Concanavalin A modulates tyrosine phosphorylation and activation of a type II phosphatidylinositol 4-kinase in rat splenic lymphocytes

Abstract

Activation of rat splenic lymphocytes by concanavalin A resulted in two-fold increase in PtdIns 4-kinase activity and rapid tyrosine phosphorylation of the enzyme. The activation kinetics showed a strong correlation with tyrosine phosphorylation state of the enzyme. Characterization of the enzyme activity suggests that it is a type II PtdIns 4-kinase. Kinetic analysis of the enzyme reaction showed three-fold decrease in K-m for PtdIns and two-fold increase in V-max in Con A stimulated cells. These results suggest that a type II PtdIns 4-kinase is an integral component of the early signal transduction machinery during T-cell activation by concanavalin A and is actively regulated by protein tyrosine phosphorylation-dephosphorylation. (C) 1998 . .