Interaction of the monoclonal antibodies alpha IR-1 and alpha IR-3 with insulin and somatomedin-C receptors.
alpha IR-3, a monoclonal antibody that interacts with the somatomedin-C receptor, inhibited the binding of somatomedin-C, but not of insulin, to human placental membranes and intact IM-9 cells. alpha IR-1, a monoclonal antibody that interacts with the insulin receptor, did not inhibit the binding of either hormone. Inhibition of somatomedin-C binding by alpha IR-3 was mainly due to a decrease in its affinity. 125I-Labeled alpha IR-3 bound specifically to placental membranes and intact IM-9 cells and was inhibited by concentrations of unlabeled alpha IR-3 that were lower than those required to inhibit somatomedin-C binding. [125I]alpha IR-3 binding was also inhibited by somatomedin-C and insulin, but only at very high concentrations. A410, a rabbit antiserum that reacts with both receptors for insulin and somatomedin-C, also inhibited labeled alpha IR-3 binding. alpha IR-I did not. These results help to define the epitopes with which these antibodies interact.
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S
Jacobs
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Cook
M E
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Svoboda
J J
JJ
Van Wyk
D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology*; D001667:Binding, Competitive; D002462:Cell Membrane / Q000378:metabolism; D000939:Epitopes / Q000276:immunology; D005260:Female; D006801:Humans; D007328:Insulin / Q000378:metabolism; D007334:Insulin-Like Growth Factor I / Q000378:metabolism; D010920:Placenta / Q000378:metabolism; D011247:Pregnancy; D051381:Rats; D011972:Receptor, Insulin / Q000276:immunology* / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000276:immunology* / Q000378:metabolism; D017451:Receptors, Somatomedin
D000911:Antibodies, Monoclonal; D000939:Epitopes; D007328:Insulin; D011956:Receptors, Cell Surface; D017451:Receptors, Somatomedin; D007334:Insulin-Like Growth Factor I; D011972:Receptor, Insulin