The nonclassical insulin binding of insulin receptors from rat liver is due to the presence of two interacting alpha-subunits in the receptor complex.
The binding characteristics of the insulin receptor tetramer (alpha 2 beta 2) and dimer (alpha beta) were examined. Unlabelled insulin enhanced the dilution-induced dissociation only of the receptor tetramer-bound 125I-insulin. Furthermore, when both the receptor forms had been preincubated with anti-receptor-antibodies (B9-antiserum), insulin binding only to the receptor tetramer but not to the dimer was inhibited. However, both oligomers are not immunologically distinct since more than 80% of the two forms were immunoprecipitated by the antiserum. These results suggest that both insulin and anti-receptor-antibodies induce cooperative interactions between the two linked alpha-subunits of the receptor tetramer leading to a decrease in insulin binding of this receptor form.
D000345:Affinity Labels; D000818:Animals; D000906:Antibodies / Q000494:pharmacology; D011232:Chemical Precipitation; D007120:Immunochemistry; D007328:Insulin / Q000378:metabolism*; D008099:Liver / Q000378:metabolism*; D010446:Peptide Fragments / Q000378:metabolism; D010777:Photochemistry; D051381:Rats; D011919:Rats, Inbred Strains; D011972:Receptor, Insulin / Q000276:immunology / Q000378:metabolism*
D000345:Affinity Labels; D000906:Antibodies; D007328:Insulin; D010446:Peptide Fragments; D011972:Receptor, Insulin