Red-shifted channelrhodopsin from Chlamydomonas noctigama (ChrimsonR)

ChrimsonR opsin is a red-light-activated channelrhodopsin originally engineered from *Chlamydomonas noctigama* for optogenetic applications, offering a red-shifted activation spectrum (>590 nm) that enables deeper tissue penetration and minimized interference from endogenous blue-light photoreceptors[1][4]. It forms a seven-transmembrane helix structure typical of rhodopsins, containing a covalently bound retinal chromophore. Upon stimulation by red light, ChrimsonR opens a cation-conducting pore, producing rapid membrane depolarization and neural activation. Engineered mutations increase proton selectivity and accelerate channel kinetics, making ChrimsonR an effective, fast-acting tool for multicolor optogenetics and precise in vivo neural circuit manipulation[1][2][4][6][7]. ChrimsonR's red-shifted absorption allows for dual-color optogenetics when combined with blue light-gated channelrhodopsins, avoiding cross-activation[7]. ChrimsonR is not naturally occurring; it is a synthetic variant specifically optimized for mammalian expression, trafficking, and reduced blue light sensitivity[6]. No therapeutic drugs target ChrimsonR; it operates solely as a genetically encoded, light-gated actuator in experimental research[1][4].

Other names

ChrimsonRChrimsonRed-shifted channelrhodopsinRed-activatable channelrhodopsin

Red light illumination (~590–630 nm) induces conformational changes, opening the channel to selectively conduct cations (primarily protons), depolarizing the cell membrane and enabling action potentials