Specificity of charge-carrying residues in the voltage sensor of potassium channels

被引:68
作者
Ahern, CA [1 ]
Horn, R [1 ]
机构
[1] Thomas Jefferson Univ, Jefferson Med Coll, Dept Physiol, Philadelphia, PA 19107 USA
关键词
gating current; S4; segment; Shaker; cysteine modification;
D O I
10.1085/jgp.200308993
中图分类号
Q4 [生理学];
学科分类号
071003 ;
摘要
Positively charged voltage sensors of sodium and potassium channels are driven outward through the membrane's electric field upon depolarization. This movement is coupled to channel opening. A recent model based on studies of the KvAP channel proposes that the positively charged voltage sensor, christened the "voltage-sensor paddle", is a peripheral domain that shuttles its charged cargo through membrane lipid like a hydrophobic cation. We tested this idea by attaching charged adducts to cysteines introduced into the putative voltage-sensor paddle of Shaker potassium channels and measuring fractional changes in the total gating charge front gating currents. The only residues capable of translocating attached charges through the membrane-electric field are those that serve this function in the native channel. This remarkable specificity indicates that charge movement involves highly specialized interactions between the voltage sensor and other regions of the protein, a mechanism inconsistent with the paddle model.
引用
收藏
页码:205 / 216
页数:12
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