Gonzalez Carlos, Contreras Gustavo F, Peyser Alexander, Larsson Peter, Neely Alan, Latorre Ramón
Centro Interdisciplinario de Neurociencia de Valparaíso, Facultad de Ciencias, Universidad de Valparaíso, Pasaje Harrington 287, Valparaíso, 2360103, Chile.
Department of Physiology and Biophysics, University of Miami, Miami, FL, USA.
Biophys Rev. 2012 Mar;4(1):1-15. doi: 10.1007/s12551-011-0061-8. Epub 2011 Dec 16.
Placed in the cell membrane (a two-dimensional environment), ion channels and enzymes are able to sense voltage. How these proteins are able to detect the difference in the voltage across membranes has attracted much attention, and at times, heated debate during the last few years. Sodium, Ca and K voltage-dependent channels have a conserved positively charged transmembrane (S4) segment that moves in response to changes in membrane voltage. In voltage-dependent channels, S4 forms part of a domain that crystallizes as a well-defined structure consisting of the first four transmembrane (S1-S4) segments of the channel-forming protein, which is defined as the voltage sensor domain (VSD). The VSD is tied to a pore domain and VSD movements are allosterically coupled to the pore opening to various degrees, depending on the type of channel. How many charges are moved during channel activation, how much they move, and which are the molecular determinants that mediate the electromechanical coupling between the VSD and the pore domains are some of the questions that we discuss here. The VSD can function, however, as a bona fide proton channel itself, and, furthermore, the VSD can also be a functional part of a voltage-dependent phosphatase.
置于细胞膜（二维环境）中的离子通道和酶能够感知电压。在过去几年里，这些蛋白质如何检测跨膜电压差异备受关注，有时还引发了激烈的争论。钠、钙和钾电压依赖性通道有一个保守的带正电荷的跨膜（S4）片段，它会随着膜电压的变化而移动。在电压依赖性通道中，S4构成一个结构域的一部分，该结构域结晶为一种明确的结构，由通道形成蛋白的前四个跨膜（S1 - S4）片段组成，被定义为电压传感结构域（VSD）。VSD与一个孔道结构域相连，VSD的移动与孔道开放在不同程度上通过变构作用相互偶联，这取决于通道的类型。通道激活过程中有多少电荷移动、移动多少以及介导VSD与孔道结构域之间机电偶联的分子决定因素有哪些，是我们在此讨论的一些问题。然而，VSD本身可以作为一个真正的质子通道发挥作用，此外，VSD还可以是电压依赖性磷酸酶的一个功能部分。
