Journal
JOURNAL OF MEMBRANE BIOLOGY
Volume 208, Issue 1, Pages 65-76Publisher
SPRINGER
DOI: 10.1007/s00232-005-0818-8
Keywords
anion channel; gating modifier; ion channel inhibition; ClC-2; peptide toxin
Funding
- NIDDK NIH HHS [DK 066409, R21 DK066409, R21 DK066409-02, DK 56481, R01 DK056481, R01 DK075016, R01 DK056481-06] Funding Source: Medline
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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.
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