Tyrosyl phosphorylation and activation of a type II phosphatidylinositol 4-kinase by p56(lck) in concanavalin A stimulated rat splenic lymphocytes.

Recent evidence suggests that concanavalin A modulates tyrosyl phosphorylation and activation of a type II PtdIns 4-kinase in rat splenic lymphocytes. However, the regulatory protein tyrosine kinase(s) remain to be elusive. The present manuscript provides evidence that a type II PtdIns 4-kinase associates with p56(lck) in Con A stimulated rat splenic lymphocytes. In vitro phosphorylation studies suggest that p56(lck) regulates phosphorylation and activation of type II PtdIns 4-kinase. Inhibition of p56(lck) activity in vivo has shown to reduce tyrosyl phosphorylation and activation of PtdIns 4-kinase by Con A. These results suggest that p56(lck) may be the physiological regulator of type II PtdIns 4-kinase.