Methods and compositions for identifying receptor effectors

• US 20030166143A1
• Filed: 10/22/2002
• Published: 09/04/2003
• Est. Priority Date: 10/07/1998
• Status: Active Grant

• Current Assignee: Andrew J. Murphy, Christine A. Klein, Jeremy Paul
• Original Assignee: Andrew J. Murphy, Christine A. Klein, Jeremy Paul
• Inventors: Murphy, Andrew J., Paul, Jeremy, Klein, Christine A.
• Granted Patent: US 7,319,009 B2
• Time in Patent Office: Days
• US Class Current: 435/69.1
• CPC Class Codes: C07K 14/723 G protein coupled receptor, e.g. TSHR-thyrotropin-receptor, LH/hCG receptor, FSH receptor

Abstract

The present invention makes available rapid, effective assays for screening and identifying pharmaceutically effective compounds that specifically interact with and modulate the activity of a cellular receptor or ion channel. The subject assays enable rapid screening of large numbers of polypeptides in a library to identify those polypeptides which induce or antagonize receptor bioactivity. The subject assays are particularly amenable for identifying agonists and antagonists for orphan receptors. In particular the present invention makes available novel ligand agonists of human formyl peptide receptor like-1 (FPRL-1) receptors. These novel ligand agonists are used in the assays of the invention to identify modulators of FPRL-1 receptor.

Claims

1. A recombinant cell which comprises:

a heterologous formyl peptide receptor like-1 (FPRL-1) receptor expressed in the cell membrane of said cell such that signal transduction activity via said receptor is modulated by interaction of an extracellular region of the receptor with an extracellular signal; and

a ligand agonist of said FPRL-1 receptor comprising a polypeptide or analog thereof, wherein said ligand agonist is transported to a location allowing interaction with the extracellular region of said FPRL-1 receptor expressed in the cell membrane, and is expressed at a level sufficient for said ligand agonist to bind to and activate said FPRL-1 receptor, thereby causing a detectable signal to be generated.

2. The cell of claim 1, wherein said heterologous FPRL-1 receptor is coupled to a signal transduction pathway.

3. The cell of claim 1, wherein said heterologous FPRL-1 receptor acts as a surrogate for an endogenous cell receptor in a signal transduction pathway of the cell and wherein binding of said ligand agonist to said receptor activates the signal transduction activity of said receptor thereby generating a detectable signal.

4. The cell of claim 1, wherein said ligand agonist has an EC₅₀ of 2×

10<sup>−

5</sup>M or less and comprises a polypeptide comprising from 3 to 80 amino acid residues.

5. The cell of claim 4, wherein said polypeptide comprises from 3 to 40 amino acid residues.

6. The cell of claim 3 further comprising a reporter construct that is activated by the signal transduction pathway, wherein the detectable signal provided by said ligand agonist is mediated by the reporter construct.

7. The cell of claim 1, wherein said FPRL-1 receptor is associated with an indicator molecule which provides a detectable signal upon binding of said ligand agonist to said receptor.

8. The cell of claim 6, wherein said detectable signal is selected from the group consisting of a growth signal, intracellular calcium mobilization, an optical signal, second messenger production, changes in GTP hydrolysis, and phospholipid hydrolysis.

9. The cell of claim 7, wherein said indicator molecule comprises GFP or a β

-arrestin-GFP conjugate.

10. The cell of claim 1 further comprising a heterologous test polypeptide, wherein the heterologous test polypeptide is transported to a location allowing interaction with the extracellular region of said FPRL-1 receptor expressed in the cell membrane;

and wherein the heterologous test polypeptide is expressed at a sufficient level such that modulation of the signal transduction activity of the receptor by the heterologous test polypeptide alters said detectable signal.

11. The cell of claim 10, wherein said heterologous test polypeptide includes a signal sequence that facilitates transport of the polypeptide to a location allowing interaction with the extracellular region of the receptor.

12. The cell of claim 1, wherein said cell is a prokaryotic cell.

13. The cell of claims 1 or 3, wherein said cell is a eukaryotic cell

14. The cell of claim 13, wherein said eukaryotic cell is a yeast cell, and wherein said heterologous FPRL-1 receptor acts as a surrogate for an endogenous yeast pheromone receptor in a pheromone response pathway of said yeast cell.

15. The cell of claim 14, which belongs to the species Saccharomyces cerevisiae.

16. The cell of claim 1, wherein said heterologous FPRL-1 is human FPRL-1.

17. The cell of claim 5, wherein said ligand agonist comprises an amino acid sequence selected from the group consisting of SEQ ID NO:

1, SEQ ID NO;

2, SEQ ID NO;

3, SEQ ID NO;

4, SEQ ID NO;

5, and SEQ ID NO;

6, or an analog thereof.

18. A recombinant yeast cell which comprises:

a heterologous formyl peptide receptor like-1 (FPRL-1) receptor expressed in the cell membrane of said yeast cell such that signal transduction activity via said receptor is modulated by interaction of an extracellular region of the receptor with an extracellular signal; and

a ligand agonist of said FPRL-1 receptor, wherein said ligand agonist is transported to a location allowing interaction with the extracellular region of said FPRL-1 receptor expressed in the cell membrane, and is expressed at a level sufficient for said ligand agonist to bind to and activate said FPRL-1 receptor, thereby causing a detectable signal to be generated.

19. The yeast cell of claim 18, wherein said heterologous FPRL-1 receptor is coupled to a signal transduction pathway.

20. The yeast cell of claim 18, wherein said heterologous FPRL-1 receptor acts as a surrogate for an endogenous yeast pheromone receptor in a pheromone response pathway of the cell and wherein binding of said ligand agonist to said receptor activates the signal transduction activity of said receptor thereby generating a detectable signal.

21. The yeast cell of claim 18, wherein said ligand has an EC₅₀ of 2×

10<sup>−

5</sup>M or less and comprises a polypeptide comprising from 3 to 80 amino acid residues.

22. The yeast cell of claim 21, wherein said polypeptide comprises from 3 to 40 amino acid residues.

23. The yeast cell of claim 20 further comprising a reporter construct that is activated by the signal transduction pathway, wherein the detectable signal provided by said ligand agonist is mediated by the reporter construct.

24. The yeast cell of claim 18, wherein said FPRL-1 receptor is associated with an indicator molecule which provides a detectable signal upon binding of said ligand agonist to said receptor.

25. The yeast cell of claim 23 or 24, wherein said detectable signal is selected from the group consisting of a growth signal, intracellular calcium mobilization, an optical signal, second messenger production, changes in GTP hydrolysis, and phospholipid hydrolysis.

26. The yeast cell of claim 24, wherein said indicator molecule comprises—

GFP or a β

-arrestin-GFP conjugate.

27. The yeast cell of claim 20 further comprising a heterologous test polypeptide, wherein the heterologous test polypeptide is transported to a location allowing interaction with the extracellular region of said FPRL-1 receptor expressed in the cell membrane;

and wherein the heterologous test polypeptide is expressed at a sufficient level such that modulation of the signal transduction activity of the receptor by the heterologous test polypeptide alters said detectable signal.

28. The yeast cell of claim 20 further comprising a mutation in at least one gene selected from the group consisting of STP22, VPS1, KRE1, CAV1, STE50, SGV1, PIK1, AFR1, FAR1, SST2, BAR1, STE2, STE3, STE14, MFa1, and MFa2.

29. The yeast cell of claim 23, wherein said reporter construct comprises a pheromone-responsive promoter operably linked to a selectable gene.

30. The yeast cell of claim 29, wherein said pheromone-responsive promoter is the FUS1 promoter.

31. The yeast cell of claim 29, wherein said selectable gene is selected from the group consisting of URA3, LYS2, HIS3, LEU2, TRP1, ADE1, ADE2, ADE3, ADE4, ADE5, ADE7, ADE8, ARG1, ARG3, ARG4, ARG5, ARG6, ARG8, HIS1, HIS4, HIS5 ILV1, ILV2, ILV5, THR1, THR4, TRP2, TRP3, TRP4, TRP5, LACZ, LEU1, LEU4, MET2, MET3, MET4, MET8, MET9, MET14, MET16, MET19, URA1, URA2, URA4, URA5, URA10, H0M3, H0M6, ASP3, CHO1, ARO 2, ARO7, CYS3, OLE1, IN01, IN02, IN04, PR01, and PR03.

32. The yeast cell of claim 27, wherein said heterologous test polypeptide includes a signal sequence that facilitates transport of the polypeptide to a location allowing interaction with the extracellular region of the receptor.

33. The yeast cell of claim 27, wherein said signal sequence corresponds to a leader peptide of the Saccharomyces cerevisiae α

factor or a-factor.

34. The yeast cell of claim 20, which is a mutant strain of a yeast cell having a pheromone system pathway that is desensitized at slower rate than a wild type strain under the same conditions of continuous stimulation of the pheromone system pathway.

35. The yeast cell of claim 20, wherein said yeast cell has a ste14 mutation.

36. The yeast cell of claim 20, wherein said yeast cell has a ste2 or ste3 mutation.

37. The yeast cell of claim 20, which belongs to the species Saccharomyces cerevisiae.

38. The yeast cell of claim 18, wherein said ligand agonist is associated with an indicator molecule which provides a detectable signal upon binding of said ligand agonist to said receptor.

39. The yeast cell of claim 18, wherein said FPRL-1 receptor is human FPRL-1.

40. The yeast cell of claim 22, wherein said ligand agonist comprises an amino acid sequence selected from the group consisting of SEQ ID NO:

1, SEQ ID NO;

2, SEQ ID NO;

3, SEQ ID NO;

4, SEQ ID NO;

5, and SEQ ID NO;

6, or an analog thereof.

41. A method for identifying a modulator of a heterologous formyl peptide receptor like-1 (FPRL-1) receptor expressed by a cell, comprising:

providing a recombinant cell comprising;

a heterologous FPRL-1 receptor expressed in the cell membrane of said cell such that signal transduction activity via said receptor is modulated by interaction of an extracellular region of the receptor with an extracellular signal, said heterologous FPRL-1 receptor acting as a surrogate for an endogenous cell receptor in a signal transduction pathway of the cell; and

a ligand agonist of said FPRL-1 receptor comprising a polypeptide or analog thereof, wherein said ligand agonist is transported to a location allowing interaction with the extracellular region of said FPRL-1 receptor expressed in the cell membrane, and is expressed at a level sufficient for said ligand agonist to bind to and activate said FPRL-1 receptor, thereby activating the signal transduction activity of said FPRL-1 receptor and generating a detectable signal;

contacting said yeast cell with a test compound; and

detecting an alteration in said signal generated by said ligand agonist to thereby identify a modulator of said receptor.

42. The method of claim 41, wherein said recombinant cell is a recombinant yeast cell and wherein said heterologous FPRL-1 receptor acts as a surrogate for an endogenous yeast pheromone receptor in a pheromone response pathway of the yeast cell.

43. The method of claim 41, wherein said ligand agonist has an EC₅₀ of 2×

10<sup>−

5</sup> M or less and comprises a polypeptide comprising from 3 to 80 amino acid residues.

44. The method of claim 43, wherein said polypeptide comprises from 3 to 40 amino acid residues.

45. The method of claim 42, wherein said yeast cell further comprises a reporter construct that is activated by the pheromone response pathway, wherein the detectable signal provided by said ligand agonist is mediated by the reporter construct.

46. The method of claims 42, wherein said yeast cell further comprises a mutation in at least one gene selected from the group consisting of STP22, VPS1, KRE1, CAV1, STE50, SGV1, PIK1, AFR1, FAR1, SST2, BAR1, STE2, STE3, STE14, MFa1, and MFa2.

47. The method of claim 45, wherein said reporter construct, comprises a pheromone-responsive promoter operably linked to a selectable gene.

48. The method of claim 47, wherein said pheromone-responsive promoter is the FUS1 promoter.

49. The method of claim 47, wherein said selectable gene is selected from the group consisting of URA3, LYS2, HIS3, LEU2, TRP1, ADE1, ADE2, ADE3, ADE4, ADE5, ADE7, ADE8, ARG1, ARG3, ARG4, ARG5, ARG6, ARG8, HIS1, HIS4, HIS5 ILV1, ILV2, ILV5, THR1, THR4, TRP2, TRP3, TRP4, TRP5, LACZ, LEU1, LEU4, MET2, MET3, MET4, MET8, MET9, MET14, MET16, MET19, URA1, URA2, URA4, URA5, URA10, H0M3, H0M6, ASP3, CHO1, ARO 2, ARO7, CYS3, OLE1, IN01, IN02, IN04, PR01, and PR03.

50. The method of claim 42, wherein said detectable signal is selected from the group consisting of a growth signal, intracellular calcium mobilization, an optical signal, second messenger production, changes in GTP hydrolysis, and phospholipid hydrolysis.

51. The method of claim 42, wherein said yeast cell is a mutant strain having a pheromone system pathway that is desensitized at slower rate than a wild type strain under the same conditions of continuous stimulation of the pheromone system pathway.

52. The method of claim 42, wherein said yeast cell has a ste14 mutation.

53. The method of claim 42, wherein said yeast cell has a ste2 or ste3 mutation.

54. The method of claim 42, wherein said yeast cell belongs to the species Saccharomyces cerevisiae.

55. The method of claim 41, wherein said heterologous FPRL-1 receptor is human FPRL-1.

56. The method of claim 44, wherein said ligand agonist comprises an amino acid sequence selected from the group consisting of SEQ ID NO:

1, SEQ ID NO;

1, SEQ ID NO;

3, SEQ ID NO;

4, SEQ ID NO;

5, and SEQ ID NO;

6, or an analog thereof.

57. The method of claim 41, wherein said test compound is a non-peptidic compound.

58. The method of claim 41, wherein said test compound is a heterologous polypeptide.

59. The method of claim 41, wherein said test compound is a heterologous polypeptide expressed by said yeast cell.

60. The method of claim 41, wherein said modulator is an agonist of said FPRL-1 receptor.

61. The method of claim 41, wherein said modulator is an antagonist of said FPRL-1 receptor.

62. A method for identifying a modulator of a heterologous formyl peptide receptor like-1 (FPRL-1) receptor expressed by a cell, comprising:

providing a recombinant cell comprising;

a heterologous FPRL-1 receptor expressed in the cell membrane of said cell such that signal transduction activity via said receptor is modulated by interaction of an extracellular region of the receptor with an extracellular signal, said heterologous FPRL-1 receptor acting as a surrogate for an endogenous receptor in a signal transduction pathway of the cell; and

a ligand agonist of said FPRL-1 receptor comprising a polypeptide or analog thereof, wherein said ligand agonist is transported to a location allowing interaction with the extracellular region of said FPRL-1 receptor expressed in the cell membrane, and is expressed at a level sufficient for said ligand agonist to bind to and activate said FPRL-1 receptor, thereby activating the signal transduction activity of said FPRL-1 receptor and generating a detectable signal;

contacting said cell with each member of a library of test compounds; and

detecting an alteration in said signal generated by said ligand agonist to thereby identify a modulator of said receptor.

63. The method of claim 62, wherein said recombinant cell is a recombinant yeast cell and wherein said heterologous FPRL-1 receptor acts as a surrogate for an endogenous yeast pheromone receptor in a pheromone response pathway of the yeast cell.

64. The method of claim 62, wherein said ligand agonists has an EC₅₀ of 2×

10<sup>−

5</sup> M or less and comprises a polypeptide comprising from 3 to 80 amino acid residues.

65. The method of claim 64, wherein said polypeptide comprises from 3-40 amino acid residues.

66. The method of claim 63, wherein said yeast cell comprises a reporter construct that is activated by the pheromone response pathway, wherein the detectable signal provided by said ligand agonist is mediated by the reporter construct.

67. The method of claim 63, wherein said yeast cell further comprises a mutation in at least one gene selected from the group consisting of STP22, VPS1, KRE1, CAV1, STE50, SGV1, PIK1, AFR1, FAR1, SST2, BAR1, STE2, STE3, STE14, MFa1, and MFa2.

68. The method of claim 66, wherein said reporter construct comprises a pheromone-responsive promoter operably linked to a selectable gene.

69. The method of claim 68, wherein said pheromone-responsive promoter is the FUS1 promoter.

70. The method of claim 68, wherein said selectable gene is selected from the group consisting of URA3, LYS2, HIS3, LEU2, TRP1, ADE1, ADE2, ADE3, ADE4, ADE5, ADE7, ADE8, ARG1, ARG3, ARG4, ARG5, ARG6, ARG8, HIS1, HIS4, HIS5 ILV1, ILV2, ILV5, THR1, THR4, TRP2, TRP3, TRP4, TRP5, LEU1, LEU4, MET2, MET3, MET4, MET8, MET9, MET14, MET16, MET19, URA1, URA2, URA4, URA5, URA10, H0M3, H0M6, ASP3, CHO1, ARO 2, ARO7, CYS3, OLE1, IN01, IN02, IN04, PR01, and PR03.

71. The method of claim 63, wherein said detectable signal is selected from the group consisting of a growth signal, intracellular calcium mobilization, an optical signal, second messenger production, changes in GTP hydrolysis, and phospholipid hydrolysis.

72. The method of claim 63, wherein said yeast cell is a mutant strain having a pheromone system pathway that is desensitized at slower rate than a wild type strain under the same conditions of continuous stimulation of the pheromone system pathway.

73. The method of claim 63, wherein said yeast cell has a ste14 mutation.

74. The method of claim 63, wherein said yeast cell has a ste2 or ste3 mutation.

75. The method of claim 63, wherein said yeast cell belongs to the species Saccharomyces cerevisiae.

76. The method of claim 63, wherein said heterologous FPRL-1 receptor is human FPRL-1.

77. The method of claim 65, wherein said ligand agonist comprises an amino acid sequence selected from the group consisting of SEQ ID NO:

1, SEQ ID NO;

2, SEQ ID NO;

3, SEQ ID NO;

4, SEQ ID NO;

5, and SEQ ID NO;

6, or an analog thereof.

78. The method of claim 62, wherein said library of test compounds is a library of heterologous polypeptides and said library is expressed by said yeast cell.

79. The method of claim 62, wherein said test compound is a non-peptidic compound.

80. The method of claim 62, wherein said test compound is a heterologous polypeptide.

81. The method of claim 62, wherein said modulator is an agonist of said FPRL-1 receptor.

82. The method of claim 62, wherein said modulator is an antagonist of said FPRL-1 receptor.

83. A method for identifying a modulator of a heterologous formyl peptide receptor like-1 (FPRL-1) receptor expressed by a cell, comprising:

providing a mixture of recombinant cells, each cell of which has a cell membrane and comprises;

a heterologous formyl peptide receptor like-1 (FPRL-1) receptor expressed in the cell membrane of said cell such that signal transduction activity via said receptor is modulated by interaction of an extracellular region of the receptor with an extracellular signal, said heterologous FPRL-1 receptor acting as a surrogate for an endogenous cell receptor in a signal transduction pathway of the cell;

a ligand agonist of said FPRL-1 receptor comprising a polypeptide or analog thereof, wherein said ligand agonist is transported to a location allowing interaction with the extracellular region of said FPRL-1 receptor expressed in the cell membrane, and is expressed at a level sufficient for said ligand agonist to bind to and activate said FPRL-1 receptor, thereby activating the signal transduction activity of said FPRL-1 receptor and generating a detectable signal; and

a heterologous test polypeptide, wherein the heterologous test polypeptide is transported to a location allowing interaction with the extracellular region of said receptor expressed in the cell membrane;

wherein collectively the mixture of cells expresses a library of said heterologous test polypeptides, said library being expressible at a sufficient level such that modulation of the signal transduction activity of said receptor by a heterologous test polypeptide within the library alters the detectable signal generated by said ligand agonist; and

detecting an alteration in said signal generated by said ligand agonist to thereby identify a modulator of said receptor.

84. The method of claim 83, wherein said recombinant cell is a recombinant yeast cell and wherein said heterologous FPRL-1 receptor acts as a surrogate for an endogenous yeast pheromone receptor in a pheromone response pathway of the yeast cell.

85. The method of claim 83, wherein said ligand agonist has an EC₅₀ of 2×

10<sup>−

5</sup> M or less and comprises a polypeptide comprising from 3 to 80 amino acid residues.

86. The method of claim 85, wherein said polypeptide comprises from 3 to 40 amino acid residues.

87. The method of claim 84 wherein said yeast cell further comprises a reporter construct that is activated by the pheromone response pathway, wherein the detectable signal provided by said ligand agonist is mediated by the reporter construct.

88. The method of claim 84, wherein said yeast cell further comprises a mutation in at least one gene selected from the group consisting of STP22, VPS1, KRE1, CAV1, STE50, SGV1, PIK1, AFR1, FAR1, SST2, BAR1, STE2, STE3, STE14, MFa1, and MFa2.

89. The method of claim 87, wherein said reporter construct comprises a pheromone-responsive promoter operably linked to a selectable gene.

90. The method of claim 89, wherein said pheromone-responsive promoter is the FUS1 promoter.

91. The method of claim 89, wherein said selectable gene is selected from the group consisting of URA3, LYS2, HIS3, LEU2, TRP1, ADE1, ADE2, ADE3, ADE4, ADE5, ADE7, ADE8, ARG1, ARG3, ARG4, ARG5, ARG6, ARG8, HIS1, HIS4, HIS5 ILV1, ILV2, ILV5, THR1, THR4, TRP2, TRP3, TRP4, TRP5, LACZ, LEU1, LEU4, MET2, MET3, MET4, MET8, MET9, MET14, MET16, MET19, URA1, URA2, URA4, URA5, URA10, H0M3, H0M6, ASP3, CHO1, ARO 2, ARO7, CYS3, OLE1, IN01, IN02, IN04, PR01, and PR03.

92. The method of claim 83, wherein said detectable signal is selected from the group consisting of a growth signal, intracellular calcium mobilization, an optical signal, second messenger production, changes in GTP hydrolysis, and phospholipid hydrolysis.

93. The method of claim 84, wherein said heterologous test polypeptide includes a signal sequence that facilitates transport of the polypeptide to a location allowing interaction with the extracellular region of the receptor.

94. The method of claim 93, wherein said signal sequence corresponds to a leader peptide of the Saccharomyces cerevisiae α

factor or a-factor.

95. The method of claim 84, wherein said yeast cell is a mutant strain having a pheromone system pathway that is desensitized at slower rate than a wild type strain under the same conditions of continuous stimulation of the pheromone system pathway.

96. The method of claim 84, wherein said yeast cell has a ste14 mutation.

97. The method of claim 84, wherein said yeast cell has a ste2 or ste3 mutation.

98. The method of claim 84, wherein said yeast cell belongs to the species Saccharomyces cerevisiae.

99. The method of claim 83, wherein said heterologous FPRL-1 receptor is human FPRL-1.

100. The method of claim 86, wherein said ligand agonist comprises an amino acid sequence selected from the group consisting of SEQ ID NO:

1, SEQ ID NO;

2, SEQ ID NO;

3, SEQ ID NO;

4, SEQ ID NO;

5, and SEQ ID NO;

6, or analog thereof.

101. The method of claim 83, wherein said modulator is an agonist of said FPRL-1 receptor.

102. The method of claim 83, wherein said modulator is an antagonist of said FPRL-1 receptor.

103. A method for identifying a modulator of a heterologous formyl peptide receptor like-1 (FPRL-1) receptor expressed by a cell, comprising:

providing a first mixture of recombinant cells, each cell of which has a cell membrane and comprises;

a heterologous formyl peptide receptor like-1 (FPRL-1) receptor expressed in the cell membrane of said cell such that signal transduction activity via said receptor is modulated by interaction of an extracellular region of the receptor with an extracellular signal, said heterologous FPRL-1 receptor acting as a surrogate for an endogenous cell receptor in a signal transduction pathway of the cell; and

a ligand agonist of said FPRL-1 receptor comprising a polypeptide or analog thereof, wherein said ligand agonist is transported to a location allowing interaction with the extracellular region of said FPRL-1 receptor expressed in the cell membrane, and is expressed at a level sufficient for said ligand agonist to bind to and activate said FPRL-1 receptor, thereby activating the signal transduction activity of said FPRL-1 receptor and generating a detectable signal;

contacting said first mixture with a second mixture of cells, wherein collectively the second mixture of cells expresses a library of heterologous test polypeptides that are transported to a location allowing interaction with the extracellular region of the FPRL-1 receptor expressed in the cell membrane of the cells of the first mixture; and

detecting an alteration by a heterologous test polypeptide of said signal generated by said ligand agonist to thereby identify a modulator of said receptor.

104. The method of claim 103, wherein said recombinant cell is a recombinant yeast cell and wherein said heterologous FPRL-1 receptor acts as a surrogate for an endogenous yeast pheromone receptor in a pheromone response pathway of the yeast cell.

105. The method of claim 103, wherein said ligand agonist has an EC₅₀ of 2×

10<sup>−

5</sup> M or less and comprises a polypeptide comprising from 3 to 80 amino acid residues.

106. The method of claim 105, wherein said polypeptide comprises from 3-40 amino acid residues.

107. The method of claim 104, wherein said yeast cell further comprises a reporter construct that is activated by the pheromone response pathway, wherein the detectable signal provided by said ligand agonist is mediated by the reporter construct.

108. The method of claim 104, wherein said yeast cell further comprises a mutation in at least one gene selected from the group consisting of STP22, VPS1, KRE1, CAV1, STE50, SGV1, PIK1, AFR1, FAR1, SST2, BAR1, STE2, STE3, STE14, MFa1, and MFa2.

109. The method of claim 107, wherein said reporter construct comprises a pheromone-responsive promoter operably linked to a selectable gene.

110. The method of claim 109, wherein said pheromone-responsive promoter is the FUS1 promoter.

111. The method of claim 109, wherein said selectable gene is selected from the group consisting of URA3, LYS2, HIS3, LEU2, TRP1, ADE1, ADE2, ADE3, ADE4, ADE5, ADE7, ADE8, ARG1, ARG3, ARG4, ARG5, ARG6, ARG8, HIS1, HIS4, HIS5 ILV1, ILV2, ILV5, THR1, THR4, TRP2, TRP3, TRP4, TRP5, LACZ, LEU1, LEU4, MET2, MET3, MET4, MET8, MET9, MET14, MET16, MET19, URA1, URA2, URA4, URA5, URA10, H0M3, H0M6, ASP3, CHO1, ARO 2, ARO7, CYS3, OLE1, IN01, IN02, IN04, PR01, and PR03.

112. The method of claim 103, wherein said detectable signal is selected from the group consisting of a growth signal, intracellular calcium mobilization, an optical signal.

113. The method of claim 104, wherein said heterologous test polypeptide includes a signal sequence that facilitates transport of the polypeptide to a location allowing interaction with the extracellular region of the receptor.

114. The method of claim 113, wherein said signal sequence corresponds to a leader peptide of the Saccharomyces cerevisiae α

factor or a-factor.

115. The method of claim 104, wherein said yeast cell is a mutant strain having a pheromone system pathway that is desensitized at slower rate than a wild type strain under the same conditions of continuous stimulation of the pheromone system pathway.

116. The method of claim 104, wherein said yeast cell has a ste14 mutation.

117. The method of claim 104, wherein said yeast cell has a ste2 or ste3 mutation.

118. The method of claim 104, wherein said yeast cell belongs to the species Saccharomyces cerevisiae.

119. The method of claim 103, wherein said heterologous FPRL-1 receptor is human FPRL-1.

120. The method of claim 106, wherein said ligand agonist comprises an amino acid sequence selected from the group consisting of SEQ ID NO:

1, SEQ ID NO;

2, SEQ ID NO;

3, SEQ ID NO;

4, SEQ ID NO;

5, and SEQ ID NO;

6, or an analog thereof.

121. The method of claim 103, wherein said modulator is an agonist of said FPRL-1 receptor.

122. The method of claim 103, wherein said modulator is an antagonist of said FPRL-1 receptor.

123. A method for identifying a modulator of a heterologous formyl peptide receptor like-1 (FPRL-1) receptor expressed by a cell, comprising:

providing a recombinant cell comprising a heterologous FPRL-1 receptor expressed in the cell membrane of said cell such that signal transduction activity via said receptor is modulated by interaction of an extracellular region of the receptor with an extracellular signal; and

contacting said recombinant cell with a ligand agonist of said FPRL-1 receptor, said ligand agonist comprising a polypeptide, or analog thereof, to permit said ligand agonist to bind to and activate said FPRL-1 receptor, thereby activating the signal transduction activity of said FPRL-1 receptor and generating a detectable signal;

contacting said cell with a test compound; and

detecting an alteration in said signal generated by said ligand agonist to thereby identify a modulator of said receptor.

124. The method of claim 123, wherein said ligand agonist has an EC₅₀ of 2×

10<sup>−

5</sup> M or less and comprises a polypeptide comprising from 3 to 80 amino acid residues.

125. The method of claim 124, wherein said polypeptide comprises from 3 to 40 amino acid residues.

126. The method of claim 123, wherein said heterologous FPRL-1 receptor is coupled to a signal transduction pathway.

127. The method of claim 123, wherein said heterologous FPRL-1 receptor acts as a surrogate for an endogenous cell receptor in a signal transduction pathway of the cell and wherein binding of said ligand agonist to said receptor activates the signal transduction activity of said receptor thereby generating a detectable signal.

128. The method of claim 123, wherein said recombinant cell is a recombinant yeast cell and wherein said heterologous FPRL-1 receptor acts as a surrogate for an endogenous yeast pheromone receptor in a pheromone response pathway of the yeast cell.

129. The method of claim 126, wherein said cell comprises a reporter construct that is activated by the signal transduction pathway, wherein the detectable signal provided by said ligand agonist is mediated by the reporter construct.

130. The method of claim 128, wherein said yeast cell further comprises a reporter construct that is activated by the pheromone response pathway, wherein the detectable signal provided by said ligand agonist is mediated by the reporter construct.

131. The method of claim 123, wherein said FPRL-1 receptor is associated with a first indicator molecule which provides a detectable signal resulting from binding of said ligand agonist to said receptor.

132. The method of claim 131, wherein said ligand agonist is associated with a second indicator molecule which provides a detectable signal resulting from binding of said ligand agonist to said receptor.

133. The method of claims 131 or 132, wherein said indicator molecule comprises GFP or a β

-arrestin-GFP conjugate.

134. The method of claim 132, wherein said first and second indicator molecules comprise fluorescent indicator molecules, and said detectable signal comprises fluorescent resonance energy transfer between said first and second fluorescent indicator molecules.

135. The method of claim 134, wherein said first and second fluorescent indicator molecules comprise GFP.

136. The method of claims 129 or 130, wherein said detectable signal is selected from the group consisting of a growth signal, intracellular calcium mobilization, an optical signal, second messenger production, changes in GTP hydrolysis, and phospholipid hydrolysis.

137. The method of claim 128, wherein said yeast cell belongs to the species Saccharomyces cerevisiae.

138. The method of claim 123, wherein said heterologous FPRL-1 is human FPRL-1.

139. The method of claim 125, wherein said ligand agonist comprises an amino acid sequence selected from the group consisting of SEQ ID NO:

1, SEQ ID NO;

2, SEQ ID NO;

3, SEQ ID NO;

4, SEQ ID NO;

5, and SEQ ID NO;

6, or an analog thereof.

140. The method of claim 128, wherein said yeast cell further comprises a mutation in at least one gene selected from the group consisting of STP22, VPS1, KRE1, CAV1, STE50, SGV1, PIK1, AFR1, FAR1, SST2, BAR1, STE2, STE3, STE14, MFa1, and MFa2.

141. The method of claim 130, wherein said reporter construct comprises a pheromone-responsive promoter operably linked to a selectable gene.

142. The method of claim 141, wherein said pheromone-responsive promoter is the FUS1 promoter.

143. The method of claim 141, wherein said selectable gene is selected from the group consisting of URA3, LYS2, HIS3, LEU2, TRP1, ADE1, ADE2, ADE3, ADE4, ADE5, ADE7, ADE8, ARG1, ARG3, ARG4, ARG5, ARG6, ARG8, HIS1, HIS4, HIS5 ILV1, ILV2, ILV5, THR1, THR4, TRP2, TRP3, TRP4, TRP5, LACZ, LEU1, LEU4, MET2, MET3, MET4, MET8, MET9, MET14, MET16, MET19, URA1, URA2, URA4, URA5, URA10, H0M3, H0M6, ASP3, CHO1, ARO 2, ARO7, CYS3, OLE1, IN01, IN02, IN04, PR01, and PR03.

144. The method of claim 128, wherein said yeast cell is a mutant strain having a pheromone system pathway that is desensitized at slower rate than a wild type strain under the same conditions of continuous stimulation of the pheromone system pathway.

145. The method of claim 128, wherein said yeast cell has a ste14 mutation.

146. The method of claim 128, wherein said yeast cell has a ste2 or ste3 mutation.

147. The method of claim 123, wherein said test compound is a non-peptidic compound.

148. The method of claim 123, wherein said test compound is a heterologous polypeptide.

149. The method of claim 123, wherein said test compound is a heterologous polypeptide expressed by said yeast cell.

150. The method of claim 123, wherein said modulator is an agonist of said FPRL-1 receptor.

151. The method of claim 123, wherein said modulator is an antagonist of said FPRL-1 receptor.

152. A method for identifying a modulator of a heterologous formyl peptide receptor like-1 (FPRL-1) receptor expressed in the membrane of a cell, said method comprising:

contacting said cell with a a ligand agonist of said FPRL-1 receptor, said ligand agonist comprising a polypeptide, or analog thereof, in the presence of a test compound under conditions to permit binding of said ligand agonist to said receptor; and

determining the inhibition by said test compound of binding of said ligand agonist to said receptor, by assessing the amount of said ligand agonist bound to said receptor, such that reduction of binding of said ligand agonist to said receptor identifies said test compound as a modulator of said receptor.

153. The method of claim 152, wherein said FPRL-1 receptor is associated with a first indicator molecule which provides a detectable signal upon binding of said ligand agonist to said receptor.

154. The method of claim 153, wherein said ligand agonist is associated with a second indicator molecule which provides a detectable signal upon binding of said ligand agonist to said receptor.

155. The method of claims 153 or 154, wherein said indicator molecule comprises GFP or a β

-arrestin-GFP conjugate.

156. The method of claim 154, wherein said first and second indicator molecules comprise fluorescent indicator molecules, and said detectable signal comprises fluorescent resonance energy transfer between said first and second fluorescent indicator molecules.

157. The method of claim 156, wherein said first and second fluorescent indicator molecules comprise GFP.

158. The method of claim 152, wherein said ligand agonist has an EC₅₀ of 2×

10<sup>−

5</sup>M or less and comprises a polypeptide comprising from 3 to 80 amino acid residues.

159. The method of claim 158, wherein said polypeptide comprises from 3 to 40 amino acid residues.

160. The method of claim 152, wherein said cell is a prokaryotic cell.

161. The method of claim 152, wherein said cell is a eukaryotic cell.

162. The method of claim 161, wherein said eukaryotic cell is a yeast cell.

163. The method of claim 162, which belongs to the species Saccharomyces cerevisiae.

164. The method of claim 152, wherein said heterologous FPRL-1 is human FPRL-1.

165. The method of claim 159, wherein said ligand agonist comprises an amino acid sequence selected from the group consisting of SEQ ID NO:

1, SEQ ID NO;

2, SEQ ID NO;

3, SEQ ID NO;

4, SEQ ID NO;

5, and SEQ ID NO;

6, or an analog thereof.

166. The method of claim 152, wherein said test compound is a non-peptidic compound.

167. The method of claim 152, wherein said test compound is a heterologous polypeptide.

168. The method of claim 152, wherein said test compound is a heterologous polypeptide expressed by said yeast cell.

169. The method of claim 152, wherein said modulator is an agonist of said FPRL-1 receptor.

170. The method of claim 152, wherein said modulator is an antagonist of said FPRL-1 receptor.

171. A method for identifying a modulator of a heterologous formyl peptide receptor like-1 (FPRL-1) receptor expressed by a cell, comprising:

providing a first mixture of recombinant cells, each cell of which has a cell membrane and comprises;

a heterologous FPRL-1 receptor expressed in the cell membrane of said cell such that signal transduction activity via said receptor is modulated by interaction of an extracellular region of the receptor with an extracellular signal, said heterologous FPRL-1 receptor acting as a surrogate for an endogenous cell receptor in a signal transduction pathway of the cell; and

contacting said first mixture of recombinant cells with a ligand agonist of said FPRL-1 receptor comprising a polypeptide, or analog thereof, to permit said ligand agonist to bind to and activate said FPRL-1 receptor, thereby activating the signal transduction activity of said FPRL-1 receptor and generating a detectable signal;

contacting said first mixture with a second mixture of cells, wherein collectively the second mixture of cells expresses a library of heterologous test polypeptides that are transported to a location allowing interaction with the extracellular region of the FPRL-1 receptor expressed in the cell membrane of the cells of the first mixture; and

detecting an alteration in said signal generated by said ligand agonist to thereby identify a modulator of said receptor.

172. The method of claim 171, wherein said recombinant cell is a recombinant yeast cell and wherein said heterologous FPRL-1 receptor acts as a surrogate for an endogenous yeast pheromone receptor in a pheromone response pathway of the yeast cell.

173. The method of claim 172, wherein said ligand agonist has an EC₅₀ of 2×

10<sup>−

5</sup> M or less and comprises a polypeptide comprising from 3 to 80 amino acid residues.

174. The method of claim 172, wherein said yeast cell further comprises a reporter construct that is activated by the pheromone response pathway, wherein the detectable signal provided by said ligand agonist is mediated by the reporter construct.

175. A ligand agonist of formyl peptide receptor like-1 (FPRL-1) receptor comprising a polypeptide or analog thereof, said polypeptide comprising from 3 to 80 amino acid residues, wherein said ligand agonist binds to and activates said FPRL-1 receptor, and has an EC₅₀ of 2×

10<sup>−

5</sup> M or less.

176. A ligand agonist of formyl peptide receptor like-1 receptor comprising the amino acid sequence of SEQ ID NO:

1 or analog thereof.

177. A ligand agonist of formyl peptide receptor like-1 receptor comprising the amino acid sequence of SEQ ID NO:

2 or analog thereof.

178. A ligand agonist of formyl peptide receptor like-1 receptor comprising the amino acid sequence of SEQ ID NO:

3 or analog thereof.

179. A ligand agonist of formyl peptide receptor like-1 receptor comprising the amino acid sequence of SEQ ID NO:

4 or analog thereof.

180. A ligand agonist of formyl peptide receptor like-1 receptor comprising the amino acid sequence of SEQ ID NO:

5 or analog thereof.

181. A ligand agonist of formyl peptide receptor like-1 receptor comprising the amino acid sequence of SEQ ID NO:

6 or analog thereof.