Voltage-insensitive gating after charge-neutralizing mutations in the S4 segment of Shaker channels.
Voltage-insensitive gating after charge-neutralizing mutations in the S4 segment of Shaker channels.
复制标题
电荷不中和突变后的振动通道S4段中和不敏感的门控。
DOI：
10.1085/jgp.113.1.139
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发表时间：
1999-01
影响因子：
3.8
通讯作者：
Rayner, MD
中科院分区：
文献类型：
--
作者：
Bao, HX;Hakeem, A;Henteleff, M;Starkus, JG;Rayner, MD
Shaker 通道突变体（其中 S4 片段中的第一个 (R362)、第二个 (R365) 和第四个 (R371) 碱性残基已被中和）在非洲爪蟾卵母细胞中表达时，会以电压不敏感动力学传递钾电流。单通道记录表明，这些通道以恒定的打开概率 (P o) 从 −160 到 +80 mV 持续打开和关闭。尽管这些突变体中的 Po 较低（~0.15），但平均开放时间与电压无关，并且与对照 Shaker 通道相似。此外，这些突变通道保留了特征性的 Shaker 通道选择性、对 4-氨基吡啶阻断的敏感性，并且在非常负的电位下被外部 Ca2+ 离子部分阻断。此外，当 Rb+ 取代 K+ 作为渗透离子种类时，在突变体通道和对照 Shaker 通道中，平均开放时间大约加倍。突变体通道和对照 Shaker 通道之间如此强烈的相似性表明孔区域并未因 S4 电荷中和而发生实质性改变。我们得出的结论是，这些突变体中的单通道动力学可能表明 Shaker 通道在没有电压传感器输入的情况下将如何表现。因此，平均打开时间主要由接近打开状态的电压不敏感转变决定，而不是由电压传感器移动决定，即使在控制、电压敏感的振荡器通道中也是如此。相比之下，在这些突变通道中看到的低且对电压不敏感的 Po 表明正常通道开放的重要决定因素源自 S4 电荷和孔域之间的静电耦合。
Shaker channel mutants, in which the first (R362), second (R365), and fourth (R371) basic residues in the S4 segment have been neutralized, are found to pass potassium currents with voltage-insensitive kinetics when expressed in Xenopus oocytes. Single channel recordings clarify that these channels continue to open and close from −160 to +80 mV with a constant opening probability (P o). Although P o is low (∼0.15) in these mutants, mean open time is voltage independent and similar to that of control Shaker channels. Additionally, these mutant channels retain characteristic Shaker channel selectivity, sensitivity to block by 4-aminopyridine, and are partially blocked by external Ca2+ ions at very negative potentials. Furthermore, mean open time is approximately doubled, in both mutant channels and control Shaker channels, when Rb+ is substituted for K+ as the permeant ion species. Such strong similarities between mutant channels and control Shaker channels suggests that the pore region has not been substantially altered by the S4 charge neutralizations. We conclude that single channel kinetics in these mutants may indicate how Shaker channels would behave in the absence of voltage sensor input. Thus, mean open times appear primarily determined by voltage-insensitive transitions close to the open state rather than by voltage sensor movement, even in control, voltage-sensitive Shaker channels. By contrast, the low and voltage-insensitive P o seen in these mutant channels suggests that important determinants of normal channel opening derive from electrostatic coupling between S4 charges and the pore domain.
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DOI：
10.1085/jgp.92.2.179
发表时间：
1988-08
期刊：
The Journal of general physiology
影响因子：
--
作者：
Llano I;Webb CK;Bezanilla F
通讯作者：
Bezanilla F
影响因子：
16.2
作者：
Aggarwal, SK;MacKinnon, R
通讯作者：
MacKinnon, R
影响因子：
16.2
作者：
Larsson, HP;Baker, OS;Isacoff, EY
通讯作者：
Isacoff, EY
影响因子：
56.9
作者：
Doyle, DA;Cabral, JM;MacKinnon, R
通讯作者：
MacKinnon, R
DOI：
10.1073/pnas.83.2.508
发表时间：
1986-01-01
影响因子：
11.1
作者：
GUY, HR;SEETHARAMULU, P
通讯作者：
SEETHARAMULU, P