Microbial rhodopsin

Microbial rhodopsin, also known as type-I rhodopsin, is a photochemically active membrane protein composed of seven transmembrane alpha-helices with a retinal chromophore. It includes light-driven proton pumps, ion pumps and ion channels, as well as light sensors. Microbial rhodopsins are found in all three domains of life: Archaea, Bacteria, and Eukaryota, as well as in viruses. It is rare in complex multicellular organisms.