N-methyltransferase accepting primarily 1-benzylisoquinoline and aporphine substrates possessing a tertiary amine. The preferred substrates are (R)- and (S)-reticuline and (S)-corytuberine, but can also use (R,S)-tetrahydropapaverine, papaverine, (+)-bulbocapnine, (+)-glaucine, (+)-isocorydine, (+)-isothebaine, boldine, noscapine, narcotine hemiacetal and hydrastine as substrates. Involved in the biosynthesis of magnoflorine. (S)-reticuline + S-adenosyl-L-methionine = (S)-tembetarine + H(+) + S-adenosyl-L-homocysteine (R)-reticuline + S-adenosyl-L-methionine = (R)-tembetarine + H(+) + S-adenosyl-L-homocysteine (S)-corytuberine + S-adenosyl-L-methionine = magnoflorine + S-adenosyl-L-homocysteine (R)-tetrahydropapaverine + S-adenosyl-L-methionine = (R)-N-methyltetrahydropapaverine + H(+) + S-adenosyl-L-homocysteine (S)-glaucine + S-adenosyl-L-methionine = (S)-N-methylglaucine + H(+) + S-adenosyl-L-homocysteine (S)-bulbocapnine + S-adenosyl-L-methionine = (S)-N-methylbulbocapnine + H(+) + S-adenosyl-L-homocysteine kcat is 0.028 sec(-1) with (S)-reticuline as substrate. kcat is 0.053 sec(-1) with (R)-reticuline as substrate. kcat is 0.047 sec(-1) with S-adenosyl-L-methionine as substrate. Optimum pH is 8.5 with (R)-reticuline as substrate. Optimum pH is 7.0-9.0 with (S)-reticuline as substrate. Optimum temperature is 30 degrees Celsius. Expressed in roots and stems. Detected in leaves and flower buds. Belongs to the CFA/CMAS family.