DIMT1 (DIMT1L) dimethylates the N(6) position of adenosine-1850 and adenosine-1851 of a precursor to 18S rRNA in the nucleolus (Zorbas et al. 2015). Dimethylation is observed on the 21S precursor and therefore occurs at this stage of rRNA processing or prior. Dimethylation of adenosine residues appears to occur after N(7)-methylation of guanosine-1639 by WBSCR22:TRMT112 (Zorbas et al. 2015). PNO1 is required for the methylation activity of DIMT1 (Zorbas et al. 2015). DIMT1 protein but not DIMT1 methylase activity is also required for efficient concomitant cleavage of 47S precursor rRNA at site A0 and site 1 (Zorbas et al. 2015).