Monoamine oxidase

monoamine oxidase A
Ribbon diagram of a monomer of human MAO-A, with FAD and clorgiline bound, oriented as if attached to the outer membrane of a mitochondrion. From PDB: 2BXS​.
Identifiers
Symbol	MAOA
NCBI gene	4128
HGNC	6833
OMIM	309850
RefSeq	NM_000240
UniProt	P21397
Other data
Locus	Chr. X p11.4-p11.3
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monoamine oxidase B
Ribbon diagram of human MAO-B. From PDB: 1GOS​.
Identifiers
Symbol	MAOB
NCBI gene	4129
HGNC	6834
OMIM	309860
RefSeq	NM_000898
UniProt	P27338
Other data
Locus	Chr. X p11.4-p11.3
Search for Structures Swiss-model Domains InterPro

Monoamine oxidases (MAO) (EC 1.4.3.4) are a family of enzymes that catalyze the oxidation of monoamines, employing oxygen to clip off their amine group.^[1][2] They are found bound to the outer membrane of mitochondria in most cell types of the body. The first such enzyme was discovered in 1928 by Mary Bernheim in the liver and was named tyramine oxidase.^[3][4] The MAOs belong to the protein family of flavin-containing amine oxidoreductases.^[5]

MAOs are important in the breakdown of monoamines ingested in food, and also serve to inactivate monoamine neurotransmitters. Because of the latter, they are involved in a number of psychiatric and neurological diseases, some of which can be treated with monoamine oxidase inhibitors (MAOIs) which block the action of MAOs.^[6]