Transcription Factor B2, Mitochondrial (TFB2M)

TFB2M shares 53% amino acid identity with its mouse homolog, but only 25% identity with TFB1M across a conserved region, suggesting a gene duplication event early in metozoan evolution. Northern blot analysis showed that TFB1M and TFB2M are expressed ubiquitously. Both TFB1M and TFB2M independently supported promoter-specific mtDNA transcription in a pure recombinant in vitro system containing mitochondrial RNA polymerase (POLRMT) and mitochondrial transcription factor A (TFAM); however, TFB2M was at least 1 order of magnitude more active in promoting transcription than TFB1M. Both factors are highly homologous to bacterial rRNA dimethyltransferases, which suggests that an RNA-modifying enzyme was recruited during evolution to function as a mitochondrial transcription factor.