Involved in the biosynthesis of benzylisoquinoline alkaloids. Catalyzes specifically the methylation of norreticuline at position seven to produce norlaudanine. No activity with norcoclaurine, reticuline, norlaudanosoline, norisoorientaline, scoulerine, salutaridinol, oripavine, salsolinol, codeine or morphine. Involved in papaverine biosynthesis