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 phosphorylat ion and activation of a type II PtdIns 4-kinase in rat splenic lymphocytes. However, the regulatory protein tyrosine kinase(s) remain to be elusive. T he present manuscript provides evidence that a type II PtdIns 4-kinase asso ciates with p56(lck) in Con A stimulated rat splenic lymphocytes. In vitro phosphorylation studies suggest that p561(lck) regulates phosphorylation an d activation of type II PtdIns 4-kinase. Inhibition of p561(lck) activity i n 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 physiolo gical regulator of type II PtdIns 4-kinase. (C) 2000 Elsevier Science Ltd. All rights reserved.