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cellular retinol-binding protein 2 Cellular retinol-binding proteins (CRBPs) participate in the cellular uptake of vitamin A in the form of free retinol. Retinol achieves a higher chemical stability when bound to CRBPs, and its interaction with retinol-binding proteins allows the solubilization in the aqueous medium of the hydrophobic retinol molecule. There are four human CRBP types (CRBP1, -2, -3, -4) which differ in their tissue-specific expression pattern, as well as in their different ligand affinities. CRBP2 is also known as: "retinol-binding protein 2, cellular", CRABP-II, CRBP2, CRBPII, and RBPC2. Expression of CRBP2 is limited to the small intestine. CRBP2 binds both retinol and retinal; rat CRBP2 appears to bind both with equal affinity, human CRBP2 showed a significantly higher affinity for retinol relative to retinal. CRBP2 can bind all-trans-retinol, all trans-retinal and 13-cis-retinol, but not 9-cis-retinol. CRBPs belong to the intracellular fatty acid-binding protein (FABP) family, members of which are small proteins that bind hydrophobic ligands in a non-covalent, reversible manner, and, besides CRBPS, include the cellular retinoic acid-binding proteins (CRABPs) and the fatty acid-binding proteins (FABPs). |
Jiyao W et al.(2023). "The conserved domain database in 2023.",