This gene encodes a mitochondrial transcription factor that is a key activator of mitochondrial transcription as well as a participant in mitochondrial genome replication. Studies in mice have demonstrated that this gene product is required to regulate the mitochondrial genome copy number and is essential for embryonic development. A mouse model for Kearns-Sayre syndrome was produced when expression of this gene was eliminated by targeted disruption in heart and muscle cells.Synonyms: Mitochondrial transcription factor 1, MtTF1, TCF-6, TCF6L2, Transcription factor 6, Transcription factor 6-like 2, mitochondrial Transcription factor A