Tyrosine phosphorylation of phospholipase Cγ1 couples the Fcε receptor mediated signal to mast cells secretion

摘要: Mast cells respond to clustering of the type I Fc epsilon receptor (Fc RI) on their membranes by mediator secretion. Recently, a marked enhancement tyrosine phosphorylation several proteins has been observed as result antigen-induced RI aggregation these cells. We report here that phosphatidyl inositide specific phospholipase C gamma 1 (PLC 1) is one prime undergoes this stimulus. This was determined immunoprecipitation phosphotyrosine containing from detergent lysates rat mucosal mast (rat basophilic leukemia cells, subline 2H3; RBL-2H3) and Western blotting analysis separated components. A fast appearance phosphorylated residues PLC observed, reaching its maximal intensity at approximately 1-3 min after stimulation declined afterwards basal levels. Moreover, depended maintaining aggregated did other cellular responses (e.g. inositides hydrolysis secretion). The time course both induced activation, monitored formation inositol phosphates, secretory response followed phosphorylation. Furthermore, tyrphostin AG490, protein kinase inhibitor, caused similar inhibition RI-induced phosphorylation, phosphates formation, Significantly, no Ca2+ ionophore, ionomycin, even doses cause optimal response.(ABSTRACT TRUNCATED AT 250 WORDS)