[English] 日本語
Yorodumi
- PDB-9uo4: Cryo-EM structure of the chimeric human IgM-Fc hexamer -

+
Open data


ID or keywords:

Loading...

-
Basic information

Entry
Database: PDB / ID: 9uo4
TitleCryo-EM structure of the chimeric human IgM-Fc hexamer
ComponentsImmunoglobulin heavy constant mu
KeywordsIMMUNE SYSTEM / Complex / polymeric antibody
Function / homology
Function and homology information


hexameric IgM immunoglobulin complex / IgM B cell receptor complex / pentameric IgM immunoglobulin complex / pre-B cell allelic exclusion / IgM immunoglobulin complex / CD22 mediated BCR regulation / antigen binding / Antigen activates B Cell Receptor (BCR) leading to generation of second messengers / Cell surface interactions at the vascular wall / B cell receptor signaling pathway ...hexameric IgM immunoglobulin complex / IgM B cell receptor complex / pentameric IgM immunoglobulin complex / pre-B cell allelic exclusion / IgM immunoglobulin complex / CD22 mediated BCR regulation / antigen binding / Antigen activates B Cell Receptor (BCR) leading to generation of second messengers / Cell surface interactions at the vascular wall / B cell receptor signaling pathway / antibacterial humoral response / blood microparticle / defense response to Gram-negative bacterium / Potential therapeutics for SARS / adaptive immune response / innate immune response / cell surface / extracellular space / extracellular exosome / plasma membrane
Similarity search - Function
: / Immunoglobulin/major histocompatibility complex, conserved site / Immunoglobulins and major histocompatibility complex proteins signature. / Immunoglobulin C-Type / Immunoglobulin C1-set / Immunoglobulin C1-set domain / Ig-like domain profile. / Immunoglobulin-like domain / Immunoglobulin-like domain superfamily / Immunoglobulin-like fold
Similarity search - Domain/homology
Immunoglobulin heavy constant mu
Similarity search - Component
Biological speciesHomo sapiens (human)
MethodELECTRON MICROSCOPY / single particle reconstruction / cryo EM / Resolution: 3.29 Å
AuthorsJi, C. / Zhang, R. / Xiao, J.
Funding support China, 1items
OrganizationGrant numberCountry
National Science Foundation (NSF, China) China
CitationJournal: Sci Adv / Year: 2025
Title: IgX informs engineering strategies of IgM and IgG hexamers.
Authors: Ruixue Zhang / Chenggong Ji / Shuhan Li / Ningning Li / Ning Gao / Junyu Xiao /
Abstract: Polymeric immunoglobulins are essential components of the immune system in jawed vertebrates. While mammalian immunoglobulin M (IgM) typically forms a pentamer linked by the joining chain (J-chain), ...Polymeric immunoglobulins are essential components of the immune system in jawed vertebrates. While mammalian immunoglobulin M (IgM) typically forms a pentamer linked by the joining chain (J-chain), IgX can assemble into a J-chain-independent polymer. Here, we present the cryo-electron microscopy (cryo-EM) structure of IgX, revealing its hexameric configuration. By incorporating the IgX tailpiece into human IgM, we achieved efficient IgM hexamer formation. Truncating IgM's natural tailpiece to a range of 11 to 16 residues also substantially enhanced hexamerization efficiency. Furthermore, introducing a shortened IgM tailpiece to IgG resulted in effective IgG hexamer formation. We further show that the engineered IgM and IgG hexamers targeting CD20 demonstrated robust complement-dependent cytotoxicity (CDC) against several B lymphoma cells. In addition, the IgG-Fc hexamer functioned as a decoy, attenuating CDC in cell cultures. These findings deepen our understanding of polymeric immunoglobulin evolution and introduce innovative strategies for the development of IgM- and IgG-based biologics.
History
DepositionApr 25, 2025Deposition site: PDBJ / Processing site: PDBC
Revision 1.0Dec 17, 2025Provider: repository / Type: Initial release
Revision 1.0Dec 17, 2025Data content type: EM metadata / Data content type: EM metadata / Provider: repository / Type: Initial release
Revision 1.0Dec 17, 2025Data content type: Half map / Part number: 1 / Data content type: Half map / Provider: repository / Type: Initial release
Revision 1.0Dec 17, 2025Data content type: Half map / Part number: 2 / Data content type: Half map / Provider: repository / Type: Initial release
Revision 1.0Dec 17, 2025Data content type: Image / Data content type: Image / Provider: repository / Type: Initial release
Revision 1.0Dec 17, 2025Data content type: Primary map / Data content type: Primary map / Provider: repository / Type: Initial release

-
Structure visualization

Structure viewerMolecule:
MolmilJmol/JSmol

Downloads & links

-
Assembly

Deposited unit
A: Immunoglobulin heavy constant mu
B: Immunoglobulin heavy constant mu
C: Immunoglobulin heavy constant mu
D: Immunoglobulin heavy constant mu
E: Immunoglobulin heavy constant mu
F: Immunoglobulin heavy constant mu
G: Immunoglobulin heavy constant mu
H: Immunoglobulin heavy constant mu
I: Immunoglobulin heavy constant mu
J: Immunoglobulin heavy constant mu
K: Immunoglobulin heavy constant mu
L: Immunoglobulin heavy constant mu


Theoretical massNumber of molelcules
Total (without water)493,23512
Polymers493,23512
Non-polymers00
Water00
1


  • Idetical with deposited unit
  • defined by author&software
  • Evidence: electron microscopy, not applicable
TypeNameSymmetry operationNumber
identity operation1_5551

-
Components

#1: Protein
Immunoglobulin heavy constant mu / Ig mu chain C region / Ig mu chain C region BOT / Ig mu chain C region GAL / Ig mu chain C region OU


Mass: 41102.953 Da / Num. of mol.: 12
Source method: isolated from a genetically manipulated source
Source: (gene. exp.) Homo sapiens (human) / Gene: IGHM / Production host: Homo sapiens (human) / References: UniProt: P01871
Has protein modificationY

-
Experimental details

-
Experiment

ExperimentMethod: ELECTRON MICROSCOPY
EM experimentAggregation state: PARTICLE / 3D reconstruction method: single particle reconstruction

-
Sample preparation

ComponentName: The hexamer of human chimeric IgM-Fc / Type: COMPLEX / Entity ID: all / Source: RECOMBINANT
Source (natural)Organism: Homo sapiens (human)
Source (recombinant)Organism: Homo sapiens (human)
Buffer solutionpH: 7.4
SpecimenEmbedding applied: NO / Shadowing applied: NO / Staining applied: NO / Vitrification applied: YES
VitrificationCryogen name: ETHANE

-
Electron microscopy imaging

Experimental equipment
Model: Tecnai Polara / Image courtesy: FEI Company
MicroscopyModel: FEI POLARA 300
Electron gunElectron source: FIELD EMISSION GUN / Accelerating voltage: 300 kV / Illumination mode: FLOOD BEAM
Electron lensMode: BRIGHT FIELD / Nominal defocus max: 1400 nm / Nominal defocus min: 1000 nm
Image recordingElectron dose: 60 e/Å2 / Film or detector model: GATAN K3 (6k x 4k)

-
Processing

EM softwareName: PHENIX / Version: 1.20.1_4487 / Category: model refinement
CTF correctionType: NONE
3D reconstructionResolution: 3.29 Å / Resolution method: FSC 0.143 CUT-OFF / Num. of particles: 1099811 / Symmetry type: POINT
RefinementHighest resolution: 3.29 Å
Stereochemistry target values: REAL-SPACE (WEIGHTED MAP SUM AT ATOM CENTERS)
Refine LS restraints
Refine-IDTypeDev idealNumber
ELECTRON MICROSCOPYf_bond_d0.00320496
ELECTRON MICROSCOPYf_angle_d0.68128056
ELECTRON MICROSCOPYf_dihedral_angle_d5.4392748
ELECTRON MICROSCOPYf_chiral_restr0.0483276
ELECTRON MICROSCOPYf_plane_restr0.0063612

+
About Yorodumi

-
News

-
Feb 9, 2022. New format data for meta-information of EMDB entries

New format data for meta-information of EMDB entries

  • Version 3 of the EMDB header file is now the official format.
  • The previous official version 1.9 will be removed from the archive.

Related info.:EMDB header

External links:wwPDB to switch to version 3 of the EMDB data model

-
Aug 12, 2020. Covid-19 info

Covid-19 info

URL: https://pdbj.org/emnavi/covid19.php

New page: Covid-19 featured information page in EM Navigator.

Related info.:Covid-19 info / Mar 5, 2020. Novel coronavirus structure data

+
Mar 5, 2020. Novel coronavirus structure data

Novel coronavirus structure data

Related info.:Yorodumi Speices / Aug 12, 2020. Covid-19 info

External links:COVID-19 featured content - PDBj / Molecule of the Month (242)：Coronavirus Proteases

+
Jan 31, 2019. EMDB accession codes are about to change! (news from PDBe EMDB page)

EMDB accession codes are about to change! (news from PDBe EMDB page)

  • The allocation of 4 digits for EMDB accession codes will soon come to an end. Whilst these codes will remain in use, new EMDB accession codes will include an additional digit and will expand incrementally as the available range of codes is exhausted. The current 4-digit format prefixed with “EMD-” (i.e. EMD-XXXX) will advance to a 5-digit format (i.e. EMD-XXXXX), and so on. It is currently estimated that the 4-digit codes will be depleted around Spring 2019, at which point the 5-digit format will come into force.
  • The EM Navigator/Yorodumi systems omit the EMD- prefix.

Related info.:Q: What is EMD? / ID/Accession-code notation in Yorodumi/EM Navigator

External links:EMDB Accession Codes are Changing Soon! / Contact to PDBj

+
Jul 12, 2017. Major update of PDB

Major update of PDB

  • wwPDB released updated PDB data conforming to the new PDBx/mmCIF dictionary.
  • This is a major update changing the version number from 4 to 5, and with Remediation, in which all the entries are updated.
  • In this update, many items about electron microscopy experimental information are reorganized (e.g. em_software).
  • Now, EM Navigator and Yorodumi are based on the updated data.

External links:wwPDB Remediation / Enriched Model Files Conforming to OneDep Data Standards Now Available in the PDB FTP Archive

-
Yorodumi

Thousand views of thousand structures

  • Yorodumi is a browser for structure data from EMDB, PDB, SASBDB, etc.
  • This page is also the successor to EM Navigator detail page, and also detail information page/front-end page for Omokage search.
  • The word "yorodu" (or yorozu) is an old Japanese word meaning "ten thousand". "mi" (miru) is to see.

Related info.:EMDB / PDB / SASBDB / Comparison of 3 databanks / Yorodumi Search / Aug 31, 2016. New EM Navigator & Yorodumi / Yorodumi Papers / Jmol/JSmol / Function and homology information / Changes in new EM Navigator and Yorodumi

Read more