Vitamin E Research Today is a free monthly online journal that collates and summarizes the latest research about Vitamin E, including details on benefits, dosage, supplements, antioxidants.

Molecular mechanism of alpha-tocopheryl-phosphate transport across the cell membrane.

Negis Y, Meydani M, Zingg JM, Azzi A

Vascular Biology Laboratory, The Jean Mayer USDA Human Nutrition Center at Tufts University, Boston, MA 02111, USA.

alpha-Tocopheryl-phosphate (alpha-TP) is synthesized and hydrolyzed in animal cells and tissues where it modulates several functions. alpha-TP is more potent than alpha-T in inhibiting cell proliferation, down-regulating CD36 transcription, inhibiting atherosclerotic plaque formation. Administration of alpha-TP to cells or animals requires its transfer through membranes, via a transporter. We show here that alpha-TP is passing the plasma membrane via a system that is inhibited by glibenclamide and probenecid, inhibitors of a number of transporters. Glibenclamide and probenecid prevent dose-dependently alpha-TP inhibition of cell proliferation. The two inhibitors act on ATP binding cassette (ABC) and organic anion transporters (OAT). Since ABC transporters function to export solutes and alpha-TP is transported into cells, it may be concluded that alpha-TP transport may occur via an OAT family member. Due to the protection by glibenclamide and probenecid on the alpha-TP induced cell growth inhibition it appears that alpha-TP acts after its uptake inside cells.

Published 13 June 2007 in Biochem Biophys Res Commun, 359(2): 348-53.
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