Table 1.
Commonly Used opsins for Optogenetics
| Opsins | Mode | Features | References |
|---|---|---|---|
| ChR2 (H134R) | Excitatory | 470-nm blue light excitation. A mutant of ChR2, the protein can generate twice as much photocurrent. | Bang et al. 202216 |
| ChR2 (C128S/D156A) | Excitatory | A mutant of ChR2, an SFO ChR2 light-sensitive channel, it can open its ion channel for up to 30 min by activating the channel with 470 nm and then closing the channel with a 590-nm laser. | Bergs et al. 201817 |
| ChrimsonR | Excitatory | 590-600 nm excitation; the closing speed of the channel is increased by point mutation, which is suitable for experiments of higher stimulation frequency. | Klapoetke et al. 201418 |
| ChETA | Excitatory | Blue light excites it at around 470 nm. Mutants of ChR2, which have faster kinetics, can emit 200-Hz spikes in some neurons when stimulated by laser light. | Moshkforoush et al. 202119 |
| oChIEF | Excitatory | 450-470 nm blue light excitation. Some neurons can respond to high-frequency light stimulation, accelerate the speed of channel closure, and reduce the inactivation rate under continuous light stimulation. | López-Hernández et al. 201720 |
| Chronos | Excitatory | 500-530 nm excitation. It is the fastest native blue ChR reported so far. | Huet and Rankovic 202121 |
| ChRmine | Excitatory | Fast red-shifted opsin. Compared with other variants, it exhibits extremely large photocurrents with a 100-fold improved operational light sensitivity. | Chen et al. 202122 |
| ChRger | Excitatory | High-photocurrent ChRs with high light sensitivity can enable transcranial optogenetics. | Bedbrook et al. 201923 |
| SOUL | Excitatory | It has extremely high light sensitivity and can be photoactivated under significantly attenuated light power conditions. | Gong et al. 202024 |
| eNpHR3.0 | Inhibitory | 589-nm yellow light excitation. It pumps chloride ions into neurons and inhibits neuronal activity when illuminated by a yellow-green laser. eNpHR3.0 has good targeting to the cell membrane, the current is relatively durable, and the response is sensitive. | Ferenczi et al. 201625 |
| Arch | Inhibitory | Excitation around 566 nm. It is a yellow-laser-activated outwardly rectifying proton pump capable of moving protons from within the neuron into the extracellular environment, making the neuron hyperpolarized. | Chow et al. 201026 |
| Mac | Inhibitory | 540-nm excitation. Its mechanism of action is similar to that of NpHR. | Husson et al. 201227 |
| ST-eGtACR1 | Inhibitory | 515-nm excitation. GtACR is a Cl- channel with much higher efficiency than plasma pumps such as NpHR and Arch. | Antinucci et al. 202028 |
| Jaws | Inhibitory | 632-nm excitation. It is a red-shifted opsin that induces an influx of chloride ions under red light. | Chuong et al. 201429 |
Arch, archaerhodopsin; ChETA, channelrhodopsin-2 with E123T mutation; ChR2, channelrhodopsin-2; ChRger, channelrhodopsin Gaussian process-engineered recombinant opsin; eNpHR3.0, third-generation enhanced halorhodopsins; Mac, Leptosphaeria maculans fungal opsins; oChIEF, mammalian codon-optimized chimera E.F. with I170V mutation; SFO, step-function opsin; SOUL, step-function opsin with ultra-high light sensitivity.