Gating and inward rectifying properties of the MthK K+ channel with and without the gating ring.
Gating and inward rectifying properties of the MthK K+ channel with and without the gating ring.
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DOI：
10.1085/jgp.200609655
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发表时间：
2007-02
期刊：
影响因子：
--
通讯作者：
Jiang Y
中科院分区：
文献类型：
--
作者：
Li Y;Berke I;Chen L;Jiang Y
在MthK中，来自热自养甲烷杆菌的Ca 2+门控K+通道，八个细胞质RCK结构域形成八聚体门控环，其控制离子传导孔的细胞内门控。Ca 2+离子与RCK结构域的结合改变了门控环的构象，从而打开了门。在本研究中，我们研究了Ca 2+和pH调节门控和整流传导特性的MthK在单通道水平。MthK的开放概率（Po）与胞内[Ca 2 +]呈S形关系，Hill系数>1才能描述Po对[Ca 2 +]的依赖性，表明通道的协同Ca 2+激活。此外，细胞内Ca 2+也以电压依赖性方式阻断MthK孔，呈现明显的内向整流I-V关系。细胞内pH对MthK门控具有双重作用。pH低于7.5时，通道对Ca 2+不敏感。这是因为门控环在该pH下结构不稳定并且倾向于分解（Ye，S.，Y.利湖，加-地Chen和Y.蒋2006. Cell. 126：1161-1173）。相比之下，在pH 7.5以上，pH的进一步增加使Po-[Ca 2 +]关系向较低的Ca 2+浓度移动，在饱和[Ca 2 +]时增加Po，并且即使在不存在Ca 2+的情况下也激活通道。通道活动的特点是快速开放和关闭的爆发，由相对较长的爆发间关闭分开。爆发间关闭的持续时间和爆发长度是高度依赖于Ca 2+和pH值，而爆发内事件的动力学是Ca 2+和pH值独立的。快速爆发内的开放和关闭也观察到与孤立的MthK孔缺乏连接的细胞内门控环。快速的动力学事件，独立的Ca 2+和pH值，因此似乎是由离子传导孔内发生的过程，而缓慢的事件反映了门控过程控制的Ca 2+和pH值通过门控环。
In MthK, a Ca2+-gated K+ channel from Methanobacterium thermoautotrophicum, eight cytoplasmic RCK domains form an octameric gating ring that controls the intracellular gate of the ion conduction pore. The binding of Ca2+ ions to the RCK domains alters the conformation of the gating ring, thereby opening the gate. In the present study, we examined the Ca2+- and pH-regulated gating and the rectifying conduction properties of MthK at the single-channel level. The open probability (Po) of MthK exhibits a sigmoidal relationship with intracellular [Ca2+], and a Hill coefficient >1 is required to describe the dependence of Po on [Ca2+], suggesting cooperative Ca2+ activation of the channel. Additionally, intracellular Ca2+ also blocks the MthK pore in a voltage-dependent manner, rendering an apparently inwardly rectifying I-V relation. Intracellular pH has a dual effect on MthK gating. Below pH 7.5, the channel becomes insensitive to Ca2+. This occurs because the gating ring is structurally unstable at this pH and tends to disassemble (Ye, S., Y. Li, L. Chen, and Y. Jiang. 2006. Cell. 126:1161–1173). In contrast, above pH 7.5, a further increase in pH shifts the Po-[Ca2+] relation towards a lower Ca2+ concentration, augments Po at saturating [Ca2+], and activates the channel even in the absence of Ca2+. Channel activity is marked by bursts of rapid openings and closings separated by relatively longer interburst closings. The duration of interburst closing and the burst length are highly Ca2+ and pH dependent, whereas the kinetics of intraburst events is Ca2+ and pH independent. The rapid intraburst openings and closings are also observed with the isolated MthK pore lacking the attached intracellular gating ring. The fast kinetic events, independent of both Ca2+ and pH, therefore appear to be determined by processes occurring within the ion conduction pore, whereas the slow events reflect the gating process controlled by Ca2+ and pH through the gating ring.
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影响因子：
56.9
作者：
Doyle, DA;Cabral, JM;MacKinnon, R
通讯作者：
MacKinnon, R
影响因子：
4.8
作者：
Parfenova, Lyubov V.;Crane, Brittany M.;Rothberg, Brad S.
通讯作者：
Rothberg, Brad S.
影响因子：
5.5
作者：
HORIE, M;IRISAWA, H;NOMA, A
通讯作者：
NOMA, A
DOI：
10.1085/jgp.114.4.551
发表时间：
1999-10
期刊：
The Journal of general physiology
影响因子：
--
作者：
Heginbotham L;LeMasurier M;Kolmakova-Partensky L;Miller C
通讯作者：
Miller C
影响因子：
3.4
作者：
Avdonin, V;Tang, XD;Hoshi, T
通讯作者：
Hoshi, T