GO:0047635 L-alanine:oxo-acid transaminase activity: Mechanism, Genes and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0047635 describes the molecular function that catalyzes the reversible transfer of an amino group from L-alanine to a 2-oxocarboxylate acceptor, yielding pyruvate and a new L-alpha-amino acid.
• This activity is central to amino acid interconversion and nitrogen shuttling, and it is widely measured using coupled enzymatic assays with 2-oxo acid substrates.
• Enzymes with this activity participate in branched-chain amino acid degradation in skeletal muscle and in the metabolism of sulfur-containing amino acids such as L-cystathionine and L-cystine.
• The reaction contributes to oxalate metabolism and is relevant to disorders of glyoxylate detoxification, as shown in studies of magnesium-deficient rats and HOGA1-deficient mice.
• In the nervous system, transamination reactions related to this activity support glutamate and GABA biosynthesis from ornithine in synaptosomes.
• CRISPR-based knockout, point-mutation, knock-in, and overexpression models enable causal testing of genes encoding L-alanine:oxo-acid transaminase activity in disease and metabolism.
Description
GO:0047635, L-alanine:oxo-acid transaminase activity, is a molecular function defined by the reversible reaction L-alanine + a 2-oxocarboxylate = an L-alpha-amino acid + pyruvate. This activity belongs to the class of aminotransferases that use pyridoxal phosphate chemistry to move amino groups between amino acids and 2-oxo acids, thereby linking amino acid pools to central carbon metabolism. The term is distinct from more narrowly named transaminases because it explicitly accepts a broad range of 2-oxocarboxylate substrates, making it a hub for nitrogen redistribution in cells. Researchers study this activity because it sits at the intersection of amino acid catabolism, neurotransmitter precursor supply, and detoxification pathways. For example, coupled enzymatic assays for branched-chain L-amino acid aminotransferase activity with 2-oxo acid substrates have been used to quantify flux through this type of reaction in tissue extracts. In skeletal muscle, leucine degradation depends on transamination reactions that generate 2-oxo acids for further oxidation. In kidney and liver, transamination of L-cystathionine, L-cystine, and related compounds by a bovine kidney transaminase illustrates the broad substrate tolerance of this activity. Beyond core metabolism, this activity has been linked to oxalate homeostasis. Studies in magnesium-deficient rats and in HOGA1-deficient mice with peroxisomal AGT expression have examined how transamination and related reactions influence urinary oxalate excretion. In the brain, a synaptosomal pathway converts ornithine to glutamate and GABA through transamination steps that are negatively feedback-inhibited by GABA. These diverse contexts make GO:0047635 a useful annotation for interpreting metabolic, neurological, and renal phenotypes.
L-alanine:oxo-acid transaminase activity At A Glance
| GO ID | GO:0047635 |
|---|---|
| GO term | L-alanine:oxo-acid transaminase activity |
| Ontology | molecular_function |
| Synonym | alanine-keto acid aminotransferase activity; alanine--oxo-acid aminotransferase activity; alanine-oxo acid aminotransferase activity; alanine-oxo-acid aminotransferase activity; L-alanine:2-oxo-acid aminotransferase activity; L-alanine-alpha-keto acid aminotransferase activity; leucine-alanine transaminase activity |
| Major function | Reversible transfer of an amino group from L-alanine to a 2-oxocarboxylate, producing pyruvate and an L-alpha-amino acid |
| Reaction direction | Reversible; can operate in amino acid degradation or synthesis depending on substrate availability |
| Cofactor | Pyridoxal phosphate (PLP), typical of aminotransferases |
| Substrate scope | Broad 2-oxo acid acceptor specificity, including branched-chain and sulfur-containing amino acid derivatives |
| Tissue contexts | Skeletal muscle, kidney, liver, and brain synaptosomes |
What Is GO:0047635?
In simple terms, GO:0047635 is the enzyme activity that swaps an amino group from L-alanine onto a 2-oxo acid, producing pyruvate and a different amino acid. The QuickGO definition states: Catalysis of the reaction: L-alanine + a 2-oxocarboxylate = an L-alpha-amino acid + pyruvate. This is a reversible transamination reaction that requires pyridoxal phosphate as a cofactor and accepts a range of 2-oxocarboxylate acceptors, which is why the term is broader than alanine aminotransferase alone.
Why Is L-alanine:oxo-acid transaminase activity Important in Cell Biology?
GO:0047635 is important because it defines a central node in nitrogen and amino acid metabolism that connects alanine, pyruvate, branched-chain amino acids, sulfur-containing amino acids, and neurotransmitter precursors. Dysregulation of transamination flux can alter energy substrate availability, ammonia handling, and detoxification of glyoxylate-related metabolites, with consequences for muscle wasting, neurological function, and kidney stone risk. Because the activity is reversible and substrate-tolerant, it is also a frequent annotation in enzyme discovery and metabolic engineering, where precise functional assignment matters for interpreting knockout and overexpression phenotypes.
• Provides a reversible route for nitrogen transfer between L-alanine and 2-oxo acids, linking amino acid pools to pyruvate and central carbon metabolism.
• Supports branched-chain amino acid degradation in skeletal muscle, a key process in energy homeostasis during fasting or exercise.
• Participates in the transamination of L-cystathionine, L-cystine, and related sulfur-containing compounds in kidney tissue.
• Contributes to oxalate metabolism and glyoxylate detoxification pathways relevant to hyperoxaluria and kidney stone disease.
• Supports synaptosomal biosynthesis of glutamate and GABA from ornithine, with feedback inhibition by GABA.
• Serves as a functional annotation target in microbial and mammalian enzyme discovery, including D-amino acid transaminases that complement glutamate racemase deletion.
• Enables coupled enzymatic assays for quantifying aminotransferase activity with 2-oxo acid substrates in tissue extracts.
• Is relevant to substrate-specificity studies of omega-aminotransferases and related PLP enzymes.
• Provides a mechanistic basis for interpreting metabolic phenotypes in CRISPR knockout and knock-in models.
• Helps explain tissue-specific metabolic flexibility in muscle, kidney, liver, and brain.
What Happens During L-alanine:oxo-acid transaminase activity?
Substrate binding and Schiff base formation
In simple terms: The enzyme first grabs L-alanine and holds it using a helper molecule called pyridoxal phosphate.
The reaction begins when L-alanine binds to the enzyme active site and forms a Schiff base with the pyridoxal phosphate cofactor. This step is characteristic of aminotransferases and is required for subsequent group transfer. The enzyme can also accept a range of 2-oxocarboxylate acceptors, which is why GO:0047635 is defined broadly rather than as a single-substrate alanine aminotransferase.
Amino group transfer to the 2-oxo acid acceptor
In simple terms: The amino group is moved from alanine onto the 2-oxo acid, turning alanine into pyruvate.
After Schiff base formation, the amino group is transferred to the 2-oxocarboxylate acceptor, generating pyruvate and a new L-alpha-amino acid. This reversible step is the defining chemistry of GO:0047635 and allows the enzyme to operate in either amino acid degradation or synthesis depending on substrate concentrations. In skeletal muscle, this type of transamination is part of leucine degradation, where the resulting 2-oxo acid is further oxidized.
Product release and reaction reversibility
In simple terms: The products leave the enzyme, and the reaction can run backward if the cell needs to make alanine instead.
Pyruvate and the newly formed L-alpha-amino acid are released from the active site, regenerating the enzyme for another catalytic cycle. Because the reaction is reversible, the same activity can support alanine synthesis when 2-oxo acid and amino donor pools favor the reverse direction. This reversibility is important for nitrogen shuttling between tissues and for maintaining amino acid balance during metabolic stress.
Role in sulfur-containing amino acid metabolism
In simple terms: The enzyme can also act on sulfur-containing amino acids, helping the kidney process them.
A bovine kidney transaminase with activity toward L-cystathionine, L-cystine, and related compounds demonstrates that enzymes annotated with this activity can participate in sulfur amino acid metabolism. This broad substrate tolerance expands the metabolic roles of GO:0047635 beyond alanine and branched-chain amino acids, linking it to cysteine and methionine pathways.
Contribution to oxalate and glyoxylate metabolism
In simple terms: Transamination reactions can influence how the body handles oxalate, which is relevant to kidney stones.
Studies in magnesium-deficient rats and in HOGA1-deficient mice with AGT expression in peroxisomes have examined how transamination and related reactions affect oxalate metabolism. These findings connect GO:0047635 to glyoxylate detoxification and urinary oxalate excretion, although the exact contribution of each enzyme depends on tissue and subcellular localization.
Neurotransmitter precursor supply in the brain
In simple terms: In nerve endings, transamination helps make glutamate and GABA, which are brain signaling molecules.
A synaptosomal pathway converts ornithine to glutamate and GABA through transamination steps, and this pathway is negatively feedback-inhibited by GABA. This illustrates how GO:0047635-related chemistry supports neurotransmitter biosynthesis and how product feedback can regulate flux through the pathway.
Key Genes Involved in GO:0047635 L-alanine:oxo-acid transaminase activity
The following genes and proteins are experimentally linked to L-alanine:oxo-acid transaminase activity or to the metabolic pathways in which this activity has been measured.
| Gene | Major Role | Research Relevance |
|---|---|---|
| BCAT1 | Branched-chain amino acid transaminase; transfers amino groups to 2-oxo acids | Measured with coupled assays using 2-oxo acid substrates; linked to leucine degradation |
| BCAT2 | Mitochondrial branched-chain amino acid transaminase | Participates in branched-chain amino acid catabolism in muscle and other tissues |
| AGT | Alanine-glyoxylate aminotransferase; uses alanine and glyoxylate as substrates | Studied in HOGA1-deficient mice for oxalate metabolism and peroxisomal localization |
| HOGA1 | 4-hydroxy-2-oxo-glutarate aldolase 1; involved in glyoxylate metabolism | HOGA1-deficient mice show normal urinary oxalate when AGT is peroxisomal |
| GPT | Glutamate pyruvate transaminase; catalyzes alanine-pyruvate interconversion | Classic enzyme with L-alanine:oxo-acid transaminase chemistry |
| GPT2 | Mitochondrial glutamate pyruvate transaminase | Contributes to alanine and pyruvate metabolism in tissues |
| KYAT1 | Kynurenine aminotransferase; broad substrate aminotransferase | Example of PLP-dependent transamination with multiple 2-oxo acid acceptors |
| KYAT3 | Kynurenine aminotransferase 3; related PLP enzyme | Relevant to substrate specificity studies of aminotransferases |
| GOT1 | Aspartate aminotransferase; related transamination chemistry | Provides comparative context for 2-oxo acid substrate specificity |
| GOT2 | Mitochondrial aspartate aminotransferase | Related transaminase in nitrogen shuttling |
| OAT | Ornithine aminotransferase; supports glutamate and GABA precursor synthesis | Linked to synaptosomal pathway from ornithine |
| GAD1 | Glutamate decarboxylase; produces GABA | Downstream of transamination-derived glutamate in brain |
| GAD2 | Glutamate decarboxylase 2; produces GABA | Relevant to feedback inhibition by GABA in synaptosomal pathway |
| DAAO | D-amino acid oxidase; related amino acid metabolism | Context for D-amino acid transaminase studies in Mycobacterium smegmatis |
| MurI | Glutamate racemase; complemented by D-amino acid transaminase overexpression | Used to test transaminase function in bacteria |
| MSMEG_6292 | D-amino acid transaminase in Mycobacterium smegmatis | Overexpression complements glutamate racemase deletion |
| PHGDH | Phosphoglycerate dehydrogenase; related amino acid metabolism | Context for amino acid interconversion pathways |
| SHMT1 | Serine hydroxymethyltransferase; one-carbon and amino acid metabolism | Related to nitrogen transfer networks |
How Is L-alanine:oxo-acid transaminase activity Regulated?
The activity is regulated by substrate availability, product feedback, and tissue-specific expression of the enzymes that carry it. In the brain, the synaptosomal pathway producing glutamate and GABA from ornithine is negatively feedback-inhibited by GABA, providing a direct example of product-level control. In muscle, leucine degradation via transamination is influenced by the availability of 2-oxo acid acceptors and by the energetic state of the cell. Enzyme abundance and subcellular localization also matter: AGT expression in peroxisomes versus mitochondria affects oxalate metabolism in HOGA1-deficient mice. Broader metabolic regulation by nutrient-sensing pathways and transcriptional control of aminotransferase genes is likely but is not fully defined for every enzyme annotated with GO:0047635.
L-alanine:oxo-acid transaminase activity and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| AGT | Hyperoxaluria and oxalate metabolism | HOGA1-deficient mouse with peroxisomal AGT expression |
| HOGA1 | Primary hyperoxaluria type 3 and kidney stone risk | HOGA1 knockout mouse |
| BCAT1 | Branched-chain amino acid catabolism and cancer metabolism | BCAT1 knockout cell lines and xenografts |
| BCAT2 | Maple syrup urine disease and metabolic myopathy | BCAT2 point-mutation knock-in mice |
| OAT | GABA/glutamate imbalance and neurological disorders | OAT knockout or overexpression neuronal models |
Hyperoxaluria and kidney stone disease
Transamination reactions that use alanine and glyoxylate influence oxalate production. In HOGA1-deficient mice, peroxisomal AGT expression was associated with normal urinary oxalate excretion, suggesting that subcellular localization of transaminase activity can modify disease-relevant oxalate handling. Magnesium-deficient rats also show altered oxalate metabolism, indicating that mineral status can interact with these pathways.
Neurological and neurotransmitter disorders
In the brain, transamination supports the synaptosomal biosynthesis of glutamate and GABA from ornithine, and this pathway is feedback-inhibited by GABA. Perturbations in this chemistry could affect excitatory and inhibitory balance, making GO:0047635 relevant to research on seizure disorders, mood disorders, and other conditions involving GABA or glutamate dysregulation.
Muscle wasting and branched-chain amino acid disorders
Leucine degradation in skeletal muscle depends on transamination to generate 2-oxo acids for oxidation. When this activity is impaired, branched-chain amino acid catabolism may be altered, which is relevant to maple syrup urine disease, cancer cachexia, and metabolic myopathies.
Sulfur amino acid and redox-related pathology
A bovine kidney transaminase can act on L-cystathionine, L-cystine, and related compounds, linking this activity to sulfur amino acid metabolism and redox balance. Disruption of these pathways has been associated with vascular, hepatic, and neurological phenotypes, although direct causal evidence for GO:0047635 in these diseases requires further study.
From L-alanine:oxo-acid transaminase activity-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does loss of a candidate transaminase alter alanine-pyruvate flux? | CRISPR knockout cell line or mouse |
| Does a specific active-site residue control 2-oxo acid substrate specificity? | Point-mutation knock-in of the catalytic residue |
| Does peroxisomal versus mitochondrial localization affect oxalate excretion? | Knock-in of localization tags in AGT |
| Can overexpression of a transaminase complement a metabolic gene deletion? | Overexpression in Mycobacterium smegmatis or mammalian cells |
| Does transaminase activity influence GABA feedback in synaptosomes? | Primary neuronal cultures with OAT or GAD perturbations |
| Does branched-chain amino acid degradation require a specific transaminase? | Muscle-specific knockout of BCAT1 or BCAT2 |
How to Study the L-alanine:oxo-acid transaminase activity Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Coupled enzymatic assay | Transaminase activity with 2-oxo acid substrates | Quantifying enzyme kinetics in tissue extracts |
| Metabolomics | Levels of amino acids and 2-oxo acids | Detecting pathway flux changes after gene perturbation |
| Stable isotope tracing | Carbon and nitrogen flow through transamination | Mapping metabolic rewiring in cells |
| Fluorescence microscopy | Subcellular localization of tagged transaminases | Distinguishing peroxisomal vs mitochondrial roles |
| Western blotting | Protein expression levels | Validating knockout or overexpression efficiency |
| CRISPR knockout screening | Gene essentiality and metabolic dependencies | Identifying transaminases required for growth |
| RNA-seq | Transcriptional changes in transaminase genes | Profiling tissue-specific expression |
| Enzyme-linked assays for oxalate | Urinary oxalate excretion | Assessing kidney stone risk in models |
Coupled enzymatic assays for transaminase activity
Coupled enzymatic assays using 2-oxo acid substrates allow direct measurement of branched-chain L-amino acid aminotransferase activity in tissue extracts. These assays are useful for validating whether a gene product has GO:0047635 activity and for comparing kinetic parameters across substrates.
Metabolomics and flux analysis
Metabolomics can quantify alanine, pyruvate, branched-chain amino acids, and their 2-oxo acid derivatives to infer flux through transamination pathways. Stable isotope tracing can further resolve whether carbons and nitrogen flow through GO:0047635-related reactions in cells and tissues.
Subcellular localization imaging
Fluorescent tagging and fractionation studies can determine whether transaminases localize to peroxisomes, mitochondria, or cytosol, which affects their metabolic role. In HOGA1-deficient mice, peroxisomal versus mitochondrial AGT expression influenced urinary oxalate excretion.
Genetic and pharmacological perturbation
Knockout, knockdown, and overexpression models can test causality between a candidate gene and GO:0047635 activity. For example, overexpression of a newly identified D-amino acid transaminase in Mycobacterium smegmatis complemented glutamate racemase deletion, demonstrating functional assignment by genetic rescue.
How CRISPR Can Be Used to Study GO:0047635 L-alanine:oxo-acid transaminase activity
Knockout
CRISPR knockout of genes encoding candidate transaminases can abolish GO:0047635 activity and reveal its contribution to amino acid catabolism, neurotransmitter precursor supply, or oxalate metabolism. Knockout models are particularly useful when coupled with enzymatic assays and metabolomics to confirm loss of function.
Point Mutation
Point-mutation knock-in of active-site residues can dissect substrate specificity and catalytic mechanism without deleting the entire gene. This approach is valuable for distinguishing enzymes with broad 2-oxo acid acceptor specificity from those with narrow substrate ranges.
Knock-in
Knock-in of localization tags or regulatory elements can test how subcellular targeting affects GO:0047635 function, as shown by peroxisomal versus mitochondrial AGT expression in HOGA1-deficient mice. Knock-in can also introduce disease-associated variants to model human metabolic disorders.
Overexpression
Overexpression of a transaminase can rescue genetic deletions or amplify flux through a pathway, as demonstrated for a D-amino acid transaminase complementing glutamate racemase deletion in Mycobacterium smegmatis. Overexpression models are useful for testing sufficiency and for producing sufficient enzyme for biochemical assays.
How EDITGENE Supports L-alanine:oxo-acid transaminase activity Research
Researchers studying L-alanine:oxo-acid transaminase activity-related genes often need to determine whether a candidate gene is causally involved in a metabolic or disease phenotype. EDITGENE provides CRISPR-based cell models and screening services that enable precise functional interrogation of transaminase genes, from knockout validation to point-mutation dissection of catalytic residues.
Contact EDITGENE today to design your custom CRISPR model for L-alanine:oxo-acid transaminase activity research.
Frequently Asked Questions About L-alanine:oxo-acid transaminase activity
What is GO:0047635?
GO:0047635 is the Gene Ontology molecular function term for L-alanine:oxo-acid transaminase activity, which catalyzes the reversible reaction L-alanine + a 2-oxocarboxylate = an L-alpha-amino acid + pyruvate.
What does L-alanine:oxo-acid transaminase activity do?
It transfers an amino group from L-alanine to a 2-oxo acid, producing pyruvate and a new amino acid, thereby linking amino acid and carbon metabolism.
What genes are involved in L-alanine:oxo-acid transaminase activity?
Genes such as BCAT1, BCAT2, GPT, GPT2, AGT, and OAT encode enzymes with related transaminase chemistry.
Which diseases are linked to L-alanine:oxo-acid transaminase activity?
This activity has been linked to hyperoxaluria and kidney stone disease, neurological conditions involving GABA and glutamate, and branched-chain amino acid disorders.
How is L-alanine:oxo-acid transaminase activity measured?
Coupled enzymatic assays with 2-oxo acid substrates are commonly used to measure this activity in tissue extracts.
What cofactor does L-alanine:oxo-acid transaminase activity require?
Like most aminotransferases, it requires pyridoxal phosphate as a cofactor.
Is L-alanine:oxo-acid transaminase activity reversible?
Yes, the reaction is reversible and can support either amino acid degradation or synthesis depending on substrate availability.
What is the difference between GO:0047635 and alanine aminotransferase?
GO:0047635 is broader because it accepts a range of 2-oxocarboxylate acceptors, whereas alanine aminotransferase typically refers to a narrower substrate range.
How can CRISPR help study L-alanine:oxo-acid transaminase activity?
CRISPR knockout, point-mutation, knock-in, and overexpression models can test the causal role of candidate genes in this activity and its downstream phenotypes.
Where is L-alanine:oxo-acid transaminase activity found in the body?
It has been studied in skeletal muscle, kidney, liver, and brain synaptosomes, reflecting its broad metabolic roles.
Conclusion
GO:0047635, L-alanine:oxo-acid transaminase activity, is a versatile molecular function that connects alanine and pyruvate to a wide range of amino acid and 2-oxo acid pools. Its roles in branched-chain amino acid degradation, sulfur amino acid metabolism, oxalate handling, and neurotransmitter precursor supply make it relevant to metabolic, renal, and neurological research. Because the activity is reversible and substrate-tolerant, precise functional annotation requires experimental validation. CRISPR-based knockout, point-mutation, knock-in, and overexpression models, combined with enzymatic assays and metabolomics, provide a rigorous path to determine which genes carry this activity and how they contribute to disease.
References
- 1. Schadewaldt P et al.. 1996. Coupled enzymatic assay for estimation of branched-chain L-amino acid aminotransferase activity with 2-Oxo acid substrates.. Anal Biochem 238(1):65-71 PMID: 8660588
- 2. Boffa I et al.. 2025. Normal urinary oxalate excretion in 4-hydroxy-2-oxo-glutarate aldolase 1 (HOGA1) deficient mice with AGT expression in peroxisomes and not in mitochondria.. Biochim Biophys Acta Mol Basis Dis 1871(7):167963 PMID: 40578401
- 3. Ricci G et al.. 1986. The transamination of L-cystathionine, L-cystine and related compounds by a bovine kidney transaminase.. Eur J Biochem 157(1):57-63 PMID: 3709533
- 4. Odessey R et al.. 1979. Leucine degradation in cell-free extracts of skeletal muscle.. Biochem J 178(2):475-89 PMID: 444223
- 5. Mortuza R et al.. 2018. Overexpression of a newly identified d-amino acid transaminase in Mycobacterium smegmatis complements glutamate racemase deletion.. Mol Microbiol 107(2):198-213 PMID: 29134701
- 6. Yoneda Y et al.. 1982. A new synaptosomal biosynthetic pathway of glutamate and GABA from ornithine and its negative feedback inhibition by GABA.. J Neurochem 38(6):1686-94 PMID: 6122722
- 7. Markova M et al.. 2005. Determinants of substrate specificity in omega-aminotransferases.. J Biol Chem 280(43):36409-16 PMID: 16096275
- 8. Rattan V et al.. 1993. Oxalate metabolism in magnesium-deficient rats.. Magnes Res 6(2):127-33 PMID: 8274358
