Eukaryotic voltage gated sodium-selective channels (VGSCs) enable influx of Na⁺ into excitable cells in response to a change in the transmembrane potential. This movement of ions causes the membrane depolarization occurring during the rising phase of the action potential and, as such, underlies propagation of electrical signals in neurons. The transmembrane region of VGSCs is characterized by a fourfold pseudosymmetrical architecture. In particular, the channel is constituted of four homologous repeats (referred to as domains, DI through DIV), each comprising six helical segments (S1 through S6). The first four helices (S1–S4) of each domain assemble into a separate helix bundle, the so-called voltage sensor domain, which undergoes a conformational transition in response to membrane depolarization. The remaining S5 and S6 helices from all of the domains form a tetrameric assembly, the pore domain, containing a lumen in its center. The latter constitutes a pathway connecting the extracellular and intracellular compartments, enabling diffusion of water molecules and ions across the membrane. Crucial milestones along this pathway are the selectivity filter, a section permeable to Na⁺ but not K⁺, and the activation gate, a hydrophobic plug that hinders the passage of waters and ions when the channel is in the closed state.

中文翻译：

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质子化是补药与用途依赖的基础[生物物理学与计算生物学]

真核电压门控钠选择性通道（VGSC）可使Na ⁺流入响应跨膜电位的变化进入兴奋性细胞。离子的这种移动会导致在动作电位上升阶段发生膜去极化，从而使电信号在神经元中传播成为潜在问题。VGSC的跨膜区的特征是四重假对称结构。特别地，通道由四个同源重复（称为域，DI至DIV）构成，每个重复均包含六个螺旋区段（S1至S6）。每个域的前四个螺旋（S1-S4）组装成一个单独的螺旋束，即所谓的电压传感器域，其响应膜去极化而经历构象转变。来自所有结构域的其余S5和S6螺旋形成一个四聚体组装，即孔结构域，在其中心包含一个管腔。后者构成连接细胞外和细胞内区室的途径，使水分子和离子能够在整个膜上扩散。沿着这条途径的关键里程碑是选择性过滤器，这是Na可渗透的部分⁺而不是K ⁺，还有激活门，即通道处于关闭状态时会阻止水和离子通过的疏水塞。