TY - JOUR
T1 - Identification of an additional class of C3-binding membrane proteins of human peripheral blood leukocytes and cell lines
AU - Cole, J. L.
AU - Housley, G. A.
AU - Dykman, T. R.
AU - MacDermott, R. P.
AU - Atkinson, J. P.
PY - 1985
Y1 - 1985
N2 - Proteins binding the third component of complement (C3) were isolated by affinity chromatography from surface-labeled solubilized membranes of human peripheral blood cells and cell lines. The isolated molecules were subjected to NaDodSO4/PAGE, and autoradiographs of these gels indicated that C3-binding proteins could be divided into three groups based on M(r): (i) gp200, an ~ 200,000 M(r) molecule previously identified as the C3b/C4b receptor or CR1; (ii) gp140, an ~ 140,000 M(r) molecule previously identified as the C3d receptor or CR2; and (iii) gp45-70, a heretofore unrecognized group of 45,000-70,000 M(r) C3-binding molecules. The cell distribution, M(r), antigenic cross-reactivity, and specificity of gp45-70 were examined. Erythrocytes have no detectable gp45-70, but all leukocyte populations examined possess this group of molecules. On neutrophils and mononuclear phagocytes, CR1 is the predominant C3-binding glycoprotein, but gp45-70 is present on both cell populations and on macrophage and neutrophil cell lines. B plus null cells, chronic lymphocytic leukemia cells, and Epstein-Barr virus-transformed B-cell line possess CR1, CR2, and gp45-70. On T cells and T-cell lines gp45-70 is the predominant or, in some cases, the only C3-binding protein isolated, gp45-70 is structurally characterized as a broad band or doublet with a mean M(r) that is slightly different for each cell population, gp45-70 binds iC3, C3b, and C4b, but not C3d, indicating that the binding region is probably within the C3c portion of C3b. A polyclonal antibody to CR1 and monoclonal antibodies to CR1 and Cr2 do not immunoprecipitate gp45-70. While gp45-70 has not been previously characterized on human cells, a C3b-binding glycoprotein of similar M(r) is present on rabbit alveolar macrophages. We conclude that gp45-70 is an additional group of membrane proteins present on human leukocytes that possess ligand-binding activity for C3b.
AB - Proteins binding the third component of complement (C3) were isolated by affinity chromatography from surface-labeled solubilized membranes of human peripheral blood cells and cell lines. The isolated molecules were subjected to NaDodSO4/PAGE, and autoradiographs of these gels indicated that C3-binding proteins could be divided into three groups based on M(r): (i) gp200, an ~ 200,000 M(r) molecule previously identified as the C3b/C4b receptor or CR1; (ii) gp140, an ~ 140,000 M(r) molecule previously identified as the C3d receptor or CR2; and (iii) gp45-70, a heretofore unrecognized group of 45,000-70,000 M(r) C3-binding molecules. The cell distribution, M(r), antigenic cross-reactivity, and specificity of gp45-70 were examined. Erythrocytes have no detectable gp45-70, but all leukocyte populations examined possess this group of molecules. On neutrophils and mononuclear phagocytes, CR1 is the predominant C3-binding glycoprotein, but gp45-70 is present on both cell populations and on macrophage and neutrophil cell lines. B plus null cells, chronic lymphocytic leukemia cells, and Epstein-Barr virus-transformed B-cell line possess CR1, CR2, and gp45-70. On T cells and T-cell lines gp45-70 is the predominant or, in some cases, the only C3-binding protein isolated, gp45-70 is structurally characterized as a broad band or doublet with a mean M(r) that is slightly different for each cell population, gp45-70 binds iC3, C3b, and C4b, but not C3d, indicating that the binding region is probably within the C3c portion of C3b. A polyclonal antibody to CR1 and monoclonal antibodies to CR1 and Cr2 do not immunoprecipitate gp45-70. While gp45-70 has not been previously characterized on human cells, a C3b-binding glycoprotein of similar M(r) is present on rabbit alveolar macrophages. We conclude that gp45-70 is an additional group of membrane proteins present on human leukocytes that possess ligand-binding activity for C3b.
UR - http://www.scopus.com/inward/record.url?scp=0013622288&partnerID=8YFLogxK
U2 - 10.1073/pnas.82.3.859
DO - 10.1073/pnas.82.3.859
M3 - Article
C2 - 3871945
AN - SCOPUS:0013622288
VL - 82
SP - 859
EP - 863
JO - Proceedings of the National Academy of Sciences of the United States of America
JF - Proceedings of the National Academy of Sciences of the United States of America
SN - 0027-8424
IS - 3
ER -