Does constitutive phosphorylation protect against photoreceptor degeneration in Rpe65-/- mice?
Despite the presence of this virgin opsin, Rpe65-/- rods are behaving like dark-adapted rods. These results argue that opsin which has not been exposed to 11-cis retinal and is constitutively phosphorylated, does not generate the activity generally associated with the bleached apoprotein. However, increased light-independent activation of transducin (due to bleached opsin) could be demonstrated after the addition of exogenous 11-cis retinal. We hypothesize that free opsin in the Rpe65-/- rods does not cause degeneration of rods by constitutive activation of the phototransduction cascade; but rather rods may die due to other causes such as the impairment of RPE function due to excess unprocessed retinyl-esters in the RPE.
Rohrer
Baerbel
B
Department of Ophthalmology, Medical University of South Carolina, Charleston, SC, USA. rohrer@musc.edu
Ablonczy
Zsolt
Z
Znoiko
Sergei
S
Redmond
Michael
M
Ma
Jian-Xing
JX
Crouch
Rosalie
R
D000818:Animals; D002352:Carrier Proteins; D004596:Electroretinography; D005136:Eye Proteins; D051379:Mice; D018345:Mice, Knockout / Q000235:genetics; D010766:Phosphorylation; D010786:Photoreceptor Cells / Q000473:pathology*; D011499:Protein Processing, Post-Translational; D011506:Proteins / Q000235:genetics / Q000378:metabolism*; D012160:Retina / Q000378:metabolism* / Q000503:physiopathology; D012162:Retinal Degeneration / Q000503:physiopathology / Q000517:prevention & control*; D017299:Rod Opsins / Q000235:genetics / Q000378:metabolism*; D019745:cis-trans-Isomerases; D000099178:Retinoid Isomerohydrolase
D002352:Carrier Proteins; D005136:Eye Proteins; D011506:Proteins; D017299:Rod Opsins; D019745:cis-trans-Isomerases; D000099178:Retinoid Isomerohydrolase