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Article: Effect of S6 tail mutations on charge movement in Shaker potassium channels
- Article from:
- Biophysical Journal
- Article date:
- January 1, 2003
- Author:
CopyrightCopyright Biophysical Society Jan 2003. Provided by ProQuest LLC. (Hide copyright information)
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ABSTRACT The cytoplasmic ends of the four S6 transmembrane segments of voltage-gated potassium channels converge in a bundle crossing that acts as the activation gate that opens in response to a depolarization. To explore whether the cytoplasmic extension of the S6 segment (the S6 tail) plays a role in coupling voltage sensor and activation gate movements, we examined the effect of cysteine substitution from residues N482 to T489 on the kinetics and voltage-dependence of S4 charge movement and on the kinetics of deactivation of ionic current. Among these mutants, F484C has the steepest voltage-- dependent charge movement, the largest Q-Vshift, and the fastest OFF gating currents. Further ...