8WYR

Cryo-EM structure of human CD5L bound to IgM-Fc/J

Summary for 8WYR

• Entry DOI: 10.2210/pdb8wyr/pdb
• EMDB information: 37936
• Descriptor: Interleukin-2,Isoform 1 of Immunoglobulin heavy constant mu, Immunoglobulin J chain, Interleukin-2,CD5 antigen-like, ... (6 entities in total)
• Functional Keywords: immunoglobulin, cd5 antigen-like, pentamer, immune system
• Biological source: Homo sapiens (human); More
• Total number of polymer chains: 12
• Total formula weight: 502543.52

Authors

Wang, Y.X.,Su, C.,Xiao, J.Y. (deposition date: 2023-10-31, release date: 2024-10-09, Last modification date: 2024-11-06)

Primary citation

Wang, Y.,Su, C.,Ji, C.,Xiao, J.
CD5L associates with IgM via the J chain.
Nat Commun, 15:8397-8397, 2024

PubMed Abstract: CD5 antigen-like (CD5L), also known as Spα or AIM (Apoptosis inhibitor of macrophage), emerges as an integral component of serum immunoglobulin M (IgM). However, the molecular mechanism underlying the interaction between IgM and CD5L has remained elusive. In this study, we present a cryo-electron microscopy structure of the human IgM pentamer core in complex with CD5L. Our findings reveal that CD5L binds to the joining chain (J chain) in a Ca-dependent manner and further links to IgM via a disulfide bond. We further corroborate recently published data that CD5L reduces IgM binding to the mucosal transport receptor pIgR, but does not impact the binding of the IgM-specific receptor FcμR. Additionally, CD5L does not interfere with IgM-mediated complement activation. These results offer a more comprehensive understanding of IgM and shed light on the function of the J chain in the immune system.

PubMed: 39333069
DOI: 10.1038/s41467-024-52175-y

Experimental method

ELECTRON MICROSCOPY (3.39 Å)