Lack of effect of RPE65 removal on the enzymatic processing of all-trans-retinol into 11-cis-retinol in vitro.
RPE65 is a major membrane associated protein found in the vertebrate retinal pigment epithelium (RPE). Various studies have shown this protein to be essential for visual function, possibly at the level of the processing of retinoids. The pigment epithelium is the anatomical site in which the visual chromophore 11-cis retinal is generated. The two critical RPE enzymes in the isomerization pathway are lecithin retinol acyl transferase (LRAT) and isomerohydrolase, which processes all-trans-retinyl esters into 11-cis-retinol. Both enzymes are membrane bound. It is shown here that RPE65 can be largely extracted (90-95%) from RPE membranes by 1 M KCl by itself, or with added detergent CHAPS. The almost quantitative extraction of RPE65 from RPE membranes has little or no effect on in vitro LRAT and isomerohydrolase activities in quantitative enzymatic assays using RPE membranes, suggesting that RPE65 may not have an important role to play in the enzymatic processing of all-trans-retinol into 11-cis-retinol in vitro.
Choo
D W
DW
Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA.
Cheung
E
E
Rando
R R
RR
D000217:Acyltransferases / Q000378:metabolism; D000818:Animals; D015153:Blotting, Western; D002417:Cattle; D002793:Cholic Acids; D005136:Eye Proteins / Q000502:physiology*; D006863:Hydrogen-Ion Concentration; D008565:Membrane Proteins / Q000502:physiology; D010857:Pigment Epithelium of Eye / Q000378:metabolism*; D011189:Potassium Chloride; D011506:Proteins; D012995:Solubility; D014801:Vitamin A / Q000378:metabolism*; D019745:cis-trans-Isomerases / Q000378:metabolism; D000099178:Retinoid Isomerohydrolase
D000217:Acyltransferases; D002793:Cholic Acids; D005136:Eye Proteins; D008565:Membrane Proteins; D011189:Potassium Chloride; D011506:Proteins; D014801:Vitamin A; D019745:cis-trans-Isomerases; D000099178:Retinoid Isomerohydrolase; C056942:lecithin-retinol acyltransferase; C028213:3-((3-cholamidopropyl)dimethylammonium)-1-propanesulfonate