7K0C

Structure of Secretory IgM Core

Summary for 7K0C

• Entry DOI: 10.2210/pdb7k0c/pdb
• EMDB information: 22591
• Descriptor: Polymeric immunoglobulin receptor, Immunoglobulin heavy constant mu, Immunoglobulin J chain, ... (4 entities in total)
• Functional Keywords: immunoglobulin m, immune system
• Biological source: Homo sapiens (Human); More
• Total number of polymer chains: 12
• Total formula weight: 487966.00

Authors

Kumar, N.,Arthur, C.P.,Ciferri, C.,Matsumoto, M.L. (deposition date: 2020-09-04, release date: 2021-01-20, Last modification date: 2025-05-28)

Primary citation

Kumar, N.,Arthur, C.P.,Ciferri, C.,Matsumoto, M.L.
Structure of the human secretory immunoglobulin M core.
Structure, 29:564-571.e3, 2021

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.

PubMed: 33513362
DOI: 10.1016/j.str.2021.01.002

Experimental method

ELECTRON MICROSCOPY (3.3 Å)