It makes a protein called channelrhodopsin - 2 (ChR2) that acts as an antenna to receive blue light and convert it to an ion flow. (discovermagazine.com)
Several years ago, however, an exotic group of molecules known as Channelrhodopsins was discovered in green algae. (sciencedaily.com)
«Mode of action of protein channelrhodopsin - 2 decoded: Findings facilitate manufacture of optogenetic tools.» (sciencedaily.com)