OsK2, a new selective inhibitor of Kv1.2 potassium channels purified from the venom of the scorpion Orthochirus scrobiculosus

A novel inhibitor of voltage-gated K+ channels has been purified to homogen eity from the venom of the black scorpion Orthoehirus scrobiculosus. This t oxin, named OsK2, has been characterized as a 28-residue peptide, containin g six conserved cysteine residues and was shown to be a potent and selectiv e blocker of Kv1.2 channels (K-d=97 nM). OsK2 is the second member of the 1 3th subfamily of short-chain K+ channel-blocking peptides known thus far an d is therefore called alpha -KTx 13.2. (C) 2001 Academic Press.