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| {{STRUCTURE_2nxx| PDB=2nxx | SCENE= }} | | {{STRUCTURE_2nxx| PDB=2nxx | SCENE= }} |
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| '''Crystal Structure of the Ligand-Binding Domains of the T.castaneum (Coleoptera) Heterodimer EcrUSP Bound to Ponasterone A'''
| | ===Crystal Structure of the Ligand-Binding Domains of the T.castaneum (Coleoptera) Heterodimer EcrUSP Bound to Ponasterone A=== |
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| ==Overview==
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| 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.
| | The line below this paragraph, {{ABSTRACT_PUBMED_17673910}}, adds the Publication Abstract to the page |
| | (as it appears on PubMed at http://www.pubmed.gov), where 17673910 is the PubMed ID number. |
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| | {{ABSTRACT_PUBMED_17673910}} |
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| ==About this Structure== | | ==About this Structure== |
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| [[Category: Hormone receptor]] | | [[Category: Hormone receptor]] |
| [[Category: Hormone/growth factor complex]] | | [[Category: Hormone/growth factor complex]] |
| ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun May 4 10:03:11 2008'' | | |
| | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Mon Jul 28 12:58:42 2008'' |
