Tarantula toxins interacting with voltage sensors in potassium channels

Voltage-activated ion channels open and close in response to changes in membrane voltage, a process that is crucial for electrical signaling in the nervous system. The venom from many poisonous creatures contains a diverse array of small protein toxins that bind to voltage-activated channels and modify the gating mechanism. Hanatoxin and a growing number of related tarantula toxins have been shown to inhibit activation of voltage-activated potassium (K v) channels by interacting with their voltage-sensing domains. This review summarizes our current understanding of the mechanism by which these toxins alter gating, the location of the toxin receptor within K v channels and the disposition of this receptor with respect to the lipid membrane. The conservation of tarantula toxin receptors among voltage-activated ion channels will also be discussed.