ADVANCES ON VITAMIN-A AND RETINOL-BINDING PROTEINS

The recent interest in the study of vitamin A is due to the discovery of an increasing variety of functions, actions or associations of this vitamin with cellular differentiation of epithelial tissues, growth, reproduction and vision. This review describes the recent advances on the metabolism of vitamin A especially in regard to the retinoid-binding proteins in the transport of hydrophobic retinoids and their participation in the transformation of the different retinoids in the organism as well as in the interior of the cell. Seven binding proteins have been discovered and well characterized: retinol binding protein (REP); cellular retinol-binding protein (CRBP); cellular retinol-binding protein type two (CRBP-II); cellular retinoic acid binding protein (CRABP); cellular retinoic acid binding protein type two (CPABP-II); cellular retinal-binding protein (CRALBP) and interphotoreceptor retinol-binding protein (IRBP). Their specific roles are presented. Also the function and mechanisms of the regulation of gene expression by retinoic acid is described.