Aromatic L-amino acid decarboxylase: a neglected and misunderstood enzyme

Classically, aromatic L-amino acid decarboxylase (AADC) has been regarded as an unregulated, rather uninteresting enzyme. In this review, we describe advances made during the past 10 years, demonstrating that AADC is regulated both pre- and post-translation. The significance of such regulatory mechanisms is poorly understood at present, but the presence of tissue specific control of expression raises the real possibility of AADC being involved in processes other than neuro-transmitter synthesis. We further discuss clinical and physiological situations in which such regulatory mechanisms may be important, including the intriguing possibility of AADC gene regulation being linked to that of factors thought to have a role in apoptosis and its prevention.