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Retinol Metabolism in Human Liver

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Vitamin-A (all-trans-Retinol), one of the essential micronutrient in the human is obtained chiefly in form of Retinyl Esters from meat, and Carotenoids, such as Beta-Carotene, from plant tissue. Beta-carotene and other Carotenoids are converted by the body into Retinol and are referred to as Provitamin-A Carotenoids. Hundreds of different Carotenoids are synthesized by plants, but only about 10 percent of them are Provitamin-A Carotenoids (Ref.1). The main site for synthesis and storage of Vitamin-A is in the liver. The pRBPs (Plasma Retinol-Binding Proteins) and Ttr (Transthyretin) facilitate the transfer of insoluble Vitamin-A between tissues, principally from storage sites in the liver to peripheral tissues. In the absence of pRBPs and Ttr the supply of Vitamin-A to target tissues is accomplished [...]


1.Young monozygotic twin sisters with fundus albipunctatus and cone dystrophy.
Nakamura M, Lin J, Miyake Y.
Arch. Ophthalmol. 2004 Aug;122(8):1203-7.
2.A novel RDH5 gene mutation in a patient with fundus albipunctatus presenting with macular atrophy and fading white dots.
Yamamoto H, Yakushijin K, Kusuhara S, Escano MF, Nagai A, Negi A.
Am. J. Ophthalmol. 2003 Sep;136(3):572-4.
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