野生类型和突变Shaker通道中的封闭电荷的大小
N E Schoppa1, K McCormack, M A Tanouye
1Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, CT 06510.
概括
电压离子通道在打开时移动电荷. 直接测量显示,Shaker通道中的12.3个基本电荷 (e0) 的电荷位移 (q) 较高,与之前的估计不同.
科学领域:
- 分子生物学分子生物学
- 生物物理学的生物物理.
- 神经科学是一个神经科学.
背景情况:
- 电压离子通道对于细胞电信号传输至关重要.
- 它们的功能对膜电位敏感,涉及电荷运动.
- 以前的电荷位移估计 (q) 是间接的,范围为4-8e0.
研究的目的:
- 在Shaker通道的打开过程中直接测量电荷位移 (q).
- 为了研究突变对电压灵敏度和电荷运动的影响.
- 改进电压依赖通道激活的模型.
主要方法:
- 利用电生理学技术测量Drosophila melanogaster Shaker 29-4通道中的电荷运动.
- 采用位点定向的突变发生来改变电压敏感性.
- 分析了通道激活的电压依赖性.
主要成果:
- 在野生类型的Shaker通道中直接测量电荷位移 (q) 的结果是12.3 e0.
- 变异的Shaker通道具有降低电压灵敏度,显示了类似的高q值.
- 这些发现挑战了先前的估计,并表明突变物中的平衡发生了变化.
结论:
- 与Shaker通道门关联的电荷运动明显大于此前估计的.
- 影响电压灵敏性的突变不会相应地减少电荷位移.
- 一个在电压依赖的步骤中结合改变平衡的模型解释了突变通道的结果.
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