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- EMDB-2710: E. coli potassium channel 3D structure by electron crystallography -
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Open data
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Basic information
Entry | Database: EMDB / ID: EMD-2710 | |||||||||
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Title | E. coli potassium channel 3D structure by electron crystallography | |||||||||
![]() | The four-fold symmetrized map was generated by averaging the 3D maps rotated at 0degree, 90degree, 180degree, and 270degree around the c-axis. The structure of MlotiK1 (PDB ID: 3BEH) was docked as a similar protein to Kch into the symmetrized map using Chimera. | |||||||||
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![]() | Potassium channel / 6TM / RCK | |||||||||
Function / homology | ![]() transport / potassium channel activity / membrane => GO:0016020 / monoatomic ion transport / potassium ion transmembrane transport / potassium ion transport / protein-containing complex / identical protein binding / membrane / plasma membrane Similarity search - Function | |||||||||
Biological species | ![]() ![]() | |||||||||
Method | electron crystallography / cryo EM / negative staining / Resolution: 10.0 Å | |||||||||
![]() | Kuang Q / Purhonen P / Jegerschold C / Koeck PJB / Hebert H | |||||||||
![]() | ![]() Title: Free RCK arrangement in Kch, a putative escherichia coli potassium channel, as suggested by electron crystallography. Authors: Qie Kuang / Pasi Purhonen / Caroline Jegerschöld / Philip J B Koeck / Hans Hebert / ![]() Abstract: The ligand-gated potassium channels are stimulated by various kinds of messengers. Previous studies showed that ligand-gated potassium channels containing RCK domains (the regulator of the ...The ligand-gated potassium channels are stimulated by various kinds of messengers. Previous studies showed that ligand-gated potassium channels containing RCK domains (the regulator of the conductance of potassium ion) form a dimer of tetramer structure through the RCK octameric gating ring in the presence of detergent. Here, we have analyzed the structure of Kch, a channel of this type from Escherichia coli, in a lipid environment using electron crystallography. By combining information from the 3D map of the transmembrane part of the protein and docking of an atomic model of a potassium channel, we conclude that the RCK domains face the solution and that an RCK octameric gating ring arrangement does not form under our crystallization condition. Our findings may be applied to other potassium channels that have an RCK gating ring arrangement. | |||||||||
History |
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Structure visualization
Movie |
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Structure viewer | EM map: ![]() ![]() ![]() |
Supplemental images |
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Downloads & links
-EMDB archive
Map data | ![]() | 107.8 KB | ![]() | |
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Header (meta data) | ![]() ![]() | 12.2 KB 12.2 KB | Display Display | ![]() |
Images | ![]() | 152.1 KB | ||
Archive directory | ![]() ![]() | HTTPS FTP |
-Related structure data
Related structure data | ![]() 2709C C: citing same article ( |
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Similar structure data | Similarity search - Function & homology ![]() |
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Links
EMDB pages | ![]() ![]() |
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Related items in Molecule of the Month |
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Map
File | ![]() | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Annotation | The four-fold symmetrized map was generated by averaging the 3D maps rotated at 0degree, 90degree, 180degree, and 270degree around the c-axis. The structure of MlotiK1 (PDB ID: 3BEH) was docked as a similar protein to Kch into the symmetrized map using Chimera. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Projections & slices | Image control
Images are generated by Spider. generated in cubic-lattice coordinate | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Voxel size | X: 3.25 Å / Y: 3.1731 Å / Z: 3.1731 Å | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Density |
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Symmetry | Space group: 1 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Details | EMDB XML:
CCP4 map header:
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-Supplemental data
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Sample components
-Entire : voltage-gated potassium channel, four-fold symmetrized map
Entire | Name: voltage-gated potassium channel, four-fold symmetrized map |
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Components |
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-Supramolecule #1000: voltage-gated potassium channel, four-fold symmetrized map
Supramolecule | Name: voltage-gated potassium channel, four-fold symmetrized map type: sample / ID: 1000 / Oligomeric state: tetramers / Number unique components: 1 |
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-Macromolecule #1: Kch
Macromolecule | Name: Kch / type: protein_or_peptide / ID: 1 / Number of copies: 4 / Oligomeric state: tetramer / Recombinant expression: Yes |
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Source (natural) | Organism: ![]() ![]() |
Recombinant expression | Organism: ![]() ![]() |
Sequence | UniProtKB: Voltage-gated potassium channel Kch GO: transport, monoatomic ion transport, potassium ion transport, plasma membrane, potassium ion transmembrane transport, membrane, membrane => GO:0016020 InterPro: INTERPRO: IPR003091, Regulator of K+ conductance, N-terminal, Voltage-gated potassium channel |
-Experimental details
-Structure determination
Method | negative staining, cryo EM |
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![]() | electron crystallography |
Aggregation state | 2D array |
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Sample preparation
Concentration | 0.7 mg/mL |
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Buffer | Details: 25 mM Na-acetate at pH 7, 20% glycerol, 100 mM KCl, 0.1 mM EDTA, 1 mM reduced glutathione, 50 mM MgCl2, with or without 5% (w/v) glycine |
Staining | Type: NEGATIVE / Details: Embedded in trehalose |
Grid | Details: Copper grid with carbon |
Vitrification | Cryogen name: NITROGEN / Chamber humidity: 20 % / Chamber temperature: 77 K / Instrument: HOMEMADE PLUNGER / Details: Manual freezing |
Details | Crystal grown by dialysis away the detergent |
Crystal formation | Details: Crystal grown by dialysis away the detergent |
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Electron microscopy
Microscope | JEOL 2100F |
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Temperature | Average: 95 K |
Date | Mar 1, 2010 |
Image recording | Category: FILM / Film or detector model: KODAK SO-163 FILM / Digitization - Scanner: ZEISS SCAI / Digitization - Sampling interval: 7 µm / Number real images: 33 / Average electron dose: 12 e/Å2 / Bits/pixel: 16 |
Tilt angle min | 0 |
Electron beam | Acceleration voltage: 200 kV / Electron source: ![]() |
Electron optics | Illumination mode: FLOOD BEAM / Imaging mode: BRIGHT FIELD / Cs: 2 mm / Nominal defocus max: 2.7 µm / Nominal defocus min: 0.9 µm / Nominal magnification: 50000 |
Sample stage | Specimen holder model: GATAN LIQUID NITROGEN / Tilt angle max: 45 / Tilt series - Axis1 - Min angle: 0 ° / Tilt series - Axis1 - Max angle: 45 ° |
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Image processing
Details | The four-fold symmetrized map was generated using ccp4. B = -500 is used to boost the fall-off of the amplitudes at intermediate and high resolution in the map. |
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Final reconstruction | Resolution.type: BY AUTHOR / Resolution: 10.0 Å / Resolution method: OTHER / Software - Name: MRC |
Crystal parameters | Unit cell - A: 143 Å / Unit cell - B: 82 Å / Unit cell - γ: 90 ° / Plane group: C 1 2 |
CTF correction | Details: Each image |
-Atomic model buiding 1
Initial model | PDB ID: |
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Software | Name: ![]() |
Refinement | Space: REAL / Protocol: RIGID BODY FIT |