Monoamine oxidase B (MAO-B) is an enzyme that in humans is encoded by the MAOB gene.
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]
- ^ a b c GRCh38: Ensembl release 89: ENSG00000069535 – Ensembl, May 2017
- ^ a b c GRCm38: Ensembl release 89: ENSMUSG00000040147 – Ensembl, May 2017
- ^ "Human PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.
- ^ "Mouse PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.
- ^ "Entrez Gene: MAOB monoamine oxidase B".
- ^ Tan YY, Jenner P, Chen SD (2022). "Monoamine Oxidase-B Inhibitors for the Treatment of Parkinson's Disease: Past, Present, and Future". Journal of Parkinson's Disease. 12 (2): 477–493. doi:10.3233/JPD-212976. PMC 8925102. PMID 34957948.
There are two MAO isoenzymes: MAO-A and MAO-B. MAO-A is mainly distributed in the gastrointestinal tract, platelets, and heart, and can promote the metabolism of tyramine-containing substances in food so avoiding hypertensive crises caused by the accumulation of tyramine ("cheese reaction"). MAO-A also exists in catecholaminergic neurons, such as dopaminergic neurons in SN, norepinephrine neurons in locus coeruleus, etc. [18]. MAO-B is mainly distributed in platelets and glial cells, and total MAO activity within the brain is composed of approximately 20% MAO-A and 80% MAO-B [19–22]. Both MAO-A and MAO-B regulate the amine neurotransmitters, including dopamine. MAO-A metabolizes dopamine in presynaptic neurons, while MAO-B metabolizes dopamine released to synaptic cleft and taken up by glial cells. The number of glial cells was shown to increase with age, and in neurodegenerative diseases, as expected, the activity of MAO-B also increased [23–25]. MAO-B inhibitors inhibit MAO-B activity in the brain, block dopamine catabolism, enhance dopamine signaling, and selectively enhance dopamine levels at synaptic cleft [21].