Fig. 1 in A single residue determines substrate preference in benzylisoquinoline alkaloid N-methyltransferases

Fig. 1. Involvement of N-methyltransferases in BIA biosynthesis. Coclaurine N-methyltransferase (CNMT) acts in the core BIA pathway and converts an unmethylated secondary amine to a mono-methylated tertiary amine. Reticuline N-methyltransferase (RNMT) and Pavine N-methyltransferase (PavNMT) act in several branch pathways and primarily convert mono-methylated tertiary amines into a di-methylated quaternary amines. Tetrahydroprotoberberine N-methyltransferase (TNMT) acts in other branch pathways and converts a bicyclic unmethylated tertiary amine into a quaternary amine. † denotes activities that have been demonstrated in vitro but not conclusively associated with the enzyme via in planta experimental evidence (e.g. gene silencing).