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I_ <kr>频道的孔形成子单位由HERG编码。我们研究了第六个跨膜段（S6）对HERG通道缓慢失活以及S6与弹药末端区域之间可能涉及减慢失活的影响的影响。我们还研究了失活率的变化是否影响各种药物对HERG通道的影响。（1）用PHE，TYR或TRP在S6中647在647取代ILE导致失活动力学的放缓。该居住地就在钾通道打开时内螺旋弯曲的门控铰链旁边。 HERG通道的铰链干扰关闭旁边的地点的笨重芳香住宅可能。（2）删除了WT和I647F的氨基末端区域以生成WTδ2-354和I647Fδ2-354。当比较WT的失活动力学时，比较了I647F及其氨基末端缺失突变体时，I647FΔ2-354停用了MAR…比I647F快得多，但比WTΔ2-354更慢。该结果表明，氨基末端区域和S6通过不同的机制影响失活动力学。（3）在I647F，I647Y和I647W中，各种药物的作用降低了失活动力学的减慢。为了研究停用动力学本身的变化是否导致药物的影响减少，它们对I647FΔ2-354的影响是研究的。 I647Fδ2-354的电流被药物抑制明显小于I647F，但明显大于WT。尽管较慢的失活动力学可能部分负责药物的作用减少，但I647的突变可能会影响药物的结合，而不是改变失活动力学。（4）我们无法研究需要多少个氨基末端来减慢失活动力学，因为没有通过WT和氨基末端缺失突变体的串联构建体观察到可检测的电流。较少的