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ISOTYPE SELECTIVITY OF THE HUMAN RETINOIC ACID NUCLEAR RECEPTOR HRAR: THE COMPLEX WITH THE RARBETA/GAMMA-SELECTIVE RETINOID CD564
Structural highlights
FunctionRARG_HUMAN Receptor for retinoic acid. Retinoic acid receptors bind as heterodimers to their target response elements in response to their ligands, all-trans or 9-cis retinoic acid, and regulate gene expression in various biological processes. The RAR/RXR heterodimers bind to the retinoic acid response elements (RARE) composed of tandem 5'-AGGTCA-3' sites known as DR1-DR5. In the absence of ligand, acts mainly as an activator of gene expression due to weak binding to corepressors. Required for limb bud development. In concert with RARA or RARB, required for skeletal growth, matrix homeostasis and growth plate function (By similarity). 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 PubMedThe human retinoic acid receptor (hRAR) belongs to the family of nuclear receptors that regulate transcription in a ligand-dependent way. The isotypes RARalpha,beta and gamma are distinct pharmacological targets for retinoids that are involved in the treatment of various skin diseases and cancers, in particular breast cancer and acute promyelocytic leukemia. Therefore, synthetic retinoids have been developed aiming at isotype selectivity and reduced side-effects. We report the crystal structures of three complexes of the hRARgamma ligand-binding domain (LBD) bound to agonist retinoids that possess selectivity either for RARgamma (BMS184394) or for RARbeta/gamma (CD564), or that are potent for all RAR-isotypes (panagonist BMS181156). The high resolution data (1.3-1. 5 A) provide a description at the atomic level of the ligand pocket revealing the molecular determinants for the different degrees of ligand selectivity. The comparison of the complexes of the chemically closely related retinoids BMS184394 and CD564 shows that the side-chain of Met272 adopts different conformations depending on the presence of a hydrogen bond between its sulfur atom and the ligand. This accounts for their different isotype selectivity. On the other hand, the difference between the pan- and the RARbeta, gamma-selective agonist is probably due to a steric discrimination at the level of the 2-naphthoic acid moiety of CD564. Based on this study, we propose a model for a complex with the RARgamma-specific agonist CD666 that shows the possible applications for structure-based drug design of RAR isotype-selective retinoids. Structural basis for isotype selectivity of the human retinoic acid nuclear receptor.,Klaholz BP, Mitschler A, Moras D J Mol Biol. 2000 Sep 8;302(1):155-70. PMID:10964567[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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