In enzymology, a 1-phosphatidylinositol-5-phosphate 4-kinase is an enzyme that catalyzes the chemical reaction ATP + 1-phosphatidyl-1D-myo-inositol 5-phosphate ⇌ {\displaystyle \rightleftharpoons } ADP + 1-phosphatidyl-1D-myo-inositol 4,5-bisphosphateThus, the two substrates of this enzyme are ATP and 1-phosphatidyl-1D-myo-inositol 5-phosphate, whereas its two products are ADP and 1-phosphatidyl-1D-myo-inositol 4,5-bisphosphate. Wikipedia