21NX | pdb_000021nx

Cryo-EM structure of mouse IgG2b-Fc in complex with FcgammaRIV

• PDB DOI: https://doi.org/10.2210/pdb21NX/pdb
• EM Map EMD-67855: EMDB EMDataResource

• Classification: IMMUNE SYSTEM
• Organism(s): Mus musculus
• Expression System: Homo sapiens
• Mutation(s): No 


• Deposited: 2025-12-21 Released: 2026-08-26 
• Deposition Author(s): Xu, S.R., Du, S., Xiao, J.Y.
• Funding Organization(s): Not funded

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Experimental Data Snapshot

• Method: ELECTRON MICROSCOPY
• Resolution: 2.99 Å
• Aggregation State: PARTICLE 
• Reconstruction Method: SINGLE PARTICLE 

Literature

Cryo-EM structure of mouse IgG2b-Fc in complex with FcgammaRIV

Xu, S.R., Du, S., Xiao, J.Y.

To be published.

Biological Assembly 1  

Global Symmetry: Asymmetric - C1 
Global Stoichiometry: Hetero 3-mer - A2B1 Local Symmetry: Cyclic - C2  (Explore in 3D)
Local Stoichiometry: Homo 2-mer - A2 

Local Symmetry: Cyclic - C2  (Explore in 3D)
Local Stoichiometry: Homo 2-mer - A2 

Biological assembly 1 assigned by authors.

Biological Assembly Evidence: electron microscopy

Macromolecule Content 

• Total Structure Weight: 86.4 kDa 
• Atom Count: 4,860 
• Modeled Residue Count: 595 
• Deposited Residue Count: 751 
• Unique protein chains: 2

Macromolecules

Entity ID: 1
Molecule	Chains	Sequence Length	Organism	Details	Image
Low affinity immunoglobulin gamma Fc region receptor III-A	A	225	Mus musculus	Mutation(s): 0  Gene Names: Fcgr4, Fcgr3a
UniProt
Find proteins for A0A0B4J1G0 (Mus musculus) Explore A0A0B4J1G0  Go to UniProtKB:  A0A0B4J1G0
Glycosylation
Glycosylation Sites: 1		Go to GlyGen: A0A0B4J1G0-1

Entity ID: 2
Molecule	Chains	Sequence Length	Organism	Details	Image
Isoform 2 of Immunoglobulin heavy constant gamma 2B	B, C	263	Mus musculus	Mutation(s): 0  Gene Names: Ighg2b, Igh-3
UniProt
Find proteins for P01867 (Mus musculus) Go to UniProtKB:  P01867
Glycosylation
Glycosylation Sites: 1		Go to GlyGen: P01867-1

Oligosaccharides

Help  

Entity ID: 3
Molecule	Chains	Length	2D Diagram	Glycosylation	D Interactions
beta-D-mannopyranose-(1-4)-2-acetamido-2-deoxy-beta-D-glucopyranose-(1-4)-[alpha-L-fucopyranose-(1-6)]2-acetamido-2-deoxy-beta-D-glucopyranose	D, E	4		N-Glycosylation

Small Molecules

Ligands 1 Unique
ID	Chains	Name / Formula / InChI Key	2D Diagram
NAG (Subject of Investigation/LOI)	F [auth A]	2-acetamido-2-deoxy-beta-D-glucopyranose C8 H15 N O6 OVRNDRQMDRJTHS-FMDGEEDCSA-N

Experimental Data & Validation

Experimental Data

• Method: ELECTRON MICROSCOPY
• Resolution: 2.99 Å
• Aggregation State: PARTICLE 
• Reconstruction Method: SINGLE PARTICLE 

EM Software:

Task	Software Package	Version
MODEL REFINEMENT	PHENIX	1.19.2_4158
RECONSTRUCTION	cryoSPARC

Structure Validation

Entry History 

& Funding Information

Deposition Data

• Released Date: 2026-08-26 
Deposition Author(s): Xu, S.R., Du, S., Xiao, J.Y.

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Funding Organization	Location	Grant Number
Not funded		--

Revision History  

• Version 1.0: 2026-08-26
  Type: Initial release