Members of the mTERF family, including MTERF, MTERFD1, MTERFD2 and MTERFD3, are mitochondrial proteins that are believed to be transcription termination factors. MTERF (mitochondrial transcription termination factor 1) is composed of 399 amino acids and contains three leucine zippers that form a three-stranded coiled-coil that binds to DNA. It has been suggested that only the phosphorylated form of MTERF has transcription termination activity. MTERFD1 is also thought to act as a mitochondrial transcription regulator and is expressed as two isoforms produced by alternative splicing. MTERFD3 is believed to be involved in cell cycle regulation and cell growth by modulating mitochondrial transcription. MTERFD3 is expressed in heart, skeletal muscle, pancreas and liver.
