Cysteine Substitution and Labeling Provide Insight into Channelrhodopsin-2 Ion Conductance

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• 作者：Ryan Richards ; Robert E. Dempski
• 刊名：Biochemistry
• 出版年：2015
• 出版时间：September 22, 2015
• 年：2015
• 卷：54
• 期：37
• 页码：5665-5668
• 全文大小：238K
• ISSN：1520-4995

文摘

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.