Transmembrane movement of the Shaker K+ channel S4
Transmembrane movement of the Shaker K+ channel S4
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DOI：
10.1016/s0896-6273(00)80056-2
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发表时间：
1996-02-01
期刊：
影响因子：
16.2
通讯作者：
Isacoff, EY
中科院分区：
文献类型：
--
作者：
Larsson, HP;Baker, OS;Isacoff, EY
我们在开放和封闭的半胱氨酸取代的Shaker K+通道中，研究了S4残基对膜-不含硫醇试剂甲基乙硫磺酸-乙基三甲基铵（MTSET）的内部和外部可及性。我们的研究结果表明，S4以不超过5个氨基酸的封闭状态穿过膜，并且当通道打开时，埋藏残基的分布发生了变化。这种变化证明了S4通过膜平面的位移，其中最初的细胞内残留物移动到细胞外溶液的3个氨基酸内。这些结果表明，假定的S4的电压感应电荷实际上驻留在膜上，并且当通道打开时它们向外移动。我们考虑了这些结果对通道结构的限制。
We have probed internal and external accessibility of S4 residues to the membrane-impermeant thiol reagent methanethiosulfonate-ethyltrimethylammonium (MTSET) in both open and closed, cysteine-substituted Shaker K+ channels. Our results indicate that S4 traverses the membrane with no more than 5 amino acids in the closed state, and that the distribution of buried residues changes when channels open. This change argues for a displacement of S4 through the plane of the membrane in which an initially intracellular residue moves to within 3 amino acids of the extracellular solution. These results demonstrate that the putative voltage-sensing charges of S4 actually reside in the membrane and that they move outward when channels open. We consider constraints placed on channel structure by these results.