trans-aconitate 3-methyltransferase activity

Catalysis of the reaction: S-adenosyl-L-methionine(1+) + trans-aconitate = (E)-2-(methoxycarbonylmethyl)but-2-enedioate + S-adenosyl-L-homocysteine.

Source:http://purl.uniprot.org/go/0046547