1cbq | pdb_00001cbq
CRYSTAL STRUCTURE OF CELLULAR RETINOIC-ACID-BINDING PROTEINS I AND II IN COMPLEX WITH ALL-TRANS-RETINOIC ACID AND A SYNTHETIC RETINOID
Structural highlights
Function[RABP2_HUMAN] Transports retinoic acid to the nucleus. Regulates the access of retinoic acid to the nuclear retinoic acid receptors. Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedBACKGROUND: Retinoic acid (RA) plays a fundamental role in diverse cellular activities. Cellular RA binding proteins (CRABPs) are thought to act by modulating the amount of RA available to nuclear RA receptors. CRABPs and cellular retinol-binding proteins (CRBPs) share a unique fold of two orthogonal beta-sheets that encapsulate their ligands. It has been suggested that a trio of residues are the prime determinants defining the high specificity of CRBPs and CRABPs for their physiological ligands. RESULTS: Bovine/murine CRABP I and human CRABP II have been crystallized in complex with their natural ligand, all-trans-RA. Human CRABP II has also been crystallized in complex with a synthetic retinoid, 'compound 19'. Their structures have been determined and refined at resolutions of 2.9 A, 1.8 A and 2.2 A, respectively. CONCLUSIONS: The retinoid-binding site in CRABPs differs significantly from that observed in CRBP. Structural changes in three juxtaposed areas of the protein create a new, displaced binding site for RA. The carboxylate of the ligand interacts with the expected trio of residues (Arg132, Tyr134 and Arg111; CRABP II numbering). The RA ligand is almost flat with the beta-ionone ring showing a significant deviation (-33 degrees) from a cis conformation relative to the isoprene tail. The edge atoms of the beta-ionone ring are accessible to solvent in a suitable orientation for presentation to metabolizing enzymes. The bulkier synthetic retinoid causes small conformational changes in the protein structure. Crystal structures of cellular retinoic acid binding proteins I and II in complex with all-trans-retinoic acid and a synthetic retinoid.,Kleywegt GJ, Bergfors T, Senn H, Le Motte P, Gsell B, Shudo K, Jones TA Structure. 1994 Dec 15;2(12):1241-58. PMID:7704533[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also
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