Shaker potassium channel gating. II: Transitions in the activation pathway.
Shaker potassium channel gating. II: Transitions in the activation pathway.
复制标题
振动钾通道门控。 II：激活途径中的过渡。
DOI：
10.1085/jgp.103.2.279
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发表时间：
1994-02
期刊：
影响因子：
--
通讯作者：
Aldrich RW
中科院分区：
文献类型：
--
作者：
Zagotta WN;Hoshi T;Dittman J;Aldrich RW
研究了非洲爪蟾卵母细胞无n型失活的Shaker钾通道（ShB δ 6-46）的电压依赖性门控行为。稳态开概率的电压依赖性表明，激活过程涉及等效12-16个电子电荷在膜上的运动。激活过程的s型动力学，在至少+100 mV的去极化电压下保持，表明在打开之前至少存在5个顺序的构象变化。门控电荷运动的电压依赖性表明，每个初等跃迁涉及3.5个电子电荷。从单通道第一潜伏期分布、宏观离子电流激活末相、离子电流再激活和ON门控电流时间过程来看，正向打开率的电压依赖性表明，大量的激活跃迁与相当于0.3 ~ 0.5个电子电荷的运动有关。1.1个电子电荷的等效电荷运动与闭合构象变化有关。结果通常与涉及许多独立和相同转变的模型一致，但主要例外是第一个关闭转变比预期慢，如尾电流和关断门控电荷测量所示。
Voltage-dependent gating behavior of Shaker potassium channels without N-type inactivation (ShB delta 6-46) expressed in Xenopus oocytes was studied. The voltage dependence of the steady-state open probability indicated that the activation process involves the movement of the equivalent of 12-16 electronic charges across the membrane. The sigmoidal kinetics of the activation process, which is maintained at depolarized voltages up to at least +100 mV indicate the presence of at least five sequential conformational changes before opening. The voltage dependence of the gating charge movement suggested that each elementary transition involves 3.5 electronic charges. The voltage dependence of the forward opening rate, as estimated by the single- channel first latency distribution, the final phase of the macroscopic ionic current activation, the ionic current reactivation and the ON gating current time course, showed movement of the equivalent of 0.3 to 0.5 electronic charges were associated with a large number of the activation transitions. The equivalent charge movement of 1.1 electronic charges was associated with the closing conformational change. The results were generally consistent with models involving a number of independent and identical transitions with a major exception that the first closing transition is slower than expected as indicated by tail current and OFF gating charge measurements.