Acts on phosphatidylinositol (PtdIns) in the first committed step in the production of the second messenger inositol-1,4,5,-trisphosphate (Probable). Can bind to phosphatidylinositol 4-monophosphate (PI-4-P or PtdIns4P), phosphatidylinositol 4,5-bisphosphate (PI-4,5-P2 or PtdIns4,5P2), and phosphatidic acid (PtdOH), but not to 3-phosphoinositides (PubMed:9712908). May function upstream of the cold response phosphoinositide-dependent phospholipase C (PI-PLC) pathway (PubMed:22318862). a 1,2-diacyl-sn-glycero-3-phospho-(1D-myo-inositol) + ATP = a 1,2-diacyl-sn-glycero-3-phospho-(1D-myo-inositol 4-phosphate) + ADP + H(+) Repressed by PtdIns4P, adenosine and wortmannin, but stimulated by other negatively charged lipids such as PtdIns3P, PtdOH, and phosphatidyl-serine (PtdSer). Interacts in vitro with actin filaments via its PH domain. Present in leaves and inflorescences. Lethal. Belongs to the PI3/PI4-kinase family. Type III PI4K subfamily.