Controls the night/day rhythm of melatonin production in the pineal gland. Catalyzes the N-acetylation of serotonin into N-acetylserotonin, the penultimate step in the synthesis of melatonin.
Subcellular locations: Cytoplasm
Highly expressed in pineal gland and in the photoreceptor outer segments in the retina. Expressed at about 100-fold lower levels in the pituitary gland and testis. Not detected in other tissues.