Serotonin-N-Acetyltransferase

• OMIM: 600950
• UniProt: Q16613

Serotonin N- acetyltransferase ( AANAT ), the enzyme that catalyzes the transfer of an acid moiety to serotonin. This reaction is the first and rate limiting of two steps in the biosynthesis of melatonin. AANAT occurs in two-sided animals. In humans it is mainly localized in the pineal gland, in the upper digestive tract and in the retina. Their activity is indirectly dependent on daylight.

Catalyzed reaction

CH3CO -S -CoA HS -CoA

Serotonin is converted to N - acetylserotonin. Other 2- arylethylamines be accepted as a substrate.

Regulation

The activity of the AANAT rises at night to the tens to hundreds of times. The time to double the activity is about 15 minutes and the time in which the activity is halved in the morning is about 3.5 minutes. This dramatic effect is achieved by activation of the enzyme by means of phosphorylation, and complexation of 14-3 -3 protein, which is from the intracellular cAMP level dependent. This in turn is regulated by a signaling cascade from the hormone norepinephrine, which is distributed according to daylight suprachiasmatic nucleus from.

The production of AANAT is coupled to the endocannabinoid system in the pineal gland, which was first discovered in 2008 in rats. The nightly reinforcement of AANAT translation is genetically regulated by the protein hnRNP Q.