title: Cysteine Substitution and Labeling Provide Insight into Channelrhodopsin-2 Ion Conductance.
abstract: 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.
authors: Department of Chemistry and Biochemistry, Worcester Polytechnic Institute , Worcester, Massachusetts 01609, United States.
authors: Ryan
authors: R
authors: Richards
authors: Department of Chemistry and Biochemistry, Worcester Polytechnic Institute , Worcester, Massachusetts 01609, United States.
authors: Robert E
authors: RE
authors: Dempski
mesh_terms: D000818:Animals; D016825:Chlamydomonas reinhardtii; D003545:Cysteine / Q000235:genetics*; D004560:Electricity; D005260:Female; D007202:Indicators and Reagents; D015640:Ion Channel Gating; D007700:Kinetics; D008027:Light; D008698:Mesylates / Q000737:chemistry; D008958:Models, Molecular; D016297:Mutagenesis, Site-Directed; D009865:Oocytes / Q000502:physiology; D018408:Patch-Clamp Techniques; D010539:Permeability; D017434:Protein Structure, Tertiary; D012243:Rhodopsin / Q000737:chemistry* / Q000235:genetics; D014982:Xenopus laevis
chemical_list: D007202:Indicators and Reagents; D008698:Mesylates; C109153:(2-sulfonatoethyl)methanethiosulfonate; D012243:Rhodopsin; D003545:Cysteine