RPE65 antibody

Background of RPE65 antibody

The visual cycle consisting of retinoids, the enzymatic pathway that produces chromophore after light absorption, is located primarily in the retinal pigment epithelium (RPE) and is essential for rod photoreceptor survival. This visual cycle is naturally disrupted in humans with Leber congenital amaurosis (LCA) which primarily caused by mutations in a retinal epithelial specific 6kDa protein (RPE65). The RPE65 is expressed exclusively in central retinal pigment epithelium and appeared to be concentrated in the central retina. The central retinal RPE layer also showed a 4-fold higher retinoid isomerase activity than more peripheral RPE (1). RPE65 is a isomerhydrolase catalyzing the key step in regeneration of 11-cis-retinal, a chromophore for retinal pigment. The regeneration of retinal pigment was faster in cone cells than rod cells as evident by 12-fold higher isomerhydrlase activity (RPE65 activity) in rod enriched chicken RPE compared to cone dominant bovine RPE after normalization of protein based on RPE65 levels (2).
RPE65 encodes a 65 kDa protein in microsomes of the retinal epithelium. Several mutations in RPE65 has been noted and described in RPE65 in patients with autosomal recessive, severe, childhood-onset retinal dystrophy. The longest open reading frame for RPE gene (2.4kb) encode a 533 amino acid protein with predicted molecular weight of 61 kDa, the protein after post-translational modification migrates at 65 kDa on reducing SDS-PAGE system. RPE65 sequence is highly conserved among various mammalian species Sequence comparison of RPE with other species suggest. A 4 bp deletion in putative Exxon 5 of the canine RPE65 gene led to an autosomal recessive, early onset and progressive retinal dystrophy in inbred kinship of Swedish briard beagle dogs due to a frame shift mutation resulting in an early stop codon making it an attractive model for human disease. The soluble form of RPE65 binds vitamin A preparing it for conversion to all-trans-retinyl ester via LRAT activity. The membrane bound form binds to all-trans-retinyl-esters making them available for processing by all-cis-retinol a reaction catalyzed by LRAT. The protein also undergo lipid modification during post-translational modification.