Reaction catalyzed by protein geranylgeranyltransferase type I (2.5.1.59)

		+		Rap1A-cysteine	=		S-geranylgeranyl-Rap1A	+
	geranylgeranyl diphosphate	+		Rap1A-cysteine	=		S-geranylgeranyl-Rap1A	+		diphosphate