The ligand binding subunit of the insulin-like growth factor 1 receptor has properties of a peripheral membrane protein.
125I-insulin-like growth factor 1 was cross-linked to its receptor in human placenta microsomal membranes. The microsomes were treated with urea, with dithiothreitol or with both reagents prior to centrifugation at 100,000 X g. We found that greater than 80% of the label was membrane-associated following separate treatment with urea or dithiothreitol, but greater than 80% of the radioactivity remained in the supernatant after simultaneous exposure to both reagents. In identical experiments employing 125I-epidermal growth factor, no condition led to the release of greater than 10% of label from the membrane. We conclude that the ligand binding subunit of the insulin-like growth factor 1 receptor, like peripheral membrane proteins, lacks a membrane anchoring domain.
D004229:Dithiothreitol / Q000494:pharmacology; D005260:Female; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000378:metabolism; D046911:Macromolecular Substances; D008565:Membrane Proteins / Q000378:metabolism*; D008861:Microsomes / Q000378:metabolism; D008970:Molecular Weight; D010920:Placenta / Q000378:metabolism / Q000648:ultrastructure; D011247:Pregnancy; D011956:Receptors, Cell Surface / Q000378:metabolism*; D017451:Receptors, Somatomedin; D014508:Urea / Q000378:metabolism
D046911:Macromolecular Substances; D008565:Membrane Proteins; D011956:Receptors, Cell Surface; D017451:Receptors, Somatomedin; D007334:Insulin-Like Growth Factor I; D014508:Urea; D004229:Dithiothreitol