Studies on the effects of protease substrate analogues on some of the actions of insulin.

Added TAME (N alpha-p-tosyl-1-anginine methyl ester) or BAME (benzoyl-anginine methyl ester) inhibited insulin induced activation of glucose oxidation and fat cell PDH activation without affecting spermine action on PDH activation and glucose oxidation in fat cells. BAME inhibited insulin-induced generation of both PDH stimulator and PDH inhibitor from liver particulate fraction. In contrast, insulin-induced internalization of insulin receptors and negative cooperativity of insulin receptors were not affected by protease substrate inhibitors. These results suggest that certain actions of insulin (glucose oxidation, generation of PDH regulators) are mediated by proteolytic events, while insulin-induced down regulation and negative cooperativity of insulin receptors are not mediated by activation of endogenous proteases.