Cloning of GPR37, a gene located on chromosome 7 encoding a putative g- protein-coupled peptide receptor, from a human frontal brain EST library

A cDNA sequence encoding a putative peptide-specific G-protein-coupled receptor (GPR37) was isolated from a set of human brain frontal lobe expressed sequence tags. The GPR37 cDNA predicts a single open reading frame coding for a 613-amino-acid protein with seven hydrophobic transmembrane domains. The GPR37 genomic sequence was mapped to chromosome 7q31, and it was isolated upon screening of a chromosome 7-specific genomic library. The GPR37 gene spans more than 25 kb and contains two exons and a single intron which interrupts the GPR37 cDNA within the sequence encoding the presumed third transmembrane domain. Northern blot analysis with GPR37 probes revealed a main 3.8-kb mRNA and a less abundant 8-kb mRNA, both expressed in human brain tissues, particularly in corpus callosum, medulla, putamen, and caudate nucleus. The lowest level of expression was detected in cerebellum. The 3.8- kb mRNA is also less abundantly expressed in liver and placenta. Although the ligand for the putative GPR37 receptor has not been identified, its deduced amino acid sequence shows a high degree of homology (~40% in the transmembrane regions) with most mammalian peptide-specific G-protein- coupled receptors and particularly with the human endothelin-B bombesin-BB1, and bombesin-BB2 receptors.