The protein encoded by this gene belongs to the flavin monoamine oxidase family. It is an enzyme located in the outer mitochondrial membrane. It catalyzes the oxidative deamination of biogenic and xenobiotic amines and plays an important role in the catabolism of neuroactive and vasoactive amines in the central nervous system and peripheral tissues. This protein preferentially degrades benzylamine and phenethylamine.[5] Similar to monoamine oxidase A (MAO-A), MAO-B is also involved in the catabolism of dopamine.[6]
Differences between MAOA and MAOB[edit]
MAO-A generally metabolizes tyramine, norepinephrine, serotonin, and dopamine (and other less clinically relevant chemicals). In contrast, MAO-B metabolizes dopamine and phenethylamine, as well as other less clinically relevant chemicals.[9] The differences between the substrate selectivity of the two enzymes are utilized clinically when treating specific disorders; MAO-A inhibitors have been typically used in the treatment of depression, whereas MAO-B inhibitors are typically used in the treatment of Parkinson's disease.[10][11] Concurrent use of MAO-A inhibitors with sympathomimetic drugs can induce a hypertensive crisis as a result of excessive norepinephrine.[12] Likewise, the consumption of tyramine-containing substances, such as cheese, whilst using MAO-A inhibitors also carries the risk of hypertensive crisis.[6][12] Selective MAO-B inhibitors bypass this problem by preferentially inhibiting MAO-B, which allows tyramine to be metabolized freely by MAO-A in the gastrointestinal tract.[6][12]