Conversation between voltage sensors and gates of ion channels
Conversation between voltage sensors and gates of ion channels
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DOI：
10.1021/bi0020473
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发表时间：
2000-12-26
期刊：
影响因子：
2.9
通讯作者：
Horn, R
中科院分区：
文献类型：
--
作者：
Horn, R
离子通道是一种跨膜蛋白，它催化离子在脂质双分子层的疏水环境中运动。离子通道不像它们较小的亲戚，如valinomycin(1)，离子通道不通过脂质运送它们的货物；相反，它们创造了一个亲水的途径，离子可以通过这个途径扩散，在某些情况下，离子几乎可以像穿过浸泡在细胞膜上的水溶液一样容易(2)。这种下坡的离子通量由离子的跨膜电化学梯度提供动力，被用于多种细胞功能，最显著的是神经和肌肉细胞中电信号的产生。为了使这些过程有效地进行，细胞必须保持跨细胞膜的离子梯度。这需要能量驱动的泵，比如钠钾atp酶。然而，这些泵本身无法跟上通过通道的大量离子流量，尤其是钠和钙通道。因此，这些通道必须在大部分时间保持关闭，以尽量减少离子梯度的耗散，只有在被要求为细胞执行某些任务时才会短暂打开。通道的打开和关闭是一个称为门控的过程，它主要通过两种方式进行调节，一种是通过配体的结合，另一种是通过跨膜电位的变化(2)。后一种过程，电压依赖性门控，是本综述的主题。
Ion channels are transmembrane proteins that catalyze the movement of ions across the hostile hydrophobic environment of the lipid bilayer. Unlike their smaller relatives, carriers such as valinomycin (1), ion channels do not shuttle their cargo across the lipid; instead they create a hydrophilic pathway through which ions can diffuse, almost as easily in some cases as they move through the aqueous solutions that bathe the cell membrane (2). This downhill ion flux, powered by the ions’ transmembrane electrochemical gradient, is exploited for a variety of cellular functions, most notably the generation of electrical signals in nerve and muscle cells. For these processes to work efficiently, the cell must maintain the ionic gradients across cell membranes. This requires energy-driven pumps, like the sodium-potassium ATPase. However, these pumps cannot by themselves keep up with the massive fluxes of ions moving through channels, especially sodium and calcium channels. So these channels must remain shut most of the time to minimize dissipating the ion gradients and only open transiently when called upon to perform some task for the cell. The opening and closing of channels is a process called gating, and it is regulated primarily in two ways, either by the binding of ligands or by changes in transmembrane potential (2). The latter process, voltage-dependent gating, is the subject of this review.