Glucagon structure and function. II. Increased activity of iodoglucagon

Abstract Iodination of glucagon with ICl markedly enhances biological activity as measured by activation of rat liver adenylate cyclase and by hyperglycemia in rabbits. Adenylate cyclase activity is increased about 5-fold after monoiodination of glucagon and about 10-fold after more extensive iodination. Our finding that iodoglucagon exhibits enhanced biological activity may affect the interpretations of recent receptor studies involving the binding of [ 125 I]glucagon to plasma membranes.