Hamster gastric inhibitory polypeptide receptor expressed in pancreatic islets and clonal insulin-secreting cells: its structure and functional properties.

We have isolated a cDNA encoding a gastric inhibitory polypeptide (GIP) receptor from a hamster insulinoma (HIT-T15) cDNA library. The hamster GIP receptor is a 462 amino acid protein having seven transmembrane segments. Expression of recombinant of hamster GIP receptors in Chinese hamster ovary (CHO) cells shows that it binds specifically to GIP with high affinity (IC50 = 9.6 nM) and is positively coupled to adenylate cyclase, but not to phospholipase C. RNA blot analysis reveals that a 3.8-kb GIP receptor mRNA is expressed at high levels in rat pancreatic islets as well as in HIT-T15 cells.