Biological Assembly 1  

 3D View: Structure | 1D-3D View | Electron Density | Validation Report

Global Symmetry: Asymmetric - C1 
Global Stoichiometry: Hetero 12-mer - A10B1C1 Local Symmetry: Cyclic - C2  (3D View)
Local Stoichiometry: Homo 10-mer - A10 

Local Symmetry: Cyclic - C2  (3D View)
Local Stoichiometry: Homo 10-mer - A10 

Biological assembly 1 assigned by authors.

Biological Assembly Evidence: gel filtration

Macromolecule Content

• Total Structure Weight: 487.97 kDa 
• Atom Count: 22540 
• Modelled Residue Count: 2898 
• Deposited Residue Count: 4418 
• Unique protein chains: 3

7K0C

Structure of Secretory IgM Core

• PDB DOI: 10.2210/pdb7K0C/pdb
• EM Map EMD-22591:EMDBEMDataResource

• Classification: IMMUNE SYSTEM
• Organism(s): Homo sapiens
• Expression System: Cricetulus griseus
• Mutation(s): No 


• Deposited: 2020-09-04 Released: 2021-01-20 
• Deposition Author(s): Kumar, N., Arthur, C.P., Ciferri, C., Matsumoto, M.L.

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Experimental Data Snapshot

• Method: ELECTRON MICROSCOPY
• Resolution: 3.30 Å
• Aggregation State: PARTICLE 
• Reconstruction Method: SINGLE PARTICLE 

Literature

Structure of the human secretory immunoglobulin M core.

Kumar, N., Arthur, C.P., Ciferri, C., Matsumoto, M.L.

(2021) Structure 29: 564-571.e3

• PubMed: 33513362 
• DOI: 10.1016/j.str.2021.01.002
• Primary Citation of Related Structures:  
  7K0C


• PubMed 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) 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.

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Organizational Affiliation: 

Department of Structural Biology, Genentech, 1 DNA Way, South San Francisco, CA 94080, USA. Electronic address: [e-mail].

Macromolecules

Entity ID: 1
Molecule	Chains	Sequence Length	Organism	Details	Image
Polymeric immunoglobulin receptor	A [auth C]	591	Homo sapiens	Mutation(s): 0  Gene Names: PIGR
UniProt & NIH Common Fund Data Resources
Find proteins for P01833 (Homo sapiens) Explore P01833  Go to UniProtKB:  P01833
PHAROS:  P01833 GTEx:  ENSG00000162896

Entity ID: 2
Molecule	Chains	Sequence Length	Organism	Details	Image
Immunoglobulin heavy constant mu	B [auth A], C [auth B], H [auth E], L [auth F], K [auth G], I [auth H], F [auth I], G [auth J], D [auth K], E [auth L]	369	Homo sapiens	Mutation(s): 0  Gene Names: IGHM
UniProt & NIH Common Fund Data Resources
Find proteins for P01871 (Homo sapiens) Explore P01871  Go to UniProtKB:  P01871
PHAROS:  P01871 GTEx:  ENSG00000211899

Entity ID: 3
Molecule	Chains	Sequence Length	Organism	Details	Image
Immunoglobulin J chain	J [auth D]	137	Homo sapiens	Mutation(s): 0  Gene Names: JCHAIN, IGCJ, IGJ
UniProt & NIH Common Fund Data Resources
Find proteins for P01591 (Homo sapiens) Explore P01591  Go to UniProtKB:  P01591
PHAROS:  P01591 GTEx:  ENSG00000132465

Oligosaccharides

Help

Entity ID: 4
Molecule	Chains	Chain Length	2D Diagram	Glycosylation
2-acetamido-2-deoxy-beta-D-glucopyranose-(1-4)-2-acetamido-2-deoxy-beta-D-glucopyranose	M	2		N-Glycosylation
Glycosylation Resources
GlyTouCan:  G42666HT GlyCosmos:  G42666HT GlyGen:  G42666HT

Experimental Data & Validation

Experimental Data

• Method: ELECTRON MICROSCOPY
• Resolution: 3.30 Å
• Aggregation State: PARTICLE 
• Reconstruction Method: SINGLE PARTICLE 

Structure Validation

Entry History 

Deposition Data

• Deposited Date: 2020-09-04 
• Released Date: 2021-01-20 
Deposition Author(s): Kumar, N., Arthur, C.P., Ciferri, C., Matsumoto, M.L.

Revision History  

• Version 1.0: 2021-01-20
  Type: Initial release
  
• Version 1.1: 2021-02-10
  Changes: Database references
• Version 1.2: 2021-06-16
  Changes: Database references