The MAOB gene encodes a 520-amino acid protein with a molecular mass of 58.8 kD and shows 70% amino acid identity to MAOA. MAOA and MAOB are present in the outer mitochondrial membrane in the central nervous system and peripheral tissues.A comparison of highly purified human placental MAOA and human liver MAOB revealed that the A form of the enzyme is larger by 2 kDa and only one potential N-glycosylation site exists in each protein,with each site in a different relevant position.