View source for 3bb4


==Crystal structure of Toc33 from Arabidopsis thaliana in complex with Mg2+ and GMPPNP==
<StructureSection load='3bb4' size='340' side='right' caption='[[3bb4]], [[Resolution|resolution]] 2.85&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[3bb4]] is a 1 chain structure with sequence from [http://en.wikipedia.org/wiki/Arath Arath]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=3BB4 OCA]. For a <b>guided tour on the structure components</b> use [http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=3BB4 FirstGlance]. <br>
</td></tr><tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat"><scene name='pdbligand=GNP:PHOSPHOAMINOPHOSPHONIC+ACID-GUANYLATE+ESTER'>GNP</scene>, <scene name='pdbligand=MG:MAGNESIUM+ION'>MG</scene></td></tr>
<tr id='related'><td class="sblockLbl"><b>[[Related_structure|Related:]]</b></td><td class="sblockDat">[[3bb1|3bb1]], [[3bb3|3bb3]]</td></tr>
<tr id='gene'><td class="sblockLbl"><b>[[Gene|Gene:]]</b></td><td class="sblockDat">T7I23.11 ([http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&srchmode=5&id=3702 ARATH])</td></tr>
<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=3bb4 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=3bb4 OCA], [http://pdbe.org/3bb4 PDBe], [http://www.rcsb.org/pdb/explore.do?structureId=3bb4 RCSB], [http://www.ebi.ac.uk/pdbsum/3bb4 PDBsum], [http://prosat.h-its.org/prosat/prosatexe?pdbcode=3bb4 ProSAT]</span></td></tr>
</table>
== Function ==
[[http://www.uniprot.org/uniprot/TOC33_ARATH TOC33_ARATH]] GTPase involved in protein precursor import into chloroplasts. Seems to recognize chloroplast-destined precursor proteins and regulate their presentation to the translocation channel through GTP hydrolysis. Binds GTP, GDP, XTP, but not ATP. Probably specialized in the import of nuclear encoded photosynthetic preproteins from the cytoplasm to the chloroplast, especially during early development stages.<ref>PMID:11553737</ref> <ref>PMID:12741849</ref> <ref>PMID:12782294</ref> <ref>PMID:12869544</ref> <ref>PMID:12951325</ref> <ref>PMID:12897258</ref> <ref>PMID:15053763</ref> <ref>PMID:16412428</ref> <ref>PMID:16435266</ref> <ref>PMID:18054337</ref>  
== Evolutionary Conservation ==
[[Image:Consurf_key_small.gif|200px|right]]
Check<jmol>
  <jmolCheckbox>
    <scriptWhenChecked>; select protein; define ~consurf_to_do selected; consurf_initial_scene = true; script "/wiki/ConSurf/bb/3bb4_consurf.spt"</scriptWhenChecked>
    <scriptWhenUnchecked>script /wiki/extensions/Proteopedia/spt/initialview01.spt</scriptWhenUnchecked>
    <text>to colour the structure by Evolutionary Conservation</text>
  </jmolCheckbox>
</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=3bb4 ConSurf].
<div style="clear:both"></div>
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
Transport of precursor proteins across chloroplast membranes involves the GTPases Toc33/34 and Toc159 at the outer chloroplast envelope. The small GTPase Toc33/34 can homodimerize, but the regulation of this interaction has remained elusive. We show that dimerization is independent of nucleotide loading state, based on crystal structures of dimeric Pisum sativum Toc34 and monomeric Arabidopsis thaliana Toc33. An arginine residue is--in the dimer--positioned to resemble a GAP arginine finger. However, GTPase activation by dimerization is sparse and active site features do not explain catalysis, suggesting that the homodimer requires an additional factor as coGAP. Access to the catalytic center and an unusual switch I movement in the dimeric structure support this finding. Potential binding sites for interactions within the Toc translocon or with precursor proteins can be derived from the structures.

The GTPase cycle of the chloroplast import receptors Toc33/Toc34: implications from monomeric and dimeric structures.,Koenig P, Oreb M, Hofle A, Kaltofen S, Rippe K, Sinning I, Schleiff E, Tews I Structure. 2008 Apr;16(4):585-96. PMID:18400179<ref>PMID:18400179</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
</div>
<div class="pdbe-citations 3bb4" style="background-color:#fffaf0;"></div>
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Arath]]
[[Category: Koenig, P]]
[[Category: Schleiff, E]]
[[Category: Sinning, I]]
[[Category: Tews, I]]
[[Category: Chloroplast import]]
[[Category: Gtpase domain]]
[[Category: Hydrolase]]
[[Category: Rossmann fold]]