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| | ==Crystal structure of a lysosomal potassium-selective channel TMEM175 homolog from Chamaesiphon Minutus== | | ==Crystal structure of a lysosomal potassium-selective channel TMEM175 homolog from Chamaesiphon Minutus== |
| - | <StructureSection load='5vre' size='340' side='right' caption='[[5vre]], [[Resolution|resolution]] 3.30Å' scene=''> | + | <StructureSection load='5vre' size='340' side='right'caption='[[5vre]], [[Resolution|resolution]] 3.30Å' scene=''> |
| | == Structural highlights == | | == Structural highlights == |
| - | <table><tr><td colspan='2'>[[5vre]] is a 4 chain structure with sequence from [http://en.wikipedia.org/wiki/Chap6 Chap6]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=5VRE OCA]. For a <b>guided tour on the structure components</b> use [http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=5VRE FirstGlance]. <br> | + | <table><tr><td colspan='2'>[[5vre]] is a 4 chain structure with sequence from [https://en.wikipedia.org/wiki/Chamaesiphon_minutus_PCC_6605 Chamaesiphon minutus PCC 6605]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=5VRE OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=5VRE FirstGlance]. <br> |
| - | </td></tr><tr id='gene'><td class="sblockLbl"><b>[[Gene|Gene:]]</b></td><td class="sblockDat">Cha6605_3372 ([http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&srchmode=5&id=1173020 CHAP6])</td></tr> | + | </td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">X-ray diffraction, [[Resolution|Resolution]] 3.299Å</td></tr> |
| - | <tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=5vre FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=5vre OCA], [http://pdbe.org/5vre PDBe], [http://www.rcsb.org/pdb/explore.do?structureId=5vre RCSB], [http://www.ebi.ac.uk/pdbsum/5vre PDBsum], [http://prosat.h-its.org/prosat/prosatexe?pdbcode=5vre ProSAT]</span></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=5vre FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=5vre OCA], [https://pdbe.org/5vre PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=5vre RCSB], [https://www.ebi.ac.uk/pdbsum/5vre PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=5vre ProSAT]</span></td></tr> |
| | </table> | | </table> |
| - | <div style="background-color:#fffaf0;">
| + | == Function == |
| - | == Publication Abstract from PubMed == | + | [https://www.uniprot.org/uniprot/TM175_CHAP6 TM175_CHAP6] Potassium channel (PubMed:28723891). The channel is permeable for K(+), Rb(+) and Cs(+), while it is unable to conduct Na(+) (PubMed:28723891).<ref>PMID:28723891</ref> |
| - | TMEM175 is a lysosomal K+ channel that is important for maintaining the membrane potential and pH stability in lysosomes. It contains two homologous copies of a six-transmembrane-helix (6-TM) domain, which has no sequence homology to the canonical tetrameric K+ channels and lacks the TVGYG selectivity filter motif found in these channels. The prokaryotic TMEM175 channel, which is present in a subset of bacteria and archaea, contains only a single 6-TM domain and functions as a tetramer. Here, we present the crystal structure of a prokaryotic TMEM175 channel from Chamaesiphon minutus, CmTMEM175, the architecture of which represents a completely different fold from that of canonical K+ channels. All six transmembrane helices of CmTMEM175 are tightly packed within each subunit without undergoing domain swapping. The highly conserved TM1 helix acts as the pore-lining inner helix, creating an hourglass-shaped ion permeation pathway in the channel tetramer. Three layers of hydrophobic residues on the carboxy-terminal half of the TM1 helices form a bottleneck along the ion conduction pathway and serve as the selectivity filter of the channel. Mutagenesis analysis suggests that the first layer of the highly conserved isoleucine residues in the filter is primarily responsible for channel selectivity. Thus, the structure of CmTMEM175 represents a novel architecture of a tetrameric cation channel whose ion selectivity mechanism appears to be distinct from that of the classical K+ channel family.
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| - | The lysosomal potassium channel TMEM175 adopts a novel tetrameric architecture.,Lee C, Guo J, Zeng W, Kim S, She J, Cang C, Ren D, Jiang Y Nature. 2017 Jul 27;547(7664):472-475. doi: 10.1038/nature23269. Epub 2017 Jul, 19. PMID:28723891<ref>PMID:28723891</ref>
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| - | From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.<br>
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| - | </div>
| + | |
| - | <div class="pdbe-citations 5vre" style="background-color:#fffaf0;"></div>
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| | == References == | | == References == |
| | <references/> | | <references/> |
| | __TOC__ | | __TOC__ |
| | </StructureSection> | | </StructureSection> |
| - | [[Category: Chap6]] | + | [[Category: Chamaesiphon minutus PCC 6605]] |
| - | [[Category: Guo, J]] | + | [[Category: Large Structures]] |
| - | [[Category: Jiang, Y]] | + | [[Category: Guo J]] |
| - | [[Category: Lee, C]] | + | [[Category: Jiang Y]] |
| - | [[Category: Potassium channel]] | + | [[Category: Lee C]] |
| - | [[Category: Transport protein]]
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