Discovery and mapping of ten novel G protein-coupled receptor genes

We report the identification, cloning and tissue distributions of ten novel human genes encoding G protein-coupled receptors (GPCRs) GPR78, GPR80, GPR81, GPR82, GPR93, GPR94, GPR95, GPR101, GPR102, GPR103 and a pseudogene, ψGPR79. Each novel orphan GPCR (oGPCR) gene was discovered using customized searches of the GenBank high-throughput genomic sequences database with previously known GPCR-encoding sequences. The expressed genes can now be used in assays to determine endogenous and pharmacological ligands. GPR78 shared highest identity with the oGPCR gene GPR26 (56% identity in the transmembrane (TM) regions). ψGPR79 shared highest sequence identity with the P2Y 2 gene and contained a frame-shift truncating the encoded receptor in TM5, demonstrating a pseudogene. GPR80 shared highest identity with the P2Y 1 gene (45% in the TM regions), while GPR81, GPR82 and GPR93 shared TM identities with the oGPCR genes HM74 (70%), GPR17 (30%) and P2Y 5 (40%), respectively. Two other novel GPCR genes, GPR94 and GPR95, encoded a subfamily with the genes encoding the UDP-glucose and P2Y 12 receptors (sharing >50% identities in the TM regions). GPR101 demonstrated only distant identities with other GPCR genes and GPR102 shared identities with GPR57, GPR58 and PNR (35–42% in the TM regions). GPR103 shared identities with the neuropeptide FF 2, neuropeptide Y2 and galanin GalR1 receptors (34–38% in the TM regions). Northern analyses revealed GPR78 mRNA expression in the pituitary and placenta and GPR81 expression in the pituitary. A search of the GenBank databases with the GPR82 sequence retrieved an identical sequence in an expressed sequence tag (EST) partially encoding GPR82 from human colonic tissue. The GPR93 sequence retrieved an identical, human EST sequence from human primary tonsil B-cells and an EST partially encoding mouse GPR93 from small intestinal tissue. GPR94 was expressed in the frontal cortex, caudate putamen and thalamus of brain while GPR95 was expressed in the human prostate and rat stomach and fetal tissues. GPR101 revealed mRNA transcripts in caudate putamen and hypothalamus. GPR103 mRNA signals were detected in the cortex, pituitary, thalamus, hypothalamus, basal forebrain, midbrain and pons.