Referenced in: none

Automatically associated channels: Kv1.3

Title: OcyKTx2, a new K⁺-channel toxin characterized from the venom of the scorpion Opisthacanthus cayaporum.

Authors: Elisabeth F Schwartz, Adam Bartok, Carlos Alberto Schwartz, Ferenc Papp, Froylan Gómez-Lagunas, Gyorgy Panyi, Lourival D Possani

Journal, date & volume: Peptides, 2013 Aug , 46, 40-6

PubMed link: http://www.ncbi.nlm.nih.gov/pubmed/23684923

Abstract
Opisthacanthus cayaporum belongs to the Liochelidae family, and the scorpions from this genus occur in southern Africa, Central America and South America and, therefore, can be considered a true Gondwana heritage. In this communication, the isolation, primary structure characterization, and K⁺-channel blocking activity of new peptide from this scorpion venom are reported. OcyKTx2 is a 34 amino acid long peptide with four disulfide bridges and molecular mass of 3807 Da. Electrophysiological assays conducted with pure OcyKTx2 showed that this toxin reversibly blocks Shaker B K⁺-channels with a Kd of 82 nM, and presents an even better affinity toward hKv1.3, blocking it with a Kd of ∼18 nM. OcyKTx2 shares high sequence identity with peptides belonging to subfamily 6 of α-KTxs that clustered very closely in the phylogenetic tree included here. Sequence comparison, chain length and number of disulfide bridges analysis classify OcyKTx2 into subfamily 6 of the α-KTx scorpion toxins (systematic name, α-KTx6.17).