Alanine transaminase or ALT is found in serum and in various bodily tissues, but is most commonly associated with the liver. It catalyzes the reversible transamination between alanine and 2-oxoglutarate to generate pyruvate and glutamate and plays a key role in the intermediary metabolism of glucose and amino acids. Serum activity levels of this enzyme are routinely used as a biomarker of liver injury caused by drug toxicity, infection, alcohol, and fatty liver disease.