Molecular mechanisms of the slow deactivation of HERG channel

HERG通道缓慢失活的分子机制

基本信息

批准号：
12670081
负责人：
ISHII Kuniaki
金额：
$ 2.5万
依托单位：
Yamagata University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2001
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-12670081/
关键词：
Herg deactivation amino-terminal region sixth transmembrane region tandem oocyte 抗不整脈薬 Herg

项目摘要

The pore-forming subunit of human I_<Kr> channel is encoded by HERG. We have investigated influence of the sixth transmembrane segment (S6) on the slow deactivation of HERG channel and possible relationship between the S6 and the ammo-terminal region that is known to be involved in slowing the deactivation. We have also investigated whether changes in the deactivation rate affect the effects of various drugs on the HERG channel. (1) Substitution of Ile at 647 in the S6 with Phe, Tyr or Trp resulted in slowing of the deactivation kinetics. This residue is just next to the gating hinge Gly at which the inner helices bend when the potassium channels open. It might be possible that the bulky aromatic residue at the site next to the hinge interferes closing of the HERG channel. (2) Amino-terminal region of WT and I647F was deleted to generate WTΔ2-354 and I647FΔ2-354. When deactivation kinetics of WT, I647F and their amino-terminal deletion mutants were compared, I647FΔ2-354 deactivated mar … More kedly faster than I647F, but slower than WTΔ2-354. This result suggests that the amino-terminal region and the S6 affect the deactivation kinetics through different mechanisms. (3) Effects of various drugs were reduced in I647F, I647Y and I647W that exhibited slowing of the deactivation kinetics. To investigate whether the change in deactivation kinetics itself is responsible for the reduced effects of the drugs, their effects on I647FΔ2-354 were studied. Currents of I647FΔ2-354 were inhibited by the drugs significantly less than I647F, but markedly greater than WT. Thus, although the slower deactivation kinetics might be partly responsible for the reduced effects of the drugs, the mutation of I647 probably affects the binding of the drugs besides changing the deactivation kinetics. (4) We could not investigate how many amino-termini are needed to slow the deactivation kinetics, since no detectable currents were observed through tandem constructs of WT and the amino-terminal deletion mutants. Less

人类 I_<Kr> 通道的成孔亚基由 HERG 编码。我们研究了第六跨膜片段 (S6) 对 HERG 通道缓慢失活的影响以及 S6 和氨基末端区域之间的可能关系。我们还研究了失活率的变化是否会影响各种药物对 HERG 通道的影响 (1) Ile 在 647 处的取代。 S6 与 Phe、Tyr 或 Trp 导致失活动力学减慢。该残基紧邻门控铰链 Gly，当钾通道打开时，内部螺旋可能会在该位置弯曲。 (2) WT 和 I647F 的氨基末端区域被删除，生成 WTΔ2-354 和当比较 WT、I647F 及其氨基末端缺失突变体的失活动力学时，I647FΔ2-354 失活速度比 I647F 快，但比 WTΔ2-354 慢。 S6通过不同的机制影响失活动力学（3）各种药物的作用均降低。 I647F、I647Y 和 I647W 表现出失活动力学减慢为了研究失活动力学本身的变化是否导致药物效果降低，研究了它们对 I647FΔ2-354 的影响。显着低于药物 I647F，但显着高于 WT，因此，尽管失活动力学较慢。可能是药物作用减弱的部分原因，I647 的突变除了改变失活动力学外，还可能影响药物的结合 (4) 我们无法研究需要多少个氨基末端来减缓失活动力学，因为通过WT和氨基末端缺失突变体的串联构建体没有观察到可检测到的电流。