Fc epsilon R1-mediated tyrosine phosphorylation of multiple proteins, including phospholipase C gamma 1 and the receptor beta gamma 2 complex, in RBL-2H3 rat basophilic leukemia cells.
In basophils, mast cells, and the RBL-2H3 tumor mast cell line, cross-linking the high-affinity immunoglobulin E receptor (Fc epsilon R1) stimulates a series of responses, particularly the activation of phospholipase C (PLC), that lead to allergic and other immediate hypersensitivity reactions. The mechanism of activation of PLC, however, is not clear. Here, we show that cross-linking Fc epsilon R1 on RBL-2H3 cells causes the tyrosine phosphorylation of at least 12 cellular proteins, including PLC gamma 1 (PLC gamma 1) and the receptor beta and gamma subunits. 32P-labeled PLC gamma 1 can be detected by anti-phosphotyrosine antibody as early as 10 s after the addition of antigen. The tyrosine-phosphorylated 33-kDa beta subunit and 9- to 11-kDa gamma subunit of the Fc epsilon R1 are additionally phosphorylated on serine and theonine residues, respectively, and are found as complexes with other phosphotyrosine-containing proteins in antigen-stimulated cells. Our results indicate a means by which the Fc epsilon R1 may control PLC activity in RBL-2H3 cells and raise the possibility that other receptor-mediated signalling events in mast cells may also be controlled through protein tyrosine phosphorylation.
Li
W
W
Department of Pharmacology, New York University Medical Center, NY 10016.
Deanin
G G
GG
Margolis
B
B
Schlessinger
J
J
Oliver
J M
JM
D000818:Animals; D000944:Antigens, Differentiation, B-Lymphocyte / Q000378:metabolism*; D003432:Cross-Linking Reagents; D004789:Enzyme Activation; D015471:Leukemia, Basophilic, Acute / Q000378:metabolism; D008407:Mast Cells / Q000378:metabolism*; D010750:Phosphoproteins / Q000378:metabolism*; D010766:Phosphorylation; D051381:Rats; D011961:Receptors, Fc / Q000378:metabolism*; D017455:Receptors, IgE; D015398:Signal Transduction; D014407:Tumor Cells, Cultured; D010738:Type C Phospholipases / Q000378:metabolism*; D014443:Tyrosine / Q000378:metabolism*
D000944:Antigens, Differentiation, B-Lymphocyte; D003432:Cross-Linking Reagents; D010750:Phosphoproteins; D011961:Receptors, Fc; D017455:Receptors, IgE; D014443:Tyrosine; D010738:Type C Phospholipases