A cDNA encoding a novel member of the G-protein-coupled receptor (GCR) superfamily. an ATP receptor, has been isolated from an embryonic chtck whole brain cDNA hbrary by hybridizatton screenmg. The encoded protein has a sequence of 362 amino acids (41 kDa) and shares no more than 27% amino acid identity with any known GCR. When expressed as a complementary RNA (cRNA) m Xenopus oocytes a slowly-developing inward current was observed in response to application of ATP. The pharmacology of this expressed protem defines it as a PZv purinoceptor.