K+ channel types targeted by synthetic OSK1, a toxin from Orthochirus scrobiculosus scorpion venom

Stéphanie Mouhat, Violeta Visan, S. Ananthakrishnan, Heike Wulff, Nicolas Andreotti, Stephan Grissmer, Hervé Darbon, Michel De Waard, Jean Marc Sabatier

Research output: Contribution to journalArticlepeer-review

93 Scopus citations


OSK1 (α-KTx3.7) is a 38-residue toxin cross-linked by three disulphide bridges that was initially isolated from the venom of the Asian scorpion Orthochirus scrobiculosus. OSK1 and several structural analogues were produced by solid-phase chemical synthesis, and were tested for lethality in mice and for their efficacy in blocking a series of 14 voltage-gated and Ca 2+-activated K+ channels in vitro. In the present paper, we report that OSK1 is lethal in mice by intracerebroventricular injection, with a LD50 (50 % lethal dose) value of 2 μg/kg. OSK1 blocks K v 1.1, Kv1.2, Kv1.3 channels potently and KCa3.1 channel moderately, with IC50 values of 0.6, 5.4, 0.014 and 225 nM respectively. Structural analogues of OSK1, in which we mutated positions 16 (Glu16 → Lys) and/or 20 (Lys20 → Asp) to amino acid residues that are conserved in all other members of the α-KTx3 toxin family except OSK1, were also produced and tested. Among the OSK1 analogues, [K16,D20]-OSK1 (OSK1 with Glu16 → Lys and Lys20 → Asp mutations) shows an increased potency on Kv 1.3 channel, with an IC50 value of 0.003 nM, without loss of activity on KCa3.1 channel. These data suggest that OSK1 or [K16,D20]-OSK1 could serve as leads for the design and production of new immunosuppressive drugs.

Original languageEnglish (US)
Pages (from-to)95-104
Number of pages10
JournalBiochemical Journal
Issue number1
StatePublished - Jan 1 2005


  • Ca-activated K channel
  • OSK1
  • Peptide synthesis
  • Scorpion toxin
  • Voltage-gated K channel

ASJC Scopus subject areas

  • Biochemistry


Dive into the research topics of 'K+ channel types targeted by synthetic OSK1, a toxin from Orthochirus scrobiculosus scorpion venom'. Together they form a unique fingerprint.

Cite this