Phospholipase C-γ1 association with CD3 structure in T cells

Recently, we and others have reported tyrosine phosphorylation of phospholipase C-γ1 (PLCγ,1)enzyme after CD3 activation of T cells, and have proposed that PLCγl mediates signal transduction through the T cell receptor (TCR/CD3). Here, using immunoblotting and immune complex PLC assays, we show that CD3 stimulation of Jurkat cells induces the association of PLCγ1 enzymewith CD3 complex. PLC activity is also found to co-precipitate with the CD3ζ chain from activated cells. In addition, in vitro PLC assays show that CD3 activation leads to about10-fold stimulation of PLCγ1 activity. Theseresults, along with the observation that Jurkat cells preferentially express PLCγ1, indicate that PLCγ1 participates in CD3 signaling.