Insulin receptors: differences in structural organization on adipocyte and liver plasma membranes.

Comparison was made of the distribution of the insulin receptor sites on adipocyte and liver plasma membranes by using ferritin-insulin. Two-thirds of the occupied insulin receptors on adipocytes occurred in groups of two or more whereas up to two-thirds of the receptors on liver occurred as single receptors. Ferritin-insulin did not cause aggregation of the receptor sites in either tissue. The naturally occurring groups of receptors on adipocyte membranes may play a role in the greater sensitivity of adipocytes to insulin.