G-protein coupled receptor 39 is a protein that in humans is encoded by the GPR39 gene. The predicted 453-amino acid GPR39 protein contains the 7 transmembrane domains characteristic of GPCRs. By sequence comparison with other GPCRs, the protein sequence of GPR39 is 27% and 32% identical to that of GSHR and neurotensin receptor-1, respectively. Northern blot analysis revealed that GPR39 is expressed widely as a 1.8- to 2-kb mRNA. A 3-kb transcript is present on Northern blots of some tissues, either in addition to the smaller mRNA or as the only hybridizing band.