title: Tyrosine phosphorylation is essential for microfilament assembly in B lymphocytes.
abstract: The B cell antigen receptor regulates the tyrosine kinase signal transduction pathway and it mediates a variety of morphological changes such as capping and membrane ruffling. The relationship between these two events is unclear. We show here that cross-linking the antigen receptor on human B lymphocytes, in addition to increasing tyrosine phosphorylation of specific substrates, induces the conversion of G-actin to F-actin. Preincubation of B lymphocytes with two different tyrphostins blocked anti-IgM-induced tyrosine phosphorylation and actin polymerization. The ability of the tyrphostins to block anti-IgM induced conversion of G-actin to F-actin indicates that a tyrosine kinase acts as an essential link between the B cell antigen receptor the early changes in cytoskeletal reorganization.
authors.affiliation: Department of Pediatrics, Hospital for Sick Children, Toronto, Ontario, Canada.
authors.forename: I
authors.initials: I
authors.lastname: Melamed
authors.forename: G P
authors.initials: GP
authors.lastname: Downey
authors.forename: C M
authors.initials: CM
authors.lastname: Roifman
mesh_terms: D008841:Actin Cytoskeleton / Q000502:physiology* / Q000648:ultrastructure; D000199:Actins / Q000032:analysis / Q000378:metabolism; D000888:Antibodies, Anti-Idiotypic / Q000276:immunology; D001402:B-Lymphocytes / Q000276:immunology / Q000502:physiology* / Q000648:ultrastructure; D006801:Humans; D007075:Immunoglobulin M / Q000276:immunology; D009570:Nitriles / Q000494:pharmacology; D009596:Nitrophenols / Q000494:pharmacology; D010636:Phenols / Q000494:pharmacology; D010766:Phosphorylation; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D011947:Receptors, Antigen, B-Cell / Q000502:physiology; D014443:Tyrosine; D020032:Tyrphostins
chemical_list: D000199:Actins; D000888:Antibodies, Anti-Idiotypic; D007075:Immunoglobulin M; D009570:Nitriles; D009596:Nitrophenols; D010636:Phenols; D011947:Receptors, Antigen, B-Cell; D020032:Tyrphostins; C069028:AG 127; C069027:AG 30; C069029:AG 183; D014443:Tyrosine; D011505:Protein-Tyrosine Kinases