The ω-atracotoxin-2 family of toxins appear to be the most potent blockers of insect voltage-gated calcium channels reported to date. They have exceptional phylogenetic specificity, with at least a 10,000-fold preference for insect over vertebrate channels. In contrast with most other cystine knot toxins, they contain a structurally disordered, highly hydrophobic C-terminal tail which is essential for neurotoxic activity. We proposed a model in which the lipophilic tail initiates toxin binding by penetrating the membrane either adjacent to the channel or, more likely, by intercalation between transmembrane segments of the channel protein.
Wang, X-H., Connor, M., Wilson, D., Wilson, H.I., Nicholson, G.M., Smith, R., Shaw, D., Mackay, J.P., Alewood, P.F., Christie, M.J. and King, G.F. (2001) Discovery and structure of a potent and highly specific blocker of insect calcium channels. Journal of Biological Chemistry 276, 40306-40312.