Structural insights into the regulation of aromatic amino acid hydroxylation

- The aromatic amino acid hydroxylases contain catalytic and regulatory domains.
- The regulatory domains of tyrosine and phenylalanine hydroxylase are ACT domains.
- The regulatory domains of tyrosine and phenylalanine hydroxylase form dimers.
- Dimerization of the ACT domain of phenylalanine hydroxylase is linked to binding of phenylalanine.