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Last Updated: 2019-09-12
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
Kim DW, Eum WS, Jang SH, Yoon CS, Kim YH, Choi SH, Choi HS, Kim SY, Kwon HY, Kang JH, Kwon OS, Cho SW, Park J, Choi SY: Molecular gene cloning, expression, and characterization of bovine brain glutamate dehydrogenase. J Biochem Mol Biol. 2003 Nov 30;36(6):545-51.Pubmed: 14659072
Moon K, Smith EL: Sequence of bovine liver glutamate dehydrogenase. 8. Peptides produced by specific chemical cleavages; the complete sequence of the protein. J Biol Chem. 1973 May 10;248(9):3082-8.Pubmed: 4735572
Julliard JH, Smith EL: Partial amino acid sequence of the glutamate dehydrogenase of human liver and a revision of the sequence of the bovine enzyme. J Biol Chem. 1979 May 10;254(9):3427-38.Pubmed: 429360
Augustin R, Pocar P, Navarrete-Santos A, Wrenzycki C, Gandolfi F, Niemann H, Fischer B: Glucose transporter expression is developmentally regulated in in vitro derived bovine preimplantation embryos. Mol Reprod Dev. 2001 Nov;60(3):370-6. doi: 10.1002/mrd.1099.Pubmed: 11599048
Abe H, Morimatsu M, Nikami H, Miyashige T, Saito M: Molecular cloning and mRNA expression of the bovine insulin-responsive glucose transporter (GLUT4). J Anim Sci. 1997 Jan;75(1):182-8. doi: 10.2527/1997.751182x.Pubmed: 9027564
Hocquette JF, Graulet B, Castiglia-Delavaud C, Bornes F, Lepetit N, Ferre P: Insulin-sensitive glucose transporter transcript levels in calf muscles assessed with a bovine GLUT4 cDNA fragment. Int J Biochem Cell Biol. 1996 Jul;28(7):795-806.Pubmed: 8925410
This pathway was propagated using PathWhiz - Pon, A. et al. Pathways with PathWhiz (2015) Nucleic Acids Res. 43(Web Server issue): W552–W559.
Propagated from SMP0000127
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