Helical structure and packing orientation of the S2 segment in the Shaker K+ channel.
Helical structure and packing orientation of the S2 segment in the Shaker K+ channel.
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DOI：
10.1085/jgp.113.3.415
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发表时间：
1999-03
期刊：
影响因子：
--
通讯作者：
Miller C
中科院分区：
文献类型：
--
作者：
Monks SA;Needleman DJ;Miller C
在电压门控性钾通道中，六个跨膜片段S1-S6聚集在中央成孔区周围。为了研究Shaker K+通道中S2片段的结构特征，我们用色氨酸单独替换S2中的每个残基（或用丙氨酸替换天然色氨酸）。所有的23个色氨酸突变体，但一个表达电压依赖性的K+电流在爪蟾卵母细胞。突变的影响被分类为对通道门控特性具有低或高影响。这些突变效应中明显的周期性支持S2片段的α-螺旋结构。高影响残留物和低影响残留物聚集在S2段螺旋轮投影的相对面上。低影响面也耐受天冬酰胺的单一突变。所有的结果是一致的想法，即低影响面项目对膜脂质和S2包装的变化发生在通道开放。我们的结论是，S2段是一个跨膜α螺旋，高影响面包装对其他跨膜段的功能通道。
Six transmembrane segments, S1–S6, cluster around the central pore-forming region in voltage-gated K+ channels. To investigate the structural characteristics of the S2 segment in the Shaker K+ channel, we replaced each residue in S2 singly with tryptophan (or with alanine for the native tryptophan). All but one of the 23 Trp mutants expressed voltage-dependent K+ currents in Xenopus oocytes. The effects of the mutations were classified as being of low or high impact on channel gating properties. The periodicity evident in the effects of these mutations supports an α-helical structure for the S2 segment. The high- and low-impact residues cluster onto opposite faces of a helical wheel projection of the S2 segment. The low-impact face is also tolerant of single mutations to asparagine. All results are consistent with the idea that the low-impact face projects toward membrane lipids and that changes in S2 packing occur upon channel opening. We conclude that the S2 segment is a transmembrane α helix and that the high-impact face packs against other transmembrane segments in the functional channel.