Laboratory of Toxicology, University of Leuven, E. Van Evenstraat 4, 3000 Leuven, Belgium. jan.tytgat@farm.kuleuven.ac.be
Peptidyl toxins are used extensively to determine the pharmacology of ion channels. Four families of peptides have been purified from scorpion venom. In this article, the classification of K+-channel-blocking peptides belonging to family 2 peptides and comprising 30-40 amino acids linked by three or four disulfide bridges, will be discussed. Evidence is provided for the existence of 12 molecular subfamilies, named alpha-KTx1-12, containing 49 different peptides. Because of the pharmacological divergence of these peptides, the principle of classification was based on a primary sequence alignment, combined with maximum parsimony and Neighbour-Joining analysis.