Kinetic relationship between the voltage sensor and the activation gate in spHCN channels.
Kinetic relationship between the voltage sensor and the activation gate in spHCN channels.
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DOI：
10.1085/jgp.200709769
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发表时间：
2007-07
期刊：
影响因子：
--
通讯作者：
Larsson HP
中科院分区：
文献类型：
--
作者：
Bruening-Wright A;Elinder F;Larsson HP
超极化激活的环核苷酸门控（HCN）通道由膜超极化激活，所述膜超极化引起第四跨膜结构域（S4）中的正电荷向内移动，从而触发通道开放。S4电荷的运动如何触发通道开放的机制尚不清楚。在这里，我们使用电压钳荧光法（VCF）来检测S4构象变化，并将这些与sphHCN通道中的不同激活步骤相关联。我们发现，S4在电压激活过程中经历了两个不同的构象变化。荧光信号的分析表明，S4的N-末端区域在先前表征的HCN通道电压依赖性模式转变期间经历构象变化，而更多的C-末端区域在门控电荷运动期间经历额外的构象变化。我们将我们的荧光和离子电流数据拟合到先前提出的HCN通道的10态变构模型。我们的结果是不兼容的快速S4运动和限速通道开放。相反，我们的数据和建模表明，spHCN通道开放后，只有两个S4的移动和S4运动是速率限制在电压激活的spHCN通道。
Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels are activated by membrane hyperpolarizations that cause an inward movement of the positive charges in the fourth transmembrane domain (S4), which triggers channel opening. The mechanism of how the motion of S4 charges triggers channel opening is unknown. Here, we used voltage clamp fluorometry (VCF) to detect S4 conformational changes and to correlate these to the different activation steps in spHCN channels. We show that S4 undergoes two distinct conformational changes during voltage activation. Analysis of the fluorescence signals suggests that the N-terminal region of S4 undergoes conformational changes during a previously characterized mode shift in HCN channel voltage dependence, while a more C-terminal region undergoes an additional conformational change during gating charge movements. We fit our fluorescence and ionic current data to a previously proposed 10-state allosteric model for HCN channels. Our results are not compatible with a fast S4 motion and rate-limiting channel opening. Instead, our data and modeling suggest that spHCN channels open after only two S4s have moved and that S4 motion is rate limiting during voltage activation of spHCN channels.
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影响因子：
64.8
作者：
Männikkö, R;Elinder, F;Larsson, HP
通讯作者：
Larsson, HP
影响因子：
5.3
作者：
Bruening-Wright, Andrew;Larsson, H. Peter
通讯作者：
Larsson, H. Peter
影响因子：
3.8
作者：
Altomare, C;Bucchi, A;DiFrancesco, D
通讯作者：
DiFrancesco, D
影响因子：
5.5
作者：
DIFRANCESCO, D
通讯作者：
DIFRANCESCO, D
影响因子：
3.8
作者：
Schoppa, NE;Sigworth, FJ
通讯作者：
Sigworth, FJ