Reaction catalyzed by protein geranylgeranyltransferase type I (2.5.1.59)

		+			=			+
	Ser-Ser-Cys-Ile-Leu-Leu	+		geranylgeranyl diphosphate	=		diphosphate	+		Ser-Ser-S-geranylgeranyl-Cys-Ile-Leu-Leu