Lysine-rich extracellular rings formed by hbeta2 subunits confer the outward rectification of BK channels.
Lysine-rich extracellular rings formed by hbeta2 subunits confer the outward rectification of BK channels.
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DOI：
10.1371/journal.pone.0002114
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发表时间：
2008-05-07
期刊：
影响因子：
3.7
通讯作者：
Ding J
中科院分区：
文献类型：
--
作者：
Chen M;Gan G;Wu Y;Wang L;Wu Y;Ding J
大电导钙激活钾通道（BK）的辅助β亚基对BK（mSlo1 α）通道的多样性有重要贡献，而这种多样性是许多组织中正常功能的基础。在这里，我们描述了hβ2辅助亚基胞外段的功能元件，其作为带正电荷的环来改变BK通道电导。hβ2细胞外环的四个连续赖氨酸，位于足够靠近孔的细胞外入口的位置，构成三个带正电荷的环。这些环可通过静电机制降低细胞外K+浓度，阻止Charybdotoxin（ChTX）进入通道的细胞外入口，导致K+流入减少或BK通道的外向整流。我们的研究结果表明，hβ2辅助亚基形成的赖氨酸环影响BK通道的内向电流，提供了一种在细胞复极化过程中电流迅速减少的机制。此外，该研究将有助于了解不同辅助β亚基贡献的BK通道功能多样性。
The auxiliary β subunits of large-conductance Ca2+-activated K+ (BK) channels greatly contribute to the diversity of BK (mSlo1 α) channels, which is fundamental to the adequate function in many tissues. Here we describe a functional element of the extracellular segment of hβ2 auxiliary subunits that acts as the positively charged rings to modify the BK channel conductance. Four consecutive lysines of the hβ2 extracellular loop, which reside sufficiently close to the extracellular entryway of the pore, constitute three positively charged rings. These rings can decrease the extracellular K+ concentration and prevent the Charybdotoxin (ChTX) from approaching the extracellular entrance of channels through electrostatic mechanism, leading to the reduction of K+ inflow or the outward rectification of BK channels. Our results demonstrate that the lysine rings formed by the hβ2 auxiliary subunits influences the inward current of BK channels, providing a mechanism by which current can be rapidly diminished during cellular repolarization. Furthermore, this study will be helpful to understand the functional diversity of BK channels contributed by different auxiliary β subunits.