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==potassium channel KcsA-Fab complex in low concentration of Tl+== | |||
<StructureSection load='1r3k' size='340' side='right'caption='[[1r3k]], [[Resolution|resolution]] 2.80Å' scene=''> | |||
== Structural highlights == | |||
<table><tr><td colspan='2'>[[1r3k]] is a 3 chain structure with sequence from [https://en.wikipedia.org/wiki/Mus_musculus Mus musculus] and [https://en.wikipedia.org/wiki/Streptomyces_lividans Streptomyces lividans]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1R3K OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=1R3K 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]] 2.8Å</td></tr> | |||
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=DGA:DIACYL+GLYCEROL'>DGA</scene>, <scene name='pdbligand=TL:THALLIUM+(I)+ION'>TL</scene></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=1r3k FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1r3k OCA], [https://pdbe.org/1r3k PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=1r3k RCSB], [https://www.ebi.ac.uk/pdbsum/1r3k PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=1r3k ProSAT]</span></td></tr> | |||
</table> | |||
== Function == | |||
[https://www.uniprot.org/uniprot/IGKC_MOUSE IGKC_MOUSE] | |||
== 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/r3/1r3k_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=1r3k ConSurf]. | |||
<div style="clear:both"></div> | |||
<div style="background-color:#fffaf0;"> | |||
== Publication Abstract from PubMed == | |||
Potassium ions diffuse across the cell membrane in a single file through the narrow selectivity filter of potassium channels. The crystal structure of the KcsA K+ channel revealed the chemical structure of the selectivity filter, which contains four binding sites for K+. In this study, we used Tl+ in place of K+ to address the question of how many ions bind within the filter at a given time, i.e. what is the absolute ion occupancy? By refining the Tl+ structure against data to 1.9A resolution with an anomalous signal, we determined the absolute occupancy of Tl+. Then, by comparing the electron density of Tl+ with that of K+, Rb+ and Cs+, we estimated the absolute occupancy of these three ions. We further analyzed how the ion occupancy affects the conformation of the selectivity filter by analyzing the structure of KcsA at different concentrations of Tl+. Our results indicate that the average occupancy for each site in the selectivity filter is about 0.63 for Tl+ and 0.53 for K+. For K+, Rb+ and Cs+, the total number of ions contained within four sites in the selectivity filter is about two. At low concentrations of permeant ion, the number of ions drops to one in association with a conformational change in the selectivity filter. We conclude that electrostatic balance and coupling of ion binding to a protein conformational change underlie high conduction rates in the setting of high selectivity. | |||
The occupancy of ions in the K+ selectivity filter: charge balance and coupling of ion binding to a protein conformational change underlie high conduction rates.,Zhou Y, MacKinnon R J Mol Biol. 2003 Nov 7;333(5):965-75. PMID:14583193<ref>PMID:14583193</ref> | |||
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.<br> | |||
</div> | |||
<div class="pdbe-citations 1r3k" style="background-color:#fffaf0;"></div> | |||
== | ==See Also== | ||
*[[Antibody 3D structures|Antibody 3D structures]] | |||
*[[Potassium channel 3D structures|Potassium channel 3D structures]] | |||
*[[3D structures of non-human antibody|3D structures of non-human antibody]] | |||
== References == | |||
<references/> | |||
__TOC__ | |||
</StructureSection> | |||
[[Category: Large Structures]] | |||
[[Category: Mus musculus]] | [[Category: Mus musculus]] | ||
[[Category: Streptomyces lividans]] | [[Category: Streptomyces lividans]] | ||
[[Category: MacKinnon | [[Category: MacKinnon R]] | ||
[[Category: Zhou | [[Category: Zhou Y]] | ||
Latest revision as of 10:17, 30 October 2024
potassium channel KcsA-Fab complex in low concentration of Tl+potassium channel KcsA-Fab complex in low concentration of Tl+
Structural highlights
FunctionEvolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedPotassium ions diffuse across the cell membrane in a single file through the narrow selectivity filter of potassium channels. The crystal structure of the KcsA K+ channel revealed the chemical structure of the selectivity filter, which contains four binding sites for K+. In this study, we used Tl+ in place of K+ to address the question of how many ions bind within the filter at a given time, i.e. what is the absolute ion occupancy? By refining the Tl+ structure against data to 1.9A resolution with an anomalous signal, we determined the absolute occupancy of Tl+. Then, by comparing the electron density of Tl+ with that of K+, Rb+ and Cs+, we estimated the absolute occupancy of these three ions. We further analyzed how the ion occupancy affects the conformation of the selectivity filter by analyzing the structure of KcsA at different concentrations of Tl+. Our results indicate that the average occupancy for each site in the selectivity filter is about 0.63 for Tl+ and 0.53 for K+. For K+, Rb+ and Cs+, the total number of ions contained within four sites in the selectivity filter is about two. At low concentrations of permeant ion, the number of ions drops to one in association with a conformational change in the selectivity filter. We conclude that electrostatic balance and coupling of ion binding to a protein conformational change underlie high conduction rates in the setting of high selectivity. The occupancy of ions in the K+ selectivity filter: charge balance and coupling of ion binding to a protein conformational change underlie high conduction rates.,Zhou Y, MacKinnon R J Mol Biol. 2003 Nov 7;333(5):965-75. PMID:14583193[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences |
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