ABSTRACT
Aim To establish a screening system of orphan G protein-coupled receptors (oGPCRs) for their ligands based on monitoring [Ca 2+]_i in engineered cells. Methods The whole ORF of a member of human oGPCR, designated human G-protein-coupled receptor c (hGPCRc), was amplified by RT-PCR from human colon tissue and its structure was analyzed with softwares. CHO-K_1 cells were transfected with the recombinant pcDNA 3.1(+)-hGPCRc to obtain engineered CHO-hGPCRc cells. As fluorescence probe, Fluo-3 was used in assaying the [Ca 2+]_i changes induced by different compounds in the CHO- hGPCRc cells.Results Bioinformatic analysis showed that hGPCRc was localized at 13q32.2, and its corresponding amino acids formed seven-transmembrane domains and was close to human P2Y_1 receptor. It was indicated that hGPCRc was a new member of human GPCR. CHO- hGPCRc cells expressing hGPCRc were obtained successfully but no one was able to activate hGPCRc among the tested compounds indicated by the [Ca 2+]_i changes. Conclusion Although hGPCRc was even though close to human P2Y_1 receptor, it can not be activated by the known compounds which activate the P2Y_1 receptor. hGPCRc might be a new member of purine receptor family but dose not belong to P2Y_1 subfamily.