The glucose-alanine cycle—also referred to in the literature as the Cahill cycle or the alanine cycle—involves muscle protein being degraded to provide more glucose to generate additional ATP for muscle contraction. It allows pyruvate and glutamate to be transported out of muscle tissue to the liver where gluconeogenesis takes place to supply the muscle tissue with more glucose as mentioned previously. To initiate the cycle, muscle and tissues that catabolize amino acids for fuel generate amino groups—most commonly in the form of glutamate—through the process of transamination. These amino groups are transferred via alanine aminotransferase to pyruvate (a product of glycolysis) to form alanine and alpha-ketoglutarate. Alanine subsequently moves through the circulatory system to the liver where the reaction previously catalyzed by alanine aminotransferase is reversed to produce pyruvate. This pyruvate is converted into glucose through the process of gluconeogenesis which subsequently is transported back to the muscle tissue. Meanwhile, glutamate dehydrogenase in the mitochondria catabolizes glutamate into ammonium. Ammonium moves on to form urea in the urea cycle.

Glucose-Alanine Cycle References