孔螺旋中的突变调节了Kcv通道孔隙中的过门和Ba2+块之间的相互作用
Noel Tewes1, Beatrice Kubitzki1, Flandrit Bytyqi1
1Membrane Biophysics, Technische Universität Darmstadt , Darmstadt, Germany.
The Journal of general physiology
|April 23, 2024
概括
一个K+通道突变增强了Ba2+阻断,而不是通道关. 这种Ba2+ () 污染会导致电压依赖的关闭,揭示过器-离子相互作用控制离子停留时间.
科学领域:
- 生物物理学的生物物理.
- 离子通道生理学 离子通道生理学
- 分子生物学分子生物学
背景情况:
- (K+) 通道对于细胞电信号传输至关重要,具有控制离子运输和门的选择性过器.
- KcvNTS通道是一个只有孔的结构,允许专门研究过门动态.
- 之前在KcvNTS中发现的一种S42T突变改变了K+的透性,并引入了电压依赖的通道关闭.
研究的目的:
- 阐明在S42T突变KcvNTS通道中观察到的电压依赖和K+敏感通道关闭背后的机制.
- 为了确定这些关闭是否是由内在的过门结构变化或外部因素造成的.
- 研究 (Ba2+) 污染对调节KcvNTS通道活动的作用.
主要方法:
- 利用了只有孔的K+通道KcvNTS及其S42T突变体.
- 在不同度的KCl和受控的Ba2+水平的溶液中进行了电生理学记录.
- 使用高亲和度Ba2+化剂 (18C6TA) 来评估Ba2+的作用.
- 分析了电压依赖的通道行为和离子块动力学.
主要成果:
- 在S42T突变体中观察到的通道关闭并不是由于内在的过门形状变化.
- 这些关闭被确定为依赖电压的阻断,通过KCl溶液中的微量Ba2+来确定.
- 极端的正电压减轻了阻塞,而添加亚微分子Ba2+则增加了阻塞.
- 在正电压下,S42T突变使过器对Ba2+的亲和度增加了200倍以上.
结论:
- S42T突变显著提高了过器对Ba2+的亲和力,导致了电压依赖的阻断.
- 与野生类型通道相比,离子在S42T突变的过器结合部位的停留时间较长.
- 孔螺旋和选择性过器之间的相互作用关键控制透和阻断离子的停留时间.
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