Molecular determinants differentiating photocurrent properties of two channelrhodopsins from chlamydomonas.

摘要: A light signal is converted into an electrical one in a single molecule named channelrhodopsin, of the archaea-type rhodopsins unicellular green algae. Although highly homologous, two molecules this family, channelrhodopsin-1 (ChR1) and -2 (ChR2), are distinct photocurrent properties such as wavelength sensitivity, desensitization, turning-on -off kinetics. However, structures regulating these have not been completely identified. Photocurrents were analyzed for several chimera made by replacing N-terminal segments ChR2 with homologous counterparts ChR1. We found that sensitivity was red-shifted negligible desensitization slowed kinetics when replacement segment containing fifth transmembrane helix Therefore, involved determination properties, characterizing ChR1 ChR2. Eight amino acid residues differentiating exchanged one-by-one, each targeted mutant further analyzed. Among them, position Tyr226(ChR1)/Asn187(ChR2) molecular determinants It suggested directly or indirectly interact chromophore well protein structure determining Some channelrhodopsins to advantages over wild-type introduction light-induced membrane depolarization purpose artificial stimulation neurons vivo visual prosthesis photoreceptor degeneration.