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- EMDB-2071: Gating movement in acetylcholine receptor analysed by time-resolv... -
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Open data
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Basic information
Entry | Database: EMDB / ID: EMD-2071 | |||||||||
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Title | Gating movement in acetylcholine receptor analysed by time-resolved electron cryo-microscopy | |||||||||
![]() | Density map of acetylcholine receptor | |||||||||
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![]() | acetylcholine receptor / freeze-trapping / asymmetric gating / allosteric mechanism | |||||||||
Function / homology | ![]() acetylcholine-gated channel complex / acetylcholine-gated monoatomic cation-selective channel activity / acetylcholine receptor signaling pathway / transmembrane signaling receptor activity / postsynaptic membrane Similarity search - Function | |||||||||
Biological species | ![]() ![]() | |||||||||
Method | helical reconstruction / cryo EM / Resolution: 6.2 Å | |||||||||
![]() | Unwin N / Fujiyoshi Y | |||||||||
![]() | ![]() Title: Gating movement of acetylcholine receptor caught by plunge-freezing. Authors: Nigel Unwin / Yoshinori Fujiyoshi / ![]() ![]() Abstract: The nicotinic acetylcholine (ACh) receptor converts transiently to an open-channel form when activated by ACh released into the synaptic cleft. We describe here the conformational change underlying ...The nicotinic acetylcholine (ACh) receptor converts transiently to an open-channel form when activated by ACh released into the synaptic cleft. We describe here the conformational change underlying this event, determined by electron microscopy of ACh-sprayed and freeze-trapped postsynaptic membranes. ACh binding to the α subunits triggers a concerted rearrangement in the ligand-binding domain, involving an ~1-Å outward displacement of the extracellular portion of the β subunit where it interacts with the juxtaposed ends of α-helices shaping the narrow membrane-spanning pore. The β-subunit helices tilt outward to accommodate this displacement, destabilising the arrangement of pore-lining helices, which in the closed channel bend inward symmetrically to form a central hydrophobic gate. Straightening and tangential motion of the pore-lining helices effect channel opening by widening the pore asymmetrically and increasing its polarity in the region of the gate. The pore-lining helices of the α(γ) and δ subunits, by flexing between alternative bent and straight conformations, undergo the greatest movements. This coupled allosteric transition shifts the structure from a tense (closed) state toward a more relaxed (open) state. | |||||||||
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 | ![]() | 2.6 MB | ![]() | |
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Header (meta data) | ![]() ![]() | 13 KB 13 KB | Display Display | ![]() |
Images | ![]() | 185.3 KB | ||
Archive directory | ![]() ![]() | HTTPS FTP |
-Validation report
Summary document | ![]() | 257.2 KB | Display | ![]() |
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Full document | ![]() | 256.4 KB | Display | |
Data in XML | ![]() | 4.1 KB | Display | |
Arichive directory | ![]() ![]() | HTTPS FTP |
-Related structure data
Related structure data | ![]() 4aq5MC ![]() 2072C ![]() 4aq9C M: atomic model generated by this map C: citing same article ( |
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Similar structure data |
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Links
EMDB pages | ![]() ![]() |
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Related items in Molecule of the Month |
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Map
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Annotation | Density map of acetylcholine receptor | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Projections & slices | Image control
Images are generated by Spider. generated in cubic-lattice coordinate | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Voxel size | X=Y=Z: 1 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 : nicotinic acetylcholine receptor in native postsynaptic membrane ...
Entire | Name: nicotinic acetylcholine receptor in native postsynaptic membrane from Torpedo marmorata |
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Components |
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-Supramolecule #1000: nicotinic acetylcholine receptor in native postsynaptic membrane ...
Supramolecule | Name: nicotinic acetylcholine receptor in native postsynaptic membrane from Torpedo marmorata type: sample / ID: 1000 / Oligomeric state: 5 subunits / Number unique components: 1 |
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Molecular weight | Experimental: 300 KDa / Theoretical: 300 KDa Method: molecular weight based on amino acid sequence data and attached sugars |
-Macromolecule #1: nicotinic acetylcholine receptor
Macromolecule | Name: nicotinic acetylcholine receptor / type: protein_or_peptide / ID: 1 / Name.synonym: nicotinic receptor Details: Protein is embedded in postsynaptic membrane isolated from Torpedo marmorata electric organ Oligomeric state: pentamer / Recombinant expression: No / Database: NCBI |
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Source (natural) | Organism: ![]() ![]() |
Molecular weight | Experimental: 300 KDa / Theoretical: 300 KDa |
-Experimental details
-Structure determination
Method | cryo EM |
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![]() | helical reconstruction |
Aggregation state | helical array |
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Sample preparation
Buffer | pH: 7 / Details: 100 mM sodium cacodylate, 1 mM calcium chloride |
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Grid | Details: 300 mesh copper grid with pre-irradiated thick holey carbon support, glow discharged in amylamine atmosphere |
Vitrification | Cryogen name: ETHANE / Chamber humidity: 85 % / Chamber temperature: 120 K / Instrument: HOMEMADE PLUNGER Details: Vitrification carried out at an ambient temperature of 8 degrees C Timed resolved state: Vitrified within 10ms of exposure to acetylcholine (applied as the grid is being plunged,using a fine, focussed spray positioned about 1cm above the ethane surface) Method: Blot until applied droplet loses contact with filter paper (indicated by loss of transparency; typically 6s) |
Details | Tubular membrane crystals of acetylcholine receptors grow spontaneously from isolated postsynaptic membranes when incubated in low salt buffer at 17 degrees C for two weeks |
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Electron microscopy
Microscope | JEOL 3000SFF |
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Temperature | Min: 10 K / Max: 20 K / Average: 10 K |
Alignment procedure | Legacy - Astigmatism: Objective lens astigmatism was corrected based on appearance of carbon film at 250,000 times magnification |
Details | Standard low dose imaging of specimens over holes in the carbon support film |
Date | Nov 1, 2005 |
Image recording | Category: FILM / Film or detector model: KODAK SO-163 FILM / Digitization - Scanner: OTHER / Digitization - Sampling interval: 2.5 µm / Number real images: 111 / Average electron dose: 25 e/Å2 Details: All images recorded on film, developed in Kodak d19 developer Od range: 1 / Bits/pixel: 16 |
Electron beam | Acceleration voltage: 300 kV / Electron source: ![]() |
Electron optics | Calibrated magnification: 38500 / Illumination mode: FLOOD BEAM / Imaging mode: BRIGHT FIELD / Cs: 1.6 mm / Nominal defocus max: 2.0 µm / Nominal defocus min: 0.9 µm / Nominal magnification: 40000 |
Sample stage | Specimen holder: Top-entry holder for liquid helium cooled stage (the temperature of the specimen in this holder is usually at 4K) Specimen holder model: OTHER |
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Image processing
Details | Alignment and distortion correction of each tube image was done using a segmental Fourier-Bessel method (Beroukhim & Unwin (1997) Ultramicroscopy, 70:57-81) with 50% overlap between successive segments |
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Final reconstruction | Algorithm: OTHER / Resolution.type: BY AUTHOR / Resolution: 6.2 Å / Resolution method: FSC 0.5 CUT-OFF / Software - Name: MRC, and, own, programs Details: Final maps were calculated from 111 tube images(closed class) and 123 tube images (open class) |
CTF correction | Details: Each tube image |
-Atomic model buiding 1
Initial model | PDB ID: Chain - #0 - Chain ID: A / Chain - #1 - Chain ID: B / Chain - #2 - Chain ID: C / Chain - #3 - Chain ID: D / Chain - #4 - Chain ID: E |
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Software | Name: DireX |
Details | Protocol: Maximisation of correlation between experimental densities and atomic model, using a deformable elastic network algorithm. Identical refinement procedures were applied to both density maps. The fits were validated by applying the same refinement procedures to independent density maps calculated from half-datasets |
Refinement | Space: REAL / Protocol: FLEXIBLE FIT |
Output model | ![]() PDB-4aq5: |