Agitoxin-1

Agitoxins are peptide toxins originally isolated from L. quinquestriatus hebraeus scorpion venom. This group of toxins blocks potassium (K⁺) channels and has a central role in the investigation and understanding of the physiological importance of K⁺ channels and their function in membrane biophysics¹.

Agitoxins 1, 2 and 3 have been isolated and characterized. Each toxin is comprised of 38 amino acids. They are highly homologous and differ only in the identity of the residues at positions 7, 15, 29 and 31.

Agitoxins appear to be specific for the Shaker K⁺ channel of Drosophila melanogaster and many of the mammalian homologues of Shaker. Agitoxin-1 blocks the Shaker channel in a stoichiometry of one to one, it binds the channel site in the extracellular vestibule and prevents ion conduction by occluding the pore².

Using scorpion toxins for molecular dissection of ion channels has led to direct evidence that specific mutations can be correlated to changes in the propagation and conduction of electrical impulses in the body³.