rRNA methyltransferase-related mitochondrial transcription factors B1 (TFB1M) and B2 (TFB2M) perform unique, yet cooperative functions. In addition to being mitochondrial transcription factors, they can dimethylate two adjacent adenines in a stem-loop structure close to the 3' end of the small subunit rRNA, a modification that is highly conserved in nature [, ]. The primary function of TFB2 is mtDNA transcription and maintenance, which is independent of its rRNA methyltransferase activity, while that of TFB1M is mitochondrial rRNA methylation []. TFB1M and TFB2M. This family represents TFB2M. Compared to TFB1M, TFB2M activates transcription of mitochondrial DNA more efficiently, while it has less methyltransferase activity [].
