. "\"Catalysis of the reaction: S-adenosyl-L-methionine + 3-demethylubiquinone-9 = S-adenosyl-L-homocysteine + ubiquinone-9.\" [EC:2.1.1.64]" . . "3-demethylubiquinone-9 3-O-methyltransferase activity" . "5-demethylubiquinone-9 methyltransferase activity" . "OMHMB-methyltransferase activity" . "S-adenosyl-L-methionine:2-nonaprenyl-3-methyl-5-hydroxy-6-methoxy-1,4-benzoquinone 3-O-methyltransferase activity" . "S-adenosyl-L-methionine:2-octaprenyl-3-methyl-5-hydroxy-6-methoxy-1,4-benzoquinone-O-methyltransferase activity" . "EC:2.1.1.64" . "MetaCyc:DHHB-METHYLTRANSFER-RXN" . "RHEA:17052" . . .