Table 1.

Commonly-used Opsins in Neuroscience Research

Function	Opsin	Protein nature	Activation wavelength (nm)	Feature
Excitatory	Channelrhodopsin (ChR) 2	Nonspecific cation channel	470	Slow kinetics
	ChETA	ChR2 variant	470	Faster kinetics
	VChR1	Volvox ChR1	589	Red-shifted
	oChIEF	Chimeric opsin of ChR1 and ChR2	450–470	Reliable response to high-frequency stimulation
	ReaChR	Red-activatable ChR	590–630	Red-shifted, more light sensitive
	Chronos	ChR	500–530	More light sensitive, faster kinetics
	Chrimson	ChR	590–600	Red-shifted
	ChroME	Chronos variant	490	Ultrafast and highly potent
	C1V1	Chimeric opsin of ChR1 and VChR1	540–560	Red-shifted, suitable for two-photo optogenetics
	SFOs	Step function opsins	470	Deactivated by 542 nm green light
	SSFOs	Stabilized step-function ChR2	470	Deactivated by 590 nm yellow light
Inhibitory	eNpHR	Engineered halorhodopsin, chloride pump	589	More light sensitive
	Archaerhodopsin (ArchT)	Enhanced proton pump	566	More potent
	Mac	Proton pump	540
	ChloCs	Chloride-conducting ChR	465	Increased light sensitivity
	iC1C2	Chloride-conducting ChR	475	More light sensitive
	Jaws	Cruxhalorhodopsin, chloride-conducting	632	Red-shifted, highly light sensitive
	GtACR1	Anion-conducting ChR	515	Fast kinetics, high potency