Information on EC 2.6.1.96 - 4-aminobutyrate-pyruvate transaminase

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The enzyme appears in viruses and cellular organisms

EC NUMBER
COMMENTARY hide
2.6.1.96
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RECOMMENDED NAME
GeneOntology No.
4-aminobutyrate-pyruvate transaminase
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REACTION
REACTION DIAGRAM
COMMENTARY hide
ORGANISM
UNIPROT
LITERATURE
4-aminobutanoate + glyoxylate = succinate semialdehyde + glycine
show the reaction diagram
(2)
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4-aminobutanoate + pyruvate = succinate semialdehyde + L-alanine
show the reaction diagram
(1)
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PATHWAY
BRENDA Link
KEGG Link
MetaCyc Link
4-aminobutanoate degradation IV
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Alanine, aspartate and glutamate metabolism
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Butanoate metabolism
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L-glutamate degradation IV
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Metabolic pathways
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Microbial metabolism in diverse environments
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SYSTEMATIC NAME
IUBMB Comments
4-aminobutanoate:pyruvate aminotransferase
Requires pyridoxal 5'-phosphate. The enzyme is found in plants that do not have the 2-oxoglutarate dependent enzyme (cf. EC 2.6.1.19). The reaction with pyruvate is reversible while the reaction with glyoxylate only takes place in the forward direction.
ORGANISM
COMMENTARY hide
LITERATURE
UNIPROT
SEQUENCE DB
SOURCE
gene GABAT1-1 (Salk_007661) and knockout line of ecotype Columbia
UniProt
Manually annotated by BRENDA team
POP2; gene pop2, POP2-3 (CS6387) and knockout line of ecotypes Wassilewskija
UniProt
Manually annotated by BRENDA team
Borkh. cv. Empire
UniProt
Manually annotated by BRENDA team
GENERAL INFORMATION
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
malfunction
enzyme-deficient pop2 flowers accumulate GABA, and the growth of many pop2 pollen tubes is arrested, consistent with their in vitro GABA hypersensitivity. Some pop2 tubes continue to grow toward ovules, yet they are misguided, presumably because they target ectopic GABA on the ovule surface. Wild-type tubes decreased POP2 activity leads to increased levels of GABA throughout the ovule, coupled with aberrant growth and guidance of pop2 pollen tubes
physiological function
additional information
SUBSTRATE
PRODUCT                       
REACTION DIAGRAM
ORGANISM
UNIPROT
COMMENTARY
(Substrate) hide
LITERATURE
(Substrate)
COMMENTARY
(Product) hide
LITERATURE
(Product)
Reversibility
r=reversible
ir=irreversible
?=not specified
4-aminobutanoate + glyoxylate
succinate semialdehyde + glycine
show the reaction diagram
4-aminobutanoate + pyruvate
succinate semialdehyde + L-alanine
show the reaction diagram
glyoxylate + L-alanine
?
show the reaction diagram
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?
additional information
?
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NATURAL SUBSTRATES
NATURAL PRODUCTS
REACTION DIAGRAM
ORGANISM
UNIPROT
COMMENTARY
(Substrate) hide
LITERATURE
(Substrate)
COMMENTARY
(Product) hide
LITERATURE
(Product)
REVERSIBILITY
r=reversible
ir=irreversible
?=not specified
4-aminobutanoate + glyoxylate
succinate semialdehyde + glycine
show the reaction diagram
4-aminobutanoate + pyruvate
succinate semialdehyde + L-alanine
show the reaction diagram
COFACTOR
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
pyridoxal 5'-phosphate
INHIBITORS
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
Aminooxyacetate
effective inhibition at 250 microM
aminooxyacetic acid
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80% inhibition at 2 mM
beta-Alanine
gabaculine
L-glutamine
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11% inhibition at 2 mM
L-ornithine
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40% inhibition at 2 mM
ornithine
Succinic semialdehyde
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67% inhibition at 2 mM
vigabatrin
vinyl-GABA
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specific inhibitor
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additional information
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no or poor inhibition by proline and succinate
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KM VALUE [mM]
SUBSTRATE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
0.077 - 1.2
4-aminobutanoate
0.017 - 0.14
glyoxylate
2.2 - 2.4
L-alanine
0.019 - 0.24
pyruvate
0.014
succinate semialdehyde
reverse reaction with L-alanine, pH 9.0, 30°C
additional information
additional information
Michaelis-Menten kinetic analysis, overview
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TURNOVER NUMBER [1/s]
SUBSTRATE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
0.84 - 10.6
4-aminobutanoate
0.74 - 12.1
glyoxylate
14.1 - 15.4
L-alanine
0.8 - 10.6
pyruvate
10.8
succinate semialdehyde
Arabidopsis thaliana
Q94CE5
reverse reaction with L-alanine, pH 9.0, 30°C
kcat/KM VALUE [1/mMs-1]
SUBSTRATE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
10.4 - 39
4-aminobutanoate
597
45.6 - 88
glyoxylate
101
6.4 - 6.5
L-alanine
103
42.7 - 76
pyruvate
31
770
succinate semialdehyde
Arabidopsis thaliana
Q94CE5
reverse reaction with L-alanine, pH 9.0, 30°C
528
Ki VALUE [mM]
INHIBITOR
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
0.55
beta-Alanine
forward reaction with 4-aminobutanoate and pyruvate, pH 9.0, 30°C
3.7
glycine
forward reaction with 4-aminobutanoate and pyruvate, pH 9.0, 30°C
0.46
ornithine
forward reaction with 4-aminobutanoate and pyruvate, pH 9.0, 30°C
0.62
vigabatrin
forward reaction with 4-aminobutanoate and pyruvate, pH 9.0, 30°C
SPECIFIC ACTIVITY [µmol/min/mg]
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
0.0004
crude enzyme extract, substrate pyruvate, pH 9.0, 30°C
0.0005
AK103274, Q7XN11, Q7XN12
substrate glyoxylate, pH 9.0, 30°C
0.0013
AK103274, Q7XN11, Q7XN12
substrate pyruvate, pH 9.0, 30°C
0.0183
purified recombinant isozyme GABA-T2, with pyruvate as substrate, pH 9.0, 30°C
0.0209
purified recombinant isozyme GABA-T2, with glyoxylate as substrate, pH 9.0, 30°C
0.052
AK103274, Q7XN11, Q7XN12
substrate pyruvate, pH 9.0, 30°C
0.066
AK103274, Q7XN11, Q7XN12
substrate glyoxylate, pH 9.0, 30°C
0.069
AK103274, Q7XN11, Q7XN12
substrate glyoxylate, pH 9.0, 30°C
0.17
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purified enzyme, pH 8.2, temperature not specified in the publication
0.179
purified recombinant isozyme GABA-T3, with glyoxylate as substrate, pH 9.0, 30°C
3.5
purified recombinant isozyme GABA-T1, with glyoxylate as substrate, pH 9.0, 30°C
3.53
purified recombinant full-length enzyme, substrate pyruvate, pH 9.0, 30°C
5.79
purified recombinant isozyme GABA-T1, with pyruvate as substrate, pH 9.0, 30°C
7.54
purified recombinant truncated enzyme, substrate pyruvate, pH 9.0, 30°C
additional information
native GABA-T activity in cell-free extracts of Arabidopsis thaliana ecotype Columbia and corresponding knockout mutant, overview; native GABA-T activity in cell-free extracts of Arabidopsis thaliana ecotype Wassilewskija and corresponding knockout mutant, overview
pH OPTIMUM
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
8.2
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assay at
pH RANGE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
8 - 10.5
pyruvate-dependent forward reaction
TEMPERATURE OPTIMUM
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
SOURCE TISSUE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
SOURCE
; expression is slightly upregulated in veins and petioles compared to leaf veins
Manually annotated by BRENDA team
; expression is slightly upregulated in veins and petioles compared to leaf veins
Manually annotated by BRENDA team
additional information
LOCALIZATION
ORGANISM
UNIPROT
COMMENTARY hide
GeneOntology No.
LITERATURE
SOURCE
additional information
MOLECULAR WEIGHT
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
53400
x * 57500, recombinant full-length GABA-T, SDS-PAGE, x * 53400, recombinant truncated GABA-T, SDS-PAGE
57500
x * 57500, recombinant full-length GABA-T, SDS-PAGE, x * 53400, recombinant truncated GABA-T, SDS-PAGE
SUBUNITS
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
Purification/COMMENTARY
ORGANISM
UNIPROT
LITERATURE
partially from mitochondria
recombinant His-tagged isozyme GABA-T1 from Escherichia coli strain BL-21(DE3) Rosetta (pLysS) by nickel affinity chromatgraphy; recombinant His-tagged isozyme GABA-T2 from Escherichia coli strain BL-21(DE3) Rosetta (pLysS) by nickel affinity chromatgraphy; recombinant His-tagged isozyme GABA-T3 from Escherichia coli strain BL-21(DE3) Rosetta (pLysS) by nickel affinity chromatgraphy
recombinant His6-tagged GABA-T POP2 from Escherichia coli strain BL-21(DE3) Rosetta (pLysS) by nickel affinity chromatography
the pyruvate-dependent GABA-T activity is separated from 2-oxoglutarate-dependent GABA-T activity, EC 2.6.1.19, by two steps of anion exchange chromatography, purification 1530fold
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Cloned/COMMENTARY
ORGANISM
UNIPROT
LITERATURE
DNA and amino acid sequence determination and analysis, functional expression in Escherichia coli
gene GABA-T1, sequencce comparisons, expression of isozyme GABA-T1 in Escherichia coli strain BL21 (DE3), transient expression of fluorescence-labeled GABA-T proteins in onion epidermal cells, two of the four enzymes are targeted to mitochondria, a third to chloroplasts, and the fourth to cytosol; gene GABA-T2, sequencce comparisons, expression of isozyme GABA-T2 in Escherichia coli strain BL21 (DE3), transient expression of fluorescence-labeled GABA-T proteins in onion epidermal cells, two of the four enzymes are targeted to mitochondria, a third to chloroplasts, and the fourth to cytosol; gene GABA-T3, sequence comparisons, expression of isozyme GABA-T3 in Escherichia coli strain BL21 (DE3), transient expression of fluorescence-labeled GABA-T proteins in onion epidermal cells, two of the four enzymes are targeted to mitochondria, a third to chloroplasts, and the fourth to cytosol; gene GABA-T4, sequencce comparisons, expression of isozyme GABA-T4 in Escherichia coli strain BL21 (DE3), transient expression of fluorescence-labeled GABA-T proteins in onion epidermal cells, two of the four enzymes are targeted to mitochondria, a third to chloroplasts, and the fourth to cytosol
gene pop2, expression of N-termminally His6-tagged GABA-T POP2 in Escherichia coli strain BL-21(DE3) Rosetta (pLysS); transient expression of GABA-T in Nicotiana tabacum BY-2 cells. C-terminal myc-tagged GABA-T co-localizes with coexpressed mitochondrial betaATPase-CAT in BY-2 cells
genes pop2-1, pop2-2, and pop2-3, pop2-1 are located on chromosome 3, DNA and amino acid sequennce determination and analysis
isozyme GABA-T1, DNA and amino acid sequence determination and analysis, expression of His-tagged GABA-T1 in Escherichia coli strain BL-21(DE3) Rosetta (pLysS), expression and subcellular localization of tomato GABA-T isozymes in Nicotiana tabacum BY-2 suspension-cultured cells; isozyme GABA-T2, DNA and amino acid sequence determination and analysis, expression of His-tagged GABA-T2 in Escherichia coli strain BL-21(DE3) Rosetta (pLysS), expression and subcellular localization of tomato GABA-T isozymes in Nicotiana tabacum BY-2 suspension-cultured cells; isozyme GABA-T3, DNA and amino acid sequence determination and analysis, expression of His-tagged GABA-T3 in Escherichia coli strain BL-21(DE3) Rosetta (pLysS), expression and subcellular localization of tomato GABA-T isozymes in Nicotiana tabacum BY-2 suspension-cultured cells
removal of the N-terminal targeting presequences yields good recovery of the soluble recombinant proteins in Escherichia coli when they are co-expressed with the GroES/EL molecular chaperone complex
EXPRESSION
ORGANISM
UNIPROT
LITERATURE
in response to water stress, the global GABA-transaminase gene expression level is on average threefold higher; in response to water stress, the global GABA-transaminase gene expression level is on average threefold higher; in response to water stress, the global GABA-transaminase gene expression level is on average threefold higher; in response to water stress, the global GABA-transaminase gene expression level is on average threefold higher
ENGINEERING
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
additional information