Transport and storage of vitamin A.
The requirement of vitamin A (retinoids) for vision has been recognized for decades. In addition, vitamin A is involved in fetal development and in the regulation of proliferation and differentiation of cells throughout life. This fat-soluble organic compound cannot be synthesized endogenously by humans and thus is an essential nutrient; a well-regulated transport and storage system provides tissues with the correct amounts of retinoids in spite of normal fluctuations in daily vitamin A intake. An overview is presented here of current knowledge and hypotheses about the absorption, transport, storage, and metabolism of vitamin A. Some information is also presented about a group of ligand-dependent transcription factors, the retinoic acid receptors, that apparently mediate many of the extravisual effects of retinoids.
Blomhoff
R
R
Institute for Nutrition Research, School of Medicine, University of Oslo, Norway.
Green
M H
MH
Berg
T
T
Norum
K R
KR
D000818:Animals; D001692:Biological Transport; D002914:Chylomicrons / Q000378:metabolism; D007408:Intestinal Absorption; D008099:Liver / Q000378:metabolism; D012177:Retinol-Binding Proteins / Q000378:metabolism; D014212:Tretinoin / Q000378:metabolism; D014801:Vitamin A / Q000378:metabolism*
D002914:Chylomicrons; D012177:Retinol-Binding Proteins; D014801:Vitamin A; D014212:Tretinoin