Molecular cloning and characterization of a novel Gq-coupled orphan receptor GPRg1 exclusively expressed in the central nervous system

G-protein-coupled receptors (GPCRs) are important mediators of signal transduction and are therefore potential targets for pharmacological therapeutics. Here, we report the identification and characterization of an orphan GPCR, termed GPRg1, which was found in the GenBank database following searches with GPCR query sequences. Quantitative PCR analysis revealed that GPRg1 transcripts are expressed almost exclusively in the brain. Moreover, in situ hybridization experiments in brain demonstrated that GPRg1 is abundantly expressed in the ventrolateral region of caudate putamen, the habenular nucleus, the zona incerta, and the medial mammillary nucleus. In addition, overexpression of GPRg1 in 293-EBNA cells activates serum response factor mediated transcription, which was completely inhibited by the Gq/11 selective inhibitor YM-254890, indicating the coupling of GPRg1 with Gq/11. These findings suggest that GPRg1 is a candidate receptor for novel physiologically bioactive substrates and that it plays important roles in the central nervous system.