title: Anti-immunoglobulin and phorbol ester induce phosphorylation of proteins associated with the plasma membrane and cytoskeleton in murine B lymphocytes.
abstract: Protein phosphorylations are rapidly induced in intact B cells by antibodies to surface immunoglobulin (anti-IgM) and by phorbol 12-myristate 13-acetate (PMA). A comparison of the molecular weight, isoelectric points, phosphopeptides, and phosphoamino acids of the phosphoproteins induced by anti-IgM and by PMA suggests that anti-IgM acts through the activation of protein kinase C. This conclusion is strengthened by the observation that prolonged treatment with PMA ablates the ability of anti-IgM to induce phosphorylation, presumably by depleting cellular protein kinase C. Furthermore, the effects of dibutyryl cyclic AMP on protein phosphorylation are quite distinct from the effects of anti-IgM. The six most prominent phosphoproteins induced by PMA, with approximate Mr values of 47, 55, 62, 68, 68, and 65-70 X 10(3), are associated with the plasma membrane. Of these, four are apparently associated with the cytoskeleton, suggesting that the phosphorylation of cytoskeletal proteins may be important events early in B cell activation. Examination of protein phosphorylation in cell lines derived from different tissues has identified one major B cell phosphoprotein (Mr 65-70 X 10(3), which is absent in T cells, and two phosphoproteins (Mr 55 and 68 X 10(3), which are observed in cells of hematopoietic origin but which are absent or uncommon in other cell types.
mesh_terms: D000818:Animals; D000906:Antibodies; D001402:B-Lymphocytes / Q000378:metabolism*; D003994:Bucladesine / Q000494:pharmacology; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D003598:Cytoskeletal Proteins / Q000378:metabolism*; D003599:Cytoskeleton / Q000187:drug effects / Q000378:metabolism*; D008565:Membrane Proteins / Q000378:metabolism*; D051379:Mice; D010750:Phosphoproteins / Q000096:biosynthesis*; D010766:Phosphorylation; D011947:Receptors, Antigen, B-Cell / Q000276:immunology*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*
chemical_list: D000906:Antibodies; D003598:Cytoskeletal Proteins; D008565:Membrane Proteins; D010750:Phosphoproteins; D011947:Receptors, Antigen, B-Cell; D003994:Bucladesine; D013755:Tetradecanoylphorbol Acetate