InterPro: IPR001613 Flavin-containing amine oxidase

Monoamine oxidases (MAO) A and B are encoded by two genes derived from a common ancestral gene [1]. The enzymes catalyse the oxidative deamination of biogenic and xenobiotic amines and have important roles in the metabolism of neuroactive and vasoactive amines in the central nervous system and peripheral tissues [2]. MAO-A preferentially oxidises biogenic amines such as 5-hydroxytryptamine, norepinephrine and epinephrine. MAO-A deficiency has been linked to Brunner's syndrome, a form of X-linked nondysmorphic mild mental retardation [2].

The protein contains two similarly-sized subunits, one of which contains covalently-bound flavin adenine dinucleotide (FAD). The FAD binding site lies near the C terminus; at the N terminus are features characteristic of the ADP-binding fold, suggesting that this region is also involved in FAD binding [2]. The A and B forms of the enzyme share 70% sequence identity; both contain the pentapeptide Ser-Gly-Gly-Cys-Tyr, the cysteine of which binds FAD [3].