PET112L is the human homolog of the S. cerevisiae COX assembly protein pet112, a protein that is believed to play an important role in the translation of mitochondrial genes. PET112L, also known as HSPC199 or Glu-ADT subunit B (glutamyl-tRNA(Gln) amidotransferase subunit B), is a 557 amino acid protein belonging to the gatB gatE family of proteins (GatB subfamily) and is believed to play a role in energy metabolism. Localizing to mitochondria, PET112L is expressed in tissues such as heart and muscle, which exhibit high rates of oxidative phosphorylation. The gene encoding PET112L is overexpressed in recurrent ependymoma.