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[[Image:1kpk.gif|left|200px]]<br /><applet load="1kpk" size="350" color="white" frame="true" align="right" spinBox="true"
caption="1kpk, resolution 3.50&Aring;" />
'''Crystal Structure of the ClC Chloride Channel from E. coli'''<br />


==Overview==
==Crystal Structure of the ClC Chloride Channel from E. coli==
The ClC chloride channels catalyse the selective flow of Cl- ions across cell membranes, thereby regulating electrical excitation in skeletal muscle and the flow of salt and water across epithelial barriers. Genetic defects in ClC Cl- channels underlie several familial muscle and kidney diseases. Here we present the X-ray structures of two prokaryotic ClC Cl- channels from Salmonella enterica serovar typhimurium and Escherichia coli at 3.0 and 3.5 A, respectively. Both structures reveal two identical pores, each pore being formed by a separate subunit contained within a homodimeric membrane protein. Individual subunits are composed of two roughly repeated halves that span the membrane with opposite orientations. This antiparallel architecture defines a selectivity filter in which a Cl- ion is stabilized by electrostatic interactions with alpha-helix dipoles and by chemical coordination with nitrogen atoms and hydroxyl groups. These findings provide a structural basis for further understanding the function of ClC Cl- channels, and establish the physical and chemical basis of their anion selectivity.
<StructureSection load='1kpk' size='340' side='right'caption='[[1kpk]], [[Resolution|resolution]] 3.50&Aring;' scene=''>
 
== Structural highlights ==
==About this Structure==
<table><tr><td colspan='2'>[[1kpk]] is a 6 chain structure with sequence from [https://en.wikipedia.org/wiki/Escherichia_coli Escherichia coli]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1KPK OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=1KPK FirstGlance]. <br>
1KPK is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Escherichia_coli Escherichia coli]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1KPK OCA].  
</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">X-ray diffraction, [[Resolution|Resolution]] 3.5&#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=1kpk FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1kpk OCA], [https://pdbe.org/1kpk PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=1kpk RCSB], [https://www.ebi.ac.uk/pdbsum/1kpk PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=1kpk ProSAT]</span></td></tr>
==Reference==
</table>
X-ray structure of a ClC chloride channel at 3.0 A reveals the molecular basis of anion selectivity., Dutzler R, Campbell EB, Cadene M, Chait BT, MacKinnon R, Nature. 2002 Jan 17;415(6869):287-94. PMID:[http://ispc.weizmann.ac.il//pmbin/getpm?pmid=11796999 11796999]
== Function ==
[https://www.uniprot.org/uniprot/CLCA_ECOLI CLCA_ECOLI] Proton-coupled chloride transporter. Functions as antiport system and exchanges two chloride ions for 1 proton. Probably acts as an electrical shunt for an outwardly-directed proton pump that is linked to amino acid decarboxylation, as part of the extreme acid resistance (XAR) response.<ref>PMID:12384697</ref> <ref>PMID:14985752</ref> <ref>PMID:16341087</ref> <ref>PMID:16905147</ref> <ref>PMID:18678918</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/kp/1kpk_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=1kpk ConSurf].
<div style="clear:both"></div>
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Escherichia coli]]
[[Category: Escherichia coli]]
[[Category: Single protein]]
[[Category: Large Structures]]
[[Category: Cadene, M.]]
[[Category: Cadene M]]
[[Category: Campbell, E B.]]
[[Category: Campbell EB]]
[[Category: Chait, B T.]]
[[Category: Chait BT]]
[[Category: Dutzler, R.]]
[[Category: Dutzler R]]
[[Category: MacKinnon, R.]]
[[Category: MacKinnon R]]
[[Category: helical membrane protein]]
[[Category: homodimer]]
 
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