View source for 1ltb


==2.6 ANGSTROMS CRYSTAL STRUCTURE OF PARTIALLY-ACTIVATED E. COLI HEAT-LABILE ENTEROTOXIN (LT)==
<StructureSection load='1ltb' size='340' side='right'caption='[[1ltb]], [[Resolution|resolution]] 2.60&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[1ltb]] is a 7 chain structure with sequence from [https://en.wikipedia.org/wiki/Escherichia_coli Escherichia coli]. The September 2005 RCSB PDB [https://pdb.rcsb.org/pdb/static.do?p=education_discussion/molecule_of_the_month/index.html Molecule of the Month] feature on ''Cholera Toxin''  by David S. Goodsell is [https://dx.doi.org/10.2210/rcsb_pdb/mom_2005_9 10.2210/rcsb_pdb/mom_2005_9]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1LTB OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=1LTB 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]] 2.6&#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=1ltb FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1ltb OCA], [https://pdbe.org/1ltb PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=1ltb RCSB], [https://www.ebi.ac.uk/pdbsum/1ltb PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=1ltb ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/ELBP_ECOLX ELBP_ECOLX] The biological activity of the toxin is produced by the A chain, which activates intracellular adenyl cyclase.
== 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/lt/1ltb_consurf.spt"</scriptWhenChecked>
    <scriptWhenUnchecked>script /wiki/extensions/Proteopedia/spt/initialview03.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=1ltb ConSurf].
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== Publication Abstract from PubMed ==
Biological toxicity of E. coli heat-labile enterotoxin and the closely related cholera toxin requires that the assembled toxin be activated by proteolytic cleavage of the A subunit and reduction of a disulfide bond internal to the A subunit. The structural role served by this reduction and cleavage is not known, however. We have crystallographically determined the structure of the E. coli heat-labile enterotoxin AB5 hexamer in which the A subunit has been cleaved by trypsin between residues 192 and 195. The toxin is thus partially activated, in that it has been cleaved but the disulfide bond has not been reduced. The structure of the A subunit in the cleaved toxin is substantially the same as that previously observed for the uncleaved AB5 structure, suggesting that although such cleavage is required for biological activity of the toxin it does not by itself cause a conformational change.

Structure of partially-activated E. coli heat-labile enterotoxin (LT) at 2.6 A resolution.,Merritt EA, Pronk SE, Sixma TK, Kalk KH, van Zanten BA, Hol WG FEBS Lett. 1994 Jan 3;337(1):88-92. PMID:8276119<ref>PMID:8276119</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
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== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Cholera Toxin]]
[[Category: Escherichia coli]]
[[Category: Large Structures]]
[[Category: RCSB PDB Molecule of the Month]]
[[Category: Hol WGJ]]
[[Category: Merritt EA]]
[[Category: Sixma TK]]