6KXS

Cryo-EM structure of human IgM-Fc in complex with the J chain and the ectodomain of pIgR

Summary for 6KXS

• Entry DOI: 10.2210/pdb6kxs/pdb
• EMDB information: 0782
• Descriptor: Immunoglobulin heavy constant mu, Immunoglobulin J chain, Polymeric immunoglobulin receptor, ... (5 entities in total)
• Functional Keywords: immunoglobulin, pentamer, transcytosis, secreted, immune system
• Biological source: Homo sapiens (Human); More
• Total number of polymer chains: 12
• Total formula weight: 498249.35

Authors

Li, Y.,Wang, G.,Xiao, J. (deposition date: 2019-09-12, release date: 2020-02-05, Last modification date: 2025-07-02)

Primary citation

Li, Y.,Wang, G.,Li, N.,Wang, Y.,Zhu, Q.,Chu, H.,Wu, W.,Tan, Y.,Yu, F.,Su, X.D.,Gao, N.,Xiao, J.
Structural insights into immunoglobulin M.
Science, 367:1014-1017, 2020

PubMed Abstract: Immunoglobulin M (IgM) plays a pivotal role in both humoral and mucosal immunity. Its assembly and transport depend on the joining chain (J-chain) and the polymeric immunoglobulin receptor (pIgR), but the underlying molecular mechanisms of these processes are unclear. We report a cryo-electron microscopy structure of the Fc region of human IgM in complex with the J-chain and pIgR ectodomain. The IgM-Fc pentamer is formed asymmetrically, resembling a hexagon with a missing triangle. The tailpieces of IgM-Fc pack into an amyloid-like structure to stabilize the pentamer. The J-chain caps the tailpiece assembly and bridges the interaction between IgM-Fc and the polymeric immunoglobulin receptor, which undergoes a large conformational change to engage the IgM-J complex. These results provide a structural basis for the function of IgM.

PubMed: 32029689
DOI: 10.1126/science.aaz5425

Experimental method

ELECTRON MICROSCOPY (3.4 Å)