Allosteric modulation of the mouse Kir6.2 channel by intracellular H+ and ATP.
Allosteric modulation of the mouse Kir6.2 channel by intracellular H+ and ATP.
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细胞内 H 和 ATP 对小鼠 Kir6.2 通道的变构调节。
DOI：
10.1113/jphysiol.2002.025247
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发表时间：
2002
期刊：
影响因子：
--
通讯作者：
Jiang,Chun
中科院分区：
文献类型：
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作者：
Wu,Jianping;Cui,Ningren;Piao,Hailan;Wang,Ying;Xu,Haoxing;Mao,Jinzhe;Jiang,Chun
ATP敏感的K+(KATP)通道除了受ATP、ADP和磷脂的调节外，还受细胞内H+的调节。在这里，我们展示了H+与ATP在调节一个克隆的KATP通道中相互作用的证据，即Kir6.2在有或没有SUR1亚基的情况下表达。在酸性pH条件下，通道对ATP的敏感性降低，而在存在ATP的情况下，通道的pH敏感性也降低。这些效应在SUR1亚基的存在下更加明显。在Kir6.2+SUR1中，pH灵敏度在100mMATP值时降低了约0.4pH单位，在1mMATP值下降低了0.6pH单位，而当pH从7.4时降低到6.8时，其灵敏度降低了约四倍。Kir6.2+SUR1电流在pH 5.9-6.5时被强烈激活，即使在1 mMATP存在的情况下也是如此。调制似乎分别发生在His175和Lys185，这两个基因分别参与了质子和ATP的传感。His175突变完全消除了pH对ATP敏感性的影响。同样，K185E突变通道失去了依赖于ATP的pH敏感性调节。从而证实了ATP和H+对克隆的KATP通道的变构调节作用。这种调节允许质子直接激活KATP通道，并释放细胞内ATP对通道的抑制；在几种病理生理条件下，随着ATP浓度的降低，pH效应进一步增强。
The ATP‐sensitive K+(KATP) channels are regulated by intracellular H+in addition to ATP, ADP, and phospholipids. Here we show evidence for the interaction of H+with ATP in regulating a cloned KATPchannel, i.e. Kir6.2 expressed with and without the SUR1 subunit. Channel sensitivity to ATP decreases at acidic pH, while the pH sensitivity also drops in the presence of ATP. These effects are more evident in the presence of the SUR1 subunit. In the Kir6.2 + SUR1, the pH sensitivity is reduced by about 0.4 pH units with 100 μM ATP and 0.6 pH units with 1 mmATP, while a decrease in pH from 7.4 to 6.8 lowers the ATP sensitivity by about fourfold. The Kir6.2 + SUR1 currents are strongly activated at pH 5.9‐6.5 even in the presence of 1 mmATP. The modulations appear to take place at His175 and Lys185 that are involved in proton and ATP sensing, respectively. Mutation of His175 completely eliminates the pH effect on the ATP sensitivity. Similarly, the K185E mutant‐channel loses the ATP‐dependent modulation of the pH sensitivity. Thus, allosteric modulations of the cloned KATPchannel by ATP and H+are demonstrated. Such a regulation allows protons to activate directly the KATPchannels and release channel inhibition by intracellular ATP; the pH effect is further enhanced with a decrease in ATP concentration as seen in several pathophysiological conditions.