Biosynthesis and degradation of catecholamines

Catecholamines and serotonin also share the major mode of degradation. Both are substrates for monoamine oxidase (MAO), although one subtype of this enzyme (MAO A) has a preference for catecholamines, whereas the other (MAO 

B) acts more efficiently on serotonin. MAO is foimd both within the synaptic terminals, where it degrades any excess transmitter, and in the liver, where it scavenges circulating catecholamines. 

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