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Updated: Aug 17, 2026

Two Peeling Methods for the Isolation of Photoreceptor Cell Compartments in the Mouse Retina for Protein Analysis
Published on: December 7, 2021
The retinal G protein-coupled receptor (RGR) enhances isomerohydrolase activity independent of light
Andreas Wenzel1, Vitus Oberhauser, Edward N Pugh
1Laboratory for Retinal Cell Biology, University Hospital Zurich, Eye Clinic, Switzerland. awenzel@opht.unizh.ch
Abstract:
Rod and cone visual pigments use 11-cis-retinal, a vitamin A derivative, as their chromophore. Light isomerizes 11-cis- into all-trans-retinal, triggering a conformational transition of the opsin molecule that initiates phototransduction. After bleaching all-trans-retinal leaves the opsin, and light sensitivity must be restored by regeneration of 11-cis-retinal. Under bright light conditions the retinal G protein-coupled receptor (RGR) was reported to support this regeneration by acting as a photoisomerase in a proposed photic visual cycle. We analyzed the contribution of RGR to rhodopsin regeneration under different light regimes and show that regeneration, during light exposure and in darkness, is slowed about 3-fold in Rgr(-/-) mice. These findings are not in line with the proposed function of RGR as a photoisomerase. Instead, RGR, independent of light, accelerates the conversion of retinyl esters to 11-cis-retinal by positively modulating isomerohydrolase activity, a key step in the "classical" visual cycle. Furthermore, we find that light accelerates rhodopsin regeneration, independent of RGR.
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