Regulation of Na(+) channel inactivation by the DIII and DIV voltage-sensing domains.
Regulation of Na(+) channel inactivation by the DIII and DIV voltage-sensing domains.
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DOI：
10.1085/jgp.201611678
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发表时间：
2017-03-06
期刊：
影响因子：
--
通讯作者：
Silva JR
中科院分区：
文献类型：
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作者：
Hsu EJ;Zhu W;Schubert AR;Voelker T;Varga Z;Silva JR
Hsu等人用电压钳荧光测定法探测失活缺陷的电压门控Na+通道。他们发现，在动作电位的时域中，结构域IV的电压敏感结构域（VSD）调节快速失活开始，而结构域III VSD决定其恢复。功能性真核细胞电压门控Na+（NaV）通道包括四个结构域（DI-DIV），每个结构域包含六个跨膜区段（S1-S6）。电压感测由前四个跨膜区段（S1-S4）完成，它们一起形成电压感测域（VSD）。一个关键的NaV通道门控过程，失活，先前已被链接到DIII和DIV中的VSD的激活。在这里，我们探测这种相互作用，通过使用电压钳荧光法观察VSD动力学的突变的存在下，在已被证明损害NaV通道失活的位置。这些位置包括DIII-DIV接头、DIII S4-S5接头和DIV S4-S5接头。我们的研究结果表明，在快速失活的10毫秒的时间范围内，DIV-VSD是失活的主要调节器。然而，在较长的100 ms脉冲后，DIII-DIV接头减慢了DIII-VSD失活，并且DIII失活的速率与从失活恢复的速率密切相关。我们的研究结果表明，在动作电位的过程中，DIV-VSD调节快速失活的发生，而DIII-VSD决定其恢复。
Hsu et al. probe voltage-gated Na+ channels that are inactivation deficient with voltage-clamp fluorometry. They find that in the time domain of an action potential, the voltage-sensing domain (VSD) of domain IV regulates fast inactivation onset while the domain III VSD determines its recovery. Functional eukaryotic voltage-gated Na+ (NaV) channels comprise four domains (DI–DIV), each containing six membrane-spanning segments (S1–S6). Voltage sensing is accomplished by the first four membrane-spanning segments (S1–S4), which together form a voltage-sensing domain (VSD). A critical NaV channel gating process, inactivation, has previously been linked to activation of the VSDs in DIII and DIV. Here, we probe this interaction by using voltage-clamp fluorometry to observe VSD kinetics in the presence of mutations at locations that have been shown to impair NaV channel inactivation. These locations include the DIII–DIV linker, the DIII S4–S5 linker, and the DIV S4-S5 linker. Our results show that, within the 10-ms timeframe of fast inactivation, the DIV-VSD is the primary regulator of inactivation. However, after longer 100-ms pulses, the DIII–DIV linker slows DIII-VSD deactivation, and the rate of DIII deactivation correlates strongly with the rate of recovery from inactivation. Our results imply that, over the course of an action potential, DIV-VSDs regulate the onset of fast inactivation while DIII-VSDs determine its recovery.