lecithin retinol acyltransferase (phosphatidylcholine-retinol O-acyltransferase, LRAT)
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Function
- transfers the acyl group from the sn-1 position of phosphatidylcholine to all-trans retinol, producing all-trans retinyl esters
- role in vision, vitamin A processing
- provides the all-trans retinyl ester substrates for the isomerohydrolase which processes the esters into 11-cis-retinol in the retinal pigment epithelium (a membrane-associated alcohol dehydrogenase oxidizes 11 cis-retinol to 11-cis-retinaldehyde, the chromophore for rhodopsin & the cone photopigments
- inhibited by all-trans-retinyl alpha-bromoacetate & N-boc-L-biocytinyl-11-aminoundecane chloro-methyl ketone (BACMK)
- up-regulated by dietary vitamin A
- under conditions of vitamin A depletion, LRAT expression in the liver is induced by retinoic acid
Compartment
endoplasmic reticulum membrane
Expression
- expressed in testis & liver > retinal pigment epithelium, small intestine, prostate, pancreas, colon > brain
- in fetal tissues, expressed in retinal pigment epithelium & liver >> brain.
Pathology
- defects in LRAT are associated with severe early-onset retinal dystrophy