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Publié le 11 mars 2023

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1

Han, Qian, Seong Ryul Kim, Haizhen Ding et Jianyong Li. « Evolution of two alanine glyoxylate aminotransferases in mosquito ». Biochemical Journal 397, no 3 (13 juillet 2006) : 473–81. http://dx.doi.org/10.1042/bj20060469.

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In the mosquito, transamination of 3-HK (3-hydroxykynurenine) to XA (xanthurenic acid) is catalysed by an AGT (alanine glyoxylate aminotransferase) and is the major branch pathway of tryptophan metabolism. Interestingly, malaria parasites hijack this pathway to use XA as a chemical signal for development in the mosquito. Here, we report that the mosquito has two AGT isoenzymes. One is the previously cloned AeHKT [Aedes aegypti HKT (3-HK transaminase)] [Han, Fang and Li (2002) J. Biol. Chem. 277, 15781–15787], similar to hAGT (human AGT), which primarily catalyses 3-HK to XA in mosquitoes, and the other is a typical dipteran insect AGT. We cloned the second AGT from Ae. aegypti mosquitoes [AeAGT (Ae. aegypti AGT)], overexpressed the enzyme in baculovirus/insect cells and determined its biochemical characteristics. We also expressed hAGT for a comparative study. The new cloned AeAGT is highly substrate-specific when compared with hAGT and the previously reported AeHKT and Drosophila AGT, and is translated mainly in pupae and adults, which contrasts with AeHKT that is expressed primarily in larvae. Our results suggest that the physiological requirements of mosquitoes and the interaction between the mosquito and its host appear to be the driving force in mosquito AGT evolution.
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2

Wang, Bing-Jun, Jing-Ming Xia, Qian Wang, Jiang-Long Yu, Zhiyin Song et Huabin Zhao. « Diet and Adaptive Evolution of Alanine-Glyoxylate Aminotransferase Mitochondrial Targeting in Birds ». Molecular Biology and Evolution 37, no 3 (8 novembre 2019) : 786–98. http://dx.doi.org/10.1093/molbev/msz266.

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Abstract Adaptations to different diets represent a hallmark of animal diversity. The diets of birds are highly variable, making them an excellent model system for studying adaptive evolution driven by dietary changes. To test whether molecular adaptations to diet have occurred during the evolution of birds, we examined a dietary enzyme alanine-glyoxylate aminotransferase (AGT), which tends to target mitochondria in carnivorous mammals, peroxisomes in herbivorous mammals, and both mitochondria and peroxisomes in omnivorous mammals. A total of 31 bird species were examined in this study, which included representatives of most major avian lineages. Of these, 29 have an intact mitochondrial targeting sequence (MTS) of AGT. This finding is in stark contrast to mammals, which showed a number of independent losses of the MTS. Our cell-based functional assays revealed that the efficiency of AGT mitochondrial targeting was greatly reduced in unrelated lineages of granivorous birds, yet it tended to be high in insectivorous and carnivorous lineages. Furthermore, we found that proportions of animal tissue in avian diets were positively correlated with mitochondrial targeting efficiencies that were experimentally determined, but not with those that were computationally predicted. Adaptive evolution of AGT mitochondrial targeting in birds was further supported by the detection of positive selection on MTS regions. Our study contributes to the understanding of how diet drives molecular adaptations in animals, and suggests that caution must be taken when computationally predicting protein subcellular targeting.
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3

Cooper, P. J., C. J. Danpure, P. J. Wise et K. M. Guttridge. « Immunocytochemical localization of human hepatic alanine : glyoxylate aminotransferase in control subjects and patients with primary hyperoxaluria type 1. » Journal of Histochemistry & ; Cytochemistry 36, no 10 (octobre 1988) : 1285–94. http://dx.doi.org/10.1177/36.10.3418107.

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Primary hyperoxaluria type 1 (PH1) is an inherited disorder of glyoxylate metabolism caused by a deficiency of the hepatic peroxisomal enzyme alanine: glyoxylate aminotransferase (AGT; EC 2.6.1.44) [FEBS Lett (1986) 201:20]. The aim of the present study was to investigate the intracellular distribution of immunoreactive AGT protein, using protein A-gold immunocytochemistry, in normal human liver and in livers of PH1 patients with (CRM+) or without (CRM-) immunologically crossreacting enzyme protein. In all CRM+ individuals, which included three controls, a PH1 heterozygote and a PH1 homozygote immunoreactive AGT protein was confined to peroxisomes, where it was randomly dispersed throughout the peroxisomal matrix with no obvious association with the peroxisomal membrane. No AGT protein could be detected in the peroxisomes or other cytoplasmic compartments in the livers of CRM- PH1 patients (homozygotes). The peroxisomal labeling density in the CRM+ PH1 patient, who was completely deficient in AGT enzyme activity, was similar to that of the controls. In addition, in the PH1 heterozygote, who had one third normal AGT enzyme activity, peroxisomal labeling density was reduced to 50% of normal.
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4

Hameed, Mohammed, Kashif Eqbal, Beena Nair, Alexander Woywodt et Aimun Ahmed. « Late Diagnosis of Primary Hyperoxaluria by Crystals in the Bone Marrow ! » Nephrology @ Point of Care 1, no 1 (janvier 2015) : napoc.2015.1467. http://dx.doi.org/10.5301/napoc.2015.14679.

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Primary hyperoxaluria type 1 (PH1) is a rare, inherited, autosomal recessive, metabolic disorder caused by a deficiency of peroxisomal alanine-glyoxylate aminotransferase (AGT). We describe here a case of a 57-year-old man with End Stage Renal Disease, where the late age of presentation of PH T1 due to marked heterogeneity of disease expression caused a delay in diagnosis, and we discuss the causes of the poor outcome typical of this condition
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5

Danpure, Christopher J., et Patricia R. Jennings. « Further studies on the activity and subcellular distribution of alanine : Glyoxylate aminotransferase in the livers of patients with primary hyperoxaluria type 1 ». Clinical Science 75, no 3 (1 septembre 1988) : 315–22. http://dx.doi.org/10.1042/cs0750315.

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1. The activity of alanine:glyoxylate aminotransferase (AGT; EC 2.6.1.44) has been measured in the unfractionated livers of 20 patients with primary hyperoxaluria type 1 (PH1), three patients with other forms of primary hyperoxaluria and one PH1 heterozygote. The subcellular distribution of AGT activity was examined in four of the PH1 livers and in the liver of the PH1 heterozygote. 2. The mean AGT activity in the unfractionated PH1 livers was 12.6% of the mean control value. The activities of other aminotransferases and the peroxisomal marker enzymes were normal. When corrected for cross-over from glutamate:glyoxylate aminotransferase (GGT; EC 2.6.1.4), the mean AGT activity in the PH1 livers was reduced to 3.3% of the control values. 3. The livers from a patient with primary hyperoxaluria type 2 (d-glycerate dehydrogenase deficiency) and one with an undefined form of primary hyperoxaluria (possibly oxalate hyperabsorption) had normal AGT levels. The livers of a very mild PH1-type variant and a PH1 heterozygote had intermediate levels of AGT activity. 4. Subcellular fractionation of four PH1 livers by sucrose gradient isopycnic centrifugation demonstrated a complete absence of peroxisomal AGT activity. The subcellular distribution of the residual AGT activity was very similar to that of GGT activity (i.e. mainly cytosolic with a small amount mitochondrial). There were no alterations in the subcellular distributions of any of the peroxisomal marker enzymes. The subcellular distribution of AGT activity in the PH1 heterozygote liver was similar to that of the control (i.e. mainly peroxisomal). 5. The residual AGT activity in two of the PH1 livers, which could be accounted for largely by cross-over from GGT, was only slightly dependent on substrate (glyoxylate and alanine) concentration and virtually independent of cofactor (pyridoxal phosphate) concentration. 6. These data confirm our previous findings (C. J. Danpure & P. R. Jennings, FEBS Letters, 1986, 201, 20–24), but on a much larger number of patients, that AGT deficiency is pathognomic for PH1, and is not found in other forms of hyperoxaluria.
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6

Cellini, Barbara, Mariarita Bertoldi, Riccardo Montioli, Alessandro Paiardini et Carla Borri Voltattorni. « Human wild-type alanine:glyoxylate aminotransferase and its naturally occurring G82E variant : functional properties and physiological implications ». Biochemical Journal 408, no 1 (29 octobre 2007) : 39–50. http://dx.doi.org/10.1042/bj20070637.

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Human hepatic peroxisomal AGT (alanine:glyoxylate aminotransferase) is a PLP (pyridoxal 5′-phosphate)-dependent enzyme whose deficiency causes primary hyperoxaluria Type I, a rare autosomal recessive disorder. To acquire experimental evidence for the physiological function of AGT, the Keq,overall of the reaction, the steady-state kinetic parameters of the forward and reverse reactions, and the pre-steady-state kinetics of the half-reactions of the PLP form of AGT with L-alanine or glycine and the PMP (pyridoxamine 5′-phosphate) form with pyruvate or glyoxylate have been measured. The results indicate that the enzyme is highly specific for catalysing glyoxylate to glycine processing, thereby playing a key role in glyoxylate detoxification. Analysis of the reaction course also reveals that PMP remains bound to the enzyme during the catalytic cycle and that the AGT–PMP complex displays a reactivity towards oxo acids higher than that of apoAGT in the presence of PMP. These findings are tentatively related to possible subtle rearrangements at the active site also indicated by the putative binding mode of catalytic intermediates. Additionally, the catalytic and spectroscopic features of the naturally occurring G82E variant have been analysed. Although, like the wild-type, the G82E variant is able to bind 2 mol PLP/dimer, it exhibits a significant reduced affinity for PLP and even more for PMP compared with wild-type, and an altered conformational state of the bound PLP. The striking molecular defect of the mutant, consisting in the dramatic decrease of the overall catalytic activity (∼0.1% of that of normal AGT), appears to be related to the inability to undergo an efficient transaldimination of the PLP form of the enzyme with amino acids as well as an efficient conversion of AGT–PMP into AGT–PLP. Overall, careful biochemical analyses have allowed elucidation of the mechanism of action of AGT and the way in which the disease causing G82E mutation affects it.
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7

Harambat, Jérôme, Sonia Fargue, Justine Bacchetta, Cécile Acquaviva et Pierre Cochat. « Primary Hyperoxaluria ». International Journal of Nephrology 2011 (2011) : 1–11. http://dx.doi.org/10.4061/2011/864580.

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Primary hyperoxalurias (PH) are inborn errors in the metabolism of glyoxylate and oxalate. PH type 1, the most common form, is an autosomal recessive disorder caused by a deficiency of the liver-specific enzyme alanine, glyoxylate aminotransferase (AGT) resulting in overproduction and excessive urinary excretion of oxalate. Recurrent urolithiasis and nephrocalcinosis are the hallmarks of the disease. As glomerular filtration rate decreases due to progressive renal damage, oxalate accumulates leading to systemic oxalosis. Diagnosis is often delayed and is based on clinical and sonographic findings, urinary oxalate assessment, DNA analysis, and, if necessary, direct AGT activity measurement in liver biopsy tissue. Early initiation of conservative treatment, including high fluid intake, inhibitors of calcium oxalate crystallization, and pyridoxine in responsive cases, can help to maintain renal function in compliant subjects. In end-stage renal disease patients, the best outcomes have been achieved with combined liver-kidney transplantation which corrects the enzyme defect.
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8

Danpure, C. J., P. J. Cooper, P. J. Wise et P. R. Jennings. « An enzyme trafficking defect in two patients with primary hyperoxaluria type 1 : peroxisomal alanine/glyoxylate aminotransferase rerouted to mitochondria. » Journal of Cell Biology 108, no 4 (1 avril 1989) : 1345–52. http://dx.doi.org/10.1083/jcb.108.4.1345.

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Most patients with the autosomal recessive disease primary hyperoxaluria type 1 (PH1) have a complete deficiency of alanine/glyoxylate aminotransferase (AGT) enzyme activity and immunoreactive protein. However a few possess significant residual activity and protein. In normal human liver, AGT is entirely peroxisomal, whereas it is entirely mitochondrial in carnivores, and both peroxisomal and mitochondrial in rodents. Using the techniques of isopycnic sucrose and Percoll density gradient centrifugation and quantitative protein A-gold immunoelectron microscopy, we have found that in two PH1 patients, possessing 9 and 27% residual AGT activity, both the enzyme activity and immunoreactive protein were largely mitochondrial and not peroxisomal. In addition, these individuals were more severely affected than expected from the levels of their residual AGT activity. In these patients, the PH1 appears to be due, at least in part, to a unique trafficking defect, in which peroxisomal AGT is diverted to the mitochondria. To our knowledge, this is the first example of a genetic disease caused by such interorganellar rerouting.
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9

Purdue, P. E., Y. Takada et C. J. Danpure. « Identification of mutations associated with peroxisome-to-mitochondrion mistargeting of alanine/glyoxylate aminotransferase in primary hyperoxaluria type 1. » Journal of Cell Biology 111, no 6 (1 décembre 1990) : 2341–51. http://dx.doi.org/10.1083/jcb.111.6.2341.

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We have previously shown that in some patients with primary hyperoxaluria type 1 (PH1), disease is associated with mistargeting of the normally peroxisomal enzyme alanine/glyoxylate aminotransferase (AGT) to mitochondria (Danpure, C.J., P.J. Cooper, P.J. Wise, and P.R. Jennings. J. Cell Biol. 108:1345-1352). We have synthesized, amplified, cloned, and sequenced AGT cDNA from a PH1 patient with mitochondrial AGT (mAGT). This identified three point mutations that cause amino acid substitutions in the predicted AGT protein sequence. Using PCR and allele-specific oligonucleotide hybridization, a range of PH1 patients and controls were screened for these mutations. This revealed that all eight PH1 patients with mAGT carried at least one allele with the same three mutations. Two were homozygous for this allele and six were heterozygous. In at least three of the heterozygotes, it appeared that only the mutant allele was expressed. All three mutations were absent from PH1 patients lacking mAGT. One mutation encoding a Gly----Arg substitution at residue 170 was not found in any of the control individuals. However, the other two mutations, encoding Pro----Leu and Ile----Met substitutions at residues 11 and 340, respectively, cosegregated in the normal population at an allelic frequency of 5-10%. In an individual homozygous for this allele (substitutions at residues 11 and 340) only a small proportion of AGT appeared to be rerouted to mitochondria. It is suggested that the substitution at residue 11 generates an amphiphilic alpha-helix with characteristics similar to recognized mitochondrial targeting sequences, the full functional expression of which is dependent upon coexpression of the substitution at residue 170, which may induce defective peroxisomal import.
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10

AMOROSO, ANTONIO, DOROTI PIRULLI, FIORELLA FLORIAN, DANIELA PUZZER, MICHELE BONIOTTO, SERGIO CROVELLA, SILVIA ZEZLINA et al. « AGXTGene Mutations and Their Influence on Clinical Heterogeneity of Type 1 Primary Hyperoxaluria ». Journal of the American Society of Nephrology 12, no 10 (octobre 2001) : 2072–79. http://dx.doi.org/10.1681/asn.v12102072.

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Abstract. Primary hyperoxaluria type 1 (PH1) is an autosomal recessive disorder that is caused by a deficiency of alanine: glyoxylate aminotransferase (AGT), which is encoded by a single copy gene (AGXT). Molecular diagnosis was used in conjunction with clinical, biochemical, and enzymological data to evaluate genotype-phenotype correlation. Twenty-three unrelated, Italian PH1 patients were studied, 20 of which were grouped according to severe form of PH1 (group A), adult form (group B), and mild to moderate decrease in renal function (group C). All 23 patients were analyzed by using the single-strand conformation polymorphism technique followed by the sequencing of the 11AGXTexons. Relevant chemistries, including plasma, urine and dialyzate oxalate and glycolate assays, liver AGT activity, and pyridoxine responsiveness, were performed. Both mutant alleles were found in 21 out of 23 patients, and 13 different mutations were recognized in exons 1, 2, 4, and 10. Normalized AGT activity was lower in the severe form than in the adult form (P< 0.05). Double heterozygous patients presented a lower age at the onset of the disease (P= 0.025), and they were more frequent in group A (75%) than in the group B (14%;P= 0.0406). The T444C mutation was more frequent in the severe form (P< 0.05), and the opposite was observed for G630A (P< 0.05). G630A mutation homozygotes had a higher AGT residual activity (P= 0.00001). This study confirms the allelic heterogeneity of theAGXT, which could to some extent be responsible for the phenotypic heterogeneity in PH1.
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Motley, A., M. J. Lumb, P. B. Oatey, P. R. Jennings, P. A. De Zoysa, R. J. Wanders, H. F. Tabak et C. J. Danpure. « Mammalian alanine/glyoxylate aminotransferase 1 is imported into peroxisomes via the PTS1 translocation pathway. Increased degeneracy and context specificity of the mammalian PTS1 motif and implications for the peroxisome-to-mitochondrion mistargeting of AGT in primary hyperoxaluria type 1. » Journal of Cell Biology 131, no 1 (1 octobre 1995) : 95–109. http://dx.doi.org/10.1083/jcb.131.1.95.

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Alanine/glyoxylate aminotransferase 1 (AGT) is peroxisomal in most normal humans, but in some patients with the hereditary disease primary hyperoxaluria type 1 (PH1), AGT is mislocalized to the mitochondria. In an attempt to identify the sequences in AGT that mediate its targeting to peroxisomes, and to determine the mechanism by which AGT is mistargeted in PH1, we have studied the intracellular compartmentalization of various normal and mutant AGT polypeptides in normal human fibroblasts and cell lines with selective deficiencies of peroxisomal protein import, using immunofluorescence microscopy after intranuclear microinjection of AGT expression plasmids. The results show that AGT is imported into peroxisomes via the peroxisomal targeting sequence type 1 (PTS1) translocation pathway. Although the COOH-terminal KKL of human AGT was shown to be necessary for its peroxisomal import, this tripeptide was unable to direct the peroxisomal import of the bona fide peroxisomal protein firefly luciferase or the reporter protein bacterial chloramphenicol acetyltransferase. An ill-defined region immediately upstream of the COOH-terminal KKL was also found to be necessary for the peroxisomal import of AGT, but again this region was found to be insufficient to direct the peroxisomal import of chloramphenicol acetyltransferase. Substitution of the COOH-terminal KKL of human AGT by the COOH-terminal tripeptides found in the AGTs of other mammalian species (SQL, NKL), the prototypical PTS1 (SKL), or the glycosomal PTS1 (SSL) also allowed peroxisomal targeting, showing that the allowable PTS1 motif in AGT is considerably more degenerate than, or at least very different from, that acceptable in luciferase. AGT possessing the two amino acid substitutions responsible for its mistargeting in PH1 (i.e., Pro11--&gt;Leu and Gly170--&gt;Arg) was targeted mainly to the mitochondria. However, AGTs possessing each amino acid substitution on its own were targeted normally to the peroxisomes. This suggests that Gly170--&gt;Arg-mediated increased functional efficiency of the otherwise weak mitochondrial targeting sequence (generated by the Pro11--&gt;Leu polymorphism) is not due to interference with the peroxisomal targeting or import of AGT.
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12

Chen, Huaqing, Biswajit Bhowmick, Yu Tang, Jesus Lozano-Fernandez et Qian Han. « Biochemical Evolution of a Potent Target of Mosquito Larvicide, 3-Hydroxykynurenine Transaminase ». Molecules 27, no 15 (2 août 2022) : 4929. http://dx.doi.org/10.3390/molecules27154929.

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A specific mosquito enzyme, 3-hydroxykynurenine transaminase (HKT), is involved in the processing of toxic metabolic intermediates of the tryptophan metabolic pathway. The HKT enzymatic product, xanthurenic acid, is required for Plasmodium spp. development in the mosquito vectors. Therefore, an inhibitor of HKT may not only be a mosquitocide but also a malaria-transmission blocker. In this work, we present a study investigating the evolution of HKT, which is a lineage-specific duplication of an alanine glyoxylate aminotransferases (AGT) in mosquitoes. Synteny analyses, together with the phylogenetic history of the AGT family, suggests that HKT and the mosquito AGTs are paralogous that were formed via a duplication event in their common ancestor. Furthermore, 41 amino acid sites with significant evidence of positive selection were identified, which could be responsible for biochemical and functional evolution and the stability of conformational stabilization. To get a deeper understanding of the evolution of ligands’ capacity and the ligand-binding mechanism of HKT, the sequence and the 3D homology model of the common ancestor of HKT and AGT in mosquitoes, ancestral mosquito AGT (AncMosqAGT), were inferred and built. The homology model along with 3-hydroxykynurenine, kynurenine, and alanine were used in docking experiments to predict the binding capacity and ligand-binding mode of the new substrates related to toxic metabolites detoxification. Our study provides evidence for the dramatic biochemical evolution of the key detoxifying enzyme and provides potential sites that could hinder the detoxification function, which may be used in mosquito larvicide and design.
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Whatley, Jordan S., et Carla M. Koehler. « 769 – Identifying Small Molecules to Correct Abnormal Protein Trafficking of Alanine-Glyoxylate Aminotransferase (AGT) in a Human Cell Model of Primary Hyperoxaluria Type I to Avoid Need for Liver Transplantation ». Gastroenterology 156, no 6 (mai 2019) : S—1214—S—1215. http://dx.doi.org/10.1016/s0016-5085(19)40020-6.

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Michalkova, Veronika, Joshua B. Benoit, Brian L. Weiss, Geoffrey M. Attardo et Serap Aksoy. « Vitamin B6Generated by Obligate Symbionts Is Critical for Maintaining Proline Homeostasis and Fecundity in Tsetse Flies ». Applied and Environmental Microbiology 80, no 18 (18 juillet 2014) : 5844–53. http://dx.doi.org/10.1128/aem.01150-14.

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ABSTRACTThe viviparous tsetse fly utilizes proline as a hemolymph-borne energy source. In tsetse, biosynthesis of proline from alanine involves the enzyme alanine-glyoxylate aminotransferase (AGAT), which requires pyridoxal phosphate (vitamin B6) as a cofactor. This vitamin can be synthesized by tsetse's obligate symbiont,Wigglesworthia glossinidia. In this study, we examined the role ofWigglesworthia-produced vitamin B6for maintenance of proline homeostasis, specifically during the energetically expensive lactation period of the tsetse's reproductive cycle. We found that expression ofagat, as well as genes involved in vitamin B6metabolism in both host and symbiont, increases in lactating flies. Removal of symbionts via antibiotic treatment of flies (aposymbiotic) led to hypoprolinemia, reduced levels of vitamin B6in lactating females, and decreased fecundity. Proline homeostasis and fecundity recovered partially when aposymbiotic tsetse were fed a diet supplemented with either yeast orWigglesworthiaextracts. RNA interference-mediated knockdown ofagatin wild-type flies reduced hemolymph proline levels to that of aposymbiotic females. Aposymbiotic flies treated withagatshort interfering RNA (siRNA) remained hypoprolinemic even upon dietary supplementation with microbial extracts or B vitamins. Flies infected with parasitic African trypanosomes display lower hemolymph proline levels, suggesting that the reduced fecundity observed in parasitized flies could result from parasite interference with proline homeostasis. This interference could be manifested by competition between tsetse and trypanosomes for vitamins, proline, or other factors involved in their synthesis. Collectively, these results indicate that the presence ofWigglesworthiain tsetse is critical for the maintenance of proline homeostasis through vitamin B6production.
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Pey, Angel L., Armando Albert et Eduardo Salido. « Protein Homeostasis Defects of Alanine-Glyoxylate Aminotransferase : New Therapeutic Strategies in Primary Hyperoxaluria Type I ». BioMed Research International 2013 (2013) : 1–15. http://dx.doi.org/10.1155/2013/687658.

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Alanine-glyoxylate aminotransferase catalyzes the transamination between L-alanine and glyoxylate to produce pyruvate and glycine using pyridoxal 5′-phosphate (PLP) as cofactor. Human alanine-glyoxylate aminotransferase is a peroxisomal enzyme expressed in the hepatocytes, the main site of glyoxylate detoxification. Its deficit causes primary hyperoxaluria type I, a rare but severe inborn error of metabolism. Single amino acid changes are the main type of mutation causing this disease, and considerable effort has been dedicated to the understanding of the molecular consequences of such missense mutations. In this review, we summarize the role of protein homeostasis in the basic mechanisms of primary hyperoxaluria. Intrinsic physicochemical properties of polypeptide chains such as thermodynamic stability, folding, unfolding, and misfolding rates as well as the interaction of different folding states with protein homeostasis networks are essential to understand this disease. The view presented has important implications for the development of new therapeutic strategies based on targeting specific elements of alanine-glyoxylate aminotransferase homeostasis.
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Orzechowski, S., J. Socha-Hanc et A. Paszkowski. « Alanine aminotransferase and glycine aminotransferase from maize (Zea mays L.) leaves. » Acta Biochimica Polonica 46, no 2 (30 juin 1999) : 447–57. http://dx.doi.org/10.18388/abp.1999_4176.

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Alanine aminotransferase (AlaAT, EC 2.6.1.2) and glycine aminotransferase (GlyAT, EC 2.6.1.4), two different enzymes catalyzing transamination reactions with L-alanine as the amino-acid substrate, were examined in maize in which alanine participates substantially in nitrogen transport. Preparative PAGE of a partially purified preparation of aminotransferases from maize leaves gave 6 fractions differing in electrophoretic mobility. The fastest migrating fraction I represents AlaAT specific for L-alanine as amino donor and 2-oxoglutarate as amino acceptor. The remaining fractions showed three aminotransferase activities: L-alanine-2-oxoglutarate, L-alanine-glyoxylate and L-glutamate-glyoxylate. By means of molecular sieving on Zorbax SE-250 two groups of enzymes were distinguished in the PAGE fractions: of about 100 kDa and 50 kDa. Molecular mass of 104 kDa was ascribed to AlaAT in fraction I, while the molecular mass of the three enzymatic activities in 3 fractions of the low electrophoretic mobility was about 50 kDa. The response of these fractions to: aminooxyacetate, 3-chloro-L-alanine and competing amino acids prompted us to suggest that five out of the six preparative PAGE fractions represented GlyAT isoforms, differing from each other by the L-glutamate-glyoxylate:L-alanine-glyoxylate:L-alanine-2-oxoglutarate activity ratio.
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Han, Qian, Cihan Yang, Jun Lu, Yinai Zhang et Jianyong Li. « Metabolism of Oxalate in Humans : A Potential Role Kynurenine Aminotransferase/Glutamine Transaminase/Cysteine Conjugate Betalyase Plays in Hyperoxaluria ». Current Medicinal Chemistry 26, no 26 (22 octobre 2019) : 4944–63. http://dx.doi.org/10.2174/0929867326666190325095223.

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Hyperoxaluria, excessive urinary oxalate excretion, is a significant health problem worldwide. Disrupted oxalate metabolism has been implicated in hyperoxaluria and accordingly, an enzymatic disturbance in oxalate biosynthesis can result in the primary hyperoxaluria. Alanine-glyoxylate aminotransferase-1 and glyoxylate reductase, the enzymes involving glyoxylate (precursor for oxalate) metabolism, have been related to primary hyperoxalurias. Some studies suggest that other enzymes such as glycolate oxidase and alanine-glyoxylate aminotransferase-2 might be associated with primary hyperoxaluria as well, but evidence of a definitive link is not strong between the clinical cases and gene mutations. There are still some idiopathic hyperoxalurias, which require a further study for the etiologies. Some aminotransferases, particularly kynurenine aminotransferases, can convert glyoxylate to glycine. Based on biochemical and structural characteristics, expression level, and subcellular localization of some aminotransferases, a number of them appear able to catalyze the transamination of glyoxylate to glycine more efficiently than alanine glyoxylate aminotransferase-1. The aim of this minireview is to explore other undermining causes of primary hyperoxaluria and stimulate research toward achieving a comprehensive understanding of underlying mechanisms leading to the disease. Herein, we reviewed all aminotransferases in the liver for their functions in glyoxylate metabolism. Particularly, kynurenine aminotransferase-I and III were carefully discussed regarding their biochemical and structural characteristics, cellular localization, and enzyme inhibition. Kynurenine aminotransferase-III is, so far, the most efficient putative mitochondrial enzyme to transaminate glyoxylate to glycine in mammalian livers, which might be an interesting enzyme to look for in hyperoxaluria etiology of primary hyperoxaluria and should be carefully investigated for its involvement in oxalate metabolism.
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18

Sakuraba, Haruhiko. « Studies on Avian Peroxisomal Alanine : Glyoxylate Aminotransferase ». Journal of the Kyushu Dental Society 45, no 3 (1991) : 390–408. http://dx.doi.org/10.2504/kds.45.390.

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Behnam, Joseph T., Emma L. Williams, Susanne Brink, Gill Rumsby et Christopher J. Danpure. « Reconstruction of human hepatocyte glyoxylate metabolic pathways in stably transformed Chinese-hamster ovary cells ». Biochemical Journal 394, no 2 (10 février 2006) : 409–16. http://dx.doi.org/10.1042/bj20051397.

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Failure to detoxify the intermediary metabolite glyoxylate in human hepatocytes underlies the metabolic pathology of two potentially lethal hereditary calcium oxalate kidney stone diseases, PH (primary hyperoxaluria) types 1 and 2. In order to define more clearly the roles of enzymes involved in the metabolism of glyoxylate, we have established singly, doubly and triply transformed CHO (Chinese-hamster ovary) cell lines, expressing all combinations of normal human AGT (alanine:glyoxylate aminotransferase; the enzyme deficient in PH1), GR/HPR (glyoxylate/hydroxypyruvate reductase; the enzyme deficient in PH2), and GO (glycolate oxidase). We have embarked on the preliminary metabolic analysis of these transformants by studying the indirect toxicity of glycolate as a simple measure of the net intracellular production of glyoxylate. Our results show that glycolate is toxic only to those cells expressing GO and that this toxicity is diminished when AGT and/or GR/HPR are expressed in addition to GO. This finding indicates that we have been able to reconstruct the glycolate→glyoxylate, glyoxylate→glycine, and glyoxylate→glycolate metabolic pathways, catalysed by GO, AGT, and GR/HPR respectively, in cells that do not normally express them. These results are compatible with the findings in PH1 and PH2, in which AGT and GR/HPR deficiencies lead to increased oxalate synthesis, due to the failure to detoxify its immediate precursor glyoxylate. These CHO cell transformants have a potential use as a cell-based bioassay for screening small molecules that stabilize AGT or GR/HPR and might have use in the treatment of PH1 or PH2.
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Dindo, Mirco, Silvia Grottelli, Giannamaria Annunziato, Giorgio Giardina, Marco Pieroni, Gioena Pampalone, Andrea Faccini et al. « Cycloserine enantiomers are reversible inhibitors of human alanine:glyoxylate aminotransferase : implications for Primary Hyperoxaluria type 1 ». Biochemical Journal 476, no 24 (20 décembre 2019) : 3751–68. http://dx.doi.org/10.1042/bcj20190507.

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Peroxisomal alanine:glyoxylate aminotransferase (AGT) is responsible for glyoxylate detoxification in human liver and utilizes pyridoxal 5′-phosphate (PLP) as coenzyme. The deficit of AGT leads to Primary Hyperoxaluria Type I (PH1), a rare disease characterized by calcium oxalate stones deposition in the urinary tract as a consequence of glyoxylate accumulation. Most missense mutations cause AGT misfolding, as in the case of the G41R, which induces aggregation and proteolytic degradation. We have investigated the interaction of wild-type AGT and the pathogenic G41R variant with d-cycloserine (DCS, commercialized as Seromycin), a natural product used as a second-line treatment of multidrug-resistant tuberculosis, and its synthetic enantiomer l-cycloserine (LCS). In contrast with evidences previously reported on other PLP-enzymes, both ligands are AGT reversible inhibitors showing inhibition constants in the micromolar range. While LCS undergoes half-transamination generating a ketimine intermediate and behaves as a classical competitive inhibitor, DCS displays a time-dependent binding mainly generating an oxime intermediate. Using a mammalian cellular model, we found that DCS, but not LCS, is able to promote the correct folding of the G41R variant, as revealed by its increased specific activity and expression as a soluble protein. This effect also translates into an increased glyoxylate detoxification ability of cells expressing the variant upon treatment with DCS. Overall, our findings establish that DCS could play a role as pharmacological chaperone, thus suggesting a new line of intervention against PH1 based on a drug repositioning approach. To a widest extent, this strategy could be applied to other disease-causing mutations leading to AGT misfolding.
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Moreira, C., L. Martinat, J. F. Salaun et A. Bensman. « Hyperoxalurie primitive sans anomalie en alanine glyoxylate-aminotransférase (AGT) ». Archives de Pédiatrie 5, no 7 (juillet 1998) : 824. http://dx.doi.org/10.1016/s0929-693x(98)80102-4.

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夏, 敬明. « Introduction and Research Progress of Alanine-Glyoxylate Aminotransferase ». Open Journal of Nature Science 06, no 05 (2018) : 409–15. http://dx.doi.org/10.12677/ojns.2018.65053.

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Donini, Stefano, Manuela Ferrari, Chiara Fedeli, Marco Faini, Ilaria Lamberto, Ada Serena Marletta, Lara Mellini et al. « Recombinant production of eight human cytosolic aminotransferases and assessment of their potential involvement in glyoxylate metabolism ». Biochemical Journal 422, no 2 (13 août 2009) : 265–72. http://dx.doi.org/10.1042/bj20090748.

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PH1 (primary hyperoxaluria type 1) is a severe inborn disorder of glyoxylate metabolism caused by a functional deficiency of the peroxisomal enzyme AGXT (alanine-glyoxylate aminotransferase), which converts glyoxylate into glycine using L-alanine as the amino-group donor. Even though pre-genomic studies indicate that other human transaminases can convert glyoxylate into glycine, in PH1 patients these enzymes are apparently unable to compensate for the lack of AGXT, perhaps due to their limited levels of expression, their localization in an inappropriate cell compartment or the scarcity of the required amino-group donor. In the present paper, we describe the cloning of eight human cytosolic aminotransferases, their recombinant expression as His6-tagged proteins and a comparative study on their ability to transaminate glyoxylate, using any standard amino acid as an amino-group donor. To selectively quantify the glycine formed, we have developed and validated an assay based on bacterial GO (glycine oxidase); this assay allows the detection of enzymes that produce glycine by transamination in the presence of mixtures of potential amino-group donors and without separation of the product from the substrates. We show that among the eight enzymes tested, only GPT (alanine transaminase) and PSAT1 (phosphoserine aminotransferase 1) can transaminate glyoxylate with good efficiency, using L-glutamate (and, for GPT, also L-alanine) as the best amino-group donor. These findings confirm that glyoxylate transamination can occur in the cytosol, in direct competition with the conversion of glyoxylate into oxalate. The potential implications for the treatment of primary hyperoxaluria are discussed.
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Rumsby, G., T. Weir et C. T. Samuell. « A Semiautomated Alanine : Glyoxylate Aminotransferase Assay for the Tissue Diagnosis of Primary Hyperoxaluria Type 1 ». Annals of Clinical Biochemistry : International Journal of Laboratory Medicine 34, no 4 (juillet 1997) : 400–404. http://dx.doi.org/10.1177/000456329703400411.

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We have developed a sensitive assay for the measurement of alanine:glyoxylate aminotransferase (EC 2.6.1.44) activity in human liver. The assay is partly automated, and takes into consideration the sensitivity of the reaction to pH and to glyoxylate concentration. It is less subject to interference from other enzymes utilizing glyoxylate and to chemical interference from glyoxylate itself and can therefore be used without correction for cross-over by glutamate:glyoxylate aminotransferase (EC 2.6.1.4). The assay allows clear discrimination between normal and affected livers and is sufficiently sensitive to measure enzyme activity in fetal liver samples. Enzyme activity ranged from 17·9 to 38·5 μmol/h/mg protein in control livers ( n = 9) and 0·8 to 9·5 μmol/h/mg protein in 30 of 39 hyperoxaluric patients studied. Normal alanine: glyoxylate aminotransferase activity (from 22·8 to 45·5 μmol/h/mg protein) allowed exclusion of primary hyperoxaluria type 1 in the other nine hyperoxaluric patients.
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COOPER, Arthur J. L., Boris F. KRASNIKOV, Etsuo OKUNO et Thomas M. JEITNER. « l-Alanine–glyoxylate aminotransferase II of rat kidney and liver mitochondria possesses cysteine S-conjugate β-lyase activity : a contributing factor to the nephrotoxicity/hepatotoxicity of halogenated alkenes ? » Biochemical Journal 376, no 1 (15 novembre 2003) : 169–78. http://dx.doi.org/10.1042/bj20030988.

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Several halogenated alkenes are metabolized in part to cysteine S-conjugates, which are mitochondrial toxicants of kidney and, to a lesser extent, other organs. Toxicity is due to cysteine S-conjugate β-lyases, which convert the cysteine S-conjugate into pyruvate, ammonia and a reactive sulphur-containing fragment. A section of the human population is exposed to halogenated alkenes. To understand the health effects of such exposure, it is important to identify cysteine S-conjugate β-lyases that contribute to mitochondrial damage. Mitochondrial aspartate aminotransferase [Cooper, Bruschi, Iriarte and Martinez-Carrion (2002) Biochem. J. 368, 253–261] and mitochondrial branched-chain aminotransferase [Cooper, Bruschi, Conway and Hutson (2003) Biochem. Pharmacol. 65, 181–192] exhibit β-lyase activity toward S-(1,2-dichlorovinyl)-l-cysteine (the cysteine S-conjugate of trichloroethylene) and S-(1,1,2,2-tetrafluoroethyl)-l-cysteine (the cysteine S-conjugate of tetrafluoroethylene). Turnover leads to eventual inactivation of these enzymes. Here we report that mitochondrial l-alanine–glyoxylate aminotransferase II, which, in the rat, is most active in kidney, catalyses cysteine S-conjugate β-lyase reactions with S-(1,1,2,2-tetrafluoroethyl)-l-cysteine, S-(1,2-dichlorovinyl)-l-cysteine and S-(benzothiazolyl-l-cysteine); turnover leads to inactivation. Previous workers showed that the reactive-sulphur-containing fragment released from S-(1,1,2,2-tetrafluoroethyl)-l-cysteine and S-(1,2-dichlorovinyl)-l-cysteine is toxic by acting as a thioacylating agent – particularly of lysine residues in nearby proteins. Toxicity, however, may also involve ‘self-inactivation’ of key enzymes. The present findings suggest that alanine–glyoxylate aminotransferase II may be an important factor in the well-established targeting of rat kidney mitochondria by toxic halogenated cysteine S-conjugates. Previous reports suggest that alanine–glyoxylate aminotransferase II is absent in some humans, but present in others. Alanine–glyoxylate aminotransferase II may contribute to the bioactivation (toxification) of halogenated cysteine S-conjugates in a subset of individuals exposed to halogenated alkenes.
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Kontani, Yasuhide, Masae Kaneko, Mariko Kikugawa, Shigeko Fujimoto et Nanaya Tamaki. « Identity of D-3-aminoisobutyrate-pyruvate aminotransferase with alanine-glyoxylate aminotransferase 2 ». Biochimica et Biophysica Acta (BBA) - General Subjects 1156, no 2 (février 1993) : 161–66. http://dx.doi.org/10.1016/0304-4165(93)90131-q.

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Holbrook, Joanna D., Graeme M. Birdsey, Ziheng Yang, Michael W. Bruford et Christopher J. Danpure. « Molecular Adaptation of Alanine : Glyoxylate Aminotransferase Targeting in Primates ». Molecular Biology and Evolution 17, no 3 (1 mars 2000) : 387–400. http://dx.doi.org/10.1093/oxfordjournals.molbev.a026318.

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Ikeda, Mitsunori, Hiroaki Kanouchi et Yohsuke Minatogawa. « Characterization of Peroxisomal Targeting Signals on Alanine : Glyoxylate Aminotransferase ». Biological & ; Pharmaceutical Bulletin 31, no 1 (2008) : 131–34. http://dx.doi.org/10.1248/bpb.31.131.

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Takada, Y., et T. Noguchi. « Characteristics of alanine : glyoxylate aminotransferase from Saccharomyces cerevisiae, a regulatory enzyme in the glyoxylate pathway of glycine and serine biosynthesis from tricarboxylic acid-cycle intermediates ». Biochemical Journal 231, no 1 (1 octobre 1985) : 157–63. http://dx.doi.org/10.1042/bj2310157.

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Alanine: glyoxylate aminotransferase (EC 2.6.1.44), which is involved in the glyoxylate pathway of glycine and serine biosynthesis from tricarboxylic acid-cycle intermediates in Saccharomyces cerevisiae, was highly purified and characterized. The enzyme had Mr about 80 000, with two identical subunits. It was highly specific for L-alanine and glyoxylate and contained pyridoxal 5′-phosphate as cofactor. The apparent Km values were 2.1 mM and 0.7 mM for L-alanine and glyoxylate respectively. The activity was low (10 nmol/min per mg of protein) with glucose as sole carbon source, but was remarkably high with ethanol or acetate as carbon source (930 and 430 nmol/min per mg respectively). The transamination of glyoxylate is mainly catalysed by this enzyme in ethanol-grown cells. When glucose-grown cells were incubated in medium containing ethanol as sole carbon source, the activity markedly increased, and the increase was completely blocked by cycloheximide, suggesting that the enzyme is synthesized de novo during the incubation period. Similarity in the amino acid composition was observed, but immunological cross-reactivity was not observed among alanine: glyoxylate aminotransferases from yeast and vertebrate liver.
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30

Holmes, R. P., C. H. Hurst, D. G. Assimos et H. O. Goodman. « Glucagon increases urinary oxalate excretion in the guinea pig ». American Journal of Physiology-Endocrinology and Metabolism 269, no 3 (1 septembre 1995) : E568—E574. http://dx.doi.org/10.1152/ajpendo.1995.269.3.e568.

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Factors that influence hepatic oxalate synthesis are poorly defined. Hormones are important regulators of hepatic metabolism and could potentially be involved. The effects of hyperglucagonemia were examined in guinea pigs injected with either saline or pharmacological doses of glucagon for 4 days. Glucagon treatment increased mean urinary oxalate excretion by 77% in male and 34% in female animals. The levels of hepatic peroxisomal enzymes involved in oxalate synthesis declined with glucagon treatment, but experiments with isolated peroxisomes indicated that oxalate synthesis in vitro was unaffected. Glucagon decreased hepatic alanine levels by 66%, lactate by 69%, and pyruvate by 73%, but glycolate and glyoxylate levels were unaffected. This decrease in alanine would substantially lower the activity of alanine-to-glyoxylate aminotransferase activity in vivo and make more glyoxylate available for oxalate synthesis. The decrease in lactate and pyruvate concentrations would stimulate the enzymatic conversion of glyoxylate to oxalate and may account for the increase in oxalate synthesis without an increase in glyoxylate concentration. These results demonstrate that hepatic oxalate synthesis is influenced by metabolic changes and that alterations in hepatic alanine, lactate, and pyruvate concentrations may be important elements.
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Kah, A., D. Dörnemann et H. Senger. « Isolation and Purification to Apparent Homogeneity of 4,5-Dioxovalerate Aminotransferase from Scenedesmus obliquus Mutant C-2 A′ ». Zeitschrift für Naturforschung C 43, no 7-8 (1 août 1988) : 563–71. http://dx.doi.org/10.1515/znc-1988-7-813.

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In the present paper the purification of a specific 4,5-dioxovalerate transaminase from pigment mutant C-2 A′ of the unicellular green alga Scenedesmus obliquus to apparent homogeneity is described. The newly isolated enzyme ʟ-glutamate: 4,5-dioxovalerate aminotransferase is not identical with ʟ-alanine: 4,5-dioxovalerate aminotransferase (EC 2.6.1.43) and ʟ-alanine: glyoxylate aminotransferase (EC 2.6.1.44). A procedure for the purification is described and the resulting homogeneous protein is characterized by its Kᴍ-values for oxo-substrates and amino donors, its pyridoxal phosphate requirement, reversability of the catalysis, pH-optimum, isoelectric point and its molecular weight.
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32

Rumsby, G., R. Jones, C. J. Danpure et C. T. Samuell. « Taql polymorphism at the alanine : glyoxylate aminotransferase (AGXT) gene locus ». Human Molecular Genetics 1, no 5 (1992) : 350. http://dx.doi.org/10.1093/hmg/1.5.350-a.

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Okuno, Etsuo, Takaya Ishikawa, Jun Kawai et Ryo Kido. « Alanine : Glyoxylate aminotransferase activities in liver of Suncus murinus (insectivora) ». Comparative Biochemistry and Physiology Part B : Comparative Biochemistry 90, no 4 (janvier 1988) : 773–78. http://dx.doi.org/10.1016/0305-0491(88)90333-1.

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Allsop, Jennifer, Patricia R. Jennings et Christopher J. Danpure. « A new micro-assay for human liver alanine : Glyoxylate aminotransferase ». Clinica Chimica Acta 170, no 2-3 (décembre 1987) : 187–93. http://dx.doi.org/10.1016/0009-8981(87)90127-6.

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Schlösser, Thomas, Cornelia Gätgens, Ulrike Weber et K. Peter Stahmann. « Alanine : glyoxylate aminotransferase ofSaccharomyces cerevisiae–encoding geneAGX1 and metabolic significance ». Yeast 21, no 1 (15 janvier 2004) : 63–73. http://dx.doi.org/10.1002/yea.1058.

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Danpure, Christopher J., et Gill Rumsby. « Molecular aetiology of primary hyperoxaluria and its implications for clinical management ». Expert Reviews in Molecular Medicine 6, no 1 (9 janvier 2004) : 1–16. http://dx.doi.org/10.1017/s1462399404007203.

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The primary hyperoxalurias type 1 (PH1) and type 2 (PH2) are autosomal recessive calcium oxalate kidney stone diseases caused by deficiencies of the metabolic enzymes alanine:glyoxylate aminotransferase (AGT) and glyoxylate/hydroxypyruvate reductase (GR/HPR), respectively. Over 50 mutations have been identified in the AGXT gene (encoding AGT) in PH1, associated with a wide variety of effects on AGT, including loss of catalytic activity, aggregation, accelerated degradation, and peroxisome-to-mitochondrion mistargeting. Some of these mutations segregate and interact synergistically with a common polymorphism. Over a dozen mutations have been found in the GRHPR gene (encoding GR/HPR) in PH2, all associated with complete loss of glyoxylate reductase enzyme activity and immunoreactive protein. The crystal structure of human AGT, but not human GR/HPR, has been solved, allowing the effects of many of the mutations in PH1 to be rationalised in structural terms. Detailed analysis of the molecular aetiology of PH1 and PH2 has led to significant improvements in all aspects of their clinical management. Enzyme replacement therapy by liver transplantation can provide a metabolic cure for PH1, but it has yet to be tried for PH2. New treatments that aim to counter the effects of specific mutations on the properties of the enzymes could be feasible in the not-too-distant future.
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Kobayashi, Shigeru, Sueko Hayashi, Satoko Fujiwara et Tomoo Noguchi. « Identity of alanine : glyoxylate aminotransferase with alanine : 2-oxoglutarate aminotrasferase in rat liver cytosol ». Biochimie 71, no 4 (avril 1989) : 471–75. http://dx.doi.org/10.1016/0300-9084(89)90177-6.

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Nishiyama, K., T. Funai, S. Yokota et A. Ichiyama. « ATP-dependent degradation of a mutant serine : pyruvate/alanine:glyoxylate aminotransferase in a primary hyperoxaluria type 1 case. » Journal of Cell Biology 123, no 5 (1 décembre 1993) : 1237–48. http://dx.doi.org/10.1083/jcb.123.5.1237.

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Primary hyperoxaluria type 1 (PH 1), an inborn error of glyoxylate metabolism characterized by excessive synthesis of oxalate and glycolate, is caused by a defect in serine:pyruvate/alanine:glyoxylate aminotransferase (SPT/AGT). This enzyme is peroxisomal in human liver. Recently, we cloned SPT/AGT-cDNA from a PH 1 case, and demonstrated a point mutation of T to C in the coding region of the SPT/AGT gene encoding a Ser to Pro substitution at residue 205 (Nishiyama, K., T. Funai, R. Katafuchi, F. Hattori, K. Onoyama, and A. Ichiyama. 1991. Biochem. Biophys. Res. Commun. 176:1093-1099). In the liver of this patient, SPT/AGT was very low with respect to not only activity but also protein detectable on Western blot and immunoprecipitation analyses. Immunocytochemically detectable SPT/AGT labeling was also low, although it was detected predominantly in peroxisomes. On the other hand, the level of translatable SPT/AGT-mRNA was higher than normal, indicating that SPT/AGT had been synthesized in the patient's liver at least as effectively as in normal liver. Rapid degradation of the mutant SPT/AGT was then demonstrated in transfected COS cells and transformed Escherichia coli, accounting for the low level of immunodetectable mutant SPT/AGT in the patient's liver. The mutant SPT/AGT was also degraded much faster than normal in an in vitro system with a rabbit reticulocyte extract, and the degradation in vitro was ATP dependent. These results indicate that a single amino acid substitution in SPT/AGT found in the PH1 case leads to a reduced half-life of this protein. It appears that the mutant SPT/AGT is recognized in cells as an abnormal protein to be eliminated by degradation.
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Han, Qian, et Jianyong Li. « Comparative characterization ofAedes3-hydroxykynurenine transaminase/alanine glyoxylate transaminase andDrosophilaserine pyruvate aminotransferase ». FEBS Letters 527, no 1-3 (28 août 2002) : 199–204. http://dx.doi.org/10.1016/s0014-5793(02)03229-5.

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Satriano, Letizia, Monika Lewinska, Colm O. Rourke, Douglas VNP Oliveira, Deepak Kumar Bhatt, Andrzej Taranta, Monika Herr et al. « THU-491-The role of alanine glyoxylate aminotransferase in hepatocellular carcinoma ». Journal of Hepatology 70, no 1 (avril 2019) : e377. http://dx.doi.org/10.1016/s0618-8278(19)30738-8.

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Kukreja, Anjli, Melissa Lasaro, Christian Cobaugh, Chris Forbes, Jian-Ping Tang, Xiang Gao, Cristina Martin-Higueras et al. « Systemic Alanine Glyoxylate Aminotransferase mRNA Improves Glyoxylate Metabolism in a Mouse Model of Primary Hyperoxaluria Type 1 ». Nucleic Acid Therapeutics 29, no 2 (avril 2019) : 104–13. http://dx.doi.org/10.1089/nat.2018.0740.

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Lage, Melissa D., Adrianne M. C. Pittman, Alessandro Roncador, Barbara Cellini et Chandra L. Tucker. « Allele-specific Characterization of Alanine : Glyoxylate Aminotransferase Variants Associated with Primary Hyperoxaluria ». PLoS ONE 9, no 4 (9 avril 2014) : e94338. http://dx.doi.org/10.1371/journal.pone.0094338.

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Hayashi, Sueko, Haruhiko Sakuraba et Tomoo Noguchi. « Response of hepatic alanine : Glyoxylate aminotransferase 1 to hormone differs among mammalia ». Biochemical and Biophysical Research Communications 165, no 1 (novembre 1989) : 372–76. http://dx.doi.org/10.1016/0006-291x(89)91080-2.

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Zhao, Chaohui Lisa, Yiang Hui, Li Juan Wang, Dongfang Yang, Evgeny Yakirevich, Shamlal Mangray, Chiung-Kuei Huang et Shaolei Lu. « Alanine-glyoxylate aminotransferase 1 (AGXT1) is a novel marker for hepatocellular carcinomas ». Human Pathology 80 (octobre 2018) : 76–81. http://dx.doi.org/10.1016/j.humpath.2018.05.025.

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Baker, Paul R. S., Scott D. Cramer, Martha Kennedy, Dean G. Assimos et Ross P. Holmes. « Glycolate and glyoxylate metabolism in HepG2 cells ». American Journal of Physiology-Cell Physiology 287, no 5 (novembre 2004) : C1359—C1365. http://dx.doi.org/10.1152/ajpcell.00238.2004.

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Oxalate synthesis in human hepatocytes is not well defined despite the clinical significance of its overproduction in diseases such as the primary hyperoxalurias. To further define these steps, the metabolism to oxalate of the oxalate precursors glycolate and glyoxylate and the possible pathways involved were examined in HepG2 cells. These cells were found to contain oxalate, glyoxylate, and glycolate as intracellular metabolites and to excrete oxalate and glycolate into the medium. Glycolate was taken up more effectively by cells than glyoxylate, but glyoxylate was more efficiently converted to oxalate. Oxalate was formed from exogenous glycolate only when cells were exposed to high concentrations. Peroxisomes in HepG2 cells, in contrast to those in human hepatocytes, were not involved in glycolate metabolism. Incubations with purified lactate dehydrogenase suggested that this enzyme was responsible for the metabolism of glycolate to oxalate in HepG2 cells. The formation of14C-labeled glycine from14C-labeled glycolate was observed only when cell membranes were permeabilized with Triton X-100. These results imply that peroxisome permeability to glycolate is restricted in these cells. Mitochondria, which produce glyoxylate from hydroxyproline metabolism, contained both alanine:glyoxylate aminotransferase (AGT)2 and glyoxylate reductase activities, which can convert glyoxylate to glycine and glycolate, respectively. Expression of AGT2 mRNA in HepG2 cells was confirmed by RT-PCR. These results indicate that HepG2 cells will be useful in clarifying the nonperoxisomal metabolism associated with oxalate synthesis in human hepatocytes.
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Ishikawa, K., E. aneko et A. Ichiyama. « Pyridoxal 5'-Phosphate Binding of a Recombinant Rat Serine : Pyruvate/Alanine : Glyoxylate Aminotransferase ». Journal of Biochemistry 119, no 5 (1 mai 1996) : 970–78. http://dx.doi.org/10.1093/oxfordjournals.jbchem.a021337.

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Liu, Yang, Huihui Xu, Xinpu Yuan, Stephen J. Rossiter et Shuyi Zhang. « Multiple Adaptive Losses of Alanine-Glyoxylate Aminotransferase Mitochondrial Targeting in Fruit-Eating Bats ». Molecular Biology and Evolution 29, no 6 (19 janvier 2012) : 1507–11. http://dx.doi.org/10.1093/molbev/mss013.

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Caplin, Ben, Zhen Wang, Anna Slaviero, James Tomlinson, Laura Dowsett, Mathew Delahaye, Alan Salama, David C. Wheeler et James Leiper. « Alanine-Glyoxylate Aminotransferase-2 Metabolizes Endogenous Methylarginines, Regulates NO, and Controls Blood Pressure ». Arteriosclerosis, Thrombosis, and Vascular Biology 32, no 12 (décembre 2012) : 2892–900. http://dx.doi.org/10.1161/atvbaha.112.254078.

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NISHIJIMA, SAORI, KIMIO SUGAYA, MAKOTO MOROZUMI, TADASHI HATANO et YOSHIHIDE OGAWA. « Hepatic Alanine-glyoxylate Aminotransferase Activity and Oxalate Metabolism in Vitamin B6 Deficient Rats ». Journal of Urology 169, no 2 (février 2003) : 683–86. http://dx.doi.org/10.1016/s0022-5347(05)63992-4.

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Craigen, W. J. « Persistent glycolic aciduria in a healthy child with normal alanine-glyoxylate aminotransferase activity ». Journal of Inherited Metabolic Disease 19, no 6 (novembre 1996) : 793–94. http://dx.doi.org/10.1007/bf01799176.

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