Dynamic control of deactivation gating by a soluble amino-terminal domain in HERG K(+) channels.
Dynamic control of deactivation gating by a soluble amino-terminal domain in HERG K(+) channels.
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DOI：
10.1085/jgp.115.6.749
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发表时间：
2000-06
期刊：
影响因子：
--
通讯作者：
Robertson GA
中科院分区：
文献类型：
--
作者：
Wang J;Myers CD;Robertson GA
由人类ether-à-go-go-related基因（HERG）编码的K+通道与大多数其他电压门控K+通道的区别在于异常缓慢的失活过程，该过程使心脏IKr（心室细胞中的相应电流）有助于动作电位的复极化。当从HERG的氨基末端缺失前16个氨基酸时，失活速率快得多（Wang，J.，M.C. Trudeau，A.M. Zappia和G.A.罗伯森1998. 112：637-647）。在这项研究中，我们确定了前16个氨基酸是否包含能够减缓失活的功能结构域。我们还测试了这个“失活子域”是否通过影响通道开放时间直接或间接地通过阻断机制来减缓失活。使用从非洲爪蟾卵母细胞中切除的由内而外的macropatches，我们发现对应于HERG的前16个氨基酸的肽足以重建缺乏氨基末端的通道的缓慢失活。该肽以快速和容易可逆的方式充当可溶性结构域，反映了比在先前的研究中用较大的氨基末端肽片段观察到的缓慢修饰更动态的失活调节（Morais Cabral，J.H.，A. Lee，S.L.科恩，B.T.查特，M. Li和R.麦金农1998. Cell. 95：649-655）。通过肽的失活的减缓以剂量依赖性方式发生，希尔系数意味着每个通道至少三种肽的协同作用。与通过阻断通道间接减缓失活的内部TEA不同，肽不会降低电流幅度。氨基末端也不干扰TEA的阻断作用，表明氨基末端结合位点在空间上与TEA结合位点不同。对细胞贴附贴片中的单通道活性的分析表明，氨基末端显著增加通道的平均开放时间，而没有改变平均关闭时间或增加孔阻塞机制所预期的非导电状态。四聚体通道的末端失活亚结构域与未被通道开放所覆盖的结合位点相互作用，频道关闭
K+ channels encoded by the human ether-à-go-go-related gene (HERG) are distinguished from most other voltage-gated K+ channels by an unusually slow deactivation process that enables cardiac IKr, the corresponding current in ventricular cells, to contribute to the repolarization of the action potential. When the first 16 amino acids are deleted from the amino terminus of HERG, the deactivation rate is much faster (Wang, J., M.C. Trudeau, A.M. Zappia, and G.A. Robertson. 1998. J. Gen. Physiol. 112:637–647). In this study, we determined whether the first 16 amino acids comprise a functional domain capable of slowing deactivation. We also tested whether this “deactivation subdomain” slows deactivation directly by affecting channel open times or indirectly by a blocking mechanism. Using inside-out macropatches excised from Xenopus oocytes, we found that a peptide corresponding to the first 16 amino acids of HERG is sufficient to reconstitute slow deactivation to channels lacking the amino terminus. The peptide acts as a soluble domain in a rapid and readily reversible manner, reflecting a more dynamic regulation of deactivation than the slow modification observed in a previous study with a larger amino-terminal peptide fragment (Morais Cabral, J.H., A. Lee, S.L. Cohen, B.T. Chait, M. Li, and R. Mackinnon. 1998. Cell. 95:649–655). The slowing of deactivation by the peptide occurs in a dose-dependent manner, with a Hill coefficient that implies the cooperative action of at least three peptides per channel. Unlike internal TEA, which slows deactivation indirectly by blocking the channels, the peptide does not reduce current amplitude. Nor does the amino terminus interfere with the blocking effect of TEA, indicating that the amino terminus binding site is spatially distinct from the TEA binding site. Analysis of the single channel activity in cell-attached patches shows that the amino terminus significantly increases channel mean open time with no alteration of the mean closed time or the addition of nonconducting states expected from a pore block mechanism.We propose that the four amino-terminal deactivation subdomains of the tetrameric channel interact with binding sites uncovered by channel opening to specifically stabilize the open state and thus slow channel closing.
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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：
64.5
作者：
Cabral, JHM;Lee, A;Mackinnon, R
通讯作者：
Mackinnon, R
DOI：
10.1085/jgp.58.4.413
发表时间：
1971-10
期刊：
The Journal of general physiology
影响因子：
--
作者：
Armstrong CM
通讯作者：
Armstrong CM
影响因子：
16.2
作者：
Sewing, S;Roeper, J;Pongs, O
通讯作者：
Pongs, O
影响因子：
4.8
作者：
Chen, J;Zou, AR;Sanguinetti, MC
通讯作者：
Sanguinetti, MC