Vitamin C transporters
Journal of Physiology and Biochemistry(2008)
Abstract
Vitamin C is a wide spectrum antioxidant essential for humans, which are unable to synthesize the vitamin and must obtain
it from dietary sources. There are two biologically important forms of vitamin C, the reduced form, ascorbic acid, and the
oxidized form, dehydroascorbic acid. Vitamin C exerts most of its biological functions intracellularly and is acquired by
cells with the participation of specific membrane transporters. This is a central issue because even in those species capable
of synthesizing vitamin C, synthesis is restricted to the liver (and pancreas) from which is distributed to the organism.
Most cells express two different transproter systems for vitamin C; a transporter system with absolute specificity for ascorbic
acid and a second system that shows absolute specificity for dehydroascorbic acid. The dehydroascorbic acid transporters are
members of the GLUT family of facilitative glucose transporters, of which at least three isoforms, GLUT1, GLUT3 and GLUT4,
are dehydroascorbic acid transporters. Ascorbic acid is transported by the SVCT family of sodium-coupled transporters, with
two isoforms molecularly cloned, the transporters SVCT1 y SVCT2, that show different functional properties and differential
cell and tissue expression. In humans, the maintenance of a low daily requirement of vitamin C is attained through an efficient
system for the recycling of the vitamin involving the two families of vitamin C transporters.
MoreTranslated text
Key words
glut.,ascorbic acid,dehydroascorbic acid,svct,vitamin c,Vitamin C,Ascorbic acid,Dehydroascorbic acid,SVCT,GLUT
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