Gated access to the pore of a voltage-dependent K+ channel
Gated access to the pore of a voltage-dependent K+ channel
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DOI：
10.1016/s0896-6273(00)80357-8
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发表时间：
1997-07-01
期刊：
影响因子：
16.2
通讯作者：
Yellen, G
中科院分区：
文献类型：
--
作者：
Liu, Y;Holmgren, M;Yellen, G
电压激活的 K+ 通道是完整的膜蛋白，可响应跨膜电压的变化打开或关闭 K+ 选择性孔。尽管这些通道的 S4 区域被认为是电压传感器，但人们对如何实现孔的打开和关闭知之甚少。我们通过在 Shaker K+ 通道孔内或附近的各个位置引入半胱氨酸，并测试其化学修饰的能力来探索门控过程。我们发现S6跨膜区的一系列位置在开放状态下与水溶性硫醇试剂快速反应，但在关闭状态下则不发生反应。开放通道阻断剂可以保护其中几个半胱氨酸，表明它们位于离子传导孔中。在其中两个位点，Cd2+ 离子与半胱氨酸结合，而不影响门控能量；在第三个位点，Cd2+ 结合使通道保持开放。结果表明，这些通道是通过细胞内门的运动打开和关闭的，这与调节进入孔道的选择性过滤器不同。
Voltage-activated K+ channels are integral membrane proteins that open or close a K+-selective pore in response to changes in transmembrane voltage. Although the S4 region of these channels has been implicated as the voltage sensor, little is known about how opening and closing of the pore is accomplished. We explored the gating process by introducing cysteines at various positions thought to lie in or near the pore of the Shaker K+ channel, and by testing their ability to be chemically modified. We found a series of positions in the S6 transmembrane region that react rapidly with water-soluble thiol reagents in the open state but not the closed state. An open-channel blocker can protect several of these cysteines, showing that they lie in the ion-conducting pore. At two of these sites, Cd2+ ions bind to the cysteines without affecting the energetics of gating; at a third site, Cd2+ binding holds the channel open. The results suggest that these channels open and close by the movement of an intracellular gate, distinct from the selectivity filter, that regulates access to the pore.