Reaction catalyzed by geranylgeranylglycerol-phosphate geranylgeranyltransferase (2.5.1.42)

		+			=			+
	geranylgeranyl diphosphate	+		(S)-3-O-(geranylgeranyl)glycerol 1-phosphate	=		diphosphate	+		2,3-bis-O-(geranylgeranyl)glycerol 1-phosphate