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Open data
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Basic information
Entry | Database: PDB / ID: 7k0c | ||||||
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Title | Structure of Secretory IgM Core | ||||||
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![]() | IMMUNE SYSTEM / Immunoglobulin M | ||||||
Function / homology | ![]() hexameric IgM immunoglobulin complex / polymeric immunoglobulin receptor activity / immunoglobulin transcytosis in epithelial cells mediated by polymeric immunoglobulin receptor / dimeric IgA immunoglobulin complex / IgM B cell receptor complex / polymeric immunoglobulin binding / secretory dimeric IgA immunoglobulin complex / pentameric IgM immunoglobulin complex / monomeric IgA immunoglobulin complex / secretory IgA immunoglobulin complex ...hexameric IgM immunoglobulin complex / polymeric immunoglobulin receptor activity / immunoglobulin transcytosis in epithelial cells mediated by polymeric immunoglobulin receptor / dimeric IgA immunoglobulin complex / IgM B cell receptor complex / polymeric immunoglobulin binding / secretory dimeric IgA immunoglobulin complex / pentameric IgM immunoglobulin complex / monomeric IgA immunoglobulin complex / secretory IgA immunoglobulin complex / Fc receptor signaling pathway / IgA binding / glomerular filtration / detection of chemical stimulus involved in sensory perception of bitter taste / IgM immunoglobulin complex / pre-B cell allelic exclusion / CD22 mediated BCR regulation / azurophil granule membrane / receptor clustering / positive regulation of respiratory burst / humoral immune response / Scavenging of heme from plasma / immunoglobulin complex, circulating / immunoglobulin receptor binding / Antigen activates B Cell Receptor (BCR) leading to generation of second messengers / complement activation, classical pathway / Cell surface interactions at the vascular wall / antigen binding / B cell receptor signaling pathway / epidermal growth factor receptor signaling pathway / protein-macromolecule adaptor activity / antibacterial humoral response / protein-containing complex assembly / defense response to Gram-negative bacterium / adaptive immune response / Potential therapeutics for SARS / receptor complex / blood microparticle / immune response / innate immune response / Neutrophil degranulation / cell surface / protein homodimerization activity / extracellular space / extracellular exosome / extracellular region / plasma membrane Similarity search - Function | ||||||
Biological species | ![]() | ||||||
Method | ELECTRON MICROSCOPY / single particle reconstruction / cryo EM / Resolution: 3.3 Å | ||||||
![]() | Kumar, N. / Arthur, C.P. / Ciferri, C. / Matsumoto, M.L. | ||||||
![]() | ![]() Title: Structure of the human secretory immunoglobulin M core. Authors: Nikit Kumar / Christopher P Arthur / Claudio Ciferri / Marissa L Matsumoto / ![]() Abstract: Immunoglobulins (Ig) A and M are the only human antibodies that form oligomers and undergo transcytosis to mucosal secretions via the polymeric Ig receptor (pIgR). When complexed with the J-chain (JC) ...Immunoglobulins (Ig) A and M are the only human antibodies that form oligomers and undergo transcytosis to mucosal secretions via the polymeric Ig receptor (pIgR). When complexed with the J-chain (JC) and the secretory component (SC) of pIgR, secretory IgA and IgM (sIgA and sIgM) play critical roles in host-pathogen defense. Recently, we determined the structure of sIgA-Fc which elucidated the mechanism of polymeric IgA assembly and revealed an extensive binding interface between IgA-Fc, JC, and SC. Despite low sequence identity shared with IgA-Fc, IgM-Fc also undergoes JC-mediated assembly and binds pIgR. Here, we report the structure of sIgM-Fc and carryout a systematic comparison to sIgA-Fc. Our structural analysis reveals a remarkably conserved mechanism of JC-templated oligomerization and SC recognition of both IgM and IgA through a highly conserved network of interactions. These studies reveal the structurally conserved features of sIgM and sIgA required for function in mucosal immunity. | ||||||
History |
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Structure visualization
Movie |
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Structure viewer | Molecule: ![]() ![]() |
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Downloads & links
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Download
PDBx/mmCIF format | ![]() | 510.4 KB | Display | ![]() |
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PDB format | ![]() | 422.4 KB | Display | ![]() |
PDBx/mmJSON format | ![]() | Tree view | ![]() | |
Others | ![]() |
-Validation report
Summary document | ![]() | 1.1 MB | Display | ![]() |
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Full document | ![]() | 1.2 MB | Display | |
Data in XML | ![]() | 94.6 KB | Display | |
Data in CIF | ![]() | 141.8 KB | Display | |
Arichive directory | ![]() ![]() | HTTPS FTP |
-Related structure data
Related structure data | ![]() 22591MC M: map data used to model this data C: citing same article ( |
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Similar structure data |
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Links
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Assembly
Deposited unit | ![]()
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Components
#1: Protein | Mass: 65154.094 Da / Num. of mol.: 1 Source method: isolated from a genetically manipulated source Source: (gene. exp.) ![]() ![]() ![]() | ||||||
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#2: Protein | Mass: 40677.605 Da / Num. of mol.: 10 Source method: isolated from a genetically manipulated source Source: (gene. exp.) ![]() ![]() ![]() #3: Protein | | Mass: 15611.458 Da / Num. of mol.: 1 Source method: isolated from a genetically manipulated source Source: (gene. exp.) ![]() ![]() ![]() #4: Polysaccharide | 2-acetamido-2-deoxy-beta-D-glucopyranose-(1-4)-2-acetamido-2-deoxy-beta-D-glucopyranose | Source method: isolated from a genetically manipulated source Has ligand of interest | N | |
-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: Structure of the Human Secretory Immunoglobulin M Core Type: COMPLEX / Entity ID: #1-#3 / Source: RECOMBINANT | |||||||||||||||
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Molecular weight | Value: 480 kDa/nm / Experimental value: NO | |||||||||||||||
Source (natural) | Organism: ![]() | |||||||||||||||
Source (recombinant) | Organism: ![]() ![]() | |||||||||||||||
Buffer solution | pH: 7.2 | |||||||||||||||
Buffer component |
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Specimen | Conc.: 0.2 mg/ml / Embedding applied: NO / Shadowing applied: NO / Staining applied: NO / Vitrification applied: YES / Details: Sample was monodisperse. | |||||||||||||||
Specimen support | Grid material: GOLD / Grid mesh size: 300 divisions/in. / Grid type: UltrAuFoil R0.6/1 | |||||||||||||||
Vitrification | Instrument: FEI VITROBOT MARK IV / Cryogen name: ETHANE / Humidity: 100 % / Chamber temperature: 277 K Details: Blot for 3.5 seconds before plunging with blot force 7. |
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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 / Cs: 2.7 mm |
Specimen holder | Cryogen: NITROGEN / Specimen holder model: FEI TITAN KRIOS AUTOGRID HOLDER |
Image recording | Average exposure time: 0.2 sec. / Electron dose: 1.02 e/Å2 / Detector mode: COUNTING / Film or detector model: GATAN K2 SUMMIT (4k x 4k) |
Image scans | Movie frames/image: 50 |
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Processing
Software | Name: PHENIX / Version: 1.18.1_3865: / Classification: refinement | ||||||||||||||||||||||||
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EM software |
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CTF correction | Type: PHASE FLIPPING AND AMPLITUDE CORRECTION | ||||||||||||||||||||||||
Symmetry | Point symmetry: C1 (asymmetric) | ||||||||||||||||||||||||
3D reconstruction | Resolution: 3.3 Å / Resolution method: FSC 0.143 CUT-OFF / Num. of particles: 244123 / Symmetry type: POINT | ||||||||||||||||||||||||
Refine LS restraints |
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