O-GlcNAcylation Regulates Tyrosine Hydroxylase Serine 40 Phosphorylation and L-DOPA Levels Research Background In the nervous system, dopamine is a key neurotransmitter, and the rate-limiting enzyme in its synthesis pathway is tyrosine hydroxylase (TH). The activity of TH is regulated by various post-translational modifications (PTMs), among which ...