Glucagon1-6 binds to the glucagon receptor and activates hepatic adenylate cyclase.

A fragment of glucagon encompassing its first six NH2-terminal residues (His-Ser-Gln-Gly-Thr-Phe) binds to the glucagon receptor and stimulates adenylate cyclase activity in rat liver plasma membranes. Glucagon1-6 is a partial agonist since it stimulates, at saturating concentrations, to the extent of 75% of the maximal activity given by the native hormone. The binding affinity and potency of glucagon1-6 are 0.001% the native hormone. Discussed are the implications of these findings on the structure-function relationships required for the action of glucagon and for preparing clinically useful analogs of the hormone.