Rhodopsins and optogenetics

Rhodopsins are light-sensitive receptor proteins involved in signal transduction. All rhodopsins bind retinal as the chromophore. The best known rhodposins are the light sensitive pigments within the rods of our eyes. In microbes, rhodopsins can act as receptors that change conformation in response to light to trigger intracellular signalling, as pumps that drive protons or chloride ions across the cell membrane, or as non-specific cation channels.