Serotonin N-acetyltransferase: Proteins and Enzymes

Arylalkylamine N-Acetyltransferase (AANAT) is the main enzyme for melatonin synthesis. Hormonal melatonin has been implicated in sleep and circadian clock function, and acts as"the hormone of the night." Large changes in the abundance of AANAT are believed to be responsible for the large day/night rhythms in melatonin synthesis in the pineal gland and retina. Most research shows that AANAT activity is regulated by controlling the steady-state levels of the protein. Recent research, however, suggests that another mechanism may also play a role in controlling melatonin production without altering AANAT protein and activity. This mechanism may explain the sudden physiological increase in circulating melatonin observed at the onset of the dark period in humans.