Protease inhibitor homologues of dendrotoxin do not bind to dendrotoxin acceptors on synaptosomal membranes or facilitate neuromuscular transmission

The dendrotoxins are a homologous group of potassium channel-blocking polypeptides found in mamba snake venom. They are similar in sequence and structure to Kunitz-type serine protease inhibitors. Modified and native protease inhibitors were assayed for dendrotoxin-like activity using radioligand-binding and twitch tension-recording methods. Despite the large number and high concentration of compounds tested, no protease inhibitor displayed dendrotoxin-like activity. The results indicate that the protease-inhibiting and potassium channel-blocking activities of these two groups of polypeptides are not linked.