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==Potassium Channel KcsA-Fab complex in Barium Chloride== | |||
<StructureSection load='2itd' size='340' side='right'caption='[[2itd]], [[Resolution|resolution]] 2.70Å' scene=''> | |||
== Structural highlights == | |||
<table><tr><td colspan='2'>[[2itd]] 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=2ITD OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=2ITD 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]] 2.7Å</td></tr> | |||
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=BA:BARIUM+ION'>BA</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=2itd FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=2itd OCA], [https://pdbe.org/2itd PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=2itd RCSB], [https://www.ebi.ac.uk/pdbsum/2itd PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=2itd ProSAT]</span></td></tr> | |||
</table> | |||
== Function == | |||
[https://www.uniprot.org/uniprot/KCSA_STRLI KCSA_STRLI] Acts as a pH-gated potassium ion channel; changing the cytosolic pH from 7 to 4 opens the channel, although it is not clear if this is the physiological stimulus for channel opening. Monovalent cation preference is K(+) > Rb(+) > NH4(+) >> Na(+) > Li(+).<ref>PMID:7489706</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/it/2itd_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=2itd ConSurf]. | |||
<div style="clear:both"></div> | |||
<div style="background-color:#fffaf0;"> | |||
== Publication Abstract from PubMed == | |||
Thermodynamic measurements of ion binding to the Streptomyces lividans K(+) channel were carried out using isothermal titration calorimetry, whereas atomic structures of ion-bound and ion-free conformations of the channel were characterized by x-ray crystallography. Here we use these assays to show that the ion radius dependence of selectivity stems from the channel's recognition of ion size (i.e., volume) rather than charge density. Ion size recognition is a function of the channel's ability to adopt a very specific conductive structure with larger ions (K(+), Rb(+), Cs(+), and Ba(2+)) bound and not with smaller ions (Na(+), Mg(2+), and Ca(2+)). The formation of the conductive structure involves selectivity filter atoms that are in direct contact with bound ions as well as protein atoms surrounding the selectivity filter up to a distance of 15 A from the ions. We conclude that ion selectivity in a K(+) channel is a property of size-matched ion binding sites created by the protein structure. | |||
Structural and thermodynamic properties of selective ion binding in a K+ channel.,Lockless SW, Zhou M, MacKinnon R PLoS Biol. 2007 May;5(5):e121. PMID:17472437<ref>PMID:17472437</ref> | |||
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.<br> | |||
</div> | |||
<div class="pdbe-citations 2itd" 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: Lockless | [[Category: Lockless SW]] | ||
[[Category: MacKinnon | [[Category: MacKinnon R]] | ||
[[Category: Zhou | [[Category: Zhou M]] | ||
Latest revision as of 08:17, 17 October 2024
Potassium Channel KcsA-Fab complex in Barium ChloridePotassium Channel KcsA-Fab complex in Barium Chloride
Structural highlights
FunctionKCSA_STRLI Acts as a pH-gated potassium ion channel; changing the cytosolic pH from 7 to 4 opens the channel, although it is not clear if this is the physiological stimulus for channel opening. Monovalent cation preference is K(+) > Rb(+) > NH4(+) >> Na(+) > Li(+).[1] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedThermodynamic measurements of ion binding to the Streptomyces lividans K(+) channel were carried out using isothermal titration calorimetry, whereas atomic structures of ion-bound and ion-free conformations of the channel were characterized by x-ray crystallography. Here we use these assays to show that the ion radius dependence of selectivity stems from the channel's recognition of ion size (i.e., volume) rather than charge density. Ion size recognition is a function of the channel's ability to adopt a very specific conductive structure with larger ions (K(+), Rb(+), Cs(+), and Ba(2+)) bound and not with smaller ions (Na(+), Mg(2+), and Ca(2+)). The formation of the conductive structure involves selectivity filter atoms that are in direct contact with bound ions as well as protein atoms surrounding the selectivity filter up to a distance of 15 A from the ions. We conclude that ion selectivity in a K(+) channel is a property of size-matched ion binding sites created by the protein structure. Structural and thermodynamic properties of selective ion binding in a K+ channel.,Lockless SW, Zhou M, MacKinnon R PLoS Biol. 2007 May;5(5):e121. PMID:17472437[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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