The retinal G protein-coupled receptor (RGR) enhances isomerohydrolase activity independent of light

Andreas Wenzel, Vitus Oberhauser, Edward N Pugh Jr, Trevor D. Lamb, Christian Grimm, Marijana Samardzija, Edda Fahl, Mathias W. Seeliger, Charlotte E. Remé, Johannes Von Lintig

Research output: Contribution to journalArticlepeer-review

71 Scopus citations


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.

Original languageEnglish (US)
Pages (from-to)29874-29884
Number of pages11
JournalJournal of Biological Chemistry
Issue number33
StatePublished - Aug 19 2005
Externally publishedYes

ASJC Scopus subject areas

  • Biochemistry


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