Transcription factor capable of interacting with purine rich repeats (GA repeats). Acts as a a master regulator of nuclear-encoded mitochondrial genes. Heterotetramer of two alpha and two beta subunits. Interacts with HCFC1, causing repression of transcriptional activity. Acetylated by EP300/p300. Deacetylated by SIRT7, promoting heterotetramerization and activity.