Biochemical nature of an Fcμ receptor on human B-lineage cells

• Published in: The Journal of experimental medicine Vol. 172; no. 4; pp. 1165 - 1175
• Main Authors: OHNO, T, KUBAGAWA, H, SANDERS, S. K, COOPER, M. D
• Format: Journal Article
• Language: English
• Published: New York, NY Rockefeller University Press 01.10.1990; The Rockefeller University Press
• Subjects: B-Lymphocytes - immunology; Binding Sites; Biological and medical sciences; Fundamental and applied biological sciences. Psychology; Fundamental immunology; Humans; Immunobiology; Immunoglobulin M - metabolism; lymphocytes B; Lymphoid cells: ontogeny, maturation, markers, receptors, circulation and recirculation; Molecular Weight; Phosphatidylinositols - analysis; Receptors, Fc - analysis; Receptors, Fc - isolation & purification; Receptors, Fc - metabolism; Tetradecanoylphorbol Acetate - pharmacology; Characterization; Human; B»-Lymphocyte; Flow cytometry; Immunoglobulins; Membrane receptor; Biochemical analysis; Fc-Fragment; Activation; IgM
• ISSN: 0022-1007; 1540-9538
• DOI: 10.1084/jem.172.4.1165

An IgM-binding protein of approximately 60 kD has been identified on activated B cells, but not on resting and activated T cells, monocytes, or granulocytes. Here, we characterize this IgM-binding protein as a receptor for the Fc portion (CH3 and/or CH4 domains) of IgM molecules (Fc microR). The Fc microR can be expressed as a cell surface activation antigen throughout the pre-B and B cell stages in differentiation. Receptor expression is not directly linked with IgM production, as both mu- pre-B cells and isotype-switched B cells may express the Fc microR. The receptor molecules produced by both pre-B and B cells are identical in size and are characterized as an acidic sialoglycoprotein with O-linked, but no N-linked, oligosaccharide. The Fc microR is anchored to the surface of B-lineage cells via a glycosyl phosphatidylinositol linkage. The Fc microR is thus the third member of a family of Fc receptors expressed on B-lineage cells, and its preferential expression on activated B cells suggests a potential role in the response to antigens.