Apr 10, 1976

Site-site interactions among insulin receptors. Characterization of the negative cooperativity

The Journal of Biological Chemistry
P DeMeytsJ Roth

Abstract

By studying the dissociation of 125I-instulin from its receptors in the absence and phe negatively cooperative type for the insulin receptors. In the present study we extend oy purified mouse and rat liver membranes as well as in human circulating monocytes and human cultured lymphocytes demonstrated negative cooperativity that was extraordinarily simn membranes more slowly than it does from its receptors on whole cells. The dissociaty a small percentage of the receptor sites (1 to 5%), are sufficient to accelerate dissociation of hormone from receptor. At these insulin concentrations insulin is entirely monomeric, and in fact at higher concentrations of insulin (greater than 10(-7) M) where insulin dimers predominate, the cooperativity effect is progressively lost. The dissociation rate of 125I-insulin alone (that is at very low fractional saturation of receptors) was markedly accelerated by dripping the pH from 8.0 to 5.0, whereas the dissociation of 125I-insulin at high receptor occupancy was only slightly accelerated by the fall in pH. The dissociation rate was directly related to temperature, but the dissociation rate of 125I-insulin at low receptor occupancy was much more affected by reduction in temperature and showed a ...Continue Reading

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Mentioned in this Paper

Cations, Divalent
Tissue Membrane
Lymphocytes as Percentage of Blood Leukocytes (Lab Test)
Carmol
Hormone Receptors, Cell Surface
Lymphoid Cells
Insr
INSR
Iodopeptides
Plasma Protein Binding Capacity

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