Cellular retinoic acid binding protein CRABP

Anhydroretinol binds to plasma and intracellular RBPs, but not to the cellular retinoic acid binding proteins (CRABPs) or retinoid receptors. In experimental animals, it protects against the development of chemically induced tumors while showing none of the toxic effects of other retinoids. 

Retinoic acid may either enter the target cell from the circulation or may be formed intraceUularly by oxidation of retinol. A number of tissues - but not muscle, kidneys, small intestines, liver, lungs, or spleen - have a cellular retinoic acid binding protein (CRABP) that is distinct from CRBP. Testis and... 

Momoi T, Hanaoka K, and Momoi M (1990) Spatial and temporal expression of cellular retinoic acid binding protein (CRABP) along the anteroposterior axis in the central nervous system of mouse embryos. Biochemical and Biophysical Research Communications 169, 991-6. 

Many hydrophobic molecules such as vitamin A, vitamin D and steroid hormones play vital roles in a variety of cellular processes. Because of the low solubility of these molecules in water, it has been difficult to measure the binding properties of the site-directed mutants of the proteins that interact with these hydrophobic ligands such as cellular retinoic acid binding proteins (CRABPs) (Zhang et al. 1992 Chen et al. 1995). This has greatly hampered the studies of the quantitative structure-function relationships of these important proteins. 

Cellular retinoic acid-binding protein CRABP Not determined Sundeiin et al. (1985)... 

Oxidation of retinol produces retinoic acid tretinoin). The reaction is irreversible. Retinoic acid enters the portal blood, is transported bound to albumin, and is not stored to any great extent. The concentration of retinoic acid in plasma is normally 3-4 ng/mL. A biologically active metabolite, 5,6-epoxyretinoic acid, has been isolated from the intestinal mucosa of vitamin A-deficient rats following administration of H-retinoic acid. Several tissues have specific cellular retinoic acid-binding proteins (CRABPs). 

Cellular retinoic acid binding proteins (CRABPs) 32... 

Retinoids present within a given cell are bound by intracellular-binding proteins, such as cellular retinol-binding proteins (CRBPs) or cellular retinoic acid-binding proteins (CRABPs) (Figure 1.2), all of which exhibit extremely high affinities for their substrates (Noy 2000). CRBP-I, for example, protects retinol from oxidation... 

The protocol presented in this chapter is derived from previously published methods (1,2). It has been used to investigate the effects of retinoic acid (RA) on the expression of cellular retinoic-acid binding protein (CRABP) -I and -II m relatively early mouse embryos (6.5-9.5-d postcoitum [p.c.] E6.5-9.5 /57)> Unfortunately, the size of the tissue sample that can be used for whole-mount ISH is limited, since both a riboprobe and an antibody-enzyme conjugate must penetrate the specimen and the unbound excess of both must be removed. Early embryos are small enough to allow penetration and removal of probe and antibody. This procedure should also work well for isolated pieces of larger embryos. 

Astrom, A, Tavakkol, A, Pettersson, U, Cromie, M, Elder, J. T., and Voorhees, J J (1991) Molecular-cloning of 2 human cellular retinoic acid-binding proteins (CRABP)—retinoic acid-induced expression of CRABP-II but not CRABP-I in adult human skin in vivo and in skin fibroblasts m vitro. J Biol Chem 266, 17,662-17,666... 

Nuclear-retinoid receptors provide a mechanism of retinoid action, but most likely where expressed, the cytosolic cellular retinoic acid-binding proteins (CRABPs) also affect the ability of retinoids to initiate biological signals (1,2). holo-CBlABP I sequesters retinoic acid (RA) with a value that may be <1 nM, and serves as a high-affinity 2 nM), efficient substrate of RA... 

Fiorella, P F and Napoli, J L (1991) Expression of cellular retinoic acid binding protein (CRABP) in Escherichia coli characterization and evidence that holo-CRABP is a substrate in retinoic acid metabolism J. Biol Chem 266, 16,572-16,579. 

Comparison of the Amino Terminal Amino Acid Sequences of Cellular Retinoic Acid-Binding Proteins (CRABP) from Rat and Cow with Cellular Retinol-Binding Protein (CRBP) from Rat"... 

Retinoid activities can also be modulated by the cellular retinoic acid-binding proteins (CRABPs) I and II. These proteins bind the natural retinoid trans-RA and potentiate its metabolic oxidation at the 4-position. ( )-4-[2-(3,5-Di-f-butylphenyl)propenyl]benzoic acid (CD55), which does not bind to CRABP and cannot be metabolized at its position corresponding to the 4-position of trans-RA, is far more potent than trans-RA in inducing the differentiation of HL-60 leukemia cells [43]. 

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