Glycine amidinotransferase mitochondrial（GATM) is a mitochondrial enzyme which is a member of the amidinotransferase family. The GATM enzyme is involved in creatine biosynthesis， where it catalyzes the transfer of a guanido group from L-arginine to glycine， resulting in guanidinoacetic acid， the immediate precursor of creatine， which has an imperative role in energy metabolism in muscle tissues. GATM is significant in embryonic and central nervous system development. GATM gene mutations cause arginine:glycine amidinotransferase deficiency， an inborn error of creatine synthesis characterized by mental retardation， language impairment， and behavioral disorders.
