SAM-dependent MTase. The enzyme is neither essential for ribosome assembly nor for function. The substrate preference in vitro is deproteinized 23S rRNA. Modified residue m6A2030 is located in helix 72, close the peptidyltransferase center of Domain IV and the elongation factor binding site of Domain II in the folded 3D architecture of the ribosome. Orthologs are found mostly in proteobacteria. A possible role is stabilization of local tertiary structure of the ribosome. M6A exist also at position 1618 where it is introduced by a related MTase RlmF(UbiN) and of course at the conserved m6,2A1518, 1519 of 16S rRNA (introduced by RsmA/KsgA).