How does the W434F mutation block current in Shaker potassium channels?
How does the W434F mutation block current in Shaker potassium channels?
复制标题
振动钾通道中的W434F突变阻滞电流如何？
DOI：
10.1085/jgp.109.6.779
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发表时间：
1997-06
影响因子：
3.8
通讯作者：
Sigworth, F J
中科院分区：
文献类型：
--
作者：
Yang, Y;Yan, Y;Sigworth, F J
突变W 434 F产生一个明显的完全阻断钾电流在振荡器通道表达在非洲爪蟾卵母细胞。含有一个或两个亚基与此突变的串联四聚体结构表现出快速失活，虽然NH 2-末端失活结构域是从这些结构缺席。失活表现出选择性依赖于外部阳离子和外部TEA减缓，这些属性是C型失活的特征。失活，但是，不完全缓解超极化，这表明存在的电压无关的组件。混合通道具有接近正常的电导率和离子选择性。含有许多W 434 F通道的斑块的单通道记录显示偶尔的通道开放，与10−5或更小的开放概率一致。我们得出结论，W 434 F突变产生了一个主要在失活状态下发现的通道。
The mutation W434F produces an apparently complete block of potassium current in Shaker channels expressed in Xenopus oocytes. Tandem tetrameric constructs containing one or two subunits with this mutation showed rapid inactivation, although the NH2-terminal inactivation domain was absent from these constructs. The inactivation showed a selective dependence on external cations and was slowed by external TEA; these properties are characteristic of C-type inactivation. Inactivation was, however, incompletely relieved by hyperpolarization, suggesting the presence of a voltage-independent component. The hybrid channels had near-normal conductance and ion selectivity. Single-channel recordings from patches containing many W434F channels showed occasional channel openings, consistent with open probabilities of 10−5 or less. We conclude that the W434F mutation produces a channel that is predominantly found in an inactivated state.