Rhodopsins, visual photoreceptors, are Class A GPCRs composed of the seven transmembrane protein (opsin) covalently linked to the chromophore retinal. A photon of light stimulates the isomerization of retinal resulting in a conformational change in opsin and activation of an intracellular heterotrimeric G protein. Different rhodopsins are activated at different peak wavelengths. (Adapted from
FBrf0218480 &
FBrf0217353).