OsK-1. Potent Inhibitor of Kv1.3 and KCa3.1 K+�Channels.
OsK1 (alpha-KTx3.7) is a 38-residue toxin cross-linked by three disulphide bridges, originally isolated from the venom of the Asian scorpion Orthochirus scrobiculosus. The toxin was found to block a number of K+ channels, both voltage-dependent and Ca2+-activated isoforms. OsK-1 is lethal in mice by intracerebroventricular injection, with a LD50 value of 2 micro g/kg. OsK-1 blocks mKv1.1, mKv1.2, mKv1.3 channels potently and hKCa3.1 channel moderately, with IC50 values of 0.6, 5.4, 0.014 and 225 nM, respectively. No inhibition effects were observed on Kv1.4, Kv1.5, Kv1.6, Kv1.7, Kv11, KCa2.1, KCa2.2, KCa2.3 and KCa1.1 channels at μM concentrations.
Ion Channel Modulators; K+�Channel Blockers.