Perspectives in Diabetes Some Thoughts on the Mechanism of Action of-Insulin

Proposed mechanisms by which insulin exerts its effects are discussed. Evidence for a role for the tyrosine kinase activity of the insulin receptor and of a phosphorylationldephosphorylation cascade is presented. 'The possible roles of phospholipid breakdown, diacylglycerol, and protein kinase C are discussed. The hypothesis that insulin elicits the hydrolysis of a glycosyl phosphatidylinositol to form a mediator of certain of its actions is considered in detail. The evidence that a G protein is involved in insulin action is analyzed. Diabetes 40:521-26, 1991 Editor's note: Every now and then welcome humor grins out from under the mounds of paper found on editors ' desks. It did so recently in correspondence from a renowned Southern humorist