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3q4a

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{{STRUCTURE_3q4a| PDB=3q4a | SCENE= }}
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==Crystal structure of the TPR domain of CHIP complexed with phosphorylated Smad1 peptide==
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===Crystal structure of the TPR domain of CHIP complexed with phosphorylated Smad1 peptide===
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<StructureSection load='3q4a' size='340' side='right' caption='[[3q4a]], [[Resolution|resolution]] 1.54&Aring;' scene=''>
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{{ABSTRACT_PUBMED_21454478}}
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== Structural highlights ==
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<table><tr><td colspan='2'>[[3q4a]] is a 2 chain structure with sequence from [http://en.wikipedia.org/wiki/Mus_musculus Mus musculus]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=3Q4A OCA]. For a <b>guided tour on the structure components</b> use [http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=3Q4A FirstGlance]. <br>
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</td></tr><tr id='NonStdRes'><td class="sblockLbl"><b>[[Non-Standard_Residue|NonStd Res:]]</b></td><td class="sblockDat"><scene name='pdbligand=SEP:PHOSPHOSERINE'>SEP</scene></td></tr>
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<tr id='related'><td class="sblockLbl"><b>[[Related_structure|Related:]]</b></td><td class="sblockDat">[[3q47|3q47]], [[3q49|3q49]]</td></tr>
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<tr id='gene'><td class="sblockLbl"><b>[[Gene|Gene:]]</b></td><td class="sblockDat">Stub1, Chip ([http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&srchmode=5&id=10090 Mus musculus])</td></tr>
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<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=3q4a FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=3q4a OCA], [http://www.rcsb.org/pdb/explore.do?structureId=3q4a RCSB], [http://www.ebi.ac.uk/pdbsum/3q4a PDBsum]</span></td></tr>
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</table>
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<div style="background-color:#fffaf0;">
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== Publication Abstract from PubMed ==
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The transforming growth factor-beta (TGF-beta) superfamily of ligands signals along two intracellular pathways, Smad2/3-mediated TGF-beta/activin pathway and Smad1/5/8-mediated bone morphogenetic protein pathway. The C terminus of Hsc70-interacting protein (CHIP) serves as an E3 ubiquitin ligase to mediate the degradation of Smad proteins and many other signaling proteins. However, the molecular mechanism for CHIP-mediated down-regulation of TGF-beta signaling remains unclear. Here we show that the extreme C-terminal sequence of Smad1 plays an indispensable role in its direct association with the tetratricopeptide repeat (TPR) domain of CHIP. Interestingly, Smad1 undergoes CHIP-mediated polyubiquitination in the absence of molecular chaperones, and phosphorylation of the C-terminal SXS motif of Smad1 enhances the interaction and ubiquitination. We also found that CHIP preferentially binds to Smad1/5 and specifically disrupts the core signaling complex of Smad1/5 and Smad4. We determined the crystal structures of CHIP-TPR in complex with the phosphorylated/pseudophosphorylated Smad1 peptides and with an Hsp70/Hsc70 C-terminal peptide. Structural analyses and subsequent biochemical studies revealed that the distinct CHIP binding affinities of Smad1/5 or Smad2/3 result from the nonconservative hydrophobic residues at R-Smad C termini. Unexpectedly, the C-terminal peptides from Smad1 and Hsp70/Hsc70 bind in the same groove of CHIP-TPR, and heat shock proteins compete with Smad1/5 for CHIP interaction and concomitantly suppress, rather than facilitate, CHIP-mediated Smad ubiquitination. Thus, we conclude that CHIP inhibits the signaling activities of Smad1/5 by recruiting Smad1/5 from the functional R-/Co-Smad complex and further promoting the ubiquitination/degradation of Smad1/5 in a chaperone-independent manner.
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==Function==
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Molecular Mechanism of the Negative Regulation of Smad1/5 Protein by Carboxyl Terminus of Hsc70-interacting Protein (CHIP).,Wang L, Liu YT, Hao R, Chen L, Chang Z, Wang HR, Wang ZX, Wu JW J Biol Chem. 2011 May 6;286(18):15883-94. Epub 2011 Mar 16. PMID:21454478<ref>PMID:21454478</ref>
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[[http://www.uniprot.org/uniprot/CHIP_MOUSE CHIP_MOUSE]] E3 ubiquitin-protein ligase which targets misfolded chaperone substrates towards proteasomal degradation. Collaborates with ATXN3 in the degradation of misfolded chaperone substrates: ATXN3 restricting the length of ubiquitin chain attached to STUB1/CHIP substrates and preventing further chain extension. Ubiquitinates NOS1 in concert with Hsp70 and Hsp40. Modulates the activity of several chaperone complexes, including Hsp70, Hsc70 and Hsp90. Mediates transfer of non-canonical short ubiquitin chains to HSPA8 that have no effect on HSPA8 degradation. Mediates polyubiquitination of DNA polymerase beta (POLB) at 'Lys-41', 'Lys-61' and 'Lys-81', thereby playing a role in base-excision repair: catalyzes polyubiquitination by amplifying the HUWE1/ARF-BP1-dependent monoubiquitination and leading to POLB-degradation by the proteasome. Mediates polyubiquitination of CYP3A4. Ubiquitinates EPHA2 and may regulate the receptor stability and activity through proteasomal degradation.<ref>PMID:21855799</ref>
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==About this Structure==
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From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
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[[3q4a]] is a 2 chain structure with sequence from [http://en.wikipedia.org/wiki/Mus_musculus Mus musculus]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=3Q4A OCA].
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</div>
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== References ==
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==Reference==
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<references/>
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<ref group="xtra">PMID:021454478</ref><references group="xtra"/><references/>
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__TOC__
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</StructureSection>
[[Category: Mus musculus]]
[[Category: Mus musculus]]
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[[Category: Chen, L.]]
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[[Category: Chen, L]]
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[[Category: Wang, L.]]
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[[Category: Wang, L]]
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[[Category: Wu, J W.]]
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[[Category: Wu, J W]]
[[Category: E3 ubiquitin ligase]]
[[Category: E3 ubiquitin ligase]]
[[Category: Ligase-transcription complex]]
[[Category: Ligase-transcription complex]]

Revision as of 11:10, 19 December 2014

Crystal structure of the TPR domain of CHIP complexed with phosphorylated Smad1 peptide

3q4a, resolution 1.54Å

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