Reaction catalyzed by 1-phosphatidylinositol-4-phosphate 5-kinase (2.7.1.68)

	ATP	+			=		ADP	+
	ATP	+		1-phosphatidyl-1D-myo-inositol 4-phosphate	=		ADP	+		1-phosphatidyl-1D-myo-inositol 4,5-bisphosphate