Cellular retinol- and retinoic acid-binding proteins in vitamin A action
1979
Chytil, Frank | Ong, David E.
Two intracellular proteins that bind compounds with vitamin A activity have been found: the cellular retinol-binding protein (CRBP) and the cellular retinoic acid-binding protein (CRABP). CRBP is distinct from the serum retinol-binding protein (RBP); they have different binding sites and requirements. CRBP allows specific interaction of retinol with the nucleus, and apparently mediates retinol action in the cell. CRABP has a different tissue distribution from CRBP and has no affinity for retinol or retinal. The presence of both binding proteins in reproductive organs may mean that both retinol and retinoic acid are required for these tissues to function normally. The two proteins are regulated differently and have different immunochemical properties. The presence of CRABP in some cancerous tissues is under investigation to learn the mechanisms by which retinoids appear to be involved in tumor growth or inhibition. The effects of retinoids may be mediated by the cellular binding proteins.
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