Sodium-dependent ascorbic acid transporter family SLC23

l-Ascorbic acid (vitamin C) is an effective antioxidant and an essential cofactor in numerous enzymatic reactions. Two Na(+)-dependent vitamin C transporters (SVCT1 and SVCT2) are members of the SLC23 human gene family, which also contains two orphan members. SVCT1 and SVCT2 display similar properties, including high affinity for l-ascorbic acid, but are discretely distributed. SVCT1 is confined to epithelial systems including intestine, kidney, and liver, whereas SVCT2 serves a host of metabolically active and specialized cells and tissues including neurons, the eye, lung, and placenta, and a range of neuroendocrine, exocrine, and endothelial tissues. An SVCT2-knockout mouse reveals an obligatory requirement for SVCT2, but many of the specific roles of this transporter remain unclear.