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首页> 外文期刊>Proceedings of the National Academy of Sciences of the United States of America >A ring of eight conserved negatively charged amino acids doubles the conductance of BK channels and prevents inward rectification.
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A ring of eight conserved negatively charged amino acids doubles the conductance of BK channels and prevents inward rectification.

机译：八个保守的带负电荷的氨基酸环可将BK通道的电导率加倍，并防止向内整流。

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摘要

Large-conductance Ca2+-voltage-activated K+ channels (BK channels) control many key physiological processes, such as neurotransmitter release and muscle contraction. A signature feature of BK channels is that they have the largest single channel conductance of all K+ channels. Here we examine the mechanism of this large conductance. Comparison of the sequence of BK channels to lower-conductance K+ channels and to a crystallized bacterial K+ channel (MthK) revealed that BK channels have a ring of eight negatively charged glutamate residues at the entrance to the intracellular vestibule. This ring of charge, which is absent in lower-conductance K+ channels, is shown to double the conductance of BK channels for outward currents by increasing the concentration of K+ in the vestibule through an electrostatic mechanism. Removing the ring of charge converts BK channels to inwardly rectifying channels. Thus, a simple electrostatic mechanism contributes to the large conductance of BK channels.
机译：大电导的Ca2 +电压激活的K +通道（BK通道）控制许多关键的生理过程，例如神经递质的释放和肌肉的收缩。 BK通道的一个标志性特征是它们具有所有K +通道中最大的单通道电导率。在这里，我们检查这种大电导的机制。 BK通道与电导率较低的K +通道和结晶的细菌K +通道（MthK）的序列比较表明，BK通道在细胞内前庭的入口处有8个带负电的谷氨酸残基环。该电荷环在较低电导的K +通道中不存在，已显示通过静电机制增加前庭中K +的浓度，使BK通道的外向电流电导率翻倍。去除电荷环，可将BK通道转换为向内整流通道。因此，简单的静电机制有助于BK通道的大电导。

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