Toxins affecting k+ channels

Potassium channels are involved in modulating the excitability of neurones by regulating the membrane potential, or by affecting the amount of neurotransmitter released from nerve terminals. Potassium channels are highly diverse and can be activated by either voltage or increased intracellular calcium concentration. The potassium channel forms a highly selective membrane pore. Four subunits each with six membrane-spanning regions (S1-S6) are required to produce a functional pore. Molecular biologists have cloned more than 50 different potassium channel subtypes. Naturally occurring protein toxins have been used to pharmacologically characterize native and cloned potassium channels.