Gss encodes glutathione synthetase, the ATP-dependent ligase that catalyzes the final step of glutathione biosynthesis from gamma-glutamylcysteine and glycine. The enzyme is a cytosolic homodimer with one active site per subunit and binds one Mg(2+) ion per subunit; it phosphorylates the gamma-glutamyl dipeptide to an enzyme-bound acylphosphate intermediate that is then attacked by glycine. Rat glutathione synthetase shows negative cooperativity toward its gamma-glutamyl substrate, making it an allosteric enzyme, and it also accepts gamma-glutamyl-2-aminobutyrate, contributing to ophthalmate formation in hepatocytes. Hepatic Gss expression is co-regulated with the glutamate-cysteine ligase subunits and is induced by TNF-alpha and altered by diet and xenobiotic exposure.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0004363 glutathione synthase activity | IEA GO_REF:0000120 | ACCEPT | Summary: glutathione synthase activity is retained for Gss because it matches the documented core enzymatic role or its direct pathway consequence (IEA, GO_REF:0000120). Reason: glutathione synthase activity is directly supported by the curated function of Gss and is not merely a downstream phenotype or expression response. Supporting Evidence: UniProtKB:P46413 Reaction=gamma-L-glutamyl-L-cysteine + glycine + ATP = glutathione + |
| GO:0005524 ATP binding | IEA GO_REF:0000002 | KEEP AS NON CORE | Summary: ATP binding is retained as contextual support for Gss, but it is not the core function (IEA, GO_REF:0000002). Reason: ATP binding records localization, cofactor/substrate binding, oligomeric state, or physiological context rather than the defining molecular activity of Gss. Supporting Evidence: UniProtKB:P46413 Reaction=gamma-L-glutamyl-L-cysteine + glycine + ATP = glutathione + |
| GO:0006750 glutathione biosynthetic process | IEA GO_REF:0000120 | ACCEPT | Summary: glutathione biosynthetic process is retained for Gss because it matches the documented core enzymatic role or its direct pathway consequence (IEA, GO_REF:0000120). Reason: glutathione biosynthetic process is directly supported by the curated function of Gss and is not merely a downstream phenotype or expression response. Supporting Evidence: UniProtKB:P46413 PATHWAY: Sulfur metabolism; glutathione biosynthesis; glutathione from L-cysteine and L-glutamate: step 2/2. |
| GO:0016874 ligase activity | IEA GO_REF:0000002 | MODIFY | Summary: ligase activity captures part of Gss biology, but more specific replacement term(s) better represent the supported function (IEA, GO_REF:0000002). Reason: ligase activity is too broad or imprecise for Gss; replace with the more specific supported term(s): GO:0004363 glutathione synthase activity. Proposed replacements: glutathione synthase activity Supporting Evidence: UniProtKB:P46413 Reaction=gamma-L-glutamyl-L-cysteine + glycine + ATP = glutathione + file:rat/Gss/Gss-deep-research-falcon.md **Glutathione synthetase (GSS; EC 6.3.2.3)** catalyzes the **ATP-dependent ligation of glycine** to **Ξ³-glutamylcysteine (Ξ³-GC)** to form **glutathione (GSH)** (chen2007relationshipofglutathione pages 16-20). |
| GO:0042802 identical protein binding | ISO GO_REF:0000121 | KEEP AS NON CORE | Summary: identical protein binding is retained as contextual support for Gss, but it is not the core function (ISO, GO_REF:0000121). Reason: identical protein binding records localization, cofactor/substrate binding, oligomeric state, or physiological context rather than the defining molecular activity of Gss. Supporting Evidence: UniProtKB:P46413 SUBUNIT: Homodimer. |
| GO:0004363 glutathione synthase activity | ISO GO_REF:0000121 | ACCEPT | Summary: glutathione synthase activity is retained for Gss because it matches the documented core enzymatic role or its direct pathway consequence (ISO, GO_REF:0000121). Reason: glutathione synthase activity is directly supported by the curated function of Gss and is not merely a downstream phenotype or expression response. Supporting Evidence: PMID:7862666 Glutathione (GSH) synthetase [gamma-L-glutamyl-L-cysteine:glycine ligase (ADP-forming), EC 6.3.2.3], an enzyme present in almost all cells, catalyzes the ATP-dependent synthesis of GSH from gamma-L-glutamyl-L-cysteine and glycine. UniProtKB:P46413 Reaction=gamma-L-glutamyl-L-cysteine + glycine + ATP = glutathione + |
| GO:0006750 glutathione biosynthetic process | ISO GO_REF:0000121 | ACCEPT | Summary: glutathione biosynthetic process is retained for Gss because it matches the documented core enzymatic role or its direct pathway consequence (ISO, GO_REF:0000121). Reason: glutathione biosynthetic process is directly supported by the curated function of Gss and is not merely a downstream phenotype or expression response. Supporting Evidence: UniProtKB:P46413 PATHWAY: Sulfur metabolism; glutathione biosynthesis; glutathione from L-cysteine and L-glutamate: step 2/2. |
| GO:0005654 nucleoplasm | ISO GO_REF:0000121 | KEEP AS NON CORE | Summary: Nucleoplasm transferred by orthology from human GSS (UniProtKB:P48637), whose nucleoplasm call is a Human Protein Atlas immunofluorescence observation (IDA, GO_REF:0000052). Kept as a secondary, non-core localization. Reason: The donor annotation is a direct (antibody-based) observation on human GSS, and the reviewed human GSS record keeps it as a secondary localization alongside the cytosol. A small soluble cytosolic enzyme can plausibly be detected in the nucleoplasm and nuclear glutathione pools are physiologically relevant, so the claim is not contradicted; but it rests on a single imaging call, no rat experiment addresses it, and glutathione synthesis is cytosolic. It is therefore retained only as non-core context (previously REMOVE; revised because removal was not justified by contrary evidence). Propagation Review Root cause: NO FAILURE NON CORE Sources checked: UniProtKB:P48637 Β· human GSS SUPPORTS TRANSFER The donor's nucleoplasm annotation is a Human Protein Atlas immunofluorescence call (IDA, GO_REF:0000052); transfer to the one-to-one rat orthologue is reasonable for a secondary localization, but the site of glutathione synthesis is the cytosol. Supporting Evidence: UniProtKB:P46413 glutamylcysteine and glycine in an ATP-dependent manner (PubMed:7862666) |
| GO:0009410 response to xenobiotic stimulus | IEP PMID:18653662 Coordinated changes in xenobiotic metabolizing enzyme gene e... | MARK AS OVER ANNOTATED | Summary: response to xenobiotic stimulus reflects an expression, phenotype, or systemic context for Gss, not a direct core gene-product function (IEP, PMID:18653662). Reason: The cited/source evidence links Gss to changes in expression or a downstream physiological state; it does not establish Gss as an effector of response to xenobiotic stimulus. Supporting Evidence: PMID:18653662 Toluene exposure decreased the expression of glutathione synthetase, and dramatically increased the number of phase III genes being downregulated. |
| GO:0031667 response to nutrient levels | IEP PMID:19212806 High fat feeding and dietary L-arginine supplementation diff... | MARK AS OVER ANNOTATED | Summary: response to nutrient levels reflects an expression, phenotype, or systemic context for Gss, not a direct core gene-product function (IEP, PMID:19212806). Reason: The cited/source evidence links Gss to changes in expression or a downstream physiological state; it does not establish Gss as an effector of response to nutrient levels. Supporting Evidence: PMID:19212806 In contrast, Arg supplementation reduced mRNA levels for fatty acid binding protein 1, glycogenin, protein phosphates 1B, caspases 1 and 2, and hepatic lipase, but increased expression of PPARgamma, heme oxygenase 3, glutathione synthetase, insulin-like growth factor II, sphingosine-1-phosphate receptor, and stress-induced protein. |
| GO:0034612 response to tumor necrosis factor | IEP PMID:16011481 Tumour necrosis factor alpha induces co-ordinated activation... | MARK AS OVER ANNOTATED | Summary: response to tumor necrosis factor reflects an expression, phenotype, or systemic context for Gss, not a direct core gene-product function (IEP, PMID:16011481). Reason: The cited/source evidence links Gss to changes in expression or a downstream physiological state; it does not establish Gss as an effector of response to tumor necrosis factor. Supporting Evidence: PMID:16011481 TNFalpha induces the expression and recombinant promoter activities of GCLC, GCLM and GSS in H4IIE cells. |
| GO:0043200 response to amino acid | IEP PMID:19212806 High fat feeding and dietary L-arginine supplementation diff... | MARK AS OVER ANNOTATED | Summary: response to amino acid reflects an expression, phenotype, or systemic context for Gss, not a direct core gene-product function (IEP, PMID:19212806). Reason: The cited/source evidence links Gss to changes in expression or a downstream physiological state; it does not establish Gss as an effector of response to amino acid. Supporting Evidence: PMID:19212806 In contrast, Arg supplementation reduced mRNA levels for fatty acid binding protein 1, glycogenin, protein phosphates 1B, caspases 1 and 2, and hepatic lipase, but increased expression of PPARgamma, heme oxygenase 3, glutathione synthetase, insulin-like growth factor II, sphingosine-1-phosphate receptor, and stress-induced protein. |
| GO:0000287 magnesium ion binding | ISS GO_REF:0000024 | KEEP AS NON CORE | Summary: magnesium ion binding is retained as contextual support for Gss, but it is not the core function (ISS, GO_REF:0000024). Reason: magnesium ion binding records localization, cofactor/substrate binding, oligomeric state, or physiological context rather than the defining molecular activity of Gss. Supporting Evidence: UniProtKB:P46413 Binds 1 Mg(2+) ion per subunit. |
| GO:0000287 magnesium ion binding | ISO GO_REF:0000121 | KEEP AS NON CORE | Summary: magnesium ion binding is retained as contextual support for Gss, but it is not the core function (ISO, GO_REF:0000121). Reason: magnesium ion binding records localization, cofactor/substrate binding, oligomeric state, or physiological context rather than the defining molecular activity of Gss. Supporting Evidence: UniProtKB:P46413 Binds 1 Mg(2+) ion per subunit. |
| GO:0005524 ATP binding | ISS GO_REF:0000024 | KEEP AS NON CORE | Summary: ATP binding is retained as contextual support for Gss, but it is not the core function (ISS, GO_REF:0000024). Reason: ATP binding records localization, cofactor/substrate binding, oligomeric state, or physiological context rather than the defining molecular activity of Gss. Supporting Evidence: UniProtKB:P46413 Reaction=gamma-L-glutamyl-L-cysteine + glycine + ATP = glutathione + |
| GO:0005524 ATP binding | ISO GO_REF:0000121 | KEEP AS NON CORE | Summary: ATP binding is retained as contextual support for Gss, but it is not the core function (ISO, GO_REF:0000121). Reason: ATP binding records localization, cofactor/substrate binding, oligomeric state, or physiological context rather than the defining molecular activity of Gss. Supporting Evidence: UniProtKB:P46413 Reaction=gamma-L-glutamyl-L-cysteine + glycine + ATP = glutathione + |
| GO:0042803 protein homodimerization activity | ISS GO_REF:0000024 | KEEP AS NON CORE | Summary: protein homodimerization activity is retained as contextual support for Gss, but it is not the core function (ISS, GO_REF:0000024). Reason: protein homodimerization activity records localization, cofactor/substrate binding, oligomeric state, or physiological context rather than the defining molecular activity of Gss. Supporting Evidence: UniProtKB:P46413 SUBUNIT: Homodimer. |
| GO:0042803 protein homodimerization activity | ISO GO_REF:0000121 | KEEP AS NON CORE | Summary: protein homodimerization activity is retained as contextual support for Gss, but it is not the core function (ISO, GO_REF:0000121). Reason: protein homodimerization activity records localization, cofactor/substrate binding, oligomeric state, or physiological context rather than the defining molecular activity of Gss. Supporting Evidence: UniProtKB:P46413 SUBUNIT: Homodimer. |
| GO:0043295 glutathione binding | ISS GO_REF:0000024 | KEEP AS NON CORE | Summary: glutathione binding is retained as contextual support for Gss, but it is not the core function (ISS, GO_REF:0000024). Reason: glutathione binding records localization, cofactor/substrate binding, oligomeric state, or physiological context rather than the defining molecular activity of Gss. Supporting Evidence: UniProtKB:P46413 glutamylcysteine and glycine in an ATP-dependent manner (PubMed:7862666) |
| GO:0043295 glutathione binding | ISO GO_REF:0000121 | KEEP AS NON CORE | Summary: glutathione binding is retained as contextual support for Gss, but it is not the core function (ISO, GO_REF:0000121). Reason: glutathione binding records localization, cofactor/substrate binding, oligomeric state, or physiological context rather than the defining molecular activity of Gss. Supporting Evidence: UniProtKB:P46413 glutamylcysteine and glycine in an ATP-dependent manner (PubMed:7862666) |
| GO:0046686 response to cadmium ion | ISO GO_REF:0000121 | MARK AS OVER ANNOTATED | Summary: response to cadmium ion reflects an expression, phenotype, or systemic context for Gss, not a direct core gene-product function (ISO, GO_REF:0000121). Reason: The cited/source evidence links Gss to changes in expression or a downstream physiological state; it does not establish Gss as an effector of response to cadmium ion. Propagation Review Root cause: PROPAGATION BAD Failure modes: CONTEXT OR TISSUE MISMATCH ROLE CONFLATION Sources checked: MGI:MGI:95852 Β· mouse Gss SUPPORTS SOURCE BUT NOT TARGET The mouse Gss donor evidence is exposure/expression-based (cadmium induces glutathione-pathway genes) and does not establish Gss as an effector of the cadmium response in rat. Supporting Evidence: UniProtKB:P46413 glutamylcysteine and glycine in an ATP-dependent manner (PubMed:7862666) |
| GO:0004363 glutathione synthase activity | IDA PMID:10964706 Novel kinetics of mammalian glutathione synthetase: characte... | ACCEPT | Summary: glutathione synthase activity is retained for Gss because it matches the documented core enzymatic role or its direct pathway consequence (IDA, PMID:10964706). Reason: glutathione synthase activity is directly supported by the curated function of Gss and is not merely a downstream phenotype or expression response. Supporting Evidence: PMID:10964706 We report the detailed kinetic data for purified recombinant rat glutathione synthetase. It has the highest specific activity (11 micromol/min/mg) reported for any mammalian glutathione synthetase. |
| GO:0005524 ATP binding | IDA PMID:10964706 Novel kinetics of mammalian glutathione synthetase: characte... | KEEP AS NON CORE | Summary: ATP binding is retained as contextual support for Gss, but it is not the core function (IDA, PMID:10964706). Reason: ATP binding records localization, cofactor/substrate binding, oligomeric state, or physiological context rather than the defining molecular activity of Gss. Supporting Evidence: PMID:10964706 The apparent K(m) values for ATP and glycine are 37 and 913 microM, respectively. |
| GO:0006750 glutathione biosynthetic process | IDA PMID:10964706 Novel kinetics of mammalian glutathione synthetase: characte... | ACCEPT | Summary: glutathione biosynthetic process is retained for Gss because it matches the documented core enzymatic role or its direct pathway consequence (IDA, PMID:10964706). Reason: glutathione biosynthetic process is directly supported by the curated function of Gss and is not merely a downstream phenotype or expression response. Supporting Evidence: PMID:10964706 We report the detailed kinetic data for purified recombinant rat glutathione synthetase. It has the highest specific activity (11 micromol/min/mg) reported for any mammalian glutathione synthetase. file:rat/Gss/Gss-deep-research-falcon.md **Glutathione synthetase (GSS; gene symbol Gss)** is the **second (final) enzyme** in the canonical two-step de novo biosynthesis of glutathione (GSH), a major low-molecular-weight cellular thiol antioxidant (chen2007relationshipofglutathione pages 16-20, tandon2024unravelingthemultifaceted pages 1-2). |
| GO:0016594 glycine binding | IDA PMID:10964706 Novel kinetics of mammalian glutathione synthetase: characte... | KEEP AS NON CORE | Summary: glycine binding is retained as contextual support for Gss, but it is not the core function (IDA, PMID:10964706). Reason: glycine binding records localization, cofactor/substrate binding, oligomeric state, or physiological context rather than the defining molecular activity of Gss. Supporting Evidence: PMID:10964706 The apparent K(m) values for ATP and glycine are 37 and 913 microM, respectively. file:rat/Gss/Gss-deep-research-falcon.md β’ Core substrates are Ξ³-glutamylcysteine, glycine, and ATP. β’ Product is glutathione (GSH), the major low-molecular-weight cellular thiol antioxidant. β’ Literature supports strong substrate specificity for glycine ligation to Ξ³-glutamylcysteine. |
| GO:0042277 peptide binding | IPI PMID:10964706 Novel kinetics of mammalian glutathione synthetase: characte... | KEEP AS NON CORE | Summary: peptide binding is retained as contextual support for Gss, but it is not the core function (IPI, PMID:10964706). Reason: peptide binding records localization, cofactor/substrate binding, oligomeric state, or physiological context rather than the defining molecular activity of Gss. Supporting Evidence: PMID:10964706 The Lineweaver-Burk double reciprocal plot for gamma-glutamyl substrate binding revealed a departure from linearity indicating cooperative binding. |
| GO:0042802 identical protein binding | IPI PMID:7862666 Amino acid sequence of rat kidney glutathione synthetase. | KEEP AS NON CORE | Summary: identical protein binding is retained as contextual support for Gss, but it is not the core function (IPI, PMID:7862666). Reason: identical protein binding records localization, cofactor/substrate binding, oligomeric state, or physiological context rather than the defining molecular activity of Gss. Supporting Evidence: PMID:7862666 Glutathione (GSH) synthetase [gamma-L-glutamyl-L-cysteine:glycine ligase (ADP-forming), EC 6.3.2.3], an enzyme present in almost all cells, catalyzes the ATP-dependent synthesis of GSH from gamma-L-glutamyl-L-cysteine and glycine. file:rat/Gss/Gss-deep-research-falcon.md **Glutathione synthetase (GSS; EC 6.3.2.3)** catalyzes the **ATP-dependent ligation of glycine** to **Ξ³-glutamylcysteine (Ξ³-GC)** to form **glutathione (GSH)** (chen2007relationshipofglutathione pages 16-20). |
| GO:0043295 glutathione binding | IDA PMID:10964706 Novel kinetics of mammalian glutathione synthetase: characte... | KEEP AS NON CORE | Summary: glutathione binding is retained as contextual support for Gss, but it is not the core function (IDA, PMID:10964706). Reason: glutathione binding records localization, cofactor/substrate binding, oligomeric state, or physiological context rather than the defining molecular activity of Gss. Supporting Evidence: PMID:10964706 Glutathione (GSH) synthetase [L-gamma-glutamyl-L-cysteinyl:glycine ligase (ADP-forming), EC 6.3.2.3] catalyzes the final step in GSH biosynthesis. |
| GO:0004363 glutathione synthase activity | IDA PMID:7862666 Amino acid sequence of rat kidney glutathione synthetase. | ACCEPT | Summary: glutathione synthase activity is retained for Gss because it matches the documented core enzymatic role or its direct pathway consequence (IDA, PMID:7862666). Reason: glutathione synthase activity is directly supported by the curated function of Gss and is not merely a downstream phenotype or expression response. Supporting Evidence: PMID:7862666 Glutathione (GSH) synthetase [gamma-L-glutamyl-L-cysteine:glycine ligase (ADP-forming), EC 6.3.2.3], an enzyme present in almost all cells, catalyzes the ATP-dependent synthesis of GSH from gamma-L-glutamyl-L-cysteine and glycine. |
| GO:0004363 glutathione synthase activity | IBA GO_REF:0000033 | ACCEPT | Summary: Glutathione synthase activity inferred by PAINT from the eukaryotic glutathione synthetase family node (PANTHER:PTN000122964), consistent with direct assays of purified rat enzyme. Reason: Rat Gss is a member of the eukaryotic GSH synthase family placed under the ancestral node at which PAINT curators asserted the activity, and there is no evidence of divergence; the activity is directly measured on recombinant rat glutathione synthetase (IDA, PMID:10964706, PMID:7862666), whose own experimental annotation is among the descendant evidence for the node. Supporting Evidence: UniProtKB:P46413 Reaction=gamma-L-glutamyl-L-cysteine + glycine + ATP = glutathione + PMID:10964706 We report the detailed kinetic data for purified recombinant rat glutathione synthetase. It has the highest specific activity (11 micromol/min/mg) reported for any mammalian glutathione synthetase. |
| GO:0004363 glutathione synthase activity | ISO GO_REF:0000121 | ACCEPT | Summary: Glutathione synthase activity transferred by orthology from human GSS (UniProtKB:P48637); donor-split duplicate of the mouse-Gss-donor ISO row and consistent with direct assays on the rat enzyme. Reason: The donor is human GSS (P48637), the one-to-one orthologue of rat Gss, with directly assayed glutathione synthetase activity. The same activity is measured on purified recombinant rat enzyme, so the transfer is sound. Supporting Evidence: UniProtKB:P46413 Reaction=gamma-L-glutamyl-L-cysteine + glycine + ATP = glutathione + PMID:10964706 We report the detailed kinetic data for purified recombinant rat glutathione synthetase. It has the highest specific activity (11 micromol/min/mg) reported for any mammalian glutathione synthetase. |
| GO:0005829 cytosol | IBA GO_REF:0000033 | ACCEPT | Summary: Cytosol (is_active_in) inferred by PAINT from the glutathione synthetase family node (PANTHER:PTN000122964); the cytosol is where glutathione synthesis takes place. Reason: Glutathione synthetase is a soluble enzyme that completes glutathione synthesis in the cytosol, and the PAINT node assertion has no rat-specific counter-evidence. The rat UniProt entry records no subcellular location, so this IBA row is the main localization statement for the rat protein and is retained as the site of its core activity. Supporting Evidence: file:rat/Gss/Gss-deep-research-falcon.md Animal-cell glutathione synthesis is generally described as cytosolic, with downstream distribution of GSH to organelles including mitochondria |
| GO:0006750 glutathione biosynthetic process | IBA GO_REF:0000033 | ACCEPT | Summary: Glutathione biosynthetic process inferred by PAINT from the glutathione synthetase family node (PANTHER:PTN000122964); Gss catalyses the second and final step of the pathway. Reason: Gss performs the final ligation step of glutathione biosynthesis, so it does part of the work of the process; the IBA placement is consistent with the IDA row for the same process on rat enzyme. Supporting Evidence: UniProtKB:P46413 PATHWAY: Sulfur metabolism; glutathione biosynthesis; glutathione from L-cysteine and L-glutamate: step 2/2. |
| GO:0042277 peptide binding | IPI PMID:10964706 Novel kinetics of mammalian glutathione synthetase: characte... | KEEP AS NON CORE | Summary: Peptide binding by IPI with the gamma-glutamyl dipeptide substrate analogue gamma-glutamyl-2-aminobutyrate (PubChem_Compound:193514); donor-split duplicate of the gamma-glutamylcysteine (CHEBI:17515) peptide-binding row, kept as non-core substrate-binding context. Reason: The kinetic study characterised cooperative binding of the gamma-glutamyl dipeptide substrate by purified rat glutathione synthetase; gamma-glutamyl-2-aminobutyrate is an alternative gamma-glutamyl substrate (used in ophthalmate formation). Substrate binding is a step of the catalytic cycle already captured by glutathione synthase activity, so the term is retained only as context. Supporting Evidence: PMID:10964706 The Lineweaver-Burk double reciprocal plot for gamma-glutamyl substrate binding revealed a departure from linearity indicating cooperative binding. UniProtKB:P46413 Reaction=gamma-L-glutamyl-(2S)-2-aminobutanoate + glycine + ATP = |
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