RGR

Non-visual opsin that functions as a light-dependent facilitator of retinoid isomerization and trafficking in retinal pigment epithelium (RPE) and Mueller glia. Participates in a photic visual cycle by complementing the classical enzymatic RPE65/RDH pathway for chromophore regeneration (By similarity). Binds all-trans-retinal via a conserved Schiff-base lysine and, upon illumination, promotes photoisomerization of all-trans-retinal to 11-cis-retinal required for regeneration of visual pigments (By similarity). Also mediates light-dependent mobilization of stored all-trans-retinyl esters from lipid droplets to endoplasmic reticulum membranes, facilitating their processing into 11-cis-retinoids. May also modulate isomerohydrolase activity independent of light (By similarity). Although RGR is structurally a GPCR-family opsin, there is no consistent evidence that RGR activates G proteins or initiates a canonical second-messenger signaling cascade (Probable)..

Function from UniProtKB (P47804), read 2026-09-23. CC BY 4.0.