TY - JOUR
T1 - The Retinal G Protein-coupled Receptor (RGR) Enhances Isomerohydrolase Activity
T2 - Independent of Light
AU - Wenzel, Andreas
AU - Oberhauser, Vitus
AU - Pugh, Edward N.
AU - Lamb, Trevor D.
AU - Grimm, Christian
AU - Samardzija, Marijana
AU - Fahl, Edda
AU - Seeliger, Mathias W.
AU - Remé, Charlotte E.
AU - von Lintig, Johannes
PY - 2005/8
Y1 - 2005/8
N2 - 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.
AB - 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.
UR - http://www.scopus.com/inward/record.url?scp=23844496400&partnerID=8YFLogxK
U2 - 10.1074/jbc.M503603200
DO - 10.1074/jbc.M503603200
M3 - Article
SN - 0021-9258
VL - 280
SP - 29874
EP - 29884
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
IS - 33
ER -