Intracellular Mg(2+) enhances the function of BK-type Ca(2+)-activated K(+) channels.
Intracellular Mg(2+) enhances the function of BK-type Ca(2+)-activated K(+) channels.
复制标题
细胞内MG（2+）增强了BK型Ca（2+）激活的K（+）通道的功能。
DOI：
10.1085/jgp.118.5.589
复制
发表时间：
2001-11
影响因子：
3.8
通讯作者：
Cui, J
中科院分区：
文献类型：
--
作者：
Shi, J;Cui, J
BK channels modulate neurotransmitter release due to their activation by voltage and Ca2+. Intracellular Mg2+ also modulates BK channels in multiple ways with opposite effects on channel function. Previous single-channel studies have shown that Mg2+ blocks the pore of BK channels in a voltage-dependent manner. We have confirmed this result by studying macroscopic currents of the mslo1 channel. We find that Mg2+ activates mslo1 BK channels independently of Ca2+ and voltage by preferentially binding to their open conformation. The mslo3 channel, which lacks Ca2+ binding sites in the tail, is not activated by Mg2+. However, coexpression of the mslo1 core and mslo3 tail produces channels with Mg2+ sensitivity similar to mslo1 channels, indicating that Mg2+ sites differ from Ca2+ sites. We discovered that Mg2+ also binds to Ca2+ sites and competitively inhibits Ca2+-dependent activation. Quantitative computation of these effects reveals that the overall effect of Mg2+ under physiological conditions is to enhance BK channel function.
