Channelrhodopsin

A microbial-type rhodopsin protein found in the eyespots of algae. Channelrhodopsin proteins are associated with the phototaxic responses of algae to light during their nonvegetative life-cycle stages. They are the only known natively occurring proteins that function as light-gated ion channels (that is, light-activated channels that control the passage of ions through cell membranes). Thus far, channelrhodopsins have been cloned and described in numerous algae species. Importantly, modified versions of these proteins have been utilized as research tools by biologists interested in modulating the membrane potentials of excitable cells in heterologous expression systems.