Alanine transaminase or ALT is a transaminase enzyme. It is also called serum glutamic pyruvic transaminase (SGPT) or alanine aminotransferase (ALAT). ALT is found in serum and in various bodily tissues, but is most commonly associated with the liver. It catalyzes the transfer of an amino group from alanine to a-ketoglutarate, the products of this reversible transamination reaction being pyruvate and glutamate. It is commonly measured clinically as a part of a diagnostic liver function test, to determine liver health. GPT1 transcript is moderately expressed in kidney, liver, heart, and fat. Another GPT1 transcript shows a slightly different expression pattern, with a 3.9-kb transcript expressed at high levels in muscle, fat, kidney, and brain and at lower levels in liver and breast.