Reaction catalyzed by hypoxanthine phosphoribosyltransferase (2.4.2.8)

		+			=			+
	3-hydroxy-2-pyrazinecarboxamide	+		5-phospho-alpha-D-ribose 1-diphosphate	=		3-oxo-4-(5-O-phosphono-beta-D-ribofuranosyl)-3,4-dihydropyrazine-2-carboxamide	+		diphosphate