Identification and characterization of a novel RF-amide peptide ligand for orphan G-protein-coupled receptor SP9155.
Orphan G-protein-coupled receptors are a large class of receptors whose cognate ligands are unknown. SP9155 (also referred to as AQ27 and GPR103) is an orphan G-protein-coupled receptor originally cloned from a human brain cDNA library. SP9155 was found to be predominantly expressed in brain, heart, kidney, retina, and testis. Phylogenetic analysis shows that SP9155 shares high homology with Orexin, NPFF, and cholecystokinin (CCK) receptors, but identification of the endogenous ligand for SP9155 has not been reported. In this study, we have used a novel method to predict peptides from genome data bases. From these predicted peptides, a novel RF-amide peptide, P52 was shown to selectively activate SP9155-transfected cells. We subsequently cloned the precursor gene of the P52 ligand and characterized the activity of other possible peptides encoded by the precursor. This revealed an extended peptide, P518, which exhibited high affinity for SP9155 (EC50 = 7 nm). mRNA expression analysis revealed that the peptide P518 precursor gene is predominantly expressed in various brain regions, coronary arteries, thyroid and parathyroid glands, large intestine, colon, bladder, testes, and prostate. These results indicate the existence of a novel RF-amide neuroendocrine peptide system, and suggest that SP9155 is likely the relevant G-protein-coupled receptor for this peptide.
Jiang
Ying
Y
Department of Discovery Technology, Schering-Plough Research Institute, Kenilworth, New Jersey 07033, USA.
Luo
Lin
L
Gustafson
Eric L
EL
Yadav
Deepmala
D
Laverty
Maureen
M
Murgolo
Nicholas
N
Vassileva
Galya
G
Zeng
Ming
M
Laz
Thomas M
TM
Behan
Jiang
J
Qiu
Ping
P
Wang
Luquan
L
Wang
Suke
S
Bayne
Marvin
M
Greene
Jonathan
J
Monsma
Frederick
F
Zhang
Fang L
FL
D000465:Algorithms; D000595:Amino Acid Sequence; D000818:Animals; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D019204:GTP-Binding Proteins / Q000378:metabolism*; D015723:Gene Library; D006801:Humans; D008024:Ligands; D051379:Mice; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry*; D010802:Phylogeny; D011485:Protein Binding; D011956:Receptors, Cell Surface / Q000737:chemistry* / Q000378:metabolism* / Q000502:physiology*; D043562:Receptors, G-Protein-Coupled; D017386:Sequence Homology, Amino Acid; D014018:Tissue Distribution
D018076:DNA, Complementary; D008024:Ligands; D010455:Peptides; C476582:QRFPR protein, human; C476583:Qrfpr protein, mouse; D011956:Receptors, Cell Surface; D043562:Receptors, G-Protein-Coupled; D019204:GTP-Binding Proteins