Vitamin E and transfer proteins.
OBJECTIVE
Recently, the intracellular transport as well as cellular uptake and excretion of alpha-tocopherol, the major representative of vitamin E, have been elucidated.


RESULTS
Alpha-tocopherol transfer protein has been identified as the major intracellular transport protein for vitamin E, mediating alpha-tocopherol secretion into the plasma via a non-Golgi-dependent pathway, while other binding proteins seem to play a less important role. New information has accumulated concerning the role of this protein in the transport and supply of vitamin E to tissues such as the central nervous system and the feto-maternal unit. The scavenger receptor class B type I receptor, a membrane-bound protein, is capable of transferring vitamin E into the cell, while the ATP-binding cassette transporter A1 can excrete vitamin E out of the cell. Advances in the area of vitamin E metabolism have shown that alpha-CEHC (2,5,7,8-tetramethyl-2-(2'-carboxyethyl)-6-hydroxychroman) and gamma-CEHC (2,7,8-trimethyl-2-(2'-carboxyethyl)-6-hydroxychroman) are formed by a cytochrome p450-mediated process, important for alpha and gamma-tocopherol excretion.


CONCLUSIONS
Insights into the regulation of vitamin E transport and metabolism on the cellular level have made enormous advances, showing the complex interplay of influx, trafficking, efflux and metabolism of this crucial antioxidant.
Kaempf-Rotzoll
Daisy E
DE
Department of Health Chemistry, Graduate School of Pharmaceutical Sciences, University of Tokyo, Tokyo, Japan.
Traber
Maret G
MG
Arai
Hiroyuki
H
D018528:ATP-Binding Cassette Transporters / Q000378:metabolism; D000818:Animals; D001692:Biological Transport; D018955:CD36 Antigens / Q000378:metabolism; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008074:Lipoproteins / Q000378:metabolism; D008565:Membrane Proteins; D011971:Receptors, Immunologic; D018110:Receptors, Lipoprotein; D051116:Receptors, Scavenger; D051122:Scavenger Receptors, Class B; D015534:Trans-Activators; D014810:Vitamin E / Q000378:metabolism*; D014811:Vitamin E Deficiency / Q000503:physiopathology; D024502:alpha-Tocopherol / Q000378:metabolism
D018528:ATP-Binding Cassette Transporters; D018955:CD36 Antigens; D002352:Carrier Proteins; D008074:Lipoproteins; D008565:Membrane Proteins; D011971:Receptors, Immunologic; D018110:Receptors, Lipoprotein; D051116:Receptors, Scavenger; C495124:SCARB1 protein, human; C432422:SEC14L2 protein, human; C454739:Scarb1 protein, mouse; D051122:Scavenger Receptors, Class B; D015534:Trans-Activators; C017763:alpha-tocopherol transfer protein; D014810:Vitamin E; D024502:alpha-Tocopherol