Involved, together with the calcineurin ppb1, in cytokinesis. a 1,2-diacyl-sn-glycero-3-phospho-(1D-myo-inositol 4-phosphate) + ATP = a 1,2-diacyl-sn-glycero-3-phospho-(1D-myo-inositol-4,5-bisphosphate) + ADP + H(+) The active form of the enzyme is membrane-associated and concentrates at the septum in dividing cells. Phosphorylated by casein kinase I. Phosphorylation inactivates the enzyme.