description | Protein involved in the synthesis of melatonin (N-acetyl 5- methoxytryptamine), a neurohormone synthesized by lower plants and in the pineal gland in animals. In humans, it is involved in the regulation of sleep, mood, puberty, ovarian cycles and in the establishment of circadian rhythms. In lower vertebrates, it causes aggregation of pigment in melanophores, and thus lightens skin |