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Publication Abstract from PubMed

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. FcmuR 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 FcmuR 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 FcmuR binding explains its antibody isotype specificity. Variation in FcmuR binding sites and their occupancy reflects the asymmetry of the IgM pentameric core and the versatility of FcmuR binding. The complex explains engagement with polymeric serum IgM and the monomeric IgM B-cell receptor (BCR).

Structural basis for Fc receptor recognition of immunoglobulin M.,Chen Q, Menon RP, Masino L, Tolar P, Rosenthal PB Nat Struct Mol Biol. 2023 Jul;30(7):1033-1039. doi: 10.1038/s41594-023-00985-x. , Epub 2023 Apr 24. PMID:37095205^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.