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1xk5

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[[Image:1xk5.gif|left|200px]]<br /><applet load="1xk5" size="350" color="white" frame="true" align="right" spinBox="true"
 
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caption="1xk5, resolution 2.4&Aring;" />
 
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'''Crystal structure of the m3G-cap-binding domain of snurportin1 in complex with a m3GpppG-cap dinucleotide'''<br />
 
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==Overview==
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==Crystal structure of the m3G-cap-binding domain of snurportin1 in complex with a m3GpppG-cap dinucleotide==
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In higher eukaryotes the biogenesis of spliceosomal UsnRNPs involves a nucleocytoplasmic shuttling cycle. After the m7G-cap-dependent export of the snRNAs U1, U2, U4 and U5 to the cytoplasm, each of these snRNAs associates with seven Sm proteins. Subsequently, the m7G-cap is hypermethylated to the 2,2,7-trimethylguanosine (m3G)-cap. The import adaptor snurportin1 recognises the m3G-cap and facilitates the nuclear import of the UsnRNPs by binding to importin-beta. Here we report the crystal structure of the m3G-cap-binding domain of snurportin1 with bound m3GpppG at 2.4 A resolution, revealing a structural similarity to the mRNA-guanyly-transferase. Snurportin1 binds both the hypermethylated cap and the first nucleotide of the RNA in a stacked conformation. This binding mode differs significantly from that of the m7G-cap-binding proteins Cap-binding protein 20 (CBP20), eukaryotic initiation factor 4E (eIF4E) and viral protein 39 (VP39). The specificity of the m3G-cap recognition by snurportin1 was evaluated by fluorescence spectroscopy, demonstrating the importance of a highly solvent exposed tryptophan for the discrimination of m7G-capped RNAs. The critical role of this tryptophan and as well of a tryptophan continuing the RNA base stack was confirmed by nuclear import assays and cap-binding activity tests using several snurportin1 mutants.
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<StructureSection load='1xk5' size='340' side='right'caption='[[1xk5]], [[Resolution|resolution]] 2.40&Aring;' scene=''>
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== Structural highlights ==
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==About this Structure==
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<table><tr><td colspan='2'>[[1xk5]] is a 1 chain structure with sequence from [https://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1XK5 OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=1XK5 FirstGlance]. <br>
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1XK5 is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens] with <scene name='pdbligand=TPG:'>TPG</scene> as [http://en.wikipedia.org/wiki/ligand ligand]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1XK5 OCA].
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</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">X-ray diffraction, [[Resolution|Resolution]] 2.4&#8491;</td></tr>
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<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=TPG:2,2,7-TRIMETHYL-GUANOSINE-5-TRIPHOSPHATE-5-GUANOSINE'>TPG</scene></td></tr>
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==Reference==
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<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=1xk5 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1xk5 OCA], [https://pdbe.org/1xk5 PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=1xk5 RCSB], [https://www.ebi.ac.uk/pdbsum/1xk5 PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=1xk5 ProSAT]</span></td></tr>
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Structural basis for m3G-cap-mediated nuclear import of spliceosomal UsnRNPs by snurportin1., Strasser A, Dickmanns A, Luhrmann R, Ficner R, EMBO J. 2005 Jul 6;24(13):2235-43. Epub 2005 May 26. PMID:[http://ispc.weizmann.ac.il//pmbin/getpm?pmid=15920472 15920472]
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</table>
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== Function ==
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[https://www.uniprot.org/uniprot/SPN1_HUMAN SPN1_HUMAN] Functions as an U snRNP-specific nuclear import adapter. Involved in the trimethylguanosine (m3G)-cap-dependent nuclear import of U snRNPs. Binds specifically to the terminal m3G-cap U snRNAs.<ref>PMID:9670026</ref>
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== Evolutionary Conservation ==
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[[Image:Consurf_key_small.gif|200px|right]]
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Check<jmol>
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<jmolCheckbox>
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<scriptWhenChecked>; select protein; define ~consurf_to_do selected; consurf_initial_scene = true; script "/wiki/ConSurf/xk/1xk5_consurf.spt"</scriptWhenChecked>
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<scriptWhenUnchecked>script /wiki/extensions/Proteopedia/spt/initialview01.spt</scriptWhenUnchecked>
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<text>to colour the structure by Evolutionary Conservation</text>
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</jmolCheckbox>
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</jmol>, as determined by [http://consurfdb.tau.ac.il/ ConSurfDB]. You may read the [[Conservation%2C_Evolutionary|explanation]] of the method and the full data available from [http://bental.tau.ac.il/new_ConSurfDB/main_output.php?pdb_ID=1xk5 ConSurf].
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<div style="clear:both"></div>
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== References ==
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<references/>
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__TOC__
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</StructureSection>
[[Category: Homo sapiens]]
[[Category: Homo sapiens]]
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[[Category: Single protein]]
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[[Category: Large Structures]]
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[[Category: Dickmanns, A.]]
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[[Category: Dickmanns A]]
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[[Category: Ficner, R.]]
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[[Category: Ficner R]]
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[[Category: Luehrmann, R.]]
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[[Category: Luehrmann R]]
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[[Category: Strasser, A.]]
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[[Category: Strasser A]]
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[[Category: TPG]]
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[[Category: protein-rna-complex]]
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 15:55:37 2008''
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Current revision

Crystal structure of the m3G-cap-binding domain of snurportin1 in complex with a m3GpppG-cap dinucleotide

PDB ID 1xk5

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