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Open data
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Basic information
Entry | Database: PDB / ID: 7qdo | |||||||||||||||||||||
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Title | Cryo-EM structure of human monomeric IgM-Fc | |||||||||||||||||||||
![]() | Isoform 2 of Immunoglobulin heavy constant mu | |||||||||||||||||||||
![]() | IMMUNE SYSTEM / human monomeric IgM-Fc | |||||||||||||||||||||
Function / homology | Isoform 2 of Immunoglobulin heavy constant mu![]() | |||||||||||||||||||||
Biological species | ![]() | |||||||||||||||||||||
Method | ELECTRON MICROSCOPY / single particle reconstruction / cryo EM / Resolution: 3.6 Å | |||||||||||||||||||||
![]() | Chen, Q. / Rosenthal, P. / Tolar, P. | |||||||||||||||||||||
Funding support | ![]()
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![]() | ![]() Title: Cryomicroscopy reveals the structural basis for a flexible hinge motion in the immunoglobulin M pentamer. Authors: Qu Chen / Rajesh Menon / Lesley J Calder / Pavel Tolar / Peter B Rosenthal / ![]() Abstract: Immunoglobulin M (IgM) is the most ancient of the five isotypes of immunoglobulin (Ig) molecules and serves as the first line of defence against pathogens. Here, we use cryo-EM to image the structure ...Immunoglobulin M (IgM) is the most ancient of the five isotypes of immunoglobulin (Ig) molecules and serves as the first line of defence against pathogens. Here, we use cryo-EM to image the structure of the human full-length IgM pentamer, revealing antigen binding domains flexibly attached to the asymmetric and rigid core formed by the Cμ4 and Cμ3 constant regions and the J-chain. A hinge is located at the Cμ3/Cμ2 domain interface, allowing Fabs and Cμ2 to pivot as a unit both in-plane and out-of-plane. This motion is different from that observed in IgG and IgA, where the two Fab arms are able to swing independently. A biased orientation of one pair of Fab arms results from asymmetry in the constant domain (Cμ3) at the IgM subunit interacting most extensively with the J-chain. This may influence the multi-valent binding to surface-associated antigens and complement pathway activation. By comparison, the structure of the Fc fragment in the IgM monomer is similar to that of the pentamer, but is more dynamic in the Cμ4 domain. | |||||||||||||||||||||
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Structure visualization
Structure viewer | Molecule: ![]() ![]() |
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Downloads & links
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Download
PDBx/mmCIF format | ![]() | 90.7 KB | Display | ![]() |
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PDB format | ![]() | 65.9 KB | Display | ![]() |
PDBx/mmJSON format | ![]() | Tree view | ![]() | |
Others | ![]() |
-Validation report
Summary document | ![]() | 895.6 KB | Display | ![]() |
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Full document | ![]() | 898 KB | Display | |
Data in XML | ![]() | 29.3 KB | Display | |
Data in CIF | ![]() | 39.4 KB | Display | |
Arichive directory | ![]() ![]() | HTTPS FTP |
-Related structure data
Related structure data | ![]() 13922MC ![]() 8adyC ![]() 8adzC ![]() 8ae0C ![]() 8ae2C ![]() 8ae3C M: map data used to model this data C: citing same article ( |
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Similar structure data | Similarity search - Function & homology ![]() |
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Links
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Assembly
Deposited unit | ![]()
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Components
#1: Protein | Mass: 47687.059 Da / Num. of mol.: 2 Source method: isolated from a genetically manipulated source Source: (gene. exp.) ![]() ![]() |
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-Experimental details
-Experiment
Experiment | Method: ELECTRON MICROSCOPY |
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EM experiment | Aggregation state: PARTICLE / 3D reconstruction method: single particle reconstruction |
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Sample preparation
Component | Name: human monomeric IgM-Fc / Type: COMPLEX / Entity ID: all / Source: RECOMBINANT |
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Source (natural) | Organism: ![]() |
Source (recombinant) | Organism: ![]() |
Buffer solution | pH: 8 |
Specimen | Conc.: 0.2 mg/ml / Embedding applied: NO / Shadowing applied: NO / Staining applied: NO / Vitrification applied: YES |
Vitrification | Cryogen name: ETHANE |
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Electron microscopy imaging
Experimental equipment | ![]() Model: Titan Krios / Image courtesy: FEI Company |
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Microscopy | Model: FEI TITAN KRIOS |
Electron gun | Electron source: ![]() |
Electron lens | Mode: BRIGHT FIELD / Nominal magnification: 165000 X / Calibrated magnification: 59595 X / Nominal defocus max: 3600 nm / Nominal defocus min: 1500 nm / Calibrated defocus min: 1000 nm / Calibrated defocus max: 4000 nm / Cs: 2.7 mm / C2 aperture diameter: 50 µm |
Specimen holder | Cryogen: NITROGEN / Specimen holder model: FEI TITAN KRIOS AUTOGRID HOLDER |
Image recording | Electron dose: 66 e/Å2 / Detector mode: COUNTING / Film or detector model: GATAN K2 QUANTUM (4k x 4k) |
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Processing
Software | Name: PHENIX / Version: 1.19.2_4158: / Classification: refinement | ||||||||||||||||||||||||
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CTF correction | Type: PHASE FLIPPING AND AMPLITUDE CORRECTION | ||||||||||||||||||||||||
Symmetry | Point symmetry: C2 (2 fold cyclic) | ||||||||||||||||||||||||
3D reconstruction | Resolution: 3.6 Å / Resolution method: FSC 0.143 CUT-OFF / Num. of particles: 961072 / Symmetry type: POINT | ||||||||||||||||||||||||
Atomic model building | Space: REAL | ||||||||||||||||||||||||
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