3ilz | pdb_00003ilz
Structure of TR-alfa bound to selective thyromimetic GC-1 in P212121 space group
Structural highlights
DiseaseTHA_HUMAN Defects in THRA are the cause of congenital hypothyroidism non-goitrous type 6 (CHNG6) [MIM:614450. A disease characterized by growth retardation, developmental retardation, skeletal dysplasia, borderline low thyroxine levels and high triiodothyronine levels. There is differential sensitivity to thyroid hormone action, with retention of hormone responsiveness in the hypothalamic pituitary axis and liver but skeletal, gastrointestinal, and myocardial resistance.[1] FunctionTHA_HUMAN Nuclear hormone receptor. High affinity receptor for triiodothyronine. 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: Thyroid receptors, TRalpha and TRbeta, are involved in important physiological functions such as metabolism, cholesterol level and heart activities. Whereas metabolism increase and cholesterol level lowering could be achieved by TRbeta isoform activation, TRalpha activation affects heart rates. Therefore, beta-selective thyromimetics have been developed as promising drug-candidates for treatment of obesity and elevated cholesterol level. GC-1 [3,5-dimethyl-4-(4'-hydroxy-3'-isopropylbenzyl)-phenoxy acetic acid] has ability to lower LDL cholesterol with 600- to 1400-fold more potency and approximately two- to threefold more efficacy than atorvastatin (Lipitor(c)) in studies in rats, mice and monkeys. RESULTS: To investigate GC-1 specificity, we solved crystal structures and performed molecular dynamics simulations of both isoforms complexed with GC-1. Crystal structures reveal that, in TRalpha Arg228 is observed in multiple conformations, an effect triggered by the differences in the interactions between GC-1 and Ser277 or the corresponding asparagine (Asn331) of TRbeta. The corresponding Arg282 of TRbeta is observed in only one single stable conformation, interacting effectively with the ligand. Molecular dynamics support this model: our simulations show that the multiple conformations can be observed for the Arg228 in TRalpha, in which the ligand interacts either strongly with the ligand or with the Ser277 residue. In contrast, a single stable Arg282 conformation is observed for TRbeta, in which it strongly interacts with both GC-1 and the Asn331. CONCLUSION: Our analysis suggests that the key factors for GC-1 selectivity are the presence of an oxyacetic acid ester oxygen and the absence of the amino group relative to T3. These results shed light into the beta-selectivity of GC-1 and may assist the development of new compounds with potential as drug candidates to the treatment of hypercholesterolemia and obesity. Structural basis of GC-1 selectivity for thyroid hormone receptor isoforms.,Bleicher L, Aparicio R, Nunes FM, Martinez L, Gomes Dias SM, Figueira AC, Santos MA, Venturelli WH, da Silva R, Donate PM, Neves FA, Simeoni LA, Baxter JD, Webb P, Skaf MS, Polikarpov I BMC Struct Biol. 2008 Jan 31;8:8. PMID:18237438[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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