DENDROTOXINS - HOW DOES STRUCTURE DETERMINE FUNCTION

Dendrotoxins are a family of small proteins isolated from mamba (Dendr oaspis) snake venoms. The toxins contain 57-60 amino acid residues cro ss-linked by three disulphide bridges. They are homologous to Kunitz-t ype serine proteinase inhibitors, such as aprotinin, (BPTI) although t hey have little anti-proteinase activity. The dendrotoxins block some subtypes of voltage-dependent potassium channels in neurones. Studies with cloned K+ channels indicate that alpha-dendrotoxin from green mam ba Dendroaspis angusticeps blocks Kv1.1, Kv1.2 and Kv1.6 channels in t he nanomolar range. Engineered and modified versions of dendrotoxin ar e being investigated to define the interactive site and account for di fferences in K+ channel selectivity.