Journal: IUCrJ / Year: 2020 Title: Protein-lipid architecture of a cholinergic postsynaptic membrane. Authors: Nigel Unwin / Abstract: The cholinergic postsynaptic membrane is an acetyl-choline receptor-rich membrane mediating fast chemical communication at the nerve-muscle synapse. Here, cryo-EM is used to examine the protein-lipid ...The cholinergic postsynaptic membrane is an acetyl-choline receptor-rich membrane mediating fast chemical communication at the nerve-muscle synapse. Here, cryo-EM is used to examine the protein-lipid architecture of this membrane in tubular vesicles obtained from the (muscle-derived) electric organ of the ray. As reported earlier, the helical arrangement of the protein component of the vesicles facilitates image averaging and enables us to determine how cholesterol and phospho-lipid molecules are distributed in the surrounding matrix, using headgroup size as a means to discriminate between the two kinds of lipid. It is shown that cholesterol segregates preferentially around the receptors in both leaflets of the lipid bilayer, interacting robustly with specific transmembrane sites and creating a network of bridging microdomains. Cholesterol interactions with the receptor are apparently essential for stabilizing and maintaining its physiological architecture, since the transmembrane structure contracts, involving displacements of the helices at the outer membrane surface by ∼2 Å (1-3 Å), when this lipid is extracted. The microdomains may promote cooperativity between neighbouring receptors, leading to an enhanced postsynaptic response.
History
Deposition
Jun 29, 2020
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Header (metadata) release
Sep 16, 2020
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Map release
Sep 16, 2020
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Update
Sep 16, 2020
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Current status
Sep 16, 2020
Processing site: PDBe / Status: Released
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Structure visualization
Movie
Surface view with section colored by density value
Model: Quantifoil / Material: COPPER / Mesh: 400 / Support film - Material: CARBON / Support film - topology: HOLEY / Support film - Film thickness: 20.0 nm / Pretreatment - Type: GLOW DISCHARGE / Pretreatment - Atmosphere: OTHER
This map is simply an average of two maps of the protein derived from two families of helical membrane tubes. (-16,6) tubes: 1037 images, 51921 segments (-17,5) tubes: 1374 images, 71741 segments
Final reconstruction
Applied symmetry - Point group: C1 (asymmetric) / Algorithm: FOURIER SPACE / Resolution.type: BY AUTHOR / Resolution: 5.8 Å / Resolution method: FSC 0.143 CUT-OFF / Software - Name: RELION (ver. 2.1 and 3.0) Details: FSC is based on comparison of aligned particles cut out from the the two individual helical reconstructions Number images used: 123662
CTF correction
Software - Name: Gctf Details: CTF amplitude correction was applied locally along the axis of each tube, using the non dose-weighted images
Segment selection
Number selected: 123662
Final angle assignment
Type: NOT APPLICABLE
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