Melittin interactions with adenylate cyclase.

Melittin, a basic polypeptide from bee venom, inhibits basal and thyrotropin-stimulated adenylate cyclase of beef thyroid membranes with a Ki approximately 10 micron. Although this property resides in the basic C-terminal and not the N-terminal portion of the molecule, inhibition is due primarily to its detergent-like nature rather than charge effects. There is also a small enhancing effect of both basal and thyrotropin-stimulated adenylate cyclase of 0.3-3 micron melittin.