Retinoid-binding proteins: structural determinants important for function.
The transport and functions of biologically active naturally occurring retinoids (Vitamin A, retinol, and its metabolites) are mediated by extracellular, intracellular, and nuclear proteins. X-ray crystallographic studies to date on the extra- and intracellular proteins have helped to define distinct protein retinoid recognition mechanisms, each with a characteristic structural motif. The extracellular proteins (serum retinol-binding protein and a retinoic acid-binding protein from rat epididymis) bind retinoids with a hand-in-glove like fit in deep, hydrophobic-binding cavities. The intracellular proteins (cellular retinol-binding proteins types I and II) encapsulate the ligand in an aqueous internal cavity. The details of the mechanisms of retinoid recognition, and how they result as a consequence of the different protein structures, are described in this review.
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Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-0146, USA.
D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D018360:Crystallography, X-Ray / Q000379:methods; D006801:Humans; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011487:Protein Conformation; D012177:Retinol-Binding Proteins / Q000737:chemistry* / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D014212:Tretinoin / Q000737:chemistry / Q000378:metabolism
D012177:Retinol-Binding Proteins; D014212:Tretinoin