Inhibition of ClC-2 chloride channels by a peptide component or components of scorpion venom

C. H. Thompson, D. M. Fields, P. R. Olivetti, M. D. Fuller, Z. R. Zhang, J. Kubanek, N. A. McCarty*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

12 Scopus citations

Abstract

ClC chloride channels play essential roles in membrane excitability and maintenance of osmotic balance. Despite the recent crystallization of two bacterial ClC-like proteins, the gating mechanism for these channels remains unclear. In this study we tested scorpion venom for the presence of novel peptide inhibitors of ClC channels, which might be useful tools for dissecting the mechanisms underlying ClC channel gating. Recently, it has been shown that a peptide component of venom from the scorpion L. quinquestriatus hebraeus inhibits the CFTR chloride channel from the intracellular side. Using two-electrode voltage clamp we studied the effect of scorpion venom on ClC-0, -1, and -2, and found both dose- and voltage-dependent inhibition only of ClC-2. Comparison of voltage-dependence of inhibition by venom to that of known pore blockers revealed opposite voltage dependencies, suggesting different mechanisms of inhibition. Kinetic data show that venom induced slower activation kinetics compared to pre-venom records, suggesting that the active component(s) of venom may function as a gating modifier at ClC-2. Trypsinization abolished the inhibitory activity of venom, suggesting that the component(s) of scorpion venom that inhibits ClC-2 is a peptide.

Original languageEnglish (US)
Pages (from-to)65-76
Number of pages12
JournalJournal of Membrane Biology
Volume208
Issue number1
DOIs
StatePublished - Nov 2005

Keywords

  • Anion channel
  • ClC-2
  • Gating modifier
  • Ion channel inhibition
  • Peptide toxin

ASJC Scopus subject areas

  • Biophysics
  • Physiology
  • Cell Biology

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