Alanine aminotransferase

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Alanine aminotransferase
Alanine aminotransferase
Ribbon model of the human ALAT2 (monomer, lateral / frontal), pyridoxal phosphate as domes, according to PDB  3IHJ
Properties of human protein
Mass / length primary structure 495 amino acids
Secondary to quaternary structure Homodimer
Cofactor Pyridoxal phosphate
Gene names GPT  ; ALAT; OLD
External IDs
Enzyme classification
EC, category transaminase
Response type Amination
Substrate L-alanine + α-ketoglutarate
Products Pyruvate + L-glutamate
Homology family Aminotransferase I / II
Parent taxon Creature

The alanine aminotransferase (ALAT, ALT) , formerly glutamate-pyruvate transaminase (GPT) or serum glutamic pyruvic transaminase (SGPT) , is an enzyme that is found mainly in the cytoplasm of liver cells. It needs the coenzyme pyridoxal phosphate (a derivative of vitamin B6) for its function .

Catalyzed reaction

It catalyzes the reaction L-alanine + α-ketoglutarate pyruvate + L-glutamate .

This reaction plays an important role in the glucose-alanine cycle , whereby alanine is formed in the muscles from excess nitrogen and pyruvate by ALAT, transported in the blood to the liver and there by ALAT again to pyruvate (for gluconeogenesis ) and nitrogen (for the Urea cycle ).

Laboratory diagnostics

In laboratory diagnostics, the activity of the ALAT is determined from plasma or serum in order to clarify whether there is a liver or biliary tract disease. The reference range for measurements at 37 ° C according to IFCC is up to 50 U / l for men and up to 35 U / l (units per liter) for women. Elevated ALAT values ​​almost always indicate a liver disease in which liver cells have been damaged. For interpretation, the other liver values ​​( bilirubin , alkaline phosphatase , AST / GOT and GGT ) should also be determined.

Slight increases can be found with fatty liver , liver tumors , liver metastases , liver cell necrosis, cholangitis , gallbladder removal, cholecystectomy, as well as medication or alcohol consumption . Greater increases are found in all chronic hepatitis , cirrhosis of the liver , congestive liver or in toxic liver damage (for example from fungal poisons ). In acute hepatitis, the ALAT can rise to over 5000 U / l. In addition, there is a short-term increase in myocardial infarction .


  • Neumeister, Besenthal, Liebrich: Clinical guidelines for laboratory diagnostics , Munich / Jena, Urban & Fischer, 2003, ISBN 3-437-22231-7 .
  • Lothar Thomas: Labor und Diagnose , Frankfurt / Main, TH-Books, 2005, ISBN 3-9805215-5-9 .

Web links

Individual evidence