Biochemistry · Enzyme
Aspartate aminotransferase (AST, GOT) !
AST swaps aspartate and oxaloacetate with glutamate and α-ketoglutarate. It supplies urea cycle aspartate and marks liver injury.
Updated 2026-11-01
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Key facts
- Aspartate + α-ketoglutarate ⇌ oxaloacetate + glutamate, with pyridoxal phosphate.
- There is a cytosolic form (GOT1) and a mitochondrial form (GOT2); together they run the malate–aspartate shuttle.
- It is found in liver, heart, muscle, kidney and red cells: less liver-specific than ALT.
- It supplies the aspartate that enters the urea cycle.
Structure
- 3II0: human GOT1, a dimer with PLP bound to a lysine in each active site.
Regulation
- Glucocorticoids induce it; its activity depends on available PLP.
Inhibitors and toxins
- Aminooxyacetate (experimental inhibitor of PLP enzymes).
Clinical notes
- An AST/ALT ratio above 2 suggests alcohol-related liver disease (alcohol lowers PLP and damages mitochondria).
- It also rises in myocardial infarction, rhabdomyolysis and haemolysis.
Pathways
Related conditions
Related
- Glutamate (glutamic acid)
- Alanine aminotransferase (ALT, GPT)
- Transamination and deamination
- Argininosuccinate synthetase (ASS)
- Krebs cycle (citric acid cycle)
Test yourself
Think of the answer, then tap the question to see it.
What does AST supply to the urea cycle?
Aspartate, which carries the second nitrogen of urea to argininosuccinate synthetase.
What does an AST/ALT ratio above 2 suggest?
Alcohol-related liver disease: alcohol damages mitochondria, home of mitochondrial AST, and lowers the PLP that ALT needs.
Which shuttle do the two AST isoforms run?
The malate–aspartate shuttle, which moves the reducing power of cytosolic NADH into the mitochondrion.
Educational information, not medical advice. For any symptom, see a health professional.
Sources: GOT1: Aspartate aminotransferase, cytoplasmic (human) (UniProt, 2026); Aspartate aminotransferase (AST) blood test: MedlinePlus Medical Encyclopedia (MedlinePlus, US National Library of Medicine, 2026); 3II0: Crystal structure of human Glutamate oxaloacetate transaminase 1 (GOT1) (RCSB Protein Data Bank, 2026).
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