Regulation of extranuclear PtdIns5P production by phosphatidylinositol phosphate 4-kinase 2alpha.

Cellular levels of the phosphoinositide PtdIns5P are regulated by agonist stimulation, but the mechanisms controlling turnover of this lipid, and the subcellular location of the regulated PtdIns5P pool(s), remain poorly understood. Here we show that enhanced tyrosine phosphorylation robustly increases cellular PtdIns5P levels. Moreover, unlike PtdIns5P production enhanced by cell stress, we show that this pool of PtdIns5P is specifically regulated by the inositol lipid kinase PIP4K2a.