22FX | pdb_000022fx

Cryo-EM structure of mouse heavy-chain apoferritin at 1.24 A on CRYO ARM 200 II

• PDB DOI: https://doi.org/10.2210/pdb22FX/pdb
• EM Map EMD-68251: EMDB EMDataResource

• Classification: METAL BINDING PROTEIN
• Organism(s): Mus musculus
• Expression System: Escherichia coli 'BL21-Gold(DE3)pLysS AG
• Mutation(s): No 


• Deposited: 2026-01-09 Released: 2026-03-04 
• Deposition Author(s): Danev, R., Yanagisawa, H., Yamashita, K., Eisenstein, F., Kikkawa, M.
• Funding Organization(s): Japan Society for the Promotion of Science (JSPS), Japan Agency for Medical Research and Development (AMED)

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Experimental Data Snapshot

• Method: ELECTRON MICROSCOPY
• Resolution: 1.24 Å
• Aggregation State: PARTICLE 
• Reconstruction Method: SINGLE PARTICLE 

Starting Model: experimental

Literature

Atomic resolution cryo-EM at 200 keV.

Danev, R., Yanagisawa, H., Yamashita, K., Eisenstein, F., Kikkawa, M.

(2026) IUCrJ 13: 343-353

• PubMed: 42268577 
• DOI: https://doi.org/10.1107/S2052252526004100
• Primary Citation Related Structures: 
  22FX


• PubMed Abstract: 
  

  Atomic resolution in cryo-electron microscopy was first demonstrated six years ago. This was accomplished using 300 kV electron microscopes equipped with new hardware that provided narrower energy spread, aberration correction and energy filtering. Here, we report the achievement of 1.24 Å atomic resolution on an upgraded 200 kV electron microscope featuring a cold field emission gun, a high-resolution objective lens polepiece and an energy filter. These components transform the instrument into a cost-effective single-particle cryo-EM platform with performance comparable to that of significantly more expensive 300 kV systems. The microscope can also be operated at 100 kV and by using a high-speed hybrid-pixel detector we were able to reach sub-2 Å resolution.

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Organizational Affiliation: 
• Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan.
Research Center for Advanced Science and Technology, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo, 153-8904, Japan.
DECTRIS Ltd, Taefernweg 1, 5405 Baden-Daettwil, Switzerland.

Biological Assembly 1  

Global Symmetry: Octahedral - O  (Explore in 3D)
Global Stoichiometry: Homo 24-mer - A24 

Biological assembly 1 assigned by authors and generated by (software)

Biological Assembly Evidence: electron microscopy

Macromolecule Content 

• Total Structure Weight: 21.22 kDa 
• Atom Count: 1,814 
• Modeled Residue Count: 173 
• Deposited Residue Count: 182 
• Unique protein chains: 1

Macromolecules

Entity ID: 1
Molecule	Chains	Sequence Length	Organism	Details	Image
Ferritin heavy chain	A	182	Mus musculus	Mutation(s): 0  Gene Names: Fth1, Fth EC: 1.16.3.1
UniProt & NIH Common Fund Data Resources
Find proteins for P09528 (Mus musculus) Explore P09528  Go to UniProtKB:  P09528
IMPC:  MGI:95588

Small Molecules

Ligands 2 Unique
ID	Chains	Name / Formula / InChI Key	2D Diagram
ZN	C [auth A]	ZINC ION Zn PTFCDOFLOPIGGS-UHFFFAOYSA-N
FE	B [auth A]	FE (III) ION Fe VTLYFUHAOXGGBS-UHFFFAOYSA-N

Experimental Data & Validation

Experimental Data

• Method: ELECTRON MICROSCOPY
• Resolution: 1.24 Å
• Aggregation State: PARTICLE 
• Reconstruction Method: SINGLE PARTICLE 

EM Software:

Task	Software Package	Version
MODEL REFINEMENT	Servalcat
MODEL REFINEMENT	Coot
RECONSTRUCTION	cryoSPARC	4.5

Structure Validation

Entry History 

& Funding Information

Deposition Data

• Released Date: 2026-03-04 
Deposition Author(s): Danev, R., Yanagisawa, H., Yamashita, K., Eisenstein, F., Kikkawa, M.

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Funding Organization	Location	Grant Number
Japan Society for the Promotion of Science (JSPS)	Japan	22H02554
Japan Agency for Medical Research and Development (AMED)	Japan	JP25ama121002j0004

Revision History  

• Version 1.0: 2026-03-04
  Type: Initial release
  
• Version 1.1: 2026-07-08
  Changes: Data collection, Database references
• Version 1.2: 2026-07-15
  Changes: Data collection, Database references