein construct was made as follows: primers were designed as follows: 5'-TTAgatatcGGGGCCCACCCTAGCGGT-3' (SEQ. ID NO.: 145; sense); and 5'-ggtaccCCCACAGCCATITCATCAGGATC-3' (SEQ. ID NO.: 146; antisense).

Nucleotides in lower caps are included as spacers in the restriction sites between the G protein and H9. The sense and anti-sense primers included the restriction sites for EcoRV and KpnI, respectively such that spacers (attributed to the restriction sites) exists between the G protein and H9.

PCR was then utilized to secure the respective receptor sequences for fusion within the Gsa universal vector disclosed above, using the following protocol for each: 80 ng cDNA for H9 was added to separate tubes containing 100 ng of each primer (sense and anti-sense), and 45 uL of PCR SupermixTM (Gibco-Brl, LifeTech) (50 ul total reaction volume). Reaction temperatures and cycle times for H9 were as follows: the initial denaturing step was done it 94°C. for one, and a cycle of 94°C. for 30 seconds; 55 0

C.

for 30 seconds; 72 0 C. for two minutes. A final extension time was done at 72°C. for seven minutes. PCR product for was run on a 1% agarose gel and then purified (data not shown). The purified product was cloned into pCRII-TOPO T M System followed by identification of positive clones. Positive clones were isolated, digested with EcoRV and KpnI (New England Biolabs) and the desired inserts were isolated, purified and ligated into the Gs universal vector at the respective restriction site. The positive clones was isolated following transformation and determined by restriction enzyme digest; expression using 293 cells was accomplished following the protocol set forth infra.

Each positive clone for H9(F236K):Gs-Fusion Protein was sequenced to verify correctness. Membranes were frozen (-80 0 until utilized.

To ascertain the ability of measuring a cAMP response mediated by the Gs protein (even though H9 couples with Gz), the following cAMP membrane assay was utilized, based upon an NEN Adenyl Cyclase Activation Flahplate m Assay kit (96 well format).

"Binding Buffer" consisted of 10 mM HEPES, 100 mM NaCl and 100 mM MgCl (ph "Regeneration Buffer" was prepared in Binding Buffer and consisted of 20 mM phosphocreatine, 20 U creatine phosphokinase, 20 uM GTP, 0.2 mM ATP, and 0.6 mM IBMX. "cAMP Standards" were prepared in Binding Buffer as follows: cAMP Stock Added to Final Assay Concentration (5,000 pmol/ml in 2 ml H 2 0) amount of Binding (50 ul into 100 ul) indicated in ul Buffer to achieve indicated pmol/well A 250 1 ml B 500 of A 500 ul C 500 of B 500 ul 12.5 D 500 of C 750 ul E 500 of D 500 ul F 500 of E 500 ul 1.25 G 500 of F 750 ul Frozen membranes (both pCMV as control and the non-endogenous H(-Gs Fusion Protein) were thawed (on ice at room temperature until in solution). Membranes were homogenized with a polytron until in suspension (2x15 seconds). Membrane protein concentration was determined using the Bradford Assay Protocol (see infra).

Membrane concentration was diluted to 0.5 mg/ml in Regeneration Buffer (final assay concentration-25 ug/well). Thereafter, 50 ul of Binding Buffer was added to each well.

For control, 50 ul/well of cAMP standard was added to wells 11 and 12 A-G, with Binding Buffer alone to 12H (on the 96-well format). Thereafter, 50 ul/well of protein was added to the wells and incubated at room temperature (on shaker) for 60 min. 100 ul[12 5 I]cAMP in Detection Buffer (see infra) was added to each well (final ul[1 25 I]cAMP into 11 ml Detection Buffer). These were incubated for 2 hrs at room temperature. Plates were aspirated with an 8 channel manifold and sealed with plate covers. Results (pmoles cAMP bound) were read in a WallacTM 1450 on "prot The results presented in FIG. 3 indicate that the Gs coupled fusion was able to "drive" the cyclase reaction such that measurement of the consitutive activation of H9(F236K) was viable. Based upon these results, the direct identification of candidate compounds that are inverse agonists, agonists and partial agonists is possible using a cyclase-based assay.

Example 7 Direct Identification of Inverse Agonists and Agonists Using 35 S]GTPyS Although we have utilized endogenous, constitutively active GPCRs for the direct identification of candidate compounds as, inverse agonists, for reasons that are not altogether understood, intra-assay variation can become exacerbated. Preferably, then, a GPCR Fusion Protein, as disclosed above, is also utilized with a non-endogenous, constitutively activated GPCR. We have determined that when such a protein is used, intra-assay variation appears to be substantially stabilized, whereby an effective signalto-noise ratio is obtained. This has the beneficial result of allowing for a more robust identification of candidate compounds. Thus, it is preferred that for direct identification, a GPCR Fusion Protein be used and that when utilized, the following assay protocols be utilized.

1. Membrane Preparation Membranes comprising the non-endogenous, constitutively active orphan GPCR Fusion Protein of interest and for use in the direct identification of candidate compounds as inverse agonists, agonists or partial agonists are preferably prepared as follows: a. Materials "Membrane Scrape Buffer" is comprised of 20 mM HEPES and 10 mM EDTA, pH 7.4; "Membrane Wash Buffer" is comprised of 20 mM HEPES and 0.1 mM EDTA, pH 7.4; "Binding Buffer" is comprised of 20 mM HEPES, 100 mM NaCl, and 10 mM MgC12, pH 7.4 b. Procedure All materials are kept on ice throughout the procedure. Firstly, the medium is aspirated from a confluent monolayer of cells, followed by rinse with 10 ml cold PBS, followed by aspiration. Thereafter, 5 ml of Membrane Scrape Buffer is added to scrape cells; this is followed by transfer of cellular extract into 50 ml centrifuge tubes (centrifuged at 20,000 rpm for 17 minutes at 4 0 Thereafter, the supernatant is aspirated and the pellet is resuspended in 30 ml Membrane Wash Buffer followed by centrifuge at 20,000 rpm for 17 minutes at 4*C. The supemrnatant is then aspirated and the pellet resuspended in Binding Buffer. This is then homogenized using a Brinkman polytron T m homogenizer (15-20 second bursts until the all material is in suspension). This is referred to herein as "Membrane Protein".

c. Bradford Protein Assay Following the homogenization, protein concentration of the membranes is determined using the Bradford Protein Assay (protein can be diluted to about 1.5 mg/ml, aliquoted and frozen (-80 0 for later use; when frozen, protocol for use is as follows: on the day of the assay, frozen Membrane Protein is thawed at room temperature, followed by vortex and then homogenized with a polytron at about 12x1,000 rpm for about 5-10 seconds; it is noted that for multiple preparations, the homogenizer should be thoroughly cleaned between homogenization of different preparations).

Materials Binding Buffer (as per above); Bradford Dye Reagent; Bradford Protein Standard are utilized, following manufacturer instructions (Biorad, cat. no. 500-0006).

Procedure Duplicate tubes are prepared, one including the membrane, and one as a control "blank". Each contained 800 ul Binding Buffer. Thereafter, 10 ul of Bradford Protein Standard (1 mg/ml) is added to each tube, and 10 ul of membrane Protein is then added to just one tube (not the blank). Thereafter, 200 ul of Bradford Dye Reagent is added to each tube, followed by vortex of each. After five minutes, the tubes were revortexed and the material therein is transferred to cuvettes. The cuvettes are then read using a CECIL 3041 spectrophotometer, at wavelength 595.

d. Direct Identification Assay a. Materials GDP Buffer consists of 37.5 ml Binding Buffer and 2 mg GDP (Sigma, cat. no. G- 7127), followed by a series of dilutions in Binding Buffer to obtain 0.2 uM GDP (final concentration of GDP in each well was 0.1 uM GDP); each well comprising a candidate compound, has a final volume of 200 ul consisting of 100 ul GDP Buffer (final concentration, 0.1 uM GDP), 50 ul Membrane Protein in Binding Buffer, and ul ["S]GTPyS (0.6 nM) in Binding Buffer (2.5 ul 35 S]GTPyS per 10 ml Binding Buffer).

b. Procedure Candidate compounds are preferably screened using a 96-well plate format (these can be frozen at -80 0 Membrane Protein (or membranes with expression vector excluding the GPCR Fusion Protein, as control), are homogenized briefly until in suspension. Protein concentration is then determined using the Bradford Protein Assay set forth above. Membrane Protein (and control) is then diluted to 0.25 mg/ml in Binding Buffer (final assay concentration, 12.5 ug/well). Thereafter, 100 ul GDP Buffer is added to each well of a Wallac Scintistrip T (Wallac). A 5 ul pin-tool is then used to transfer 5 ul of a candidate compound into such well 5 ul in total assay volume of 200 ul is a 1:40 ratio such that the final screening concentration of the candidate compound is 10 uM). Again, to avoid contamination, after each transfer step the pin tool should be rinsed in three reservoirs comprising water ethanol (IX) and water (2X)-excess liquid should be shaken from the tool after each rinse and dried with paper and kimwipes. Thereafter, 50 ul of Membrane Protein is added to each well (a control well comprising membranes without the GPCR Fusion Protein is also utilized), and pre-incubated for 5-10 minutes at room temperature. Thereafter, 50 ul of ["S]GTPyS (0.6 nM) in Binding Buffer is added to each well, followed by incubation on a shaker for 60 minutes at room temperature (again, in this example, plates were covered with foil). The assay is then stopped by spinning of the plates at 4000 RPM for 15 minutes at 22 0 C. The plates are then aspirated with an 8 channel manifold and sealed with plate covers. The plates are then read on a Wallacc 1450 using setting "Prot. #37" (as per manufacturer instructions).

Example 8 Protocol: Confirmation Assay Using an independent assay approach to provide confirmation of a directly identified candidate compound as set forth above, it is preferred that a confirmation assay then be utilized. In this case, the preferred confirmation assay is a cyclase-based assay.

A modified Flash PlateTM Adenylyl Cyclase kit (New England Nuclear; Cat. No.

SMP004A) is preferably utilized for confirmation of candidate compounds directly identified as inverse agonists and agonists to non-endogenous, constitutively activated orphan GPCRs in accordance with the following protocol.

Transfected cells are harvested approximately three days after transfection. Membranes are prepared by homogenization of suspended cells in buffer containing 20 mM HEPES, pH 7.4 and 10 mM MgCl 2 Homogenization is performed on ice using a Brinkman Polytron

T

M for approximately 10 seconds. The resulting homogenate is centrifuged at 49,000 X g for 15 minutes at 4°C. The resulting pellet is then resuspended in buffer containing 20 mM HEPES, pH 7.4 and 0.1 mM EDTA, homogenized for 10 seconds, followed by centrifugation at 49,000 X g for 15 minutes at 4°C. The resulting pellet can be stored at -800 0 C. until utilized. On the day of direct identification screening, the membrane pellet is slowly thawed at room temperature, resuspended in buffer containing 20 mM HEPES, pH 7.4 and 10 mM MgCl 2 to yield a final protein concentration of 0.60 mg/ml (the resuspended membranes are placed on ice until use).

cAMP standards and Detection Buffer (comprising 2 pCi of tracer [12 5 cAMP (100 g.l] to 11 ml Detection Buffer) are prepared and maintained in accordance with the manufacturer's instructions. Assay Buffer is prepared fresh for screening and contained mM HEPES, pH 7.4, 10 mM MgCl 2 20 mM phospocreatine (Sigma), 0.1 units/ml creatine phosphokinase (Sigma), 50 JM GTP (Sigma), and 0.2 mM ATP (Sigma); Assay Buffer can be stored on ice until utilized. Candidate compounds identified as per above (if frozen, thawed at room temperature) are added, preferably, to 96-well plate wells (3 lI/well; 12 aM final assay concentration), together with 40 al Membrane Protein (30 jig/well) and 50 pl of Assay Buffer. This admixture is then incubated for minutes at room temperature, with gentle shaking.

Following the incubation, 100 pl of Detection Buffer is added to each well, followed by incubation for 2-24 hours. Plates are then counted in a Wallac MicroBetaTM plate reader using "Prot. #31" (as per manufacturer instructions).

Example Tissue Distribution of TDAG8 Before using a multiple tissue cDNA panel, two primers were designed from the TDAG8 open reading frame sequence. The oligonucleotides utilized were as follows: 5'-GCACTCATGGTCAGCCTGTCCATC-3' (sense), and 5'-GTACAGAATTGGATCAGCAACAC-3' (antisense).

Once the two primers were made and purified for PCR use, the reaction mixes were made. Each tube contained the following master mix of reagents: 36ul water, lul dNTP mix, 1 ul Taq Plus Precision DNA Polymerase (Stratagene: #600211), and Buffer for Taq Plus Precision Polymerase (Stratagene: #600211). A positive control tube containing the above solutions also contained 2ul of the G3PDH positive control primers (Clontech: #K14261-1) and 5ul of the control cDNA (Clontech: #K1426-1). A negative control tube was similar to the positive control; however, the control cDNA was replaced with 5ul water. To determine gene distribution, the MTC Panels used included the Human Panel I (Clontech: #K1420-1), the Human Panel II (Clontech: #K1421-1), and the Human Immune System Panel (Clontech: #K1426-1).

Each MTC Panel contained several tubes of cDNA from various human tissues. Using tubes containing the above master mix of reagents, 2ul of the G3PDH positive control primers, 5ul of the individual MTC Panel cDNA, and lul of each primer designed above for the TDAG8 gene were all added to complete the reaction mixture. All of the tubes were then placed into a programmable thermal cycler (Perkin Elmer). The reactions were added at 94C for 30 seconds. A cycle of 94C for 30 seconds, 55C for seconds, and 72C for two minutes was repeated 30 times. A final extension time of five minutes at 72C was run, and the cooling temperature of 4C was the final step. The reactions were added to a one percent agarose gel (FMC Bioproducts: #50004) and examined under ultraviolet light. For the positive control, an expected band of approximately 1Kb should be seen. For the negative control, no band should appear.

Finally, for all of the tubes containing various human tissue cDNA, a band is seen at 1Kb (for the control primers), and if expressed in that particular tissue, a band, varying in intensity, is seen at 450bp (for the TDAG8 primers). See Figure

Claims

1. An isolated polynucleotide encoding a non-endogenous, constitutively activated version of a human G protein-coupled receptor, wherein said polynucleotide comprises a nucleotide sequence selected from the group consisting of: a sequence encoding a polypeptide that comprises the amino acid sequence set forth in SEQ ID NO: 134; the sequence set forth in SEQ ID NO: 133; a sequence having at least about 80% identity to SEQ ID NO: 133 other than a sequence encoding a non-endogenous, constitutively activated version of a human G protein-coupled receptor comprising isoleucine residue at position 225 of SEQ ID NO: 134; and the sequence of wherein the constitutively activated version of a human G protein-coupled receptor comprises an amino acid sequence having a lysine residue at a position equivalent to position 225 of SEQ ID NO: 134.

2. The isolated polynucleotide according to claim 1 wherein said polynucleotide comprises a nucleotide sequence selected from the group consisting of: a sequence that is identical or substantially identical to SEQ ID NO: 133 wherein the codon at nucleotide positions 673-675 encoding lysine is unchanged or substituted with a codon that encodes an amino acid other than isoleucine; a sequence encoding a constitutively activated version of a human G protein-coupled receptor having an amino acid sequence identical or substantially identical to SEQ ID NO: 134 wherein the lysine residue at amino acid position 225 is unchanged or substituted with an amino acid other than isoleucine; and a sequence encoding a variant of a non-endogenous, constitutively activated version of a human G protein-coupled receptor comprising the amino acid sequence set forth in SEQ ID NO: 134 in which the lysine residue at position 225 is substituted for a different amino acid other than isoleucine.

3. An isolated polynucleotide encoding a non-endogenous, constitutively activated version of a human G protein-coupled receptor, wherein said polynucleotide comprises a nucleotide sequence selected from the group consisting of: a sequence encoding the amino acid sequence set forth in SEQ ID NO: 134; and the nucleotide sequence set forth in SEQ ID NO: 133.

4. An isolated polynucleotide encoding a GPCR fusion protein, wherein said polynucleotide comprises a nucleotide sequence of the isolated polynucleotide according to any one of claims 1 to 3. The isolated polynucleotide according to claim 4 further comprising nucleic acid encoding a G protein.

6. The isolated polynucleotide according to claim 5 wherein the G protein is a Gsa protein.

7. A vector comprising the polynucleotide according to any one of claims 1 to 6.

8. The vector of claim 7, wherein said vector is an expression vector and wherein the polynucleotide according to any one of claims 1 to 6 is operably linked to a promoter.

9. A recombinant host cell comprising the vector of claim 7. A recombinant host cell comprising the vector of claim 8.

11. A method of producing a non-endogenous, constitutively activated version of a human G protein-coupled receptor or a GPCR fusion protein comprising the steps of: transfecting the expression vector according to claim 8 into a host cell thereby producing a transfected host cell; and culturing the transfected host cell under conditions sufficient to express a non-endogenous, constitutively activated version of a human G protein-coupled receptor or GPCR fusion protein from the expression vector. 89

12. The method according to claim 11 wherein the host cell is a mammalian cell.

13. The method according to claim 12 wherein the mammalian cell is selected from the group consisting of a COS-7 cell, a 293 cell, and a 293T cell.

14. The method of claim 12 or 13 wherein the host cell is a melanophore or CHO cell. The method according to any one of claims 11 to 14 further comprising obtaining the transfected host cell.

16. The method of claim 15 further comprising obtaining or isolating a membrane fraction from the obtained transfected host cell.

17. A method of producing a non-endogenous constitutively-activated human G protein-coupled receptor comprising introducing a mutation into the coding region of nucleic acid comprising the nucleotide sequence of SEQ ID NO: 81 at a codon corresponding to positions 673-675 of said sequence, isolating or recovering the modified nucleic acid, and expressing the modified nucleic acid to thereby produce a non-endogenous constitutively-activated human G protein-coupled receptor.

18. The method of claim 17 wherein the nucleic acid is DNA.

19. The method of claim 18 wherein the DNA is cDNA. The method of claim 17 wherein the nucleic acid is RNA.

21. The method of claim 20 wherein the RNA is from lymphoid tissue.

22. The method of claim 21 wherein the lymphoid tissue is selected from the group consisting of peripheral blood leukocytes, spleen, lymph nodes and thymus.

23. The method according to any one of claims 17 to 22 wherein the mutation is the substitution of isoleucine at position 225 of SEQ ID NO: 84 for lysine.

24. An isolated membrane of a transfected host cell obtained by the method of claim 16 wherein said isolated membrane comprises a non-endogenous, constitutively activated version of said human G protein-coupled receptor encoded by the isolated polynucleotide according to any one of claims 1 to 3 or a GPCR fusion protein encoded by the isolated polynucleotide according to any one of claims 4 to 6 or a polypeptide expressed by the vector of claim 8. An isolated membrane of the recombinant host cell of claim 10 wherein said isolated membrane comprises a non-endogenous, constitutively activated version of said human G protein-coupled receptor encoded by the isolated polynucleotide according to any one of claims 1 to 3 or a GPCR fusion protein encoded by the isolated polynucleotide according to any one of claims 4 to 6 or a polypeptide expressed by the vector of claim 8.

26. An isolated or recombinant non-endogenous, constitutively activated version of a human G protein-coupled receptor polypeptide comprising an amino acid sequence selected from the group consisting of: a sequence comprising the amino acid sequence set forth in SEQ ID NO: 134; a sequence having at least about 80% identity to SEQ ID NO: 134 other than a sequence comprising isoleucine residue at position 225 of SEQ ID NO: 134; and the sequence of wherein said sequence comprises a lysine residue at a position equivalent to position 225 of SEQ ID NO: 134.

27. The isolated or recombinant non-endogenous, constitutively activated version of a human G protein-coupled receptor polypeptide according to claim 26 wherein said polypeptide comprises an amino acid sequence selected from the group consisting of: a sequence that is substantially identical to SEQ ID NO: 134 wherein the lysine residue at amino acid position 225 is unchanged or substituted with an amino acid other than isoleucine; and a sequence comprising the amino acid sequence set forth in SEQ ID NO: 134 in which the lysine residue at position 225 is substituted for a different amino acid other than isoleucine.

28. An isolated or recombinant non-endogenous, constitutively activated version of a human G protein-coupled receptor polypeptide comprising the amino acid sequence set forth in SEQ ID NO: 134.

29. An isolated or recombinant GPCR fusion protein comprising an amino acid sequence of the isolated or recombinant non-endogenous, constitutively activated version of a human G protein-coupled receptor polypeptide according to any one of claims 26 to 28.

30. The isolated or recombinant GPCR fusion protein according to claim 29 further comprising a G protein.

31. The isolated or recombinant GPCR fusion protein according to claim 30 wherein the G protein is a Gsa protein.

32. An isolated membrane of a cell wherein said isolated membrane comprises the isolated or recombinant non-endogenous, constitutively activated version of a human G protein-coupled receptor polypeptide according to any one of claims 26 to 28 or the isolated or recombinant GPCR fusion protein according to any one of claims 29 to 31.

33. A method of identifying a modulator of a G protein-coupled receptor comprising the steps of: contacting a candidate compound with a recombinant host cell that expresses the non-endogenous, constitutively activated version of a human G protein-coupled receptor polypeptide according to any one of claims 26 to 28 or an isolated membrane comprising said non-endogenous, constitutively activated version of a human G protein-coupled receptor polypeptide; and measuring the ability of the compound to inhibit or stimulate functionality of the G protein coupled receptor polypeptide wherein inhibition or stimulation of said functionality indicates that the candidate compound is a modulator of the G protein-coupled receptor polypeptide.

34. The method of claim 34 further comprising providing the host cell or membrane. The method of claim 33 or 34 wherein the host cell comprises the expression vector of claim 8.

36. The method according to any one of claims 33 to 35 wherein the human G protein-coupled receptor polypeptide comprises the amino acid sequence set forth in SEQ ID NO: 134.

37. A method of identifying a modulator of a G protein-coupled receptor comprising the steps of: contacting a candidate compound with a recombinant host cell that expresses the GPCR fusion protein according to any one of claims 29 to 31 or an isolated membrane comprising said GPCR fusion protein; and measuring the ability of the compound to inhibit or stimulate functionality of the G protein-coupled receptor polypeptide portion of said GPCR fusion protein wherein inhibition or stimulation of said functionality indicates that the candidate compound is a modulator of the G protein- coupled receptor polypeptide.

38. The method of claim 37 further comprising providing the host cell or membrane.

39. The method of claim 36 or 37 wherein the host cell comprises the expression vector of claim 8. The method according to any one of claims 36 to 39 wherein the GPCR fusion protein comprises the amino acid sequence set forth in SEQ ID NO: 134.

41. The method according to any one of claims 36 to 40 wherein the GPCR fusion protein comprises a Gsa protein.

42. A method of identifying a modulator of a G protein-coupled receptor comprising the steps of: providing a recombinant host cell that expresses a GPCR fusion protein comprising the amino acid sequence set forth in SEQ ID NO: 134 and a Gsa protein or an isolated membrane comprising said GPCR fusion protein; contacting a candidate compound with the recombinant host cell or isolated membrane; and measuring the ability of the compound to inhibit or stimulate functionality of the G protein-coupled receptor polypeptide portion of said GPCR fusion protein wherein inhibition or stimulation of said functionality indicates that the candidate compound is a modulator of the G protein- coupled receptor polypeptide.

43. A process for identifying a modulator of a G protein-coupled receptor (GPCR) comprising the steps of: providing a recombinant host cell that expresses a non-endogenous constitutively activated GPCR comprising an amino acid sequence selected from the group consisting of: a sequence comprising the amino acid sequence set forth in SEQ ID NO: 134; and (ii) a sequence encoding a constitutively activated variant of having an amino acid sequence identical or substantially identical to SEQ ID NO: 134 wherein the lysine residue at amino acid position 225 is unchanged or substituted with an amino acid other than isoleucine; contacting a candidate compound with the recombinant host cell or isolated membrane thereof; measuring the ability of the compound to modulate activity and/or expression of the G protein-coupled receptor polypeptide portion of said GPCR polypeptide wherein modulation of activity and/or expression indicates that the candidate compound is a modulator of the G protein-coupled receptor polypeptide; optionally, determining the structure of the compound; and providing the compound or modulator or the name or structure of the compound.

44. A process for identifying a modulator of a G protein-coupled receptor (GPCR) comprising the steps of: providing a recombinant host cell that expresses a GPCR comprising an amino acid sequence selected from the group consisting of: a sequence comprising the amino acid sequence set forth in SEQ ID NO: 134; and (ii) a sequence encoding a constitutively activated variant of having an amino acid sequence identical or substantially identical to SEQ ID NO: 134 wherein the lysine residue at amino acid position 225 is unchanged or substituted with an amino acid other than isoleucine; contacting a candidate compound with the recombinant host cell or isolated membrane; measuring the ability of the compound to modulate activity and/or expression of the G protein-coupled receptor polypeptide portion of said GPCR polypeptide wherein modulation of activity and/or expression indicates that the candidate compound is a modulator of the G protein-coupled receptor polypeptide; optionally, determining the structure of the compound; optionally, providing the name or structure of the compound; and producing or synthesizing the compound. A process for modulating the functionality of a G protein-coupled receptor (GPCR) comprising performing the method according to any one of claims 33 to 42 or the process of claim 43 or 44 to thereby identify or produce a modulator of the GPCR and then contacting the GPCR with the modulator or administering the modulator to a subject under conditions sufficient to modulate the functionality of the GPCR.

46. The method according to any one of claims 33 to 42 or the process according to any one of claims 43 to 45 wherein the compound comprises siRNA or shRNA comprising a nucleotide sequence derived from the nucleotide sequence encoding the GPCR.

47. The method according to any one of claims 33 to 42 or the process according to any one of claims 43 to 45 wherein the compound comprises antisense RNA that targets expression of the GPCR in a cell.

48. The method according to any one of claims 33 to 42 or the process according to any one of claims 43 to 45 wherein the compound comprises a peptide of at least about 4-10 amino acids in length derived from the amino acid sequence of the GPCR.

49. The method according to any one of claims 33 to 42 or the process according to any one of claims 43 to 45 wherein the compound is an antibody that binds to the GPCR.

50. The method according to any one of claims 33 to 42 or the process according to any one of claims 43 to 45 wherein the compound is a small molecule.

51. A process for identifying a compound that modulates signal transduction mediated by a G-protein coupled receptor in lymphoid tissue, said process comprising performing the method according to any one of claims 33 to 42 or the process according to any one of claims 43 to 45 in a cell from lymphoid tissue or a 293 cell or a 293T cell.

52. The process of claim 51 wherein the signal transduction mediated by a G-protein coupled receptor in the lymphoid tissue modulates thymocyte deletion.

53. The process of claim 51 wherein the signal transduction mediated by a G-protein coupled receptor in the lymphoid tissue modulates peripheral T-cell development.

54. The process of claim 52 wherein thymocyte deletion comprises the deletion of self-reactive immature T-cells in the thymus. The process of claim 51 wherein the signal transduction mediated by a G-protein coupled receptor in the lymphoid tissue modulates apoptosis of T cells.

56. A process for identifying a compound for delaying, preventing or reducing apoptosis of T cells or a condition associated with apoptosis of T cells said process comprising performing the method according to any one of claims 33 to 42 or the process according to any one of claims 43 to

57. A process for identifying a compound for delaying, preventing or reducing thymocyte deletion or a condition associated with thymocyte deletion said process comprising performing the method according to any one of claims 33 to 42 or the process according to any one of claims 43 to

58. A process for identifying a compound for modulating peripheral T cell development said process comprising performing the method according to any one of claims 33 to 42 or the process according to any one of claims 43 to

59. The isolated polynucleotide according to any one of claims 1 to 6 substantially as hereinbefore described with reference to the examples and/or drawings. The vector of claim 7 or 8 substantially as hereinbefore described with reference to the examples and/or drawings.

61. The recombinant host cell of claim 9 or 10 substantially as hereinbefore described with reference to the examples and/or drawings.

62. The method according to any one of claims 11 to 23 substantially as hereinbefore described with reference to the examples and/or drawings.

63. The isolated membrane according to any one of claims 24, 25, or 32 substantially as hereinbefore described with reference to the examples and/or drawings.

64. The isolated or recombinant non-endogenous, constitutively activated version of a human G protein-coupled receptor polypeptide according to any one of claims 26 to 28 substantially as hereinbefore described with reference to the examples and/or drawings. The isolated or recombinant GPCR fusion protein according to any one of claims 29 to 31 substantially as hereinbefore described with reference to the examples and/or drawings. 97

66. The method or process according to any one of claims 33 to 58 substantially as hereinbefore described with reference to the examples and/or drawings. Dated this THIRD day of JUNE 2004 Arena Pharmaceuticals, Inc. Patent Attorneys for the Applicant: F B RICE CO