Catalysis of the reaction: 2-octaprenyl-6-methoxy-1,4-benzoquinone + S-adenosyl-L-methionine = 2-octaprenyl-3-methyl-6-methoxy-1,4-benzoquinone + S-adenosyl-L-homocysteine.
Source:PMID:9045837,
GOC:kd
Comment
Note that the polyprenyl sidechain substrate for these methyltransferases varies in length between species, for example, 6 units in S. cerevisiae, 8 units in E. coli and 10 units in G. suboxidans. Where the length of the substrate polyprenyl chain is unknown, the term '2-polyprenyl-6-methoxy-1,4-benzoquinone methyltransferase activity ; GO:0008425' should be used.