EC - 2-polyprenyl-6-hydroxyphenol methylase

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IntEnz Enzyme Nomenclature


Accepted name:
2-polyprenyl-6-hydroxyphenol methylase
Other names:
ubiG (gene name) [ambiguous]
ubiG methyltransferase [ambiguous]
2-octaprenyl-6-hydroxyphenol methylase
Systematic name:
S-adenosyl-L-methionine:3-(all-trans-polyprenyl)benzene-1,2-diol 2-O-methyltransferase



UbiG catalyses both methylation steps in ubiquinone biosynthesis in Escherichia coli. The second methylation is classified as EC (3-demethylubiquinol 3-O-methyltransferase) [2]. In eukaryotes Coq3 catalyses the two methylation steps in ubiquinone biosynthesis. However, while the second methylation is common to both enzymes, the first methylation by Coq3 occurs at a different position within the pathway, and thus involves a different substrate and is classified as EC (polyprenyldihydroxybenzoate methyltransferase). The substrate of the eukaryotic enzyme (3,4-dihydroxy-5-all-trans-polyprenylbenzoate) differs by an additional carboxylate moiety.

Links to other databases

Enzymes and pathways: NC-IUBMB , BRENDA , DIAGRAM , ExplorEnz , ENZYME@ExPASy , KEGG , MetaCyc , UniPathway
Structural data: CSA , EC2PDB
UniProtKB/Swiss-Prot: (244) [show] [UniProt]


  1. Poon, W. W., Barkovich, R. J., Hsu, A. Y., Frankel, A., Lee, P. T., Shepherd, J. N., Myles, D. C., Clarke, C. F.
    Yeast and rat Coq3 and Escherichia coli UbiG polypeptides catalyze both O-methyltransferase steps in coenzyme Q biosynthesis.
    J. Biol. Chem. 274 : 21665-21672 (1999). [PMID: 10419476]
  2. Hsu, A. Y., Poon, W. W., Shepherd, J. A., Myles, D. C., Clarke, C. F.
    Complementation of coq3 mutant yeast by mitochondrial targeting of the Escherichia coli UbiG polypeptide: evidence that UbiG catalyzes both O-methylation steps in ubiquinone biosynthesis.
    Biochemistry 35 : 9797-9806 (1996). [PMID: 8703953]

[EC created 2011, modified 2013]