title: SLP-76 is a substrate of the high affinity IgE receptor-stimulated protein tyrosine kinases in rat basophilic leukemia cells.
abstract: Stimulation of the IgE high affinity receptor on rat basophilic leukemia RBL-2H3 cells results in activation of protein tyrosine kinases and rapid tyrosine phosphorylation of several substrates, many of which remain unidentified. In this report, we demonstrate that the Grb2 adapter protein, when expressed as a glutathione S-transferase fusion protein, associates with four tyrosine-phosphorylated molecules (116, 76, 36, and 31 kDa) from lysates of stimulated RBL-2H3 cells. We show further that the 76-kDa protein is SLP-76, a hematopoietic cell-specific protein first identified as a Grb2-binding protein in T cells. Upon stimulation of the high affinity receptor for IgE, SLP-76 undergoes rapid tyrosine phosphorylation and associates with two additional tyrosine phosphoproteins of 62 and 130 kDa via the SH2 domain of SLP-76. Additional studies demonstrate that the SLP-76 SH2 domain also binds a protein kinase from stimulated RBL-2H3 cell lysates. Furthermore, the phosphorylation of SLP-76 requires Syk activity but is not dependent on Ca+2 mobilization. These data, together with our previous work documenting its role in T-cell activation, suggest that SLP-76 and the proteins with which it associates may play a fundamental role in coupling signaling events in multiple cell types in the immune system.
authors.affiliation: Department of Internal Medicine, University of Iowa College of Medicine, Iowa City 52246, USA.
authors.forename: L R
authors.initials: LR
authors.lastname: Hendricks-Taylor
authors.forename: D G
authors.initials: DG
authors.lastname: Motto
authors.forename: J
authors.initials: J
authors.lastname: Zhang
authors.forename: R P
authors.initials: RP
authors.lastname: Siraganian
authors.forename: G A
authors.initials: GA
authors.lastname: Koretzky
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D002478:Cells, Cultured; D004591:Electrophoresis, Polyacrylamide Gel; D004792:Enzyme Precursors / Q000378:metabolism; D051380:GRB2 Adaptor Protein; D047908:Intracellular Signaling Peptides and Proteins; D015471:Leukemia, Basophilic, Acute / Q000378:metabolism*; D010750:Phosphoproteins / Q000378:metabolism*; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D011506:Proteins / Q000378:metabolism; D051381:Rats; D017455:Receptors, IgE / Q000378:metabolism*; D000072377:Syk Kinase; D018909:src Homology Domains
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D004792:Enzyme Precursors; D051380:GRB2 Adaptor Protein; C495950:Grb2 protein, rat; D047908:Intracellular Signaling Peptides and Proteins; D010750:Phosphoproteins; D011506:Proteins; D017455:Receptors, IgE; C092947:SLP-76 signal Transducing adaptor proteins; D011505:Protein-Tyrosine Kinases; D000072377:Syk Kinase; C000606898:Syk protein, rat