State-dependent inactivation of the alpha1G T-type calcium channel.
State-dependent inactivation of the alpha1G T-type calcium channel.
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DOI：
10.1085/jgp.114.2.185
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发表时间：
1999-08
影响因子：
3.8
通讯作者：
Jones, SW
中科院分区：
文献类型：
--
作者：
Serrano, JR;Perez-Reyes, E;Jones, SW
我们已经检查了稳定表达α1G通道的HEK 293细胞中的全细胞T电流的动力学，其中具有对称的Na+ i和Na+ o以及2 mM Ca 2 + o。在短暂的强去极化激活通道后（+60 mV时2 ms;保持电位-100 mV），电流在所有电压下呈指数松弛。弛豫的时间常数在−120到−70 mV之间呈指数电压依赖性，但是。这表明电压依赖性失活（在非常负的电压下占主导地位）和几乎不依赖于电压的失活的混合物。根据该方案通过测试脉冲测量的灭活与开放状态灭活一致。在持续100-300 ms的去极化期间，失活很强但不完全（约98%）。失活也产生了长，弱去极化，这不能解释电压无关的失活完全从开放状态。失活的恢复是指数和快速的，但弱电压依赖性。在60 ms步进至−20 mV或600 ms步进至−70 mV后，恢复相似，表明开放和闭合状态失活的快速平衡。在从失活恢复期间，在−100 mV下几乎没有电流，与≤8%的通道通过开放状态恢复一致。动力学模型很好地描述了结果，其中失活与前三个电压传感器的运动变构耦合以激活。状态依赖性失活的一个结果是，α1G通道在复极化后继续失活，主要是从开放状态，这导致重复脉冲期间的累积失活。
We have examined the kinetics of whole-cell T-current in HEK 293 cells stably expressing the α1G channel, with symmetrical Na+ i and Na+ o and 2 mM Ca2+ o. After brief strong depolarization to activate the channels (2 ms at +60 mV; holding potential −100 mV), currents relaxed exponentially at all voltages. The time constant of the relaxation was exponentially voltage dependent from −120 to −70 mV , but . This suggests a mixture of voltage-dependent deactivation (dominating at very negative voltages) and nearly voltage-independent inactivation. Inactivation measured by test pulses following that protocol was consistent with open-state inactivation. During depolarizations lasting 100–300 ms, inactivation was strong but incomplete (∼98%). Inactivation was also produced by long, weak depolarizations , which could not be explained by voltage-independent inactivation exclusively from the open state. Recovery from inactivation was exponential and fast , but weakly voltage dependent. Recovery was similar after 60-ms steps to −20 mV or 600-ms steps to −70 mV, suggesting rapid equilibration of open- and closed-state inactivation. There was little current at −100 mV during recovery from inactivation, consistent with ≤8% of the channels recovering through the open state. The results are well described by a kinetic model where inactivation is allosterically coupled to the movement of the first three voltage sensors to activate. One consequence of state-dependent inactivation is that α1G channels continue to inactivate after repolarization, primarily from the open state, which leads to cumulative inactivation during repetitive pulses.
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克隆垂体细胞中的钠通道门控。灭活步骤不取决于电压。
影响因子：
3.8
作者：
Cota, G;Armstrong, C M
通讯作者：
Armstrong, C M
DOI：
10.1085/jgp.88.3.293
发表时间：
1986-09
期刊：
The Journal of general physiology
影响因子：
--
作者：
Hess P;Lansman JB;Tsien RW
通讯作者：
Tsien RW
影响因子：
64.8
作者：
CARBONE, E;LUX, HD
通讯作者：
LUX, HD
影响因子：
5.5
作者：
BOSSU, JL;FELTZ, A
通讯作者：
FELTZ, A
影响因子：
5.5
作者：
CHANDLER, WK;MEVES, H
通讯作者：
MEVES, H