探索来自淡青链霉菌的钾通道的开放孔。
Exploring the open pore of the potassium channel from Streptomyces lividans.
作者信息
Meuser D, Splitt H, Wagner R, Schrempf H
机构信息
Angewandte Genetik der Mikroorganismen, Universität Osnabrück, Germany.
出版信息
FEBS Lett. 1999 Dec 3;462(3):447-52. doi: 10.1016/s0014-5793(99)01579-3.
The tetrameric potassium channel from Streptomyces lividans (KcsA) embedded in planar bilayers exhibits the following electrophysiological characteristics: (i) K+ ions can cross the pore in a highly hydrated state (nH2O > or = 6), (ii) the selectivity for K+ exceeds that for Na+ ions by 11 times, and both Ca2+ and Mg2+ are permeant, (iii) the internal side is blocked by Ba2+ ions in a voltage-dependent manner, (iv) intrinsic rectification is due to gating, depending on the direction of the electric field, (v) the internal side is pH-sensitive, and (vi) the open pore has a diameter of approximately 5.8 A. In conclusion, our results show that ion conduction and selectivity of KcsA cannot easily be reconciled with the properties deduced from the rigid crystal structure [Doyle et al., Science 280 (1998) 69-77], which must be concluded to have the pore trapped in its closed state.
嵌入平面双层膜中的来自淡紫链霉菌的四聚体钾通道（KcsA）表现出以下电生理特性：（i）K⁺离子能够以高度水合状态（nH₂O≥6）穿过孔道；（ii）对K⁺的选择性超过对Na⁺离子的选择性11倍，并且Ca²⁺和Mg²⁺均可通透；（iii）内侧被Ba²⁺离子以电压依赖性方式阻断；（iv）本征整流归因于门控，取决于电场方向；（v）内侧对pH敏感；（vi）开放孔道的直径约为5.8埃。总之，我们的结果表明，KcsA的离子传导和选择性很难与从刚性晶体结构推导出来的特性相协调[多伊尔等人，《科学》280（1998）69 - 77]，必须得出结论，即其孔道被困在关闭状态。
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