Purification and properties of the human placental insulin receptor.
Human placenta insulin receptor was purified 11,000-fold to near homogeneity using DEAE-cellulose chromatography and affinity chromatography on insulin-Sepharose. Approximately 200 to 300 micrograms of purified receptor were obtained from a single placenta. In solution, the native receptor is a complex (Mr = 440,000) of an acidic, multi-subunit protein with a Mr of 350,000 and bound detergent accounting for the remainder of the mass. The receptor protein is asymmetric (f/f0 = 1.4) and consists of a single Coomassie blue staining polypeptide of Mr = 135,000. In addition to the 135,000-dalton polypeptide, two smaller polypeptides of Mr = 45,000 and 90,000 were observed upon autoradiography of 125I-labeled receptor subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis. These two smaller polypeptides did not stain with Coomassie blue but migrated with native receptor activity on isoelectric focusing gels and were coimmunoprecipitated with the 135,000-dalton polypeptide by anti-insulin receptor antibody. The 135,000-dalton subunit was specifically labeled by 125I-insulin using the bifunctional cross-linking reagent disuccinimidyl suberate (P. F. Pilch, and M. P. Czech, (1979) J. Biol. Chem. 254, 3375-3381), suggesting that this component contains the insulin binding domain.
D001667:Binding, Competitive; D002462:Cell Membrane / Q000378:metabolism; D005260:Female; D006801:Humans; D007328:Insulin / Q000031:analogs & derivatives / Q000378:metabolism; D007700:Kinetics; D046911:Macromolecular Substances; D008970:Molecular Weight; D010920:Placenta / Q000378:metabolism*; D011247:Pregnancy; D011487:Protein Conformation; D011972:Receptor, Insulin / Q000302:isolation & purification* / Q000378:metabolism
D007328:Insulin; D046911:Macromolecular Substances; C008147:insulin, iodo-; D011972:Receptor, Insulin