Kinetic analysis of open- and closed-state inactivation transitions in human Kv4.2 A-type potassium channels
Kinetic analysis of open- and closed-state inactivation transitions in human Kv4.2 A-type potassium channels
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DOI：
10.1111/j.1469-7793.2001.00065.x
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发表时间：
2001-08-15
影响因子：
5.5
通讯作者：
Pongs, O
中科院分区：
文献类型：
--
作者：
Bähring, R;Boland, LM;Pongs, O
1.我们研究了神经元体树突A型电流的分子底物Kv4.2通道的门控动力学。为此，野生型和突变型通道在人胚胎肾(HEK) 293 细胞系中瞬时表达，并在全细胞膜片钳配置中测量电流。2． Kv4.2 通道从预打开关闭状态失活，-50 mV 时的平均时间常数为 959 ms。这种关闭状态失活不受 Kv4.2 N 末端 (Delta2-40) 删除的影响。3。 Kv4.2 电流在 +40 mV 时通过三指数动力学失活。快分量（tau = 11 ms）占总衰减的73%，中间分量（tau = 50 ms）占23%，慢分量（tau = 668 ms）占总衰减的4%。4． Kv4.2 N 末端的缺失（tau = 35 和 111 ms）减慢了失活的快速和中间部分，分别占总衰减的 33% 和 56%。慢速成分因截断而适度加速（tau = 346 ms），占 Kv4.2 当前失活总量的 11%。5。从开放状态失活恢复和从封闭状态失活恢复以强烈电压依赖性方式以相似的动力学发生。两种恢复反应都不受N-末端截断的影响。6． Kv4.2 Delta2-40 通道显示减慢的失活动力学，表明 N 末端截断导致 open7 稳定。实验数据支持的失活变构模型模拟表明，响应膜去极化，Kv4.2 通道在关闭失活状态下累积，并绕过开放状态直接恢复。
1. We studied the gating kinetics of Kv4.2 channels, the molecular substrate of neuronal somatodendritic A-type currents. For this purpose wild-type and mutant channels were transiently expressed in the human embryonic kidney (HEK) 293 cell line and currents were measured in the whole-cell patch-clamp configuration.2. Kv4.2 channels inactivated from pre-open closed state(s) with a mean time constant of 959 ms at -50 mV. This closed-state inactivation was not affected by a deletion of the Kv4.2 N-terminus (Delta2-40).3. Kv4.2 currents at +40 mV inactivated with triple-exponential kinetics. A fast component (tau = 11 ms) accounted for 73%, an intermediate component (tau = 50 ms) for 23% and a slow component (tau = 668 ms) for 4% of the total decay.4. Both the fast and the intermediate components of inactivation were slowed by a deletion of the Kv4.2 N-terminus (tau = 35 and 111 ms) and accounted for 33 and 56%, respectively, of the total decay. The slow component was moderately accelerated by the truncation (tau = 346 ms) and accounted for 11% of the total Kv4.2 current inactivation.5. Recovery from open-state inactivation and recovery from closed-state inactivation occurred with similar kinetics in a strongly voltage-dependent manner. Neither recovery reaction was affected by the N-terminal truncation.6. Kv4.2 Delta2-40 channels displayed slowed deactivation kinetics, suggesting that the N-terminal truncation leads to a stabilization of the open7. Simulations with an allosteric model of inactivation, supported by the experimental data, suggested that, in response to membrane depolarization, Kv4.2 channels accumulate in the closed-inactivated state(s), from which they directly recover, bypassing the open state.