- "The mechanism behind this pattern of secretion during the dark cycle is that activity of the rate-limiting enzyme in melatonin synthesis - serotonin N-acetyltransferase (NAT) - is low during daylight and peaks during the dark phase. In some species, circadian changes in NAT activity are tightly correlated with transcription of the NAT messenger RNA, while in other species, post-transcriptional regulation of NAT activity is responsible. Activity of the other enzyme involved in synthesis of melatonin from serotonin - the methyltransferase - does not show regulation by pattern of light exposure. "
- Original article
- Site-specific DNA-methyltransferase (adenine-specific)