2nxx
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(New page: 200px<br /><applet load="2nxx" size="350" color="white" frame="true" align="right" spinBox="true" caption="2nxx, resolution 2.750Å" /> '''Crystal Structure o...)
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Revision as of 11:18, 23 January 2008
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Crystal Structure of the Ligand-Binding Domains of the T.castaneum (Coleoptera) Heterodimer EcrUSP Bound to Ponasterone A
Overview
Retinoid X receptor (RXR) and Ultraspiracle (USP) play a central role as, ubiquitous heterodimerization partners of many nuclear receptors. While it, has long been accepted that a wide range of ligands can activate, vertebrate/mollusc RXRs, the existence and necessity of specific, endogenous ligands activating RXR-USP in vivo is still matter of intense, debate. Here we report the existence of a novel type of RXR-USP with a, ligand-independent functional conformation. Our studies involved Tribolium, USP (TcUSP) as representative of most arthropod RXR-USPs, with high, sequence homology to vertebrate/mollusc RXRs. The crystal structure of the, ligand-binding domain of TcUSP was solved in the context of the functional, heterodimer with the ecdysone receptor (EcR). While EcR exhibits a, canonical ligand-bound conformation, USP adopts an original apo structure., Our functional data demonstrate that TcUSP is a constitutively silent, partner of EcR, and that none of the RXR ligands can bind and activate, TcUSP. These findings together with a phylogenetic analysis suggest that, RXR-USPs have undergone remarkable functional shifts during evolution and, give insight into receptor-ligand binding evolution and dynamics.
About this Structure
2NXX is a Protein complex structure of sequences from Tribolium castaneum with as ligand. Full crystallographic information is available from OCA.
Reference
Structural and functional characterization of a novel type of ligand-independent RXR-USP receptor., Iwema T, Billas IM, Beck Y, Bonneton F, Nierengarten H, Chaumot A, Richards G, Laudet V, Moras D, EMBO J. 2007 Aug 22;26(16):3770-82. Epub 2007 Aug 2. PMID:17673910
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