title: Degradation, receptor binding affinity and biological potency of monoiodoinsulin in isolated rat fat cells.
abstract: The degradation, binding affinity and biological potency of monoiodoinsulin was studied in isolated rat fat cells. The rate of inactivation by a concentrated cell suspension was indistinguishable from that of native insulin, whereas the relative biological potency (increase in lipid synthesis from glucose) and binding affinity (inhibition of receptor binding of 125 I-labelled insulin) was 60-80%. Assuming that the insulin receptor binding is a simple, reversible, bimolecular reaction, the following are the consequences for the interpretation of experiments at equilibrium in which an unlabelled species of insulin competes with (125I) monoiodoinsulin present in a concentration much below the dissociation constant for the insulin: 1. The dissociation constant is estimated without bias. 2. The total number of receptors is slightly underestimated.
mesh_terms: D000273:Adipose Tissue / Q000378:metabolism*; D000818:Animals; D066298:In Vitro Techniques; D007328:Insulin / Q000031:analogs & derivatives* / Q000378:metabolism; D007457:Iodine Radioisotopes; D007700:Kinetics; D051381:Rats; D011972:Receptor, Insulin / Q000378:metabolism*
chemical_list: D007328:Insulin; D007457:Iodine Radioisotopes; D011972:Receptor, Insulin