Cloning and chromosomal localization of a gene (GPR18) encoding a novel seven transmembrane receptor highly expressed in spleen and testis.

Using the techniques of relaxed stringency polymerase chain reaction and genomic library screening, we have isolated homologous canine and human genes that encode a novel putative seven transmembrane G-protein-linked receptor. The gene encodes an open reading frame (ORF) of 993 bp. The sequences of the canine and human ORFs are highly conserved, sharing 89% nucleotide identity and 92% amino acid similarity between the two species. Northern blot analysis demonstrates that mRNA transcripts of the gene are abundantly expressed in testis and spleen with a lesser degree of expression observed in several other tissues associated with endocrine and immunologic/hematologic function. The gene, designated GPR18, was localized to human chromosome 13q32 using fluorescence in situ hybridization.