OAT Gene: Ornithine Aminotransferase – Function, Mutations, and Associated Diseases

The OAT gene encodes ornithine aminotransferase, a mitochondrial enzyme that catalyzes the reversible conversion of ornithine to glutamate-5-semialdehyde, linking the urea cycle and proline/glutamate metabolism. Mutations in OAT cause gyrate atrophy of the choroid and retina, an autosomal recessive disorder characterized by progressive vision loss. The enzyme is expressed in multiple tissues, with highest levels in liver, kidney, and retina. OAT is also implicated in cancer biology, where its expression can influence tumor metabolism.

Tissue Expression

Cell Line Expression

Hotspot Mutations

Mutation functional classification

• Arginine and proline metabolism

• Urea cycle and metabolism of amino groups

• Metabolic pathways

Ornithine aminotransferase (OAT) is a 439-amino-acid mitochondrial matrix enzyme that forms homodimers. It requires pyridoxal phosphate as a cofactor. The enzyme catalyzes the transamination of ornithine to glutamate-5-semialdehyde, which can be converted to proline or glutamate. OAT plays a critical role in ornithine homeostasis, particularly in the retina, where deficiency leads to gyrate atrophy. The protein is synthesized as a precursor with a mitochondrial targeting sequence and is processed to the mature form.