CRABP protein

Unfortunately antibodies to the CRABP proteins are not generally available. It IS uncertain if the PAGE method would be sufficiently sensitive to detect an antisense-induced inhibition, especially if the effect is less than complete. 

Species in Which Ceiiuiar Retinoi-Binding (CRBP) and Retinoic Acid-Binding (CRABP) Proteins Have Been Detected"... 

Cellular Retlnol-BIndlng (CRBP) and Retinoic Acld-BIndlng (CRABP) Proteins in Human Cultured Cells ... 

Nematodes provide exceptions to the rule that members of the FABP/ P2/CRBP/CRABP family of proteins are universally intracellular. Some of those secreted by nematodes may be involved in specialized functions, such as the protection of developing embryos within shelled eggs. Nematodes also provide examples of where the highly conserved tertiary structure of these proteins has been modified. 

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. 

Cellular Retinoid Binding Proteins CRBPs and CRABPs... 

M five proteins have a high affinity and are present in excess of their ligands, with CRBP 1.4-fold higher than intracellular retinol, and CRABP 20-fold higher than intracellular retinoic acid. This means that, under normal conditions, essentially all of the intracellular retinoids will be protein-bound. 

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. 

The equilibria in the two compartments that contain the wild-type CRABP-II and mutant proteins can be described by Eq. (1) and Eq. (2) ... 

Figure 1. Competitive binding assays for measuring the dissociation constant of L121A mutant relative to that of the wild-type CRABP-II. The relative radioactivity is the radioactivity count of the compartment containing the wild-type protein minus that of the compartment containing L121A.

We are indebted to Dr. Anders Astrom for providing us the wild-type cDNA clone of human CRABP-II. This work was supported by funds from the REF Center of Protein Structure and Design and the Cancer Center at Michigan State University. 

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