| Characteristic | Summary |
|---|---|
| Gene symbol | **TAT** (tyrosine aminotransferase) (pqac-00000000, pqac-00000004) |
| UniProt ID | **P17735** (from user-provided UniProt target specification) |
| EC number | **EC 2.6.1.5** (tyrosine aminotransferase) (pqac-00000001, pqac-00000003) |
| Gene location | **Chromosome 16q22.1-q22.5** (pqac-00000004) |
| Protein size | **454 amino acids**; gene contains **12 exons** (pqac-00000004) |
| Cofactor | **Pyridoxal 5′-phosphate (PLP)** (pqac-00000003, pqac-00000004) |
| Quaternary structure | **Homodimer** (pqac-00000001, pqac-00000020) |
| Subcellular localization | Predominantly **cytosolic**; human TAT is described as the **cytosolic** tyrosine aminotransferase (pqac-00000004, pqac-00000008) |
| Primary tissue expression | Expressed primarily in **liver**, especially **hepatic parenchymal cells**; tyrosine degradation is mainly hepatic with minor kidney contribution (pqac-00000009, pqac-00000014) |
| Primary reaction | Reversible **transamination of L-tyrosine to 4-hydroxyphenylpyruvate (4-HPP/pHPP)** using an amino-group acceptor; first step of tyrosine degradation (pqac-00000003, pqac-00000022) |
| Primary substrates | **L-tyrosine** and **α-ketoglutarate** as the canonical substrate pair for tyrosine catabolism (pqac-00000003, pqac-00000022) |
| Products | **4-hydroxyphenylpyruvate** and **L-glutamate** (from the canonical tyrosine + α-ketoglutarate reaction) (pqac-00000003, pqac-00000022) |
| Alternative substrates | Accepts **phenylalanine**; human cytosolic TAT also shows side activity toward **L-tryptophan** (pqac-00000001, pqac-00000006) |
| Disease association | **Tyrosinemia type II / Richner-Hanhart syndrome**; autosomal recessive TAT deficiency causing hypertyrosinemia, dendritic keratitis, palmoplantar hyperkeratosis, and sometimes learning disability (pqac-00000005, pqac-00000011, pqac-00000012) |
| Evolutionary family classification | **Class I PLP-dependent aminotransferase**; mammalian cytosolic TAT is placed in **Family I, subfamily Ig**, distinct from bacterial TyrB enzymes of subfamily Ia (pqac-00000017, pqac-00000021) |


*Table: This table summarizes the core molecular, biochemical, cellular, and disease-related properties of human tyrosine aminotransferase (TAT, UniProt P17735). It is useful as a compact reference for functional annotation and report writing.*