Bone marrow-derived mouse mast cells contain phospholipase C-γ1 (PLC-γ1), which is phosphorylated at tyrosine residues upon cross-linking of cell-bound IgE antibodies with multivalent antigen. It was found that immune complexes formed from digitonin lysates of the mast cells by monoclonal anti-PLC-γ1 antibodies contained protein-tyrosine kinase (PTK), which phosphorylated PLC-γ1 in vitro. The tyrosine kinase activity coprecipitated with PLC-γ1-anti-PLC-γ1 complexes markedly increased when the cell lysates were obtained immediately after antigen challenge. The results indicate that PTK is associated with PLC-γ1 in the mast cells and that the kinase is activated upon cross-linking of FcεRI. Neither β nor γ subunit of FcεRI nor src family PTK was coprecipitated with the PLC-γ1-anti-PLC-γ1 complexes. In situ denaturation/renaturation experiments, which detect autophosphorylated kinases, indicated that the PTK associated with PLC-γ1 was a 44-kDa protein.
|Original language||English (US)|
|Number of pages||5|
|Journal||Proceedings of the National Academy of Sciences of the United States of America|
|State||Published - Oct 15 1992|
- Signal transduction
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