This enzyme, which operates in the retinal pigment epithelium (RPE), catalyses the cleavage and isomerization of all-trans-retinyl fatty acid esters to 11-cis-retinol, a key step in the regeneration of the visual chromophore in the vertebrate visual cycle . Interaction of the enzyme with the membrane is critical for its enzymic activity .
This enzyme, which operates in the retinal pigment epithelium (RPE), catalyses the cleavage and isomerization of all-trans-retinyl fatty acid esters to 11-cis-retinol, a key step in the regeneration of the visual chromophore in the vertebrate visual cycle [4]. Interaction of the enzyme with the membrane is critical for its enzymic activity [6].
13cIMH expression is detected in the periventricular grey zone of the optic tectum and torus longitudinalis, at the fasciculus longitudinalis medialis in the medulla oblongata, and at the periventricular pretectum
enzyme homologue RPE65c is expressed in retinal Müller cells, not in the retinal pigment epithelium. Zebrafish is a cone-dominant species with 79% cones and 21% rods
isoform RPE65c is the alternative isomerohydrolase in the intra-retinal visual cycle, providing 11-cis retinal to cone photoreceptors in cone-dominant species
it is likely that the two novel homologues of RPE65 (13cIMH and RPE65c, EC 3.1.1.90 and EC 3.1.1.64, respectively) are generated through gene duplication after the separation of fish RPE65 from the ancestral RPE65, because they exhibit an extremely high level of sequence identity (97%) and are located in the same chromosome, but on a different chromosome from RPE65
the efficient recycling of the chromophore of visual pigments, 11-cis-retinal, through the retinoid visual cycle is an essential process for maintaining normal vision. RPE65 is the isomerohydrolase in retinal pigment epithelium and generates predominantly 11-cis-retinol and a minor amount of 13-cis-retinol, from all-trans-retinyl ester. Enzyme homologue RPE65c expressed in the inner retina may serve as an alternative isomerohydrolase in the inner retinal visual cycle to meet the high demand for recycling of the chromophore in the cone-dominant retina
site-directed mutagenesis, the mutation reverses the enzyme isomerization product specificity from formation of 11-cis-retinol to 13-cis-retinol, product of EC 3.1.1.90. Formation of 95.7% 13-cis-retinol and 4.3% 11-cis-retinol
site-directed mutagenesis, the mutation reverses the enzyme isomerization product specificity from formation of 11-cis-retinol to 13-cis-retinol, product of EC 3.1.1.90. Formation of 55.1% 13-cis-retinol and 44.9% 11-cis-retinol
site-directed mutagenesis, the mutation reverses the enzyme isomerization product specificity from formation of 11-cis-retinol to 13-cis-retinol, product of EC 3.1.1.90. Formation of 71-3% 13-cis-retinol and 28.7% 11-cis-retinol
site-directed mutagenesis, the mutation completely reverses the enzyme isomerization product specificity from formation of 11-cis-retinol to 13-cis-retinol, product of EC 3.1.1.90. Exclusive formation of 13-cis-retinol