4lmj: Difference between revisions
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==GLIC Liganded-closed-channel Conformation, Mutant T25'A== | |||
<StructureSection load='4lmj' size='340' side='right'caption='[[4lmj]], [[Resolution|resolution]] 3.44Å' scene=''> | |||
== Structural highlights == | |||
<table><tr><td colspan='2'>[[4lmj]] is a 5 chain structure with sequence from [https://en.wikipedia.org/wiki/Gloeobacter_violaceus Gloeobacter violaceus]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=4LMJ OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=4LMJ 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]] 3.44Å</td></tr> | |||
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=CL:CHLORIDE+ION'>CL</scene>, <scene name='pdbligand=LMT:DODECYL-BETA-D-MALTOSIDE'>LMT</scene>, <scene name='pdbligand=NA:SODIUM+ION'>NA</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=4lmj FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=4lmj OCA], [https://pdbe.org/4lmj PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=4lmj RCSB], [https://www.ebi.ac.uk/pdbsum/4lmj PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=4lmj ProSAT]</span></td></tr> | |||
</table> | |||
== Function == | |||
[https://www.uniprot.org/uniprot/GLIC_GLOVI GLIC_GLOVI] Cationic channel with similar permeabilities for Na(+) and K(+), that is activated by an increase of the proton concentration on the extracellular side. Displays no permeability for chloride ions. Shows slow kinetics of activation, no desensitization and a single channel conductance of 8 pS. Might contribute to adaptation to external pH change.<ref>PMID:17167423</ref> | |||
<div style="background-color:#fffaf0;"> | |||
== Publication Abstract from PubMed == | |||
Cryoelectron microscopy and X-ray crystallography have recently been used to generate structural models that likely represent the unliganded closed-channel conformation and the fully liganded open-channel conformation of different members of the nicotinic-receptor superfamily. To characterize the structure of the closed-channel conformation in its liganded state, we identified a number of positions in the loop between transmembrane segments 2 (M2) and 3 (M3) of a proton-gated ortholog from the bacterium Gloeobacter violaceus (GLIC) where mutations to alanine reduce the liganded-gating equilibrium constant, and solved the crystal structures of two such mutants (T25'A and Y27'A) at pH approximately 4.0. At the level of backbone atoms, the liganded closed-channel model presented here differs from the liganded open-channel structure of GLIC in the pre-M1 linker, the M3-M4 loop, and much more prominently, in the extracellular half of the pore lining, where the more pronounced tilt of the closed-channel M2 alpha-helices toward the pore's long axis narrows the permeation pathway. On the other hand, no differences between the liganded closed-channel and open-channel models could be detected at the level of the extracellular domain, where conformational changes are expected to underlie the low-to-high proton-affinity switch that drives gating of proton-bound channels. Thus, the liganded closed-channel model is nearly indistinguishable from the recently described "locally closed" structure. However, because cross-linking strategies (which could have stabilized unstable conformations) and mutations involving ionizable side chains (which could have affected proton-gated channel activation) were purposely avoided, we favor the notion that this structure represents one of the end states of liganded gating rather than an unstable intermediate. | |||
Gating of the proton-gated ion channel from Gloeobacter violaceus at pH 4 as revealed by X-ray crystallography.,Gonzalez-Gutierrez G, Cuello LG, Nair SK, Grosman C Proc Natl Acad Sci U S A. 2013 Oct 28. PMID:24167270<ref>PMID:24167270</ref> | |||
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.<br> | |||
</div> | |||
<div class="pdbe-citations 4lmj" style="background-color:#fffaf0;"></div> | |||
==See Also== | |||
*[[Ion channels 3D structures|Ion channels 3D structures]] | |||
== References == | |||
<references/> | |||
__TOC__ | |||
</StructureSection> | |||
[[Category: Gloeobacter violaceus]] | |||
[[Category: Large Structures]] | |||
[[Category: Gonzalez-Gutierrez G]] | |||
[[Category: Grosman C]] | |||