Catalytic subunit of a heterodimer with Trmt112/CG12975, which specifically methylates the 6th position of adenine in 18S rRNA. adenosine in rRNA + S-adenosyl-L-methionine = H(+) + N(6)-methyladenosine in rRNA + S-adenosyl-L-homocysteine Heterodimer; heterodimerizes with Trmt112/CG12975. Enriched in the brain. Expressed at high level in early embryo. Expression gradually decreases and remains low in the larval stages. A mild increase is observed at metamorphosis, and this level remains constant in the adult phase. Flies are viable and fertile and do not display obvious developmental defects (PubMed:32350990). They however show impaired orientation in walking behavioral assays (PubMed:32350990). Belongs to the methyltransferase superfamily. PrmA family.