biostudies-literatureHoeger SNIAID NIH HHS326-338https://www.ebi.ac.uk/biostudies/studies/S-EPMC11066716biostudies-literatureUnknown8(4)The BCR allows for Ag-driven B cell activation and subsequent Ag endocytosis, processing, and presentation to recruit T cell help. Core drivers of BCR signaling and endocytosis are motifs within the receptor's cytoplasmic tail (primarily CD79). However, BCR function can be tuned by other proximal cellular elements, such as CD20 and membrane lipid microdomains. To identify additional proteins that could modulate BCR function, we used a proximity-based biotinylation technique paired with mass spectrometry to identify molecular neighbors of the murine IgM BCR. Those neighbors include MHC class II molecules, integrins, various transporters, and membrane microdomain proteins. Class II molecules, some of which are invariant chain-associated nascent class II, are a readily detected BCR neighbor. ImmunoHorizonsProximity-Based Labeling Identifies MHC Class II and CD37 as B Cell Receptor-Proximal Proteins with Immunological Functions.PMC11066716R21 AI148730Hoeger SDrake JRDrake LAfalseProximity-Based Labeling Identifies MHC Class II and CD37 as B Cell Receptor-Proximal Proteins with Immunological Functions.The BCR allows for Ag-driven B cell activation and subsequent Ag endocytosis, processing, and presentation to recruit T cell help. Core drivers of BCR signaling and endocytosis are motifs within the receptor's cytoplasmic tail (primarily CD79). However, BCR function can be tuned by other proximal cellular elements, such as CD20 and membrane lipid microdomains. To identify additional proteins that could modulate BCR function, we used a proximity-based biotinylation technique paired with mass spectrometry to identify molecular neighbors of the murine IgM BCR. Those neighbors include MHC class II molecules, integrins, various transporters, and membrane microdomain proteins. Class II molecules, some of which are invariant chain-associated nascent class II, are a readily detected BCR neighbor. 2024-01-01T00:00:00Z2024 Apr2026-06-01T21:52:02.559Z2026-05-21T03:09:15.109ZS-EPMC110667163862512010.4049/immunohorizons.2400014