Identification of the endogenous retinoids associated with three cellular retinoid-binding proteins from bovine retina and retinal pigment epithelium.
The endogenous retinoids associated with three cellular retinoid-binding proteins from bovine retina and retinal pigment epithelium have been identified by their spectral characteristics and their co-migration with authentic retinoids on high performance liquid chromatography. All-trans-retinol is the only retinoid associated with the cellular retinol-binding protein from retina and retinal pigment epithelium. The saturation of the binding site with native ligand is 0.95 +/- 0.05 mol of retinoid/mol of protein for cellular retinol-binding protein purified from frozen and fresh retina and retinal pigment epithelium. All-trans-retinoic acid has been identified as the endogenous ligand associated with the cellular retinoic acid-binding protein of cattle retina. The saturation of the binding site of cellular retinoic acid-binding protein from frozen and fresh retina (the protein is absent in extracts of retinal pigment epithelium) is about 0.2 mol of retinoid/mol of protein, probably a minimum value due to losses of the ligand. Retinoic acid has not been detected previously in retina. Cellular retinaldehyde-binding protein from retina purifies with two endogenous ligands which cochromatograph on high performance liquid chromatography with 11-cis-retinaldehyde and 11-cis-retinol and occur in a ratio of approximately 3:1, respectively. The binding site of cellular retinaldehyde-binding protein from frozen retina is nearly fully occupied with these two ligands (saturation greater than 0.9 mol of retinoids/mol of protein). In contrast, purified cellular retinaldehyde-binding protein from retinal pigment epithelium carries only 11-cis-retinaldehyde as an endogenous ligand. The saturation of the binding site with this ligand is greater than 0.95.
D000818:Animals; D002352:Carrier Proteins / Q000378:metabolism; D002417:Cattle; D010857:Pigment Epithelium of Eye / Q000378:metabolism; D018168:Receptors, Retinoic Acid; D012160:Retina / Q000378:metabolism*; D012172:Retinaldehyde / Q000378:metabolism; D012177:Retinol-Binding Proteins / Q000378:metabolism; D054840:Retinol-Binding Proteins, Cellular; D013056:Spectrophotometry, Ultraviolet; D014801:Vitamin A / Q000031:analogs & derivatives* / Q000378:metabolism
C020932:11-cis-retinal-binding protein; D002352:Carrier Proteins; D018168:Receptors, Retinoic Acid; D012177:Retinol-Binding Proteins; D054840:Retinol-Binding Proteins, Cellular; D014801:Vitamin A; D012172:Retinaldehyde