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==Crystal structure of the KH1 domain of human RNA-binding E3 ubiquitin-protein ligase MEX-3C complex with RNA==
<StructureSection load='5www' size='340' side='right'caption='[[5www]], [[Resolution|resolution]] 1.80&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[5www]] is a 2 chain structure with sequence from [https://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens] and [https://en.wikipedia.org/wiki/Synthetic_construct Synthetic construct]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=5WWW OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=5WWW FirstGlance]. <br>
</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">X-ray diffraction, [[Resolution|Resolution]] 1.798&#8491;</td></tr>
<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=5www FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=5www OCA], [https://pdbe.org/5www PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=5www RCSB], [https://www.ebi.ac.uk/pdbsum/5www PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=5www ProSAT]</span></td></tr>
</table>
== Disease ==
[https://www.uniprot.org/uniprot/MEX3C_HUMAN MEX3C_HUMAN] Genetic variations in MEX3C may be associated with susceptibility to essential hypertension.<ref>PMID:17015768</ref> 
== Function ==
[https://www.uniprot.org/uniprot/MEX3C_HUMAN MEX3C_HUMAN] E3 ubiquitin ligase responsible for the post-transcriptional regulation of common HLA-A allotypes. Binds to the 3' UTR of HLA-A2 mRNA, and regulates its levels by promoting mRNA decay. RNA binding is sufficient to prevent translation, but ubiquitin ligase activity is required for mRNA degradation.<ref>PMID:22863774</ref> <ref>PMID:23446422</ref> 
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
MEX-3 is a KH domain-containing RNA-binding protein, first identified as a translational repressor in Caenorhabditis elegans, while its four orthologs (MEX-3A-D) in human and mouse were subsequently found to have E3 ubiquitin ligase activity mediated by a RING domain and critical for RNA degradation. Current evidence implicates human MEX-3C in many essential biological processes and suggests a strong connection with immune diseases and carcinogenesis. The highly conserved dual KH domains in MEX-3 proteins enable RNA binding and are essential for the recognition of the 3' UTR and posttranscriptional regulation of MEX-3 target transcripts. However, the molecular mechanisms of translational repression and the consensus RNA sequence recognized by the MEX-3C KH domain are unknown. Here, using X-ray crystallography and isothermal titration calorimetry, we investigated the RNA-binding activity and selectivity of human MEX-3C dual KH domains. Our high-resolution crystal structures of individual KH domains complexed with a noncanonical U-rich and a GA-rich RNA sequences revealed that the KH1/2 domains of hMEX-3C bound MRE10, a 10-mer RNA (5'-CAGAGUUUAG-3') consisting of an eight-nucleotide MEX-3-recognition element (MRE) motif, with high affinity. Of note, we also identified a consensus RNA motif recognized by human MEX-3C. The potential RNA-binding sites in the 3' UTR of the human leukocyte antigen serotype (HLA-A2) mRNA were mapped with this RNA-binding motif and were further confirmed by fluorescence polarization. The binding motif identified here will provide valuable information for future investigations of the functional pathways controlled by human MEX-3C and for predicting potential mRNAs regulated by this enzyme.

The human RNA-binding protein and E3 ligase MEX-3C binds the MEX-3-recognition element (MRE) motif with high affinity.,Yang L, Wang C, Li F, Zhang J, Nayab A, Wu J, Shi Y, Gong Q J Biol Chem. 2017 Aug 14. pii: jbc.M117.797746. doi: 10.1074/jbc.M117.797746. PMID:28808060<ref>PMID:28808060</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
</div>
<div class="pdbe-citations 5www" style="background-color:#fffaf0;"></div>
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Homo sapiens]]
[[Category: Large Structures]]
[[Category: Synthetic construct]]
[[Category: Gong Q]]
[[Category: Li F]]
[[Category: Wang C]]
[[Category: Yang L]]