Richards Ryan, Dempski Robert E
Department of Chemistry and Biochemistry, Worcester Polytechnic Institute , Worcester, Massachusetts 01609, United States.
Biochemistry. 2015 Sep 22;54(37):5665-8. doi: 10.1021/acs.biochem.5b00738. Epub 2015 Sep 8.
Channelrhodopsin-2 is a light-activated cation channel. However, the mechanism of ion conductance is unresolved. Here, we performed cysteine scanning mutagenesis on transmembrane domain 7 followed by labeling with a methanethiosulfonate compound. Analysis of our results shows that residues that line the putative pore and interface with adjacent transmembrane domains 1 and 3, as proposed by our channelrhodopsin-2 homology model, affect ion conductance, decay kinetics, and/or off kinetics. Combined, these results suggest that negative charges at the extracellular side of transmembrane domain 7 funnel cations into the pore.
视紫红质通道蛋白-2是一种光激活阳离子通道。然而，离子传导机制尚未明确。在此，我们对跨膜结构域7进行了半胱氨酸扫描诱变，随后用甲硫基磺酸盐化合物进行标记。对我们结果的分析表明，正如我们的视紫红质通道蛋白-2同源模型所提出的，构成假定孔道并与相邻跨膜结构域1和3界面的残基会影响离子传导、衰减动力学和/或关闭动力学。综合这些结果表明，跨膜结构域7细胞外侧的负电荷将阳离子导入孔道。
