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

	ATP	+		phosphatidylinsositol 3,4-bisphosphate	=		ADP	+
	ATP	+		phosphatidylinsositol 3,4-bisphosphate	=		ADP	+		phosphatidylinositol 3,4,5-trisphosphate