Features：Channelrhodopsins are light-gated ion channels that exist naturally in microalgae. hChR2 is a humanized version of ChR2 for mammalian expression. It is maximally excited by 470 nm light. Stable Step Function Opsin (SSFO) is a double mutant of ChR2 (Asp156Ala and Cys128Ser) with higher light sensitivity than other opsin variants, enabling non-invasive activation of neurons expressing SSFO. The SSFO variant with the additional T159C mutation, known as the SOUL version, has higher light sensitivity in certain brain regions, making it suitable for optogenetic control in deep brain areas.
