Reaction catalyzed by 3,7-dimethylquercetin 4'-O-methyltransferase (2.1.1.83)

		+			=			+
	S-adenosyl-L-methionine	+		5,3',4'-trihydroxy-3,7-dimethoxyflavone	=		S-adenosyl-L-homocysteine	+		5,3'-dihydroxy-3,7,4'-trimethoxyflavone