Reaction catalyzed by tRNA-guanosine34 queuine transglycosylase (2.4.2.64)

	[tRNATyr]queuine	+			=		[tRNATyr]-guanine	+
	[tRNATyr]queuine	+		guanine	=		[tRNATyr]-guanine	+		queuine