Tyrosine aminotransferase (TAT)

Tyrosine aminotransferase is a **pyridoxal phosphate-dependent enzyme** primarily found in the liver, where it catalyzes the first step in the catabolic pathway of the amino acid tyrosine. The enzyme converts **L-tyrosine and 2‑oxoglutarate into 4‑hydroxyphenylpyruvate and L-glutamate**, a reaction essential for proper amino acid degradation and nitrogen balance. Structurally, it is a dimeric protein with each subunit containing an active site lysine residue that forms a Schiff base with its PLP cofactor, which is critical for its transaminase activity. The enzyme belongs to the aminotransferase superfamily, sharing conserved catalytic residues with other family members such as aspartate aminotransferases. Its carboxyl terminus contains glutamate-rich segments resembling PEST sequences, contributing to its rapid turnover rate within cells. Deficiency or dysfunction can lead to metabolic disorders such as type II tyrosinemia due to impaired breakdown of tyrosine[1][3][5].

Other names

Tyrosine transaminaseL-tyrosine:2-oxoglutarate aminotransferase