title: Fc epsilon RI-mediated tyrosine phosphorylation and activation of the 72-kDa protein-tyrosine kinase, PTK72, in RBL-2H3 rat tumor mast cells.
abstract: In RBL-2H3 rat tumor mast cells, cross-linking the high-affinity IgE receptor Fc epsilon RI causes tyrosine phosphorylation of multiple proteins. These phosphoproteins include phospholipase C gamma 1, the beta and gamma subunits of the Fc epsilon RI, the Src family protein-tyrosine kinase Lyn, and a 72-kDa protein that coimmunoprecipitates from lysates of antigen-stimulated cells with antibody to the receptor beta subunit. We now present evidence that the 72-kDa Fc epsilon RI-associated protein is the protein-tyrosine kinase PTK72 that forms part of the antigen receptor complex in B lymphocytes. The identification is based on immunoreactivity with anti-PTK72 antiserum, chromatographic profiles on the affinity resin heparin/agarose, and one-dimensional phosphopeptide mapping studies. Enzymatic activity of the kinase is increased in anti-PTK72 immune complexes prepared from lysates of antigen-activated RBL-2H3 cells. The 72-kDa protein-tyrosine kinase is the principal substrate for in vitro tyrosine phosphorylation in anti-phosphotyrosine immunoprecipitates of RBL-2H3 cells. The discovery that RBL-2H3 mast cells share a receptor-activated protein-tyrosine kinase, PTK72, with B lymphocytes provides additional support for the existence of common signaling pathways initiated by multichain immune recognition receptors.
authors.affiliation: Department of Biological Sciences, Purdue University, West Lafayette, IN 47907.
authors.forename: J E
authors.initials: JE
authors.lastname: Hutchcroft
authors.forename: R L
authors.initials: RL
authors.lastname: Geahlen
authors.forename: G G
authors.initials: GG
authors.lastname: Deanin
authors.forename: J M
authors.initials: JM
authors.lastname: Oliver
mesh_terms: D000818:Animals; D002846:Chromatography, Affinity; D004591:Electrophoresis, Polyacrylamide Gel; D004789:Enzyme Activation; D015471:Leukemia, Basophilic, Acute; D008407:Mast Cells; D008970:Molecular Weight; D010449:Peptide Mapping; D010750:Phosphoproteins / Q000302:isolation & purification / Q000378:metabolism*; D010766:Phosphorylation; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D051381:Rats; D017455:Receptors, IgE / Q000378:metabolism*; D014407:Tumor Cells, Cultured
chemical_list: D010750:Phosphoproteins; D017455:Receptors, IgE; D011505:Protein-Tyrosine Kinases