Photoreceptor required for image-forming vision at low light intensity. Light-induced isomerization of 11-cis to all-trans retinal triggers a conformational change that activates signaling via G-proteins. Signaling mediates the activation of phospholipase C (By similarity). Subsequent receptor phosphorylation mediates displacement of the bound G-protein alpha subunit by arrestin and terminates signaling (By similarity). Detected on the rhabdomere membrane in the photoreceptor outer segment. Contains one covalently linked retinal chromophore. Upon light absorption, the covalently bound 11-cis-retinal is converted to all-trans-retinal (By similarity). After hydrolysis of the Schiff base and release of the covalently bound all-trans-retinal, active rhodopsin is regenerated by binding of a fresh molecule of 11-cis-retinal (By similarity). Belongs to the G-protein coupled receptor 1 family. Opsin subfamily.