Binding and degradation of 125I-insulin in human erythrocytes. Comparative studies with hemolysate and membranes.

Insulin degradation in human erythrocytes obtained from normal subjects is studied. Under the experimental conditions used, insulin binding and insulin degradation are strictly correlated, and no degrading activity is released in incubation medium. Comparative analysis of hemolysate and membranes shows that hemolysate possesses a definite insulin-degrading activity which is not linked to the hemoglobin molecule; the km of this enzymatic activity is of the same order of magnitude as that reported in other cells. At the concentration and in the condition used in this study, membranes degrade insulin at a lower rate than hemolysate.