View source for 4lbe


==Structure of KcsA with R122A mutation==
<StructureSection load='4lbe' size='340' side='right'caption='[[4lbe]], [[Resolution|resolution]] 2.75&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[4lbe]] 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=4LBE OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=4LBE 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]] 2.751&#8491;</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=F09:NONAN-1-OL'>F09</scene>, <scene name='pdbligand=K:POTASSIUM+ION'>K</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=4lbe FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=4lbe OCA], [https://pdbe.org/4lbe PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=4lbe RCSB], [https://www.ebi.ac.uk/pdbsum/4lbe PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=4lbe 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> 
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
The bacterial potassium channel KcsA is gated open by the binding of protons to amino acids on the intracellular side of the channel. We have identified, via channel mutagenesis and x-ray crystallography, two pH-sensing amino acids and a set of nearby residues involved in molecular interactions that influence gating. We found that the minimal mutation of one histidine (H25) and one glutamate (E118) near the cytoplasmic gate completely abolished pH-dependent gating. Mutation of nearby residues either alone or in pairs altered the channel's response to pH. In addition, mutations of certain pairs of residues dramatically increased the energy barriers between the closed and open states. We proposed a Monod-Wyman-Changeux model for proton binding and pH-dependent gating in KcsA, where H25 is a "strong" sensor displaying a large shift in pKa between closed and open states, and E118 is a "weak" pH sensor. Modifying model parameters that are involved in either the intrinsic gating equilibrium or the pKa values of the pH-sensing residues was sufficient to capture the effects of all mutations.

Molecular interactions involved in proton-dependent gating in KcsA potassium channels.,Posson DJ, Thompson AN, McCoy JG, Nimigean CM J Gen Physiol. 2013 Dec;142(6):613-24. doi: 10.1085/jgp.201311057. Epub 2013 Nov , 11. PMID:24218397<ref>PMID:24218397</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
</div>
<div class="pdbe-citations 4lbe" style="background-color:#fffaf0;"></div>

==See Also==
*[[Potassium channel 3D structures|Potassium channel 3D structures]]
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Large Structures]]
[[Category: Mus musculus]]
[[Category: Streptomyces lividans]]
[[Category: McCoy JM]]
[[Category: Nimigean CM]]
[[Category: Posson DJ]]