Total anti-C-terminal AA-NAT-specific IgG was affinity purified on resin-coupled non-phosphopeptide.
Phospho-specific carboxy-terminal IgG was subsequently isolated on resin-coupled phosphopeptide.
Pineal gland serotonin N-acetyltransferase (arylalkylamine N-acetyltransferase, AA-NAT) is an ~23 kDa protein which is the rate-limiting enzyme in melatonin synthesis. Melatonin serves as the hormonal signal of the daily light/dark cycle, or body clock. The nocturnal oscillation in enzyme activity ranges by 10- to 100-fold depending on species among vertebrates. Studies have shown that AA-NAT is regulated by cAMP at both the mRNA and protein levels. AA-NAT has putative protein kinase A (PKA) sites at Thr29 and Ser206. Phosphorylation of AA-NAT at these residues might play a role in protein inactivation via proteasome-dependent degradation.