Activation of Shaker potassium channels II.: Kinetics of the V2 mutant channel
Activation of Shaker potassium channels II.: Kinetics of the V2 mutant channel
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DOI：
10.1085/jgp.111.2.295
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发表时间：
1998-02-01
影响因子：
3.8
通讯作者：
Sigworth, FJ
中科院分区：
文献类型：
--
作者：
Schoppa, NE;Sigworth, FJ
这三篇论文中的第二篇，我们在功能上表征了Shaker钾通道的激活门控，重点是突变通道（称为V2）的特性，其中382位的亮氨酸（在Shaker B序列中）突变为缬氨酸。V2的离子和门控电流的一般特性与后期门控转换的变化一致，特别是V2破坏正常激活的野生型（WT）通道的正合作门控过程。前向和后向速率常数的分析，类似于在前一篇论文中用于WT的分析，表明V2对激活路径中的大多数跃迁的速率几乎没有影响，但对最后两个跃迁的后向速率影响很大。单通道数据表明，V2突变引起的过渡到状态，铝-电子不在激活路径的速率的适度变化，但从这些状态的速率变化不大。V2的数据还产生了对激活门控过程的一般性质的见解，这些性质不能从WT通道中容易地获得，包括中间跃迁具有快速后向速率的证据，以及对最后两个跃迁的总电荷2 e（0）的估计。总之，这些数据将有助于限制本系列第三篇论文中的激活门控模型，同时也为V2效应提供了解释。
This second of three papers, in which we functionally characterize activation gating in Shaker potassium channels, focuses on the properties of a mutant channel (called V2), in which the leucine at position 382 (in the Shaker B sequence) is mutated to valine. The general properties of V2's ionic and gating currents are consistent with changes in late gating transitions, in particular, with V2 disrupting the positively cooperative gating process of the normally activating wild type (WT) channel. An analysis of forward and backward rate constants, analogous to that used for WT in the previous paper, indicates that V2 causes little change in the rates for most of the transitions in the activation path, but causes large changes in the backward rates of the final two transitions. Single channel data indicate that the V2 mutation causes moderate changes in the rates of transitions to states that al-e not in the activation path, but little change in the rates from these states. V2's data also yield insights into the general properties of the activation gating process that could not be readily obtained from the WT channel, including evidence that intermediate transitions have rapid backward rates, and an estimate of a total charge 2 e(0) for the final two transitions. Taken together, these data will help constrain an activation gating model in the third paper of this series, while also providing an explanation for V2's effects.