Two Arylalkylamine N-Acetyltransferase Genes Mediate Melatonin Synthesis in Fish

Two AANAT genes have been identified in fish, including AANAT-1 and AANAT-2.

• AANAT-1 is primarily expressed in the retina, while AANAT-2 is found in the pineal gland.
• The levels of AANAT-1 and AANAT-2 mRNA fluctuate in a circadian rhythm, with AANAT-1 peaking in the late afternoon and AANAT-2 peaking 6 hours later.
• Both enzymes show 66% similarity in amino acid sequences but differ in their ability to bind serotonin and other compounds.
• The presence of two AANAT genes in fish may help meet specific melatonin synthesis needs in different tissues.

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