Tcl, from Tityus cambridgei, is the first member of a new subfamily of scorpion toxin that blocks K+-channels

A new peptide, Tc1, containing only 23 amino acids closely packed by three disulfide bridges was isolated from the Amazonian scorpion Tityus cambridgei. It blocks reversibly the Shaker B K+-channels with a K-d of 65 nM and displaces binding of noxiustoxin to mouse brain synaptosome membranes. It is the shortest known peptide from scorpion venom that recognizes K+-channels and constitutes a new structural subfamily of toxin, classified as alphaKTx 13.1. (C) 2000 Federation of European Biochemical Societies. Published by Elsevier Science B.V. All rights reserved.