8BPG

FcMR binding at subunit Fcu3 of IgM pentamer

Summary for 8BPG

• Entry DOI: 10.2210/pdb8bpg/pdb
• EMDB information: 16152
• Descriptor: Fas apoptotic inhibitory molecule 3, Immunoglobulin heavy constant mu, 2-acetamido-2-deoxy-beta-D-glucopyranose-(1-4)-2-acetamido-2-deoxy-beta-D-glucopyranose, ... (4 entities in total)
• Functional Keywords: igm fc receptor, immune system
• Biological source: Homo sapiens (human); More
• Total number of polymer chains: 6
• Total formula weight: 206704.80

Authors

Chen, Q.,Rosenthal, P.,Tolar, P. (deposition date: 2022-11-16, release date: 2023-04-12, Last modification date: 2024-10-16)

Primary citation

Chen, Q.,Menon, R.P.,Masino, L.,Tolar, P.,Rosenthal, P.B.
Structural basis for Fc receptor recognition of immunoglobulin M.
Nat.Struct.Mol.Biol., 30:1033-1039, 2023

PubMed Abstract: Immunoglobulin Fc receptors are cell surface transmembrane proteins that bind to the Fc constant region of antibodies and play critical roles in regulating immune responses by activation of immune cells, clearance of immune complexes and regulation of antibody production. FcμR is the immunoglobulin M (IgM) antibody isotype-specific Fc receptor involved in the survival and activation of B cells. Here we reveal eight binding sites for the human FcμR immunoglobulin domain on the IgM pentamer by cryogenic electron microscopy. One of the sites overlaps with the binding site for the polymeric immunoglobulin receptor (pIgR), but a different mode of FcμR binding explains its antibody isotype specificity. Variation in FcμR binding sites and their occupancy reflects the asymmetry of the IgM pentameric core and the versatility of FcμR binding. The complex explains engagement with polymeric serum IgM and the monomeric IgM B-cell receptor (BCR).

PubMed: 37095205
DOI: 10.1038/s41594-023-00985-x

Experimental method

ELECTRON MICROSCOPY (3.1 Å)