Function
Methyltransferase involved in phenylpropanoid polyamine conjugate biosynthesis. In vivo, methylates only one of the 5-hydroxyferuloyl moieties of N1,N5,N10-tri-(hydroxyferuloyl)-spermidine, while is able in vitro to convert all three 5-hydroxyferuloyl residues to the corresponding sinapoyl moieties and to methylate caffeoyl CoA and tricaffeoyl spermidine.