This view shows enzymes only for those organisms listed below, in the list of taxa known to possess the pathway. If an enzyme name is shown in bold, there is experimental evidence for this enzymatic activity.
|Superclasses:||Degradation/Utilization/Assimilation → Amino Acids Degradation → Proteinogenic Amino Acids Degradation → L-alanine Degradation|
Expected Taxonomic Range: Eukaryota
In eukaryotes, L-alanine is degraded through transamination to pyruvate by alanine aminotransferase. Pyruvate is transported into the mitochondrion where it is oxidatively decarboxylated by the pyruvate dehydrogenase complex to carbon dioxide and acetyl-CoA (as shown in the pathway link). Acetyl-CoA enters the TCA cycle .
Biosynthetically, pyruvate is involved in gluconeogenesis (see MetaCyc pathway gluconeogenesis I) and is also a precursor of the pyruvate family of amino acids: alanine, valine, leucine and isoleucine. In plants and bacteria, it is also a precursor of isoprenoids (see MetaCyc pathway methylerythritol phosphate pathway I).
Alanine aminotransferase is a commonly used diagnostic marker in humans. It is produced mainly in the liver and its presence in serum is an indicator of liver disease [Sherman91]. The enzyme is present as isozymes in both the cytosol and mitochondrion. Expression of the isozymes varies among tissues and is species-specific (in [Rajamohan06]).
In bacteria, alanine is converted to pyruvate by oxidative deamination ([Gottschalk86]) (see MetaCyc pathway L-alanine degradation IV). An alanine aminotransferase has been identified in the archaeon Pyrococcus furiosus and is thought to function biosynthetically, transaminating pyruvate with glutamate [Ward00] (see MetaCyc pathway pyruvate fermentation to acetate and alanine.
Rajamohan06: Rajamohan F, Nelms L, Joslin DL, Lu B, Reagan WJ, Lawton M (2006). "cDNA cloning, expression, purification, distribution, and characterization of biologically active canine alanine aminotransferase-1." Protein Expr Purif 48(1);81-9. PMID: 16495081
Umemura94: Umemura I, Yanagiya K, Komatsubara S, Sato T, Tosa T (1994). "Purification and some properties of alanine aminotransferase from Candida maltosa." Biosci Biotechnol Biochem 58(2);283-7. PMID: 7764540
Vedavathi04: Vedavathi M, Girish KS, Kumar MK (2004). "Isolation and characterization of cytosolic alanine aminotransferase isoforms from starved rat liver." Mol Cell Biochem 267(1-2);13-23. PMID: 15663181
Ward00: Ward DE, Kengen SW, van Der Oost J, de Vos WM (2000). "Purification and characterization of the alanine aminotransferase from the hyperthermophilic Archaeon pyrococcus furiosus and its role in alanine production." J Bacteriol 2000;182(9);2559-66. PMID: 10762259
Yang02a: Yang RZ, Blaileanu G, Hansen BC, Shuldiner AR, Gong DW (2002). "cDNA cloning, genomic structure, chromosomal mapping, and functional expression of a novel human alanine aminotransferase." Genomics 79(3);445-50. PMID: 11863375
Felbeck80: Felbeck H, Grieshaber MK (1980). "Investigations on some enzymes involved in the anaerobic metabolism of amino acids of Arenicola marina L." Comparative Biochemistry and Physiology Part B: Comparative Biochemistry 66(2);205-213.
Ishiguro91: Ishiguro M, Takio K, Suzuki M, Oyama R, Matsuzawa T, Titani K (1991). "Complete amino acid sequence of human liver cytosolic alanine aminotransferase (GPT) determined by a combination of conventional and mass spectral methods." Biochemistry 30(43);10451-7. PMID: 1931970
Liepman03: Liepman AH, Olsen LJ (2003). "Alanine aminotransferase homologs catalyze the glutamate:glyoxylate aminotransferase reaction in peroxisomes of Arabidopsis." Plant Physiol 131(1);215-27. PMID: 12529529
Sohocki97: Sohocki MM, Sullivan LS, Harrison WR, Sodergren EJ, Elder FF, Weinstock G, Tanase S, Daiger SP (1997). "Human glutamate pyruvate transaminase (GPT): localization to 8q24.3, cDNA and genomic sequences, and polymorphic sites." Genomics 40(2);247-52. PMID: 9119391
Tao08a: Tao Y, Ferrer JL, Ljung K, Pojer F, Hong F, Long JA, Li L, Moreno JE, Bowman ME, Ivans LJ, Cheng Y, Lim J, Zhao Y, Ballare CL, Sandberg G, Noel JP, Chory J (2008). "Rapid synthesis of auxin via a new tryptophan-dependent pathway is required for shade avoidance in plants." Cell 133(1);164-76. PMID: 18394996
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