FcepsilonRI cross-linking activates a type II phosphatidylinositol 4-kinase in RBL 2H3 cells

Crosslinking of FcepsilonRI on rat basophilic leukemia (RBL 2H3) cells leads to an increase in Phosphatidylinositol 4-kinase activity. This increase in Ptdlns 4-kinase activity is strongly correlated with its tyrosyl phosphorylation state. Characterization of the enzyme activity in anti phosphotyrosine immunoprecipitates suggests it as a type II Ptdlns 4-kinase. Membrane cholesterol depletion studies showed a reduction in type II Ptdlns 4-kinase activity suggesting that lipid rafts play an important role in activation of the enzyme. The enzyme activity was inhibited by resveratrol. In situ inhibition of type II Ptdlns 4-kinase activity showed a reduction in beta-hexosaminidase release upon FcepsilonRI cross-linking. These studies suggest that a type II Ptdlns 4-kinase is an integral component of FcepsilonRI mediated signal transduction mechanisms.