title: The GIP receptor on pancreatic beta cell tumor: molecular identification by covalent cross-linking.
abstract: 125I-GIP binds reversibly to a high affinity binding site in crude plasma membranes prepared from a hamster pancreatic beta cell tumor. The treatment of labeled membranes with the cross-linker dithiobis (succinimidylpropionate) prevents, to a greater extent, the rapid dissociation of 125I-GIP-membrane complexes which is observed when 10(-6) M native GIP is added. Polyacrylamide gel electrophoresis of membrane proteins reveals a major 125I-GIP-protein complex of Mr 64,000. This labeling decreases when increasing concentrations (10(-9) -10(-6)M) of native GIP are added but is not altered by other peptide hormones (tested at 10(-6)M) including glucagon, VIP and insulin. The Mr 64,000 complex is not observed in tissues which have no specific binding sites for GIP such as intestinal epithelium. Assuming one molecule of 125I-GIP is bound per molecule of protein, one protein with Mr 59,000 is identified as the specific GIP binding site.
mesh_terms: D007516:Adenoma, Islet Cell / Q000378:metabolism*; D000818:Animals; D001667:Binding, Competitive; D006224:Cricetinae; D003432:Cross-Linking Reagents / Q000494:pharmacology; D007340:Insulinoma / Q000378:metabolism*; D008647:Mesocricetus; D008970:Molecular Weight; D010190:Pancreatic Neoplasms / Q000378:metabolism*; D011956:Receptors, Cell Surface / Q000378:metabolism*; D011964:Receptors, Gastrointestinal Hormone; D013388:Succinimides / Q000494:pharmacology
chemical_list: D003432:Cross-Linking Reagents; D011956:Receptors, Cell Surface; D011964:Receptors, Gastrointestinal Hormone; D013388:Succinimides; C041086:gastric inhibitory polypeptide receptor; C011240:dithiobis(succinimidylpropionate)