A short-chain peptide toxin isolated from Centruroides sculpturatus scorpion venom inhibits ether-à-go-go-related gene K(+) channels.

From the venom of the American scorpion Centruroides sculpturatus Ewing we have isolated a minute peptide fraction (named CsEKerg1) which reversibly inhibits the current through ERG (ether-à-go-go-related gene) K(+) channels. Isolation was done by CM-cellulose column chromatography and reversed phase high-performance liquid chromatography. To test for an effect on ERG channels we used NG108-15 neuroblastomaxglioma hybrid cells voltage-clamped in the whole-cell mode. CsEKerg1 contains 43 amino acids and has a molecular weight of 4833. Its amino acid sequence is similar but not identical to that of ergtoxin, a peptide isolated recently from the venom of the Mexican scorpion Centruroides noxius [FASEB J. 13 (1999) 953]. Half inhibition of ERG current occurs at a peptide concentration of 1.12microg/ml.