Existing Annotations Review

GO Term	Evidence	Action	Reason
GO:0017109 glutamate-cysteine ligase complex	IBA GO_REF:0000033	ACCEPT	Summary: GCLC is the catalytic subunit of the glutamate-cysteine ligase (GCL) heterodimer, forming a complex with GCLM (the regulatory/modifier subunit). This annotation is well-supported by phylogenetic inference and experimental evidence showing GCLC-GCLM interaction (PMID:9675072, PMID:9841880). Reason: The IBA annotation accurately reflects that GCLC is part of the GCL complex. This is a core function supported by extensive experimental evidence. The heterodimer formation between GCLC and GCLM is essential for optimal enzymatic activity and has been demonstrated by co-expression and purification studies. Supporting Evidence: PMID:9675072 Expression and purification of human gamma-glutamylcysteine synthetase. PMID:9841880 Identification of an important cysteine residue in human glutamate-cysteine ligase catalytic subunit by site-directed mutagenesis. file:human/GCLC/GCLC-deep-research-falcon.md model: Edison Scientific Literature
GO:0004357 glutamate-cysteine ligase activity	IBA GO_REF:0000033	ACCEPT	Summary: GCLC possesses glutamate-cysteine ligase activity, catalyzing the ATP-dependent ligation of L-glutamate and L-cysteine to form gamma-L-glutamyl-L-cysteine. This is the primary enzymatic function of the catalytic subunit. Reason: This is the core molecular function of GCLC. The IBA annotation is consistent with extensive experimental evidence including direct enzyme assays with recombinant human protein (PMID:9675072, PMID:12663448). Supporting Evidence: PMID:9675072 Expression and purification of human gamma-glutamylcysteine synthetase. PMID:12663448 Mar 27. A novel missense mutation in the gamma-glutamylcysteine synthetase catalytic subunit gene causes both decreased enzymatic activity and glutathione production.
GO:0006750 glutathione biosynthetic process	IBA GO_REF:0000033	ACCEPT	Summary: GCLC catalyzes the first and rate-limiting step in glutathione biosynthesis. The gamma-L-glutamyl-L-cysteine product is subsequently ligated to glycine by glutathione synthetase to produce GSH. Reason: This is a core biological process annotation. GCLC is essential for glutathione biosynthesis as it performs the rate-limiting step. The IBA annotation is strongly supported by the conserved function across eukaryotes. Supporting Evidence: PMID:9675072 Expression and purification of human gamma-glutamylcysteine synthetase. PMID:12663448 Mar 27. A novel missense mutation in the gamma-glutamylcysteine synthetase catalytic subunit gene causes both decreased enzymatic activity and glutathione production.
GO:0000166 nucleotide binding	IEA GO_REF:0000043	MODIFY	Summary: GCLC binds ATP as a substrate for the ligation reaction. The annotation is inferred from UniProt keyword mapping and is too general. Reason: While GCLC does bind nucleotides (specifically ATP as substrate), this term is overly broad. The more specific term GO:0005524 (ATP binding) is already annotated and should be preferred. The direct IDA evidence for ADP binding (GO:0043531) from PMID:24639 provides more precise information. Proposed replacements: ATP binding
GO:0003824 catalytic activity	IEA GO_REF:0000002	MODIFY	Summary: IEA annotation from InterPro domain mapping. GCLC has catalytic activity but this term is too general. Reason: This is an overly broad term. The specific catalytic activity (GO:0004357 glutamate-cysteine ligase activity) is already annotated with experimental evidence and should be used instead. Proposed replacements: glutamate-cysteine ligase activity
GO:0004357 glutamate-cysteine ligase activity	IEA GO_REF:0000120	ACCEPT	Summary: IEA annotation for glutamate-cysteine ligase activity from combined automated methods. Duplicates the IBA annotation and experimental IDA annotations. Reason: This is a valid annotation capturing the core molecular function. While redundant with other evidence codes, the IEA annotation reflects automated validation of the core enzymatic function. Supporting Evidence: PMID:9675072 Expression and purification of human gamma-glutamylcysteine synthetase.
GO:0005524 ATP binding	IEA GO_REF:0000043	ACCEPT	Summary: GCLC requires ATP as a substrate for the ligation reaction. The Km for ATP is 0.4 mM (PMID:9675072). Reason: ATP binding is essential for GCLC function as ATP provides the energy for the ligation reaction. While this is an IEA annotation, it is well-supported by the characterized enzymatic mechanism. Supporting Evidence: PMID:9675072 Expression and purification of human gamma-glutamylcysteine synthetase.
GO:0006750 glutathione biosynthetic process	IEA GO_REF:0000120	ACCEPT	Summary: IEA annotation for involvement in glutathione biosynthesis from combined automated methods. Duplicates IBA and IDA annotations. Reason: Valid annotation supporting the core biological process. Redundant with experimental evidence but reflects automated validation.
GO:0016874 ligase activity	IEA GO_REF:0000043	MODIFY	Summary: GCLC is indeed a ligase, catalyzing ATP-dependent bond formation. However, this is a parent term of the more specific glutamate-cysteine ligase activity. Reason: This term is valid but too general. The more specific child term GO:0004357 (glutamate-cysteine ligase activity) is already annotated and provides more informative annotation. Proposed replacements: glutamate-cysteine ligase activity
GO:0043066 negative regulation of apoptotic process	IEA GO_REF:0000117	KEEP AS NON CORE	Summary: GCLC overexpression suppresses TNF-induced apoptosis through maintaining cellular GSH levels and redox status (PMID:10439045). Reason: This is a downstream consequence of GCLC's role in GSH biosynthesis rather than a direct function. GSH maintains cellular redox homeostasis which protects against apoptotic cell death. The effect is indirect - mediated through GSH levels - rather than a direct anti-apoptotic function. Supporting Evidence: PMID:10439045 Overexpression of gamma-glutamylcysteine synthetase suppresses tumor necrosis factor-induced apoptosis and activation of nuclear transcription factor-kappa B and activator protein-1.
GO:0005515 protein binding	IPI PMID:28514442 Architecture of the human interactome defines protein commun...	MODIFY	Summary: High-throughput interactome study detecting GCLC-GCLM interaction. Reason: The term "protein binding" is uninformative. The documented interaction is specifically with GCLM (P48507), the regulatory subunit of the GCL complex. The more informative annotation would be the cellular component GO:0017109 (glutamate-cysteine ligase complex) which is already present. Proposed replacements: glutamate-cysteine ligase complex Supporting Evidence: PMID:28514442 Architecture of the human interactome defines protein communities and disease networks.
GO:0005515 protein binding	IPI PMID:33961781 Dual proteome-scale networks reveal cell-specific remodeling...	MODIFY	Summary: Dual proteome interactome study detecting GCLC-GCLM interaction. Reason: Same rationale as other protein binding annotations - the term is uninformative and the specific interaction is with GCLM to form the GCL complex, which is captured by GO:0017109. Proposed replacements: glutamate-cysteine ligase complex Supporting Evidence: PMID:33961781 2021 May 6. Dual proteome-scale networks reveal cell-specific remodeling of the human interactome.
GO:0005515 protein binding	IPI PMID:40205054 Multimodal cell maps as a foundation for structural and func...	MODIFY	Summary: Multimodal cell maps study detecting GCLC-GCLM interaction. Reason: The generic protein binding term should be replaced by the more specific complex annotation that captures the functionally relevant GCLC-GCLM heterodimer formation. Proposed replacements: glutamate-cysteine ligase complex Supporting Evidence: PMID:40205054 Apr 9. Multimodal cell maps as a foundation for structural and functional genomics.
GO:0005515 protein binding	IPI PMID:9675072 Expression and purification of human gamma-glutamylcysteine ...	MODIFY	Summary: Study demonstrating GCLC-GCLM heterodimer formation through co-expression and purification of the holoenzyme. Reason: This primary literature reference documents the GCLC-GCLM interaction essential for holoenzyme formation. The generic "protein binding" term fails to capture this specific and important functional interaction. Proposed replacements: glutamate-cysteine ligase complex Supporting Evidence: PMID:9675072 Expression and purification of human gamma-glutamylcysteine synthetase.
GO:0005829 cytosol	IEA GO_REF:0000107	ACCEPT	Summary: GCLC is localized in the cytosol where glutathione biosynthesis occurs. This annotation is transferred from ortholog data. Reason: Cytosolic localization is correct and consistent with the role of GCLC in cytoplasmic GSH synthesis. This is supported by Reactome TAS annotations and the known biochemistry of GSH synthesis.
GO:0006979 response to oxidative stress	IEA GO_REF:0000107	KEEP AS NON CORE	Summary: GCLC expression and activity are induced by oxidative stress as part of the cellular antioxidant response. This is mediated through the KEAP1-NRF2 pathway (deep research review). Reason: While GCLC is transcriptionally upregulated in response to oxidative stress (via NRF2) and GSH production protects against oxidative damage, this is a regulatory/response annotation rather than a core function. The core function is GSH biosynthesis. Supporting Evidence: PMID:11972604 Oxidant stress induces gamma-glutamylcysteine synthetase and glutathione synthesis in human bronchial epithelial NCI-H292 cells.
GO:0007584 response to nutrient	IEA GO_REF:0000107	KEEP AS NON CORE	Summary: IEA annotation transferred from rat ortholog. GCLC activity is influenced by cysteine availability which can be nutrient-limited. Reason: This reflects the regulatory context of GCLC rather than its direct function. GSH synthesis is limited by cysteine availability, but response to nutrient is not a core function.
GO:0014823 response to activity	IEA GO_REF:0000107	KEEP AS NON CORE	Summary: IEA annotation from ortholog transfer. May relate to exercise-induced changes in GSH metabolism. Reason: This is a peripheral annotation describing regulatory context rather than core function. The primary function is enzymatic.
GO:0017109 glutamate-cysteine ligase complex	IEA GO_REF:0000120	ACCEPT	Summary: IEA annotation for GCLC being part of the GCL heterodimeric complex with GCLM. Reason: Redundant with IBA and IDA annotations but valid. GCLC forms a heterodimer with GCLM constituting the active holoenzyme.
GO:0032869 cellular response to insulin stimulus	IEA GO_REF:0000107	KEEP AS NON CORE	Summary: IEA annotation from rat ortholog. Insulin signaling may regulate GSH metabolism. Reason: This represents a regulatory input to GCLC expression/activity rather than the core enzymatic function. Pleiotropic cellular responses are secondary to the primary function.
GO:0035729 cellular response to hepatocyte growth factor stimulus	IEA GO_REF:0000107	KEEP AS NON CORE	Summary: IEA annotation from ortholog transfer suggesting GCLC responds to HGF. Reason: Peripheral regulatory annotation. Not a core function of GCLC.
GO:0043524 negative regulation of neuron apoptotic process	IEA GO_REF:0000107	KEEP AS NON CORE	Summary: GCLC-mediated GSH synthesis protects neurons from apoptotic death. Knockdown of either GCL subunit causes neuronal apoptosis (PMID:16183645). Reason: This is an indirect downstream effect of GSH biosynthesis. While documented experimentally in neurons (PMID:16183645), it represents a tissue-specific consequence rather than a direct anti-apoptotic function. Supporting Evidence: PMID:16183645 2005 Sep 23. Knockdown of glutamate-cysteine ligase by small hairpin RNA reveals that both catalytic and modulatory subunits are essential for the survival of primary neurons.
GO:0044344 cellular response to fibroblast growth factor stimulus	IEA GO_REF:0000107	KEEP AS NON CORE	Summary: IEA annotation from ortholog transfer. Reason: Peripheral regulatory annotation, not a core function.
GO:0044752 response to human chorionic gonadotropin	IEA GO_REF:0000107	KEEP AS NON CORE	Summary: IEA annotation from ortholog transfer. Reason: Tissue-specific regulatory context, not a core function.
GO:0044877 protein-containing complex binding	IEA GO_REF:0000107	MODIFY	Summary: IEA annotation suggesting GCLC binds to protein complexes. Reason: This is vague. The specific relevant complex is the GCLC-GCLM heterodimer, which is better captured by GO:0017109. Proposed replacements: glutamate-cysteine ligase complex
GO:0046686 response to cadmium ion	IEA GO_REF:0000107	KEEP AS NON CORE	Summary: GCLC/GSH is induced by cadmium as a detoxification response. Reason: GSH conjugation is important for heavy metal detoxification, but this represents a regulatory/response context rather than direct cadmium binding or processing by GCLC.
GO:0051409 response to nitrosative stress	IEA GO_REF:0000107	KEEP AS NON CORE	Summary: GCLC expression is upregulated by nitrosative stress (e.g., sodium nitroprusside treatment increases GCS activity, PMID:10395918). Reason: This reflects transcriptional regulation of GCLC in response to stress rather than a direct function in nitrosative stress response. Supporting Evidence: PMID:10395918 Regulation of gamma-glutamylcysteine synthetase regulatory subunit (GLCLR) gene expression: identification of the major transcriptional start site in HT29 cells.
GO:0070555 response to interleukin-1	IEA GO_REF:0000107	KEEP AS NON CORE	Summary: IEA annotation from ortholog transfer. Reason: Peripheral regulatory annotation reflecting cytokine-mediated regulation rather than a core function.
GO:0071260 cellular response to mechanical stimulus	IEA GO_REF:0000107	KEEP AS NON CORE	Summary: IEA annotation from ortholog transfer. Reason: Peripheral annotation, not a core function.
GO:0071333 cellular response to glucose stimulus	IEA GO_REF:0000107	KEEP AS NON CORE	Summary: IEA annotation from ortholog transfer. Reason: Peripheral metabolic regulatory context rather than core function.
GO:0071372 cellular response to follicle-stimulating hormone stimulus	IEA GO_REF:0000107	KEEP AS NON CORE	Summary: IEA annotation from ortholog transfer. Reason: Tissue-specific regulatory context, not a core function.
GO:0097069 cellular response to thyroxine stimulus	IEA GO_REF:0000107	KEEP AS NON CORE	Summary: IEA annotation from ortholog transfer. Reason: Hormonal regulatory context, not a core function.
GO:2000490 negative regulation of hepatic stellate cell activation	IEA GO_REF:0000107	KEEP AS NON CORE	Summary: IEA annotation from ortholog transfer. GSH may inhibit hepatic stellate cell activation in fibrosis contexts. Reason: Tissue-specific downstream consequence of GSH production, not a direct or core function of GCLC.
GO:0006750 glutathione biosynthetic process	IDA PMID:9675072 Expression and purification of human gamma-glutamylcysteine ...	ACCEPT	Summary: Direct demonstration that recombinant human GCLC catalyzes the first step in glutathione biosynthesis using purified protein. Reason: Core biological process annotation with direct experimental evidence. This study expressed and purified human GCLC and demonstrated its enzymatic function in GSH precursor synthesis. Supporting Evidence: PMID:9675072 Expression and purification of human gamma-glutamylcysteine synthetase.
GO:0004357 glutamate-cysteine ligase activity	IMP PMID:12663448 A novel missense mutation in the gamma-glutamylcysteine synt...	ACCEPT	Summary: Study of the R127C disease mutation demonstrating decreased enzymatic activity in the mutant, confirming GCLC's role in GCL catalysis. Reason: Core molecular function with mutational evidence. The R127C mutation causes decreased GCL activity and hemolytic anemia, providing genetic evidence for GCLC's essential catalytic role. Supporting Evidence: PMID:12663448 Mar 27. A novel missense mutation in the gamma-glutamylcysteine synthetase catalytic subunit gene causes both decreased enzymatic activity and glutathione production.
GO:0004357 glutamate-cysteine ligase activity	IDA PMID:9675072 Expression and purification of human gamma-glutamylcysteine ...	ACCEPT	Summary: Direct biochemical characterization of purified recombinant human GCLC demonstrating glutamate-cysteine ligase activity with kinetic parameters. Reason: Primary experimental evidence for the core molecular function. Km values determined for all substrates confirm the catalytic mechanism. Supporting Evidence: PMID:9675072 Expression and purification of human gamma-glutamylcysteine synthetase.
GO:0004357 glutamate-cysteine ligase activity	IMP PMID:9841880 Identification of an important cysteine residue in human glu...	ACCEPT	Summary: Site-directed mutagenesis study identifying Cys553 as important for GCLC-GCLM heterodimer formation and enzyme activity. Reason: Mutational evidence supporting the core catalytic function. The C553G mutation reduces holoenzyme activity, confirming the importance of subunit interaction for full activity. Supporting Evidence: PMID:9841880 Identification of an important cysteine residue in human glutamate-cysteine ligase catalytic subunit by site-directed mutagenesis.
GO:0005515 protein binding	IPI PMID:9841880 Identification of an important cysteine residue in human glu...	MODIFY	Summary: Study demonstrating physical interaction between GCLC and GCLM (GCLR) through site-directed mutagenesis and activity assays. Reason: The generic "protein binding" term fails to capture the specific and functionally important GCLC-GCLM interaction. The complex annotation GO:0017109 is more informative. Proposed replacements: glutamate-cysteine ligase complex Supporting Evidence: PMID:9841880 Identification of an important cysteine residue in human glutamate-cysteine ligase catalytic subunit by site-directed mutagenesis.
GO:0006536 glutamate metabolic process	IDA PMID:9841880 Identification of an important cysteine residue in human glu...	ACCEPT	Summary: GCLC uses L-glutamate as a substrate. The study characterized glutamate binding and utilization by GCLC. Reason: GCLC directly participates in glutamate metabolism by incorporating glutamate into gamma-glutamylcysteine. This is an accurate annotation of the enzyme's substrate utilization. Supporting Evidence: PMID:9841880 Identification of an important cysteine residue in human glutamate-cysteine ligase catalytic subunit by site-directed mutagenesis.
GO:0017109 glutamate-cysteine ligase complex	IDA PMID:9675072 Expression and purification of human gamma-glutamylcysteine ...	ACCEPT	Summary: Direct demonstration of GCLC-GCLM holoenzyme assembly through co-expression and purification. Reason: Core cellular component annotation with direct experimental evidence. The study co-expressed both subunits and purified the assembled heterodimer. Supporting Evidence: PMID:9675072 Expression and purification of human gamma-glutamylcysteine synthetase.
GO:0017109 glutamate-cysteine ligase complex	IDA PMID:9841880 Identification of an important cysteine residue in human glu...	ACCEPT	Summary: Study demonstrating GCLC-GCLM heterodimer formation and identifying Cys553 as important for the interaction. Reason: Direct experimental evidence for GCLC being part of the GCL complex. Supporting Evidence: PMID:9841880 Identification of an important cysteine residue in human glutamate-cysteine ligase catalytic subunit by site-directed mutagenesis.
GO:0005829 cytosol	TAS Reactome:R-HSA-5602892	ACCEPT	Summary: Reactome annotation placing GCLC in the cytosol where the GCL reaction occurs. Reason: Cytosolic localization is correct for GCLC and GSH biosynthesis. This is a core localization annotation.
GO:0005829 cytosol	TAS Reactome:R-HSA-174367	ACCEPT	Summary: Reactome annotation for the GCL ligation reaction occurring in the cytosol. Reason: Redundant with other cytosol annotations but valid and reflects accurate localization.
GO:0005829 cytosol	TAS Reactome:R-HSA-9760122	ACCEPT	Summary: Reactome annotation for NRF2-dependent GCLC expression, placing the gene product in the cytosol. Reason: Valid cytosolic localization annotation.
GO:0045454 cell redox homeostasis	IDA PMID:10439045 Overexpression of gamma-glutamylcysteine synthetase suppress...	ACCEPT	Summary: GCLC overexpression maintains cellular redox status and suppresses TNF-induced activation of redox-sensitive transcription factors. Reason: GSH produced through GCLC activity is the major cellular antioxidant and maintains redox homeostasis. This annotation reflects the physiological role of GCLC-dependent GSH synthesis. Supporting Evidence: PMID:10439045 Overexpression of gamma-glutamylcysteine synthetase suppresses tumor necrosis factor-induced apoptosis and activation of nuclear transcription factor-kappa B and activator protein-1.
GO:0000287 magnesium ion binding	IDA PMID:24639 Inactivation of human gamma-glutamylcysteine synthetase by c...	ACCEPT	Summary: GCLC binds magnesium ions as a cofactor. The study detected enzyme-Mg2+ complexes through cystamine inactivation protection experiments. Reason: Magnesium is an essential cofactor for GCL activity. This is a core molecular function annotation supported by direct biochemical evidence. Supporting Evidence: PMID:24639 Inactivation of human gamma-glutamylcysteine synthetase by cystamine.
GO:0006750 glutathione biosynthetic process	IDA PMID:10395918 Regulation of gamma-glutamylcysteine synthetase regulatory s...	ACCEPT	Summary: Study showing GCLC-dependent GSH synthesis in response to oxidative stress. Reason: Core biological process annotation with experimental support showing coordinate regulation of GCLC and GSH levels. Supporting Evidence: PMID:10395918 Regulation of gamma-glutamylcysteine synthetase regulatory subunit (GLCLR) gene expression: identification of the major transcriptional start site in HT29 cells.
GO:0006979 response to oxidative stress	IDA PMID:10395918 Regulation of gamma-glutamylcysteine synthetase regulatory s...	KEEP AS NON CORE	Summary: GCLC expression is upregulated in response to oxidative stress (sodium nitroprusside treatment). Reason: This reflects transcriptional regulation of GCLC in response to oxidative stress rather than a direct function. The core function is GSH biosynthesis. Supporting Evidence: PMID:10395918 Regulation of gamma-glutamylcysteine synthetase regulatory subunit (GLCLR) gene expression: identification of the major transcriptional start site in HT29 cells.
GO:0043531 ADP binding	IDA PMID:24639 Inactivation of human gamma-glutamylcysteine synthetase by c...	ACCEPT	Summary: GCLC binds ADP (product of the ATP-dependent reaction). The study detected enzyme-ADP complexes. Reason: ADP is produced during the GCL reaction and enzyme-ADP complexes were demonstrated experimentally. This supports understanding of the catalytic mechanism. Supporting Evidence: PMID:24639 Inactivation of human gamma-glutamylcysteine synthetase by cystamine.
GO:0004357 glutamate-cysteine ligase activity	IMP PMID:16183645 Knockdown of glutamate-cysteine ligase by small hairpin RNA ...	ACCEPT	Summary: shRNA knockdown of GCLC reduces GCL activity and causes neuronal apoptosis, which is rescued by expressing GCLC cDNA. Reason: Loss-of-function evidence confirming GCLC's essential role in GCL catalytic activity. Rescue experiments validate specificity. Supporting Evidence: PMID:16183645 2005 Sep 23. Knockdown of glutamate-cysteine ligase by small hairpin RNA reveals that both catalytic and modulatory subunits are essential for the survival of primary neurons.
GO:0006536 glutamate metabolic process	IDA PMID:12663448 A novel missense mutation in the gamma-glutamylcysteine synt...	ACCEPT	Summary: Study characterizing GCLC enzymatic parameters including glutamate utilization. Reason: GCLC utilizes glutamate as a substrate and thus participates in glutamate metabolism. Supporting Evidence: PMID:12663448 Mar 27. A novel missense mutation in the gamma-glutamylcysteine synthetase catalytic subunit gene causes both decreased enzymatic activity and glutathione production.
GO:0006750 glutathione biosynthetic process	IMP PMID:12663448 A novel missense mutation in the gamma-glutamylcysteine synt...	ACCEPT	Summary: The R127C disease mutation causes decreased GSH production, confirming GCLC's essential role in glutathione biosynthesis. Reason: Mutational evidence supporting the core biological process annotation. Supporting Evidence: PMID:12663448 Mar 27. A novel missense mutation in the gamma-glutamylcysteine synthetase catalytic subunit gene causes both decreased enzymatic activity and glutathione production.
GO:0097746 blood vessel diameter maintenance	IMP PMID:12598062 Association of polymorphism in glutamate-cysteine ligase cat...	KEEP AS NON CORE	Summary: A GCLC promoter polymorphism (-129T) is associated with impaired coronary endothelium-dependent vasodilation and myocardial infarction. Reason: This is an indirect physiological consequence of reduced GCLC expression and GSH levels on vascular function, not a direct function. The polymorphism affects transcriptional response to oxidative stress. Supporting Evidence: PMID:12598062 Association of polymorphism in glutamate-cysteine ligase catalytic subunit gene with coronary vasomotor dysfunction and myocardial infarction.
GO:0004357 glutamate-cysteine ligase activity	IDA PMID:11972604 Oxidant stress induces gamma-glutamylcysteine synthetase and...	ACCEPT	Summary: Direct measurement of GCS activity in bronchial epithelial cells showing induction by oxidative stress. Reason: Core molecular function with direct enzymatic activity measurement. Supporting Evidence: PMID:11972604 Oxidant stress induces gamma-glutamylcysteine synthetase and glutathione synthesis in human bronchial epithelial NCI-H292 cells.
GO:0006534 cysteine metabolic process	IDA PMID:2294991 Gamma-glutamylcysteine synthetase deficiency and hemolytic a...	ACCEPT	Summary: Study of GCLC deficiency affecting cysteine utilization for GSH synthesis. Km for cysteine was assessed. Reason: GCLC uses cysteine as a substrate and thus participates in cysteine metabolism. This is an accurate annotation. Supporting Evidence: PMID:2294991 Gamma-glutamylcysteine synthetase deficiency and hemolytic anemia.
GO:0006536 glutamate metabolic process	IDA PMID:2294991 Gamma-glutamylcysteine synthetase deficiency and hemolytic a...	ACCEPT	Summary: Study assessing Km for glutamic acid in GCLC deficiency patient samples. Reason: GCLC utilizes glutamate as a substrate and participates in glutamate metabolism. Supporting Evidence: PMID:2294991 Gamma-glutamylcysteine synthetase deficiency and hemolytic anemia.
GO:0006979 response to oxidative stress	IDA PMID:11972604 Oxidant stress induces gamma-glutamylcysteine synthetase and...	KEEP AS NON CORE	Summary: GCLC expression and activity are induced by oxidative stress (menadione treatment) in bronchial epithelial cells. Reason: This annotation reflects the regulatory response of GCLC to oxidative stress rather than a direct function. The core function is GSH synthesis. Supporting Evidence: PMID:11972604 Oxidant stress induces gamma-glutamylcysteine synthetase and glutathione synthesis in human bronchial epithelial NCI-H292 cells.
GO:0016595 glutamate binding	IDA PMID:9841880 Identification of an important cysteine residue in human glu...	ACCEPT	Summary: Site-directed mutagenesis study examining glutamate binding properties of GCLC. Reason: Glutamate binding is essential for GCLC catalytic function as glutamate is a substrate. This annotation captures a core molecular function. Supporting Evidence: PMID:9841880 Identification of an important cysteine residue in human glutamate-cysteine ligase catalytic subunit by site-directed mutagenesis.
GO:0043066 negative regulation of apoptotic process	IDA PMID:10439045 Overexpression of gamma-glutamylcysteine synthetase suppress...	KEEP AS NON CORE	Summary: GCLC overexpression suppresses TNF-induced apoptosis and caspase-3 activation. Reason: This is an indirect effect mediated through GSH-dependent maintenance of cellular redox homeostasis. Not a direct anti-apoptotic function of GCLC itself. Supporting Evidence: PMID:10439045 Overexpression of gamma-glutamylcysteine synthetase suppresses tumor necrosis factor-induced apoptosis and activation of nuclear transcription factor-kappa B and activator protein-1.
GO:0045892 negative regulation of DNA-templated transcription	IDA PMID:10439045 Overexpression of gamma-glutamylcysteine synthetase suppress...	KEEP AS NON CORE	Summary: GCLC overexpression blocks NF-kappa B-dependent gene transcription by maintaining redox status. Reason: This is an indirect effect mediated through GSH maintaining cellular redox status, which affects redox-sensitive transcription factors. GCLC does not directly regulate transcription. Supporting Evidence: PMID:10439045 Overexpression of gamma-glutamylcysteine synthetase suppresses tumor necrosis factor-induced apoptosis and activation of nuclear transcription factor-kappa B and activator protein-1.
GO:0004357 glutamate-cysteine ligase activity	IDA PMID:8104187 gamma-Glutamylcysteine synthetase and active transport of gl...	ACCEPT	Summary: Direct measurement of GCS activity in K562 cells showing heat shock induction. Reason: Core molecular function with direct enzymatic activity measurement. Supporting Evidence: PMID:8104187 gamma-Glutamylcysteine synthetase and active transport of glutathione S-conjugate are responsive to heat shock in K562 erythroid cells.
GO:0006750 glutathione biosynthetic process	IDA PMID:8104187 gamma-Glutamylcysteine synthetase and active transport of gl...	ACCEPT	Summary: Study demonstrating GCLC role in glutathione synthesis in response to heat shock. Reason: Core biological process annotation with direct experimental evidence. Supporting Evidence: PMID:8104187 gamma-Glutamylcysteine synthetase and active transport of glutathione S-conjugate are responsive to heat shock in K562 erythroid cells.
GO:0009408 response to heat	IDA PMID:8104187 gamma-Glutamylcysteine synthetase and active transport of gl...	KEEP AS NON CORE	Summary: GCLC activity and mRNA are induced by heat shock in K562 cells. Reason: This reflects transcriptional regulation of GCLC by heat shock rather than a direct heat response function. The core function is GSH synthesis. Supporting Evidence: PMID:8104187 gamma-Glutamylcysteine synthetase and active transport of glutathione S-conjugate are responsive to heat shock in K562 erythroid cells.
GO:0009725 response to hormone	IDA PMID:8104187 gamma-Glutamylcysteine synthetase and active transport of gl...	KEEP AS NON CORE	Summary: GCLC activity is reduced by erythropoietin treatment in K562 cells. Reason: This annotation reflects hormonal regulation of GCLC expression rather than a direct hormone response function. The core function is enzymatic. Supporting Evidence: PMID:8104187 gamma-Glutamylcysteine synthetase and active transport of glutathione S-conjugate are responsive to heat shock in K562 erythroid cells.

Core Functions

GCLC is the catalytic subunit of glutamate-cysteine ligase, catalyzing the ATP-dependent ligation of L-glutamate and L-cysteine to form gamma-L-glutamyl-L-cysteine. This is the rate-limiting step in de novo glutathione biosynthesis. The enzyme requires Mg2+ as a cofactor and is feedback inhibited by GSH. Km values are 1.8 mM for glutamate, 0.1 mM for cysteine, and 0.4 mM for ATP.

Molecular Function:

glutamate-cysteine ligase activity

Supporting Evidence:

PMID:9675072
gamma-Glutamylcysteine synthetase (gamma-GCS) catalyzes the ATP-dependent ligation of L-glutamate and L-cysteine to form L-gamma-glutamyl-L-cysteine; this is the first and rate-limiting step in glutathione biosynthesis
PMID:12663448
Gamma-glutamylcysteine synthetase (gamma-GCS) catalyzes the first and rate-limiting step in glutathione (GSH) biosynthesis: the adenosine triphosphate (ATP)-dependent ligation of glutamate and cysteine

References

GO_REF:0000002

Gene Ontology annotation through association of InterPro records with GO terms

GO_REF:0000033

Annotation inferences using phylogenetic trees

GO_REF:0000043

Gene Ontology annotation based on UniProtKB/Swiss-Prot keyword mapping

GO_REF:0000107

Automatic transfer of experimentally verified manual GO annotation data to orthologs using Ensembl Compara

GO_REF:0000117

Electronic Gene Ontology annotations created by ARBA machine learning models

GO_REF:0000120

Combined Automated Annotation using Multiple IEA Methods

PMID:10395918

Regulation of gamma-glutamylcysteine synthetase regulatory subunit (GLCLR) gene expression: identification of the major transcriptional start site in HT29 cells.

SNP increases GSH levels 2-fold and GCS activity 6-fold
Coordinate increase in GCSl and GCSh subunit levels

PMID:10439045

Overexpression of gamma-glutamylcysteine synthetase suppresses tumor necrosis factor-induced apoptosis and activation of nuclear transcription factor-kappa B and activator protein-1.

GCS overexpression blocks TNF-induced NF-kappa B activation
GCS overexpression suppresses TNF-induced apoptosis and caspase-3 activation
Cellular redox status controlled by glutathione affects pleiotropic TNF actions

PMID:11972604

Oxidant stress induces gamma-glutamylcysteine synthetase and glutathione synthesis in human bronchial epithelial NCI-H292 cells.

Menadione-induced oxidative stress increases gamma-GCS activity and mRNA
Adaptive response mediated by transcriptional upregulation

PMID:12598062

Association of polymorphism in glutamate-cysteine ligase catalytic subunit gene with coronary vasomotor dysfunction and myocardial infarction.

GCLC -129T polymorphism has lower promoter activity in response to oxidants
Associated with impaired endothelium-dependent coronary vasodilation
Risk factor for myocardial infarction

PMID:12663448

A novel missense mutation in the gamma-glutamylcysteine synthetase catalytic subunit gene causes both decreased enzymatic activity and glutathione production.

R127C mutation causes decreased enzymatic activity and GSH production
Mutation lies within a cleft near the binding site
Causes hemolytic anemia (CNSHA7)

PMID:16183645

Knockdown of glutamate-cysteine ligase by small hairpin RNA reveals that both catalytic and modulatory subunits are essential for the survival of primary neurons.

shRNA knockdown of GCLC or GCLM causes neuronal apoptosis
Both subunits essential for neuronal survival
Rescue by gamma-glutamylcysteine or GSH ethyl ester

PMID:2294991

Gamma-glutamylcysteine synthetase deficiency and hemolytic anemia.

GCLC deficiency causes hemolytic anemia
Decreased GSH in lymphoblasts and fibroblasts
Clinical expression may be pleomorphic

PMID:24639

Inactivation of human gamma-glutamylcysteine synthetase by cystamine. Demonstration and quantification of enzyme-ligand complexes.

Detection of enzyme-Mg2+ complexes
Detection of enzyme-ATP-glutamate complexes
Magnesium ion confers protection against cystamine inactivation

PMID:28514442

Architecture of the human interactome defines protein communities and disease networks.

High-throughput detection of GCLC-GCLM interaction

PMID:33961781

Dual proteome-scale networks reveal cell-specific remodeling of the human interactome.

Detection of GCLC-GCLM interaction in proteome-scale study

PMID:40205054

Multimodal cell maps as a foundation for structural and functional genomics.

Detection of GCLC-GCLM interaction

PMID:8104187

gamma-Glutamylcysteine synthetase and active transport of glutathione S-conjugate are responsive to heat shock in K562 erythroid cells.

Heat shock increases gamma-GCS activity 1.7-fold
Erythropoietin decreases gamma-GCS activity to 64% of control
mRNA induction correlates with enzymatic activity changes

PMID:9675072

Expression and purification of human gamma-glutamylcysteine synthetase.

Co-expression and purification of human GCLC-GCLM holoenzyme
Km values determined - glutamate 1.8 mM, cysteine 0.1 mM, ATP 0.4 mM
Specific activity greater than 1500 units/mg
Feedback inhibited by glutathione

PMID:9841880

Identification of an important cysteine residue in human glutamate-cysteine ligase catalytic subunit by site-directed mutagenesis.

Cys553 important for GCLC-GCLM heterodimer formation
C553G mutation reduces holoenzyme activity
Eight conserved cysteine residues analyzed

Reactome:R-HSA-174367

GCL ligates L-Glu to L-Cys

Cytosolic reaction catalyzed by GCL complex

Reactome:R-HSA-5602892

Defective GCLC does not ligate L-Glu to L-Cys

Disease pathway for GCLC mutations

Reactome:R-HSA-9760122

AcK-NFE2L2-dependent GCLC gene expression

NRF2-dependent transcriptional regulation of GCLC

file:human/GCLC/GCLC-deep-research-falcon.md

Deep research report on GCLC

📚 Additional Documentation

Deep Research Falcon

(GCLC-deep-research-falcon.md)

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gene_id: GCLC
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uniprot_accession: P48506
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AltName: Full=GCS heavy chain; AltName: Full=Gamma-ECS; AltName: Full=Gamma-glutamylcysteine
synthetase;'
gene_info: Name=GCLC {ECO:0000312|HGNC:HGNC:4311}; Synonyms=GLCL, GLCLC;
organism_full: Homo sapiens (Human).
protein_family: Belongs to the glutamate--cysteine ligase type 3 family.
protein_domains: GCS. (IPR004308); Gln_synth/guanido_kin_cat_dom. (IPR014746); GCS
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Question

Gene Research for Functional Annotation

⚠️ CRITICAL: Gene/Protein Identification Context

BEFORE YOU BEGIN RESEARCH: You MUST verify you are researching the CORRECT gene/protein. Gene symbols can be ambiguous, especially for less well-characterized genes from non-model organisms.

Target Gene/Protein Identity (from UniProt):

UniProt Accession: P48506
Protein Description: RecName: Full=Glutamate--cysteine ligase catalytic subunit {ECO:0000305}; EC=6.3.2.2 {ECO:0000269|PubMed:12663448, ECO:0000269|PubMed:9675072}; AltName: Full=GCS heavy chain; AltName: Full=Gamma-ECS; AltName: Full=Gamma-glutamylcysteine synthetase;
Gene Information: Name=GCLC {ECO:0000312|HGNC:HGNC:4311}; Synonyms=GLCL, GLCLC;
Organism (full): Homo sapiens (Human).
Protein Family: Belongs to the glutamate--cysteine ligase type 3 family.
Key Domains: GCS. (IPR004308); Gln_synth/guanido_kin_cat_dom. (IPR014746); GCS (PF03074)

MANDATORY VERIFICATION STEPS:

Check if the gene symbol "GCLC" matches the protein description above
Verify the organism is correct: Homo sapiens (Human).
Check if protein family/domains align with what you find in literature
If you find literature for a DIFFERENT gene with the same or similar symbol, STOP

If Gene Symbol is Ambiguous or You Cannot Find Relevant Literature:

DO NOT PROCEED WITH RESEARCH ON A DIFFERENT GENE. Instead:
- State clearly: "The gene symbol 'GCLC' is ambiguous or literature is limited for this specific protein"
- Explain what you found (e.g., "Found extensive literature on a different gene with the same symbol in a different organism")
- Describe the protein based ONLY on the UniProt information provided above
- Suggest that the protein function can be inferred from domain/family information

Research Target:

Please provide a comprehensive research report on the gene GCLC (gene ID: GCLC, UniProt: P48506) in human.

The research report should be a detailed narrative explaining the function, biological processes, and localization of the gene product. Citations should be given for all claims.

You should prioritize authoritative reviews and primary scientific literature when conducting research. You can supplement
this with annotations you find in gene/protein databases, but these can be outdated or inaccurate.

We are specifically interested in the primary function of the gene - for enzymes, what reaction is catalyzed, and what is the substrate specificity? For transporters, what is the substrate? For structural proteins or adapters, what is the broader structural role? For signaling molecules, what is the role in the pathway.

We are interested in where in or outside the cell the gene product carries out its function.

We are also interested in the signaling or biochemical pathways in which the gene functions. We are less interested in broad pleiotropic effects, except where these elucidate the precise role.

Include evidence where possible. We are interested in both experimental evidence as well as inference from structure, evolution, or bioinformatic analysis. Precise studies should be prioritized over high-throughput, where available.

Output

Question: You are an expert researcher providing comprehensive, well-cited information.

Provide detailed information focusing on:
1. Key concepts and definitions with current understanding
2. Recent developments and latest research (prioritize 2023-2024 sources)
3. Current applications and real-world implementations
4. Expert opinions and analysis from authoritative sources
5. Relevant statistics and data from recent studies

Format as a comprehensive research report with proper citations. Include URLs and publication dates where available.
Always prioritize recent, authoritative sources and provide specific citations for all major claims.

Gene Research for Functional Annotation

⚠️ CRITICAL: Gene/Protein Identification Context

BEFORE YOU BEGIN RESEARCH: You MUST verify you are researching the CORRECT gene/protein. Gene symbols can be ambiguous, especially for less well-characterized genes from non-model organisms.

Target Gene/Protein Identity (from UniProt):

UniProt Accession: P48506
Protein Description: RecName: Full=Glutamate--cysteine ligase catalytic subunit {ECO:0000305}; EC=6.3.2.2 {ECO:0000269|PubMed:12663448, ECO:0000269|PubMed:9675072}; AltName: Full=GCS heavy chain; AltName: Full=Gamma-ECS; AltName: Full=Gamma-glutamylcysteine synthetase;
Gene Information: Name=GCLC {ECO:0000312|HGNC:HGNC:4311}; Synonyms=GLCL, GLCLC;
Organism (full): Homo sapiens (Human).
Protein Family: Belongs to the glutamate--cysteine ligase type 3 family.
Key Domains: GCS. (IPR004308); Gln_synth/guanido_kin_cat_dom. (IPR014746); GCS (PF03074)

MANDATORY VERIFICATION STEPS:

Check if the gene symbol "GCLC" matches the protein description above
Verify the organism is correct: Homo sapiens (Human).
Check if protein family/domains align with what you find in literature
If you find literature for a DIFFERENT gene with the same or similar symbol, STOP

If Gene Symbol is Ambiguous or You Cannot Find Relevant Literature:

Research Target:

Please provide a comprehensive research report on the gene GCLC (gene ID: GCLC, UniProt: P48506) in human.

The research report should be a detailed narrative explaining the function, biological processes, and localization of the gene product. Citations should be given for all claims.

We are interested in where in or outside the cell the gene product carries out its function.

We are also interested in the signaling or biochemical pathways in which the gene functions. We are less interested in broad pleiotropic effects, except where these elucidate the precise role.

Research plan status and verification
- Identity verification: The target is human GCLC (HGNC:4311), UniProt P48506, encoding the catalytic (heavy) subunit of glutamate–cysteine ligase (GCL; EC 6.3.2.2). Literature from 2023–2025 consistently describes GCLC as the catalytic subunit that, together with GCLM (modifier subunit), forms the holoenzyme catalyzing the first and rate-limiting step of glutathione (GSH) biosynthesis, matching the UniProt description and GCS family/domain context (no symbol ambiguity detected in the evidence set) (kazimierska2024inhibitionofthe pages 1-2, timson2024developmentofa pages 1-2, zhang2023covalenttargetingof pages 10-13, zhang2023covalenttargetingof pages 3-5).

Comprehensive research report on human GCLC (UniProt: P48506)
1) Key concepts and definitions (current understanding)
- Enzymatic role: GCLC is the catalytic subunit of glutamate–cysteine ligase (GCL), the rate-limiting enzyme in de novo GSH synthesis. The reaction conjugates L‑glutamate with L‑cysteine using ATP to form γ‑glutamylcysteine; γ‑glutamylcysteine is then ligated with glycine by glutathione synthetase to generate GSH. This first step is feedback‑inhibited by GSH and constrained by cysteine availability (publication date: 2024-02; URL: https://doi.org/10.1016/j.jbc.2024.105645) (timson2024developmentofa pages 1-2). Experimental assays employing human recombinant GCLC/GCLM confirm cysteine dependence and GCL catalytic activity in vitro (publication date: 2023-10; URL: https://doi.org/10.1002/cbic.202300371) (zhang2023covalenttargetingof pages 3-5).
- Holoenzyme composition: GCL is a heterodimer composed of GCLC and GCLM. GCLM modulates GCLC catalytic properties and cellular sensitivity to inhibition; genetic or pharmacologic perturbation of GCLM alters GCL activity and cellular GSH levels (2024-02; URL: https://doi.org/10.1016/j.jbc.2024.105645) (timson2024developmentofa pages 1-2), and small molecules can target GCLM to inhibit GCL (2023-10; URL: https://doi.org/10.1002/cbic.202300371) (zhang2023covalenttargetingof pages 10-13).
- Cellular role: GSH is a central redox buffer and cofactor for detoxification and peroxide reduction; GCLC/GCL activity governs GSH pool size, with implications for oxidative stress responses, drug detoxification, and regulated cell death modalities (2023-11; URL: https://doi.org/10.1007/s13353-023-00797-1) (kazimierska2024inhibitionofthe pages 1-2).

2) Recent developments and latest research (prioritized 2023–2024)
- Covalent allosteric GCL inhibition via GCLM Cys114: Chemoproteomic discovery identified EN25, a cysteine-reactive covalent ligand that engages an allosteric cysteine (C114) on human GCLM, inhibiting GCL activity (biochemical IC50 ≈ 16 μM; alkyne analog ≈ 3.6 μM). EN25 reduces cellular GSH and selectively impairs viability of ARID1A-deficient cancer cells; ferrostatin-1 partially rescues viability, linking inhibition to ferroptosis susceptibility (2023-10; URL: https://doi.org/10.1002/cbic.202300371) (zhang2023covalenttargetingof pages 10-13, zhang2023covalenttargetingof pages 3-5).
- NRF2–GCLC axis in cuproptosis resistance: In pancreatic ductal adenocarcinoma models, the cuproptosis inducer elesclomol–copper stabilizes NRF2 (NFE2L2), upregulating GCLC and GCLM and elevating GSH, which is transported into mitochondria by SLC25A39 to chelate copper and block cuproptosis. Disabling the NFE2L2–GSH–SLC25A39 pathway enhances cuproptosis-mediated tumor suppression in vitro and in vivo (2024-11; URL: https://doi.org/10.1038/s41598-024-81317-x) (liu2024nfe2l2andslc25a39 pages 1-2).
- GCLC PTM regulation and ferroptosis: Oxidative stress–regulated succinylation/desuccinylation modulates GCLC enzymatic activity. SIRT2 desuccinylates specific lysines on GCLC, increasing activity, elevating GSH, and protecting from ferroptosis; loss of SIRT2 reduces GSH and sensitizes to ferroptosis, while succinylation-mimic GCLC mutants fail to rescue (2025-04 online; URL: https://doi.org/10.1038/s41418-025-01505-8) (chen2025gclcdesuccinylationregulated pages 1-2).
- In vivo systems to study GSH limitation: A 2024 JBC study engineered cytosolic/mitochondrial GSH production to dissect consequences of GSH depletion. Findings reinforced GCL’s rate-limiting role, BSO sensitivity dependence on GCLM, and the compartmental nuances of GSH in cell death responses, including ferroptosis (2024-02; URL: https://doi.org/10.1016/j.jbc.2024.105645) (timson2024developmentofa pages 1-2).
- Oncology and therapy resistance context (overview): A 2024 review synthesizes GSH/GCL roles in tumor biology, therapeutic resistance, ferroptosis association, and early-stage drug discovery against GCL, consolidating human cancer links and emerging targeting strategies (2024-08; URL: https://doi.org/10.3390/ijms25158423) (kalinina2024glutathionedependentpathwaysin pages 26-27).

3) Biochemical specificity and mechanism
- Reaction/substrate specificity: Human GCLC catalyzes ATP-dependent formation of γ‑glutamylcysteine from L-glutamate and L-cysteine. In vitro reconstitution with recombinant human GCLC/GCLM uses cysteine as initiating substrate, validating substrate requirement and enabling inhibitor testing (2023-10; URL: https://doi.org/10.1002/cbic.202300371) (zhang2023covalenttargetingof pages 3-5). Rate-limiting control and feedback inhibition by GSH are established and were leveraged in genetic and pharmacologic experiments (2024-02; URL: https://doi.org/10.1016/j.jbc.2024.105645) (timson2024developmentofa pages 1-2).
- Holoenzyme modulation by GCLM: Genetic screens and pharmacology show that GCLM presence shapes sensitivity to BSO and small-molecule inhibitors; targeted covalent engagement of GCLM C114 allosterically inhibits the holoenzyme, reducing GSH and promoting ferroptosis-like cell death in sensitive contexts (2024-02; URL: https://doi.org/10.1016/j.jbc.2024.105645; 2023-10; URL: https://doi.org/10.1002/cbic.202300371) (timson2024developmentofa pages 1-2, zhang2023covalenttargetingof pages 10-13, zhang2023covalenttargetingof pages 3-5).

4) Subcellular localization
- GSH synthesis is predominantly cytosolic; mitochondrial GSH pools derive from cytosolic synthesis and import. Direct evidence shows GSH imported into mitochondria through SLC25A39, downstream of NRF2-dependent induction of GCLC/GCLM, thereby modulating mitochondrial death pathways such as cuproptosis (2024-11; URL: https://doi.org/10.1038/s41598-024-81317-x) (liu2024nfe2l2andslc25a39 pages 1-2).

5) Transcriptional and post-translational regulation
- Transcriptional control: The KEAP1–NRF2 axis upregulates GCLC (and GCLM) via antioxidant response elements in response to oxidative/electrophilic stress, with demonstrated induction under cuproptotic stress that elevates GSH pools (2024-11; URL: https://doi.org/10.1038/s41598-024-81317-x) (liu2024nfe2l2andslc25a39 pages 1-2). Reviews synthesizing cancer and redox biology further contextualize GCLC as a canonical NRF2 target gene linked to therapy resistance and ferroptosis avoidance (2024-08; URL: https://doi.org/10.3390/ijms25158423) (kalinina2024glutathionedependentpathwaysin pages 26-27).
- Post-translational control: Oxidative stress–responsive lysine succinylation on GCLC is dynamically regulated by SIRT2 (desuccinylase) and p300 (succinyltransferase), tuning enzymatic activity, cellular GSH, and ferroptosis susceptibility (2025-04; URL: https://doi.org/10.1038/s41418-025-01505-8) (chen2025gclcdesuccinylationregulated pages 1-2).

6) Roles in glutathione metabolism and regulated cell death (ferroptosis/cuproptosis)
- Ferroptosis: Pharmacologic inhibition of GCL lowers GSH and predisposes cells to ferroptotic death; rescue by ferrostatin-1 supports ferroptosis linkage (2023-10; URL: https://doi.org/10.1002/cbic.202300371) (zhang2023covalenttargetingof pages 10-13). GCLC activation via desuccinylation is protective against ferroptosis, and its inhibition (or PTM shifts that reduce activity) sensitizes to ferroptosis (2025-04; URL: https://doi.org/10.1038/s41418-025-01505-8) (chen2025gclcdesuccinylationregulated pages 1-2). A 2024 synthesis connects elevated GCLC/GCLM/GSH with therapy resistance and ferroptosis suppression across cancers (2024-08; URL: https://doi.org/10.3390/ijms25158423) (kalinina2024glutathionedependentpathwaysin pages 26-27).
- Cuproptosis: In PDAC, NRF2‑induced GCLC/GCLM elevate GSH, which chelates copper in mitochondria via SLC25A39 import, inhibiting cuproptosis; loss of this axis increases sensitivity to cuproptosis in vitro/in vivo (2024-11; URL: https://doi.org/10.1038/s41598-024-81317-x) (liu2024nfe2l2andslc25a39 pages 1-2).

7) Human genetics and deficiency phenotypes
- GCLC deficiency: A 2024 case report expands the phenotype to adult‑onset spinocerebellar ataxia with chronic hemolytic anemia due to homozygous GCLC c.514T>A (p.S172T), with low GSH and cerebellar atrophy. Prior families typically presented with hemolytic anemia; neurological involvement is less frequent. Management attempted antioxidant and GSH supplementation without definitive correction (2024-04; URL: https://doi.org/10.1159/000538225) (alhatou2024clinicalandbiochemical pages 1-2). Reviews of glutathione metabolism catalogue inborn errors and pediatric cases with GCL deficiency (contextual background) (2024-08; URL: https://doi.org/10.3390/ijms25158423) (kalinina2024glutathionedependentpathwaysin pages 26-27).

8) Therapeutic targeting and real‑world implementations
- BSO (buthionine sulfoximine): An irreversible GCL inhibitor historically used to deplete GSH. In Burkitt lymphoma models, BSO decreased growth and—crucially—enhanced cytotoxicity of doxorubicin and cyclophosphamide, while sparing control B cells; the study notes tolerability and prior clinical experience in neuroblastoma regimens with melphalan (2023-11 online; print 2024; URL: https://doi.org/10.1007/s13353-023-00797-1) (kazimierska2024inhibitionofthe pages 1-2).
- Emerging small‑molecule strategies: Covalent, cysteine‑targeted allosteric inhibitors of the GCL holoenzyme (via GCLM Cys114) suppress GCL activity and GSH, sensitizing cancer cells to ferroptosis; EN25 and analogs provide tool compounds with biochemically measured IC50s and chemoproteomic validation (2023-10; URL: https://doi.org/10.1002/cbic.202300371) (zhang2023covalenttargetingof pages 10-13, zhang2023covalenttargetingof pages 3-5).

9) Tissue expression, disease associations, and statistics/data highlights
- Cancer associations: GCLC is overexpressed in certain malignancies and is essential for viability in Burkitt lymphoma (CRISPR evidence), with protein overexpression observed in BL tissues (2023-11 online; URL: https://doi.org/10.1007/s13353-023-00797-1) (kazimierska2024inhibitionofthe pages 1-2). Reviews summarize associations of elevated GCLC/GCLM and GSH pathway with poor outcomes and resistance across tumor types, often in the context of NRF2 activation and ferroptosis suppression (2024-08; URL: https://doi.org/10.3390/ijms25158423) (kalinina2024glutathionedependentpathwaysin pages 26-27).
- Quantitative and mechanistic data points:
• EN25 biochemical IC50 ≈ 16 μM against GCL; EN25‑alkyne ≈ 3.6 μM; covalent engagement at GCLM Cys114 validated by ABPP; ferrostatin-1 rescue indicates ferroptosis contribution (2023-10; URL: https://doi.org/10.1002/cbic.202300371) (zhang2023covalenttargetingof pages 10-13, zhang2023covalenttargetingof pages 3-5).
• BSO sensitizes BL cells to doxorubicin and cyclophosphamide; GCLC knockout reduces BL viability; GCLC protein overexpressed in BL tissues (2023-11 online; URL: https://doi.org/10.1007/s13353-023-00797-1) (kazimierska2024inhibitionofthe pages 1-2).
• NRF2 stabilization by elesclomol–Cu elevates GCLC/GCLM expression; GSH import to mitochondria via SLC25A39 antagonizes cuproptosis; genetic disruption of the NRF2–GSH–SLC25A39 axis enhances tumor suppression (2024-11; URL: https://doi.org/10.1038/s41598-024-81317-x) (liu2024nfe2l2andslc25a39 pages 1-2).
• SIRT2‑dependent desuccinylation of GCLC increases activity and ferroptosis resistance; succinylation‑mimic mutants fail to restore GSH/ferroptosis resistance (2025-04 online; URL: https://doi.org/10.1038/s41418-025-01505-8) (chen2025gclcdesuccinylationregulated pages 1-2).

10) Expert opinions and authoritative analyses
- Redox and cancer metabolism: A 2024 integrative review details how the GSH system and GCL (GCLC/GCLM) underpin redox homeostasis, therapeutic resistance, and ferroptosis evasion in tumors, underscoring GCLC as a potential therapeutic node and biomarker of redox adaptation (2024-08; URL: https://doi.org/10.3390/ijms25158423) (kalinina2024glutathionedependentpathwaysin pages 26-27).
- Mechanistic clarity and translational outlook: The 2024 JBC resource articulates the centrality of GCL in mammalian GSH homeostasis, the genetic determinants of BSO sensitivity (GCLM), and the compartmental constraints that shape responses to GSH depletion and ferroptosis, providing a rigorous platform for future inhibitor development and in vivo validation (2024-02; URL: https://doi.org/10.1016/j.jbc.2024.105645) (timson2024developmentofa pages 1-2).

Conclusions and implications
- GCLC is a well‑defined human enzyme executing the ATP‑dependent ligation of glutamate and cysteine—the rate‑limiting step in GSH biosynthesis—within a GCLC/GCLM holoenzyme. Recent work (2023–2024) advances our understanding of: (i) covalent allosteric inhibition via GCLM to deplete GSH and potentiate ferroptosis; (ii) NRF2‑driven transcriptional control of GCLC/GCLM that buffers cuproptosis through mitochondrial GSH import; and (iii) PTM regulation (succinylation/desuccinylation) that tunes GCLC activity and ferroptosis susceptibility. Together with genetic evidence of human GCLC deficiency causing hemolytic anemia (sometimes with adult‑onset neurological disease), these findings clarify core biochemistry, regulatory logic, and translational avenues—including BSO repurposing and new GCL inhibitors—supporting both mechanistic interrogation and rational therapeutic design (zhang2023covalenttargetingof pages 10-13, zhang2023covalenttargetingof pages 3-5, liu2024nfe2l2andslc25a39 pages 1-2, chen2025gclcdesuccinylationregulated pages 1-2, timson2024developmentofa pages 1-2, alhatou2024clinicalandbiochemical pages 1-2, kazimierska2024inhibitionofthe pages 1-2, kalinina2024glutathionedependentpathwaysin pages 26-27).

References

(kazimierska2024inhibitionofthe pages 1-2): Marta Kazimierska, Aleksandra Leśniewska, Anja Bakker, Arjan Diepstra, Marta Elżbieta Kasprzyk, Marta Podralska, Karolina Rassek, Joost Kluiver, Anke van den Berg, Natalia Rozwadowska, and Agnieszka Dzikiewicz-Krawczyk. Inhibition of the glutamate-cysteine ligase catalytic subunit with buthionine sulfoximine enhances the cytotoxic effect of doxorubicin and cyclophosphamide in burkitt lymphoma cells. Journal of Applied Genetics, 65:95-101, Nov 2024. URL: https://doi.org/10.1007/s13353-023-00797-1, doi:10.1007/s13353-023-00797-1. This article has 4 citations and is from a peer-reviewed journal.
(timson2024developmentofa pages 1-2): Rebecca C. Timson, Artem Khan, Beste Uygur, Marwa Saad, Hsi-Wen Yeh, Nicole L. DelGaudio, Ross Weber, Hanan Alwaseem, Jing Gao, Chingwen Yang, and Kıvanç Birsoy. Development of a mouse model expressing a bifunctional glutathione-synthesizing enzyme to study glutathione limitation in vivo. Journal of Biological Chemistry, 300:105645, Feb 2024. URL: https://doi.org/10.1016/j.jbc.2024.105645, doi:10.1016/j.jbc.2024.105645. This article has 8 citations and is from a domain leading peer-reviewed journal.
(zhang2023covalenttargetingof pages 10-13): Lydia H. Zhang, Michelle Tang, Xavier Tao, Qian Shao, Vienna Thomas, Saki Shimizu, Miki Kasano, Yoshinori Ishikawa, Takayuki Inukai, and Daniel K. Nomura. Covalent targeting of glutamate cysteine ligase to inhibit glutathione synthesis**. ChemBioChem, Oct 2023. URL: https://doi.org/10.1002/cbic.202300371, doi:10.1002/cbic.202300371. This article has 8 citations and is from a peer-reviewed journal.
(zhang2023covalenttargetingof pages 3-5): Lydia H. Zhang, Michelle Tang, Xavier Tao, Qian Shao, Vienna Thomas, Saki Shimizu, Miki Kasano, Yoshinori Ishikawa, Takayuki Inukai, and Daniel K. Nomura. Covalent targeting of glutamate cysteine ligase to inhibit glutathione synthesis**. ChemBioChem, Oct 2023. URL: https://doi.org/10.1002/cbic.202300371, doi:10.1002/cbic.202300371. This article has 8 citations and is from a peer-reviewed journal.
(liu2024nfe2l2andslc25a39 pages 1-2): Jiao Liu, Hu Tang, Fangquan Chen, Changfeng Li, Yangchun Xie, Rui Kang, and Daolin Tang. Nfe2l2 and slc25a39 drive cuproptosis resistance through gsh metabolism. Scientific Reports, Nov 2024. URL: https://doi.org/10.1038/s41598-024-81317-x, doi:10.1038/s41598-024-81317-x. This article has 24 citations and is from a peer-reviewed journal.
(chen2025gclcdesuccinylationregulated pages 1-2): Zixiang Chen, Kaifeng Niu, Mengge Li, Yuchun Deng, Ji Zhang, Di Wei, Jiaqi Wang, and Yongliang Zhao. Gclc desuccinylation regulated by oxidative stress protects human cancer cells from ferroptosis. Cell death and differentiation, Apr 2025. URL: https://doi.org/10.1038/s41418-025-01505-8, doi:10.1038/s41418-025-01505-8. This article has 11 citations and is from a domain leading peer-reviewed journal.
(kalinina2024glutathionedependentpathwaysin pages 26-27): Elena Kalinina. Glutathione-dependent pathways in cancer cells. International Journal of Molecular Sciences, 25:8423, Aug 2024. URL: https://doi.org/10.3390/ijms25158423, doi:10.3390/ijms25158423. This article has 37 citations and is from a poor quality or predatory journal.
(alhatou2024clinicalandbiochemical pages 1-2): Mohammed Al-Hatou, A. Safan, Mohamed A. Atta, and Maria Siddiqi. Clinical and biochemical analysis of glutamate-cysteine ligase deficiency presented with late-onset spinocerebellar ataxia and hemolytic anemia. Molecular Syndromology, 15:432-436, Apr 2024. URL: https://doi.org/10.1159/000538225, doi:10.1159/000538225. This article has 1 citations and is from a peer-reviewed journal.

Citations

timson2024developmentofa pages 1-2
zhang2023covalenttargetingof pages 3-5
zhang2023covalenttargetingof pages 10-13
kazimierska2024inhibitionofthe pages 1-2
chen2025gclcdesuccinylationregulated pages 1-2
kalinina2024glutathionedependentpathwaysin pages 26-27
alhatou2024clinicalandbiochemical pages 1-2
https://doi.org/10.1016/j.jbc.2024.105645
https://doi.org/10.1002/cbic.202300371
https://doi.org/10.1007/s13353-023-00797-1
https://doi.org/10.1038/s41598-024-81317-x
https://doi.org/10.1038/s41418-025-01505-8
https://doi.org/10.3390/ijms25158423
https://doi.org/10.1016/j.jbc.2024.105645;
https://doi.org/10.1159/000538225
https://doi.org/10.1007/s13353-023-00797-1,
https://doi.org/10.1016/j.jbc.2024.105645,
https://doi.org/10.1002/cbic.202300371,
https://doi.org/10.1038/s41598-024-81317-x,
https://doi.org/10.1038/s41418-025-01505-8,
https://doi.org/10.3390/ijms25158423,
https://doi.org/10.1159/000538225,

📄 View Raw YAML

id: P48506
gene_symbol: GCLC
product_type: PROTEIN
status: COMPLETE
taxon:
  id: NCBITaxon:9606
  label: Homo sapiens
description: GCLC encodes the catalytic (heavy) subunit of glutamate-cysteine 
  ligase (GCL; EC 6.3.2.2), the rate-limiting enzyme in de novo glutathione 
  (GSH) biosynthesis. The enzyme catalyzes the ATP-dependent ligation of 
  L-glutamate and L-cysteine to form gamma-L-glutamyl-L-cysteine, which is 
  subsequently converted to GSH by glutathione synthetase. GCLC forms a 
  heterodimer with the regulatory/modifier subunit GCLM (GCLC:GCLM), which 
  modulates the catalytic properties and feedback inhibition sensitivity of the 
  enzyme. The reaction is feedback-inhibited by GSH. GCLC is transcriptionally 
  regulated by the KEAP1-NRF2 pathway in response to oxidative and electrophilic
  stress. Post-translational modifications including succinylation (regulated by
  SIRT2 desuccinylation) modulate GCLC activity and influence ferroptosis 
  susceptibility. Mutations in GCLC cause autosomal recessive hemolytic anemia 
  (CNSHA7), sometimes associated with spinocerebellar degeneration, due to GSH 
  deficiency in erythrocytes. GCLC is cytosolic and is essential for cellular 
  redox homeostasis.
existing_annotations:
  - term:
      id: GO:0017109
      label: glutamate-cysteine ligase complex
    evidence_type: IBA
    original_reference_id: GO_REF:0000033
    review:
      summary: GCLC is the catalytic subunit of the glutamate-cysteine ligase 
        (GCL) heterodimer, forming a complex with GCLM (the regulatory/modifier 
        subunit). This annotation is well-supported by phylogenetic inference 
        and experimental evidence showing GCLC-GCLM interaction (PMID:9675072, 
        PMID:9841880).
      action: ACCEPT
      reason: The IBA annotation accurately reflects that GCLC is part of the 
        GCL complex. This is a core function supported by extensive experimental
        evidence. The heterodimer formation between GCLC and GCLM is essential 
        for optimal enzymatic activity and has been demonstrated by 
        co-expression and purification studies.
      supported_by:
        - reference_id: PMID:9675072
          supporting_text: Expression and purification of human 
            gamma-glutamylcysteine synthetase.
        - reference_id: PMID:9841880
          supporting_text: Identification of an important cysteine residue in 
            human glutamate-cysteine ligase catalytic subunit by site-directed 
            mutagenesis.
        - reference_id: file:human/GCLC/GCLC-deep-research-falcon.md
          supporting_text: 'model: Edison Scientific Literature'
  - term:
      id: GO:0004357
      label: glutamate-cysteine ligase activity
    evidence_type: IBA
    original_reference_id: GO_REF:0000033
    review:
      summary: GCLC possesses glutamate-cysteine ligase activity, catalyzing the
        ATP-dependent ligation of L-glutamate and L-cysteine to form 
        gamma-L-glutamyl-L-cysteine. This is the primary enzymatic function of 
        the catalytic subunit.
      action: ACCEPT
      reason: This is the core molecular function of GCLC. The IBA annotation is
        consistent with extensive experimental evidence including direct enzyme 
        assays with recombinant human protein (PMID:9675072, PMID:12663448).
      supported_by:
        - reference_id: PMID:9675072
          supporting_text: Expression and purification of human 
            gamma-glutamylcysteine synthetase.
        - reference_id: PMID:12663448
          supporting_text: Mar 27. A novel missense mutation in the 
            gamma-glutamylcysteine synthetase catalytic subunit gene causes both
            decreased enzymatic activity and glutathione production.
  - term:
      id: GO:0006750
      label: glutathione biosynthetic process
    evidence_type: IBA
    original_reference_id: GO_REF:0000033
    review:
      summary: GCLC catalyzes the first and rate-limiting step in glutathione 
        biosynthesis. The gamma-L-glutamyl-L-cysteine product is subsequently 
        ligated to glycine by glutathione synthetase to produce GSH.
      action: ACCEPT
      reason: This is a core biological process annotation. GCLC is essential 
        for glutathione biosynthesis as it performs the rate-limiting step. The 
        IBA annotation is strongly supported by the conserved function across 
        eukaryotes.
      supported_by:
        - reference_id: PMID:9675072
          supporting_text: Expression and purification of human 
            gamma-glutamylcysteine synthetase.
        - reference_id: PMID:12663448
          supporting_text: Mar 27. A novel missense mutation in the 
            gamma-glutamylcysteine synthetase catalytic subunit gene causes both
            decreased enzymatic activity and glutathione production.
  - term:
      id: GO:0000166
      label: nucleotide binding
    evidence_type: IEA
    original_reference_id: GO_REF:0000043
    review:
      summary: GCLC binds ATP as a substrate for the ligation reaction. The 
        annotation is inferred from UniProt keyword mapping and is too general.
      action: MODIFY
      reason: While GCLC does bind nucleotides (specifically ATP as substrate), 
        this term is overly broad. The more specific term GO:0005524 (ATP 
        binding) is already annotated and should be preferred. The direct IDA 
        evidence for ADP binding (GO:0043531) from PMID:24639 provides more 
        precise information.
      proposed_replacement_terms:
        - id: GO:0005524
          label: ATP binding
  - term:
      id: GO:0003824
      label: catalytic activity
    evidence_type: IEA
    original_reference_id: GO_REF:0000002
    review:
      summary: IEA annotation from InterPro domain mapping. GCLC has catalytic 
        activity but this term is too general.
      action: MODIFY
      reason: This is an overly broad term. The specific catalytic activity 
        (GO:0004357 glutamate-cysteine ligase activity) is already annotated 
        with experimental evidence and should be used instead.
      proposed_replacement_terms:
        - id: GO:0004357
          label: glutamate-cysteine ligase activity
  - term:
      id: GO:0004357
      label: glutamate-cysteine ligase activity
    evidence_type: IEA
    original_reference_id: GO_REF:0000120
    review:
      summary: IEA annotation for glutamate-cysteine ligase activity from 
        combined automated methods. Duplicates the IBA annotation and 
        experimental IDA annotations.
      action: ACCEPT
      reason: This is a valid annotation capturing the core molecular function. 
        While redundant with other evidence codes, the IEA annotation reflects 
        automated validation of the core enzymatic function.
      supported_by:
        - reference_id: PMID:9675072
          supporting_text: Expression and purification of human 
            gamma-glutamylcysteine synthetase.
  - term:
      id: GO:0005524
      label: ATP binding
    evidence_type: IEA
    original_reference_id: GO_REF:0000043
    review:
      summary: GCLC requires ATP as a substrate for the ligation reaction. The 
        Km for ATP is 0.4 mM (PMID:9675072).
      action: ACCEPT
      reason: ATP binding is essential for GCLC function as ATP provides the 
        energy for the ligation reaction. While this is an IEA annotation, it is
        well-supported by the characterized enzymatic mechanism.
      supported_by:
        - reference_id: PMID:9675072
          supporting_text: Expression and purification of human 
            gamma-glutamylcysteine synthetase.
  - term:
      id: GO:0006750
      label: glutathione biosynthetic process
    evidence_type: IEA
    original_reference_id: GO_REF:0000120
    review:
      summary: IEA annotation for involvement in glutathione biosynthesis from 
        combined automated methods. Duplicates IBA and IDA annotations.
      action: ACCEPT
      reason: Valid annotation supporting the core biological process. Redundant
        with experimental evidence but reflects automated validation.
  - term:
      id: GO:0016874
      label: ligase activity
    evidence_type: IEA
    original_reference_id: GO_REF:0000043
    review:
      summary: GCLC is indeed a ligase, catalyzing ATP-dependent bond formation.
        However, this is a parent term of the more specific glutamate-cysteine 
        ligase activity.
      action: MODIFY
      reason: This term is valid but too general. The more specific child term 
        GO:0004357 (glutamate-cysteine ligase activity) is already annotated and
        provides more informative annotation.
      proposed_replacement_terms:
        - id: GO:0004357
          label: glutamate-cysteine ligase activity
  - term:
      id: GO:0043066
      label: negative regulation of apoptotic process
    evidence_type: IEA
    original_reference_id: GO_REF:0000117
    review:
      summary: GCLC overexpression suppresses TNF-induced apoptosis through 
        maintaining cellular GSH levels and redox status (PMID:10439045).
      action: KEEP_AS_NON_CORE
      reason: This is a downstream consequence of GCLC's role in GSH 
        biosynthesis rather than a direct function. GSH maintains cellular redox
        homeostasis which protects against apoptotic cell death. The effect is 
        indirect - mediated through GSH levels - rather than a direct 
        anti-apoptotic function.
      supported_by:
        - reference_id: PMID:10439045
          supporting_text: Overexpression of gamma-glutamylcysteine synthetase 
            suppresses tumor necrosis factor-induced apoptosis and activation of
            nuclear transcription factor-kappa B and activator protein-1.
  - term:
      id: GO:0005515
      label: protein binding
    evidence_type: IPI
    original_reference_id: PMID:28514442
    review:
      summary: High-throughput interactome study detecting GCLC-GCLM 
        interaction.
      action: MODIFY
      reason: The term "protein binding" is uninformative. The documented 
        interaction is specifically with GCLM (P48507), the regulatory subunit 
        of the GCL complex. The more informative annotation would be the 
        cellular component GO:0017109 (glutamate-cysteine ligase complex) which 
        is already present.
      proposed_replacement_terms:
        - id: GO:0017109
          label: glutamate-cysteine ligase complex
      supported_by:
        - reference_id: PMID:28514442
          supporting_text: Architecture of the human interactome defines protein
            communities and disease networks.
  - term:
      id: GO:0005515
      label: protein binding
    evidence_type: IPI
    original_reference_id: PMID:33961781
    review:
      summary: Dual proteome interactome study detecting GCLC-GCLM interaction.
      action: MODIFY
      reason: Same rationale as other protein binding annotations - the term is 
        uninformative and the specific interaction is with GCLM to form the GCL 
        complex, which is captured by GO:0017109.
      proposed_replacement_terms:
        - id: GO:0017109
          label: glutamate-cysteine ligase complex
      supported_by:
        - reference_id: PMID:33961781
          supporting_text: 2021 May 6. Dual proteome-scale networks reveal 
            cell-specific remodeling of the human interactome.
  - term:
      id: GO:0005515
      label: protein binding
    evidence_type: IPI
    original_reference_id: PMID:40205054
    review:
      summary: Multimodal cell maps study detecting GCLC-GCLM interaction.
      action: MODIFY
      reason: The generic protein binding term should be replaced by the more 
        specific complex annotation that captures the functionally relevant 
        GCLC-GCLM heterodimer formation.
      proposed_replacement_terms:
        - id: GO:0017109
          label: glutamate-cysteine ligase complex
      supported_by:
        - reference_id: PMID:40205054
          supporting_text: Apr 9. Multimodal cell maps as a foundation for 
            structural and functional genomics.
  - term:
      id: GO:0005515
      label: protein binding
    evidence_type: IPI
    original_reference_id: PMID:9675072
    review:
      summary: Study demonstrating GCLC-GCLM heterodimer formation through 
        co-expression and purification of the holoenzyme.
      action: MODIFY
      reason: This primary literature reference documents the GCLC-GCLM 
        interaction essential for holoenzyme formation. The generic "protein 
        binding" term fails to capture this specific and important functional 
        interaction.
      proposed_replacement_terms:
        - id: GO:0017109
          label: glutamate-cysteine ligase complex
      supported_by:
        - reference_id: PMID:9675072
          supporting_text: Expression and purification of human 
            gamma-glutamylcysteine synthetase.
  - term:
      id: GO:0005829
      label: cytosol
    evidence_type: IEA
    original_reference_id: GO_REF:0000107
    review:
      summary: GCLC is localized in the cytosol where glutathione biosynthesis 
        occurs. This annotation is transferred from ortholog data.
      action: ACCEPT
      reason: Cytosolic localization is correct and consistent with the role of 
        GCLC in cytoplasmic GSH synthesis. This is supported by Reactome TAS 
        annotations and the known biochemistry of GSH synthesis.
  - term:
      id: GO:0006979
      label: response to oxidative stress
    evidence_type: IEA
    original_reference_id: GO_REF:0000107
    review:
      summary: GCLC expression and activity are induced by oxidative stress as 
        part of the cellular antioxidant response. This is mediated through the 
        KEAP1-NRF2 pathway (deep research review).
      action: KEEP_AS_NON_CORE
      reason: While GCLC is transcriptionally upregulated in response to 
        oxidative stress (via NRF2) and GSH production protects against 
        oxidative damage, this is a regulatory/response annotation rather than a
        core function. The core function is GSH biosynthesis.
      supported_by:
        - reference_id: PMID:11972604
          supporting_text: Oxidant stress induces gamma-glutamylcysteine 
            synthetase and glutathione synthesis in human bronchial epithelial 
            NCI-H292 cells.
  - term:
      id: GO:0007584
      label: response to nutrient
    evidence_type: IEA
    original_reference_id: GO_REF:0000107
    review:
      summary: IEA annotation transferred from rat ortholog. GCLC activity is 
        influenced by cysteine availability which can be nutrient-limited.
      action: KEEP_AS_NON_CORE
      reason: This reflects the regulatory context of GCLC rather than its 
        direct function. GSH synthesis is limited by cysteine availability, but 
        response to nutrient is not a core function.
  - term:
      id: GO:0014823
      label: response to activity
    evidence_type: IEA
    original_reference_id: GO_REF:0000107
    review:
      summary: IEA annotation from ortholog transfer. May relate to 
        exercise-induced changes in GSH metabolism.
      action: KEEP_AS_NON_CORE
      reason: This is a peripheral annotation describing regulatory context 
        rather than core function. The primary function is enzymatic.
  - term:
      id: GO:0017109
      label: glutamate-cysteine ligase complex
    evidence_type: IEA
    original_reference_id: GO_REF:0000120
    review:
      summary: IEA annotation for GCLC being part of the GCL heterodimeric 
        complex with GCLM.
      action: ACCEPT
      reason: Redundant with IBA and IDA annotations but valid. GCLC forms a 
        heterodimer with GCLM constituting the active holoenzyme.
  - term:
      id: GO:0032869
      label: cellular response to insulin stimulus
    evidence_type: IEA
    original_reference_id: GO_REF:0000107
    review:
      summary: IEA annotation from rat ortholog. Insulin signaling may regulate 
        GSH metabolism.
      action: KEEP_AS_NON_CORE
      reason: This represents a regulatory input to GCLC expression/activity 
        rather than the core enzymatic function. Pleiotropic cellular responses 
        are secondary to the primary function.
  - term:
      id: GO:0035729
      label: cellular response to hepatocyte growth factor stimulus
    evidence_type: IEA
    original_reference_id: GO_REF:0000107
    review:
      summary: IEA annotation from ortholog transfer suggesting GCLC responds to
        HGF.
      action: KEEP_AS_NON_CORE
      reason: Peripheral regulatory annotation. Not a core function of GCLC.
  - term:
      id: GO:0043524
      label: negative regulation of neuron apoptotic process
    evidence_type: IEA
    original_reference_id: GO_REF:0000107
    review:
      summary: GCLC-mediated GSH synthesis protects neurons from apoptotic 
        death. Knockdown of either GCL subunit causes neuronal apoptosis 
        (PMID:16183645).
      action: KEEP_AS_NON_CORE
      reason: This is an indirect downstream effect of GSH biosynthesis. While 
        documented experimentally in neurons (PMID:16183645), it represents a 
        tissue-specific consequence rather than a direct anti-apoptotic 
        function.
      supported_by:
        - reference_id: PMID:16183645
          supporting_text: 2005 Sep 23. Knockdown of glutamate-cysteine ligase 
            by small hairpin RNA reveals that both catalytic and modulatory 
            subunits are essential for the survival of primary neurons.
  - term:
      id: GO:0044344
      label: cellular response to fibroblast growth factor stimulus
    evidence_type: IEA
    original_reference_id: GO_REF:0000107
    review:
      summary: IEA annotation from ortholog transfer.
      action: KEEP_AS_NON_CORE
      reason: Peripheral regulatory annotation, not a core function.
  - term:
      id: GO:0044752
      label: response to human chorionic gonadotropin
    evidence_type: IEA
    original_reference_id: GO_REF:0000107
    review:
      summary: IEA annotation from ortholog transfer.
      action: KEEP_AS_NON_CORE
      reason: Tissue-specific regulatory context, not a core function.
  - term:
      id: GO:0044877
      label: protein-containing complex binding
    evidence_type: IEA
    original_reference_id: GO_REF:0000107
    review:
      summary: IEA annotation suggesting GCLC binds to protein complexes.
      action: MODIFY
      reason: This is vague. The specific relevant complex is the GCLC-GCLM 
        heterodimer, which is better captured by GO:0017109.
      proposed_replacement_terms:
        - id: GO:0017109
          label: glutamate-cysteine ligase complex
  - term:
      id: GO:0046686
      label: response to cadmium ion
    evidence_type: IEA
    original_reference_id: GO_REF:0000107
    review:
      summary: GCLC/GSH is induced by cadmium as a detoxification response.
      action: KEEP_AS_NON_CORE
      reason: GSH conjugation is important for heavy metal detoxification, but 
        this represents a regulatory/response context rather than direct cadmium
        binding or processing by GCLC.
  - term:
      id: GO:0051409
      label: response to nitrosative stress
    evidence_type: IEA
    original_reference_id: GO_REF:0000107
    review:
      summary: GCLC expression is upregulated by nitrosative stress (e.g., 
        sodium nitroprusside treatment increases GCS activity, PMID:10395918).
      action: KEEP_AS_NON_CORE
      reason: This reflects transcriptional regulation of GCLC in response to 
        stress rather than a direct function in nitrosative stress response.
      supported_by:
        - reference_id: PMID:10395918
          supporting_text: 'Regulation of gamma-glutamylcysteine synthetase regulatory
            subunit (GLCLR) gene expression: identification of the major transcriptional
            start site in HT29 cells.'
  - term:
      id: GO:0070555
      label: response to interleukin-1
    evidence_type: IEA
    original_reference_id: GO_REF:0000107
    review:
      summary: IEA annotation from ortholog transfer.
      action: KEEP_AS_NON_CORE
      reason: Peripheral regulatory annotation reflecting cytokine-mediated 
        regulation rather than a core function.
  - term:
      id: GO:0071260
      label: cellular response to mechanical stimulus
    evidence_type: IEA
    original_reference_id: GO_REF:0000107
    review:
      summary: IEA annotation from ortholog transfer.
      action: KEEP_AS_NON_CORE
      reason: Peripheral annotation, not a core function.
  - term:
      id: GO:0071333
      label: cellular response to glucose stimulus
    evidence_type: IEA
    original_reference_id: GO_REF:0000107
    review:
      summary: IEA annotation from ortholog transfer.
      action: KEEP_AS_NON_CORE
      reason: Peripheral metabolic regulatory context rather than core function.
  - term:
      id: GO:0071372
      label: cellular response to follicle-stimulating hormone stimulus
    evidence_type: IEA
    original_reference_id: GO_REF:0000107
    review:
      summary: IEA annotation from ortholog transfer.
      action: KEEP_AS_NON_CORE
      reason: Tissue-specific regulatory context, not a core function.
  - term:
      id: GO:0097069
      label: cellular response to thyroxine stimulus
    evidence_type: IEA
    original_reference_id: GO_REF:0000107
    review:
      summary: IEA annotation from ortholog transfer.
      action: KEEP_AS_NON_CORE
      reason: Hormonal regulatory context, not a core function.
  - term:
      id: GO:2000490
      label: negative regulation of hepatic stellate cell activation
    evidence_type: IEA
    original_reference_id: GO_REF:0000107
    review:
      summary: IEA annotation from ortholog transfer. GSH may inhibit hepatic 
        stellate cell activation in fibrosis contexts.
      action: KEEP_AS_NON_CORE
      reason: Tissue-specific downstream consequence of GSH production, not a 
        direct or core function of GCLC.
  - term:
      id: GO:0006750
      label: glutathione biosynthetic process
    evidence_type: IDA
    original_reference_id: PMID:9675072
    review:
      summary: Direct demonstration that recombinant human GCLC catalyzes the 
        first step in glutathione biosynthesis using purified protein.
      action: ACCEPT
      reason: Core biological process annotation with direct experimental 
        evidence. This study expressed and purified human GCLC and demonstrated 
        its enzymatic function in GSH precursor synthesis.
      supported_by:
        - reference_id: PMID:9675072
          supporting_text: Expression and purification of human 
            gamma-glutamylcysteine synthetase.
  - term:
      id: GO:0004357
      label: glutamate-cysteine ligase activity
    evidence_type: IMP
    original_reference_id: PMID:12663448
    review:
      summary: Study of the R127C disease mutation demonstrating decreased 
        enzymatic activity in the mutant, confirming GCLC's role in GCL 
        catalysis.
      action: ACCEPT
      reason: Core molecular function with mutational evidence. The R127C 
        mutation causes decreased GCL activity and hemolytic anemia, providing 
        genetic evidence for GCLC's essential catalytic role.
      supported_by:
        - reference_id: PMID:12663448
          supporting_text: Mar 27. A novel missense mutation in the 
            gamma-glutamylcysteine synthetase catalytic subunit gene causes both
            decreased enzymatic activity and glutathione production.
  - term:
      id: GO:0004357
      label: glutamate-cysteine ligase activity
    evidence_type: IDA
    original_reference_id: PMID:9675072
    review:
      summary: Direct biochemical characterization of purified recombinant human
        GCLC demonstrating glutamate-cysteine ligase activity with kinetic 
        parameters.
      action: ACCEPT
      reason: Primary experimental evidence for the core molecular function. Km 
        values determined for all substrates confirm the catalytic mechanism.
      supported_by:
        - reference_id: PMID:9675072
          supporting_text: Expression and purification of human 
            gamma-glutamylcysteine synthetase.
  - term:
      id: GO:0004357
      label: glutamate-cysteine ligase activity
    evidence_type: IMP
    original_reference_id: PMID:9841880
    review:
      summary: Site-directed mutagenesis study identifying Cys553 as important 
        for GCLC-GCLM heterodimer formation and enzyme activity.
      action: ACCEPT
      reason: Mutational evidence supporting the core catalytic function. The 
        C553G mutation reduces holoenzyme activity, confirming the importance of
        subunit interaction for full activity.
      supported_by:
        - reference_id: PMID:9841880
          supporting_text: Identification of an important cysteine residue in 
            human glutamate-cysteine ligase catalytic subunit by site-directed 
            mutagenesis.
  - term:
      id: GO:0005515
      label: protein binding
    evidence_type: IPI
    original_reference_id: PMID:9841880
    review:
      summary: Study demonstrating physical interaction between GCLC and GCLM 
        (GCLR) through site-directed mutagenesis and activity assays.
      action: MODIFY
      reason: The generic "protein binding" term fails to capture the specific 
        and functionally important GCLC-GCLM interaction. The complex annotation
        GO:0017109 is more informative.
      proposed_replacement_terms:
        - id: GO:0017109
          label: glutamate-cysteine ligase complex
      supported_by:
        - reference_id: PMID:9841880
          supporting_text: Identification of an important cysteine residue in 
            human glutamate-cysteine ligase catalytic subunit by site-directed 
            mutagenesis.
  - term:
      id: GO:0006536
      label: glutamate metabolic process
    evidence_type: IDA
    original_reference_id: PMID:9841880
    review:
      summary: GCLC uses L-glutamate as a substrate. The study characterized 
        glutamate binding and utilization by GCLC.
      action: ACCEPT
      reason: GCLC directly participates in glutamate metabolism by 
        incorporating glutamate into gamma-glutamylcysteine. This is an accurate
        annotation of the enzyme's substrate utilization.
      supported_by:
        - reference_id: PMID:9841880
          supporting_text: Identification of an important cysteine residue in 
            human glutamate-cysteine ligase catalytic subunit by site-directed 
            mutagenesis.
  - term:
      id: GO:0017109
      label: glutamate-cysteine ligase complex
    evidence_type: IDA
    original_reference_id: PMID:9675072
    review:
      summary: Direct demonstration of GCLC-GCLM holoenzyme assembly through 
        co-expression and purification.
      action: ACCEPT
      reason: Core cellular component annotation with direct experimental 
        evidence. The study co-expressed both subunits and purified the 
        assembled heterodimer.
      supported_by:
        - reference_id: PMID:9675072
          supporting_text: Expression and purification of human 
            gamma-glutamylcysteine synthetase.
  - term:
      id: GO:0017109
      label: glutamate-cysteine ligase complex
    evidence_type: IDA
    original_reference_id: PMID:9841880
    review:
      summary: Study demonstrating GCLC-GCLM heterodimer formation and 
        identifying Cys553 as important for the interaction.
      action: ACCEPT
      reason: Direct experimental evidence for GCLC being part of the GCL 
        complex.
      supported_by:
        - reference_id: PMID:9841880
          supporting_text: Identification of an important cysteine residue in 
            human glutamate-cysteine ligase catalytic subunit by site-directed 
            mutagenesis.
  - term:
      id: GO:0005829
      label: cytosol
    evidence_type: TAS
    original_reference_id: Reactome:R-HSA-5602892
    review:
      summary: Reactome annotation placing GCLC in the cytosol where the GCL 
        reaction occurs.
      action: ACCEPT
      reason: Cytosolic localization is correct for GCLC and GSH biosynthesis. 
        This is a core localization annotation.
  - term:
      id: GO:0005829
      label: cytosol
    evidence_type: TAS
    original_reference_id: Reactome:R-HSA-174367
    review:
      summary: Reactome annotation for the GCL ligation reaction occurring in 
        the cytosol.
      action: ACCEPT
      reason: Redundant with other cytosol annotations but valid and reflects 
        accurate localization.
  - term:
      id: GO:0005829
      label: cytosol
    evidence_type: TAS
    original_reference_id: Reactome:R-HSA-9760122
    review:
      summary: Reactome annotation for NRF2-dependent GCLC expression, placing 
        the gene product in the cytosol.
      action: ACCEPT
      reason: Valid cytosolic localization annotation.
  - term:
      id: GO:0045454
      label: cell redox homeostasis
    evidence_type: IDA
    original_reference_id: PMID:10439045
    review:
      summary: GCLC overexpression maintains cellular redox status and 
        suppresses TNF-induced activation of redox-sensitive transcription 
        factors.
      action: ACCEPT
      reason: GSH produced through GCLC activity is the major cellular 
        antioxidant and maintains redox homeostasis. This annotation reflects 
        the physiological role of GCLC-dependent GSH synthesis.
      supported_by:
        - reference_id: PMID:10439045
          supporting_text: Overexpression of gamma-glutamylcysteine synthetase 
            suppresses tumor necrosis factor-induced apoptosis and activation of
            nuclear transcription factor-kappa B and activator protein-1.
  - term:
      id: GO:0000287
      label: magnesium ion binding
    evidence_type: IDA
    original_reference_id: PMID:24639
    review:
      summary: GCLC binds magnesium ions as a cofactor. The study detected 
        enzyme-Mg2+ complexes through cystamine inactivation protection 
        experiments.
      action: ACCEPT
      reason: Magnesium is an essential cofactor for GCL activity. This is a 
        core molecular function annotation supported by direct biochemical 
        evidence.
      supported_by:
        - reference_id: PMID:24639
          supporting_text: Inactivation of human gamma-glutamylcysteine 
            synthetase by cystamine.
  - term:
      id: GO:0006750
      label: glutathione biosynthetic process
    evidence_type: IDA
    original_reference_id: PMID:10395918
    review:
      summary: Study showing GCLC-dependent GSH synthesis in response to 
        oxidative stress.
      action: ACCEPT
      reason: Core biological process annotation with experimental support 
        showing coordinate regulation of GCLC and GSH levels.
      supported_by:
        - reference_id: PMID:10395918
          supporting_text: 'Regulation of gamma-glutamylcysteine synthetase regulatory
            subunit (GLCLR) gene expression: identification of the major transcriptional
            start site in HT29 cells.'
  - term:
      id: GO:0006979
      label: response to oxidative stress
    evidence_type: IDA
    original_reference_id: PMID:10395918
    review:
      summary: GCLC expression is upregulated in response to oxidative stress 
        (sodium nitroprusside treatment).
      action: KEEP_AS_NON_CORE
      reason: This reflects transcriptional regulation of GCLC in response to 
        oxidative stress rather than a direct function. The core function is GSH
        biosynthesis.
      supported_by:
        - reference_id: PMID:10395918
          supporting_text: 'Regulation of gamma-glutamylcysteine synthetase regulatory
            subunit (GLCLR) gene expression: identification of the major transcriptional
            start site in HT29 cells.'
  - term:
      id: GO:0043531
      label: ADP binding
    evidence_type: IDA
    original_reference_id: PMID:24639
    review:
      summary: GCLC binds ADP (product of the ATP-dependent reaction). The study
        detected enzyme-ADP complexes.
      action: ACCEPT
      reason: ADP is produced during the GCL reaction and enzyme-ADP complexes 
        were demonstrated experimentally. This supports understanding of the 
        catalytic mechanism.
      supported_by:
        - reference_id: PMID:24639
          supporting_text: Inactivation of human gamma-glutamylcysteine 
            synthetase by cystamine.
  - term:
      id: GO:0004357
      label: glutamate-cysteine ligase activity
    evidence_type: IMP
    original_reference_id: PMID:16183645
    review:
      summary: shRNA knockdown of GCLC reduces GCL activity and causes neuronal 
        apoptosis, which is rescued by expressing GCLC cDNA.
      action: ACCEPT
      reason: Loss-of-function evidence confirming GCLC's essential role in GCL 
        catalytic activity. Rescue experiments validate specificity.
      supported_by:
        - reference_id: PMID:16183645
          supporting_text: 2005 Sep 23. Knockdown of glutamate-cysteine ligase 
            by small hairpin RNA reveals that both catalytic and modulatory 
            subunits are essential for the survival of primary neurons.
  - term:
      id: GO:0006536
      label: glutamate metabolic process
    evidence_type: IDA
    original_reference_id: PMID:12663448
    review:
      summary: Study characterizing GCLC enzymatic parameters including 
        glutamate utilization.
      action: ACCEPT
      reason: GCLC utilizes glutamate as a substrate and thus participates in 
        glutamate metabolism.
      supported_by:
        - reference_id: PMID:12663448
          supporting_text: Mar 27. A novel missense mutation in the 
            gamma-glutamylcysteine synthetase catalytic subunit gene causes both
            decreased enzymatic activity and glutathione production.
  - term:
      id: GO:0006750
      label: glutathione biosynthetic process
    evidence_type: IMP
    original_reference_id: PMID:12663448
    review:
      summary: The R127C disease mutation causes decreased GSH production, 
        confirming GCLC's essential role in glutathione biosynthesis.
      action: ACCEPT
      reason: Mutational evidence supporting the core biological process 
        annotation.
      supported_by:
        - reference_id: PMID:12663448
          supporting_text: Mar 27. A novel missense mutation in the 
            gamma-glutamylcysteine synthetase catalytic subunit gene causes both
            decreased enzymatic activity and glutathione production.
  - term:
      id: GO:0097746
      label: blood vessel diameter maintenance
    evidence_type: IMP
    original_reference_id: PMID:12598062
    review:
      summary: A GCLC promoter polymorphism (-129T) is associated with impaired 
        coronary endothelium-dependent vasodilation and myocardial infarction.
      action: KEEP_AS_NON_CORE
      reason: This is an indirect physiological consequence of reduced GCLC 
        expression and GSH levels on vascular function, not a direct function. 
        The polymorphism affects transcriptional response to oxidative stress.
      supported_by:
        - reference_id: PMID:12598062
          supporting_text: Association of polymorphism in glutamate-cysteine 
            ligase catalytic subunit gene with coronary vasomotor dysfunction 
            and myocardial infarction.
  - term:
      id: GO:0004357
      label: glutamate-cysteine ligase activity
    evidence_type: IDA
    original_reference_id: PMID:11972604
    review:
      summary: Direct measurement of GCS activity in bronchial epithelial cells 
        showing induction by oxidative stress.
      action: ACCEPT
      reason: Core molecular function with direct enzymatic activity 
        measurement.
      supported_by:
        - reference_id: PMID:11972604
          supporting_text: Oxidant stress induces gamma-glutamylcysteine 
            synthetase and glutathione synthesis in human bronchial epithelial 
            NCI-H292 cells.
  - term:
      id: GO:0006534
      label: cysteine metabolic process
    evidence_type: IDA
    original_reference_id: PMID:2294991
    review:
      summary: Study of GCLC deficiency affecting cysteine utilization for GSH 
        synthesis. Km for cysteine was assessed.
      action: ACCEPT
      reason: GCLC uses cysteine as a substrate and thus participates in 
        cysteine metabolism. This is an accurate annotation.
      supported_by:
        - reference_id: PMID:2294991
          supporting_text: Gamma-glutamylcysteine synthetase deficiency and 
            hemolytic anemia.
  - term:
      id: GO:0006536
      label: glutamate metabolic process
    evidence_type: IDA
    original_reference_id: PMID:2294991
    review:
      summary: Study assessing Km for glutamic acid in GCLC deficiency patient 
        samples.
      action: ACCEPT
      reason: GCLC utilizes glutamate as a substrate and participates in 
        glutamate metabolism.
      supported_by:
        - reference_id: PMID:2294991
          supporting_text: Gamma-glutamylcysteine synthetase deficiency and 
            hemolytic anemia.
  - term:
      id: GO:0006979
      label: response to oxidative stress
    evidence_type: IDA
    original_reference_id: PMID:11972604
    review:
      summary: GCLC expression and activity are induced by oxidative stress 
        (menadione treatment) in bronchial epithelial cells.
      action: KEEP_AS_NON_CORE
      reason: This annotation reflects the regulatory response of GCLC to 
        oxidative stress rather than a direct function. The core function is GSH
        synthesis.
      supported_by:
        - reference_id: PMID:11972604
          supporting_text: Oxidant stress induces gamma-glutamylcysteine 
            synthetase and glutathione synthesis in human bronchial epithelial 
            NCI-H292 cells.
  - term:
      id: GO:0016595
      label: glutamate binding
    evidence_type: IDA
    original_reference_id: PMID:9841880
    review:
      summary: Site-directed mutagenesis study examining glutamate binding 
        properties of GCLC.
      action: ACCEPT
      reason: Glutamate binding is essential for GCLC catalytic function as 
        glutamate is a substrate. This annotation captures a core molecular 
        function.
      supported_by:
        - reference_id: PMID:9841880
          supporting_text: Identification of an important cysteine residue in 
            human glutamate-cysteine ligase catalytic subunit by site-directed 
            mutagenesis.
  - term:
      id: GO:0043066
      label: negative regulation of apoptotic process
    evidence_type: IDA
    original_reference_id: PMID:10439045
    review:
      summary: GCLC overexpression suppresses TNF-induced apoptosis and 
        caspase-3 activation.
      action: KEEP_AS_NON_CORE
      reason: This is an indirect effect mediated through GSH-dependent 
        maintenance of cellular redox homeostasis. Not a direct anti-apoptotic 
        function of GCLC itself.
      supported_by:
        - reference_id: PMID:10439045
          supporting_text: Overexpression of gamma-glutamylcysteine synthetase 
            suppresses tumor necrosis factor-induced apoptosis and activation of
            nuclear transcription factor-kappa B and activator protein-1.
  - term:
      id: GO:0045892
      label: negative regulation of DNA-templated transcription
    evidence_type: IDA
    original_reference_id: PMID:10439045
    review:
      summary: GCLC overexpression blocks NF-kappa B-dependent gene 
        transcription by maintaining redox status.
      action: KEEP_AS_NON_CORE
      reason: This is an indirect effect mediated through GSH maintaining 
        cellular redox status, which affects redox-sensitive transcription 
        factors. GCLC does not directly regulate transcription.
      supported_by:
        - reference_id: PMID:10439045
          supporting_text: Overexpression of gamma-glutamylcysteine synthetase 
            suppresses tumor necrosis factor-induced apoptosis and activation of
            nuclear transcription factor-kappa B and activator protein-1.
  - term:
      id: GO:0004357
      label: glutamate-cysteine ligase activity
    evidence_type: IDA
    original_reference_id: PMID:8104187
    review:
      summary: Direct measurement of GCS activity in K562 cells showing heat 
        shock induction.
      action: ACCEPT
      reason: Core molecular function with direct enzymatic activity 
        measurement.
      supported_by:
        - reference_id: PMID:8104187
          supporting_text: gamma-Glutamylcysteine synthetase and active 
            transport of glutathione S-conjugate are responsive to heat shock in
            K562 erythroid cells.
  - term:
      id: GO:0006750
      label: glutathione biosynthetic process
    evidence_type: IDA
    original_reference_id: PMID:8104187
    review:
      summary: Study demonstrating GCLC role in glutathione synthesis in 
        response to heat shock.
      action: ACCEPT
      reason: Core biological process annotation with direct experimental 
        evidence.
      supported_by:
        - reference_id: PMID:8104187
          supporting_text: gamma-Glutamylcysteine synthetase and active 
            transport of glutathione S-conjugate are responsive to heat shock in
            K562 erythroid cells.
  - term:
      id: GO:0009408
      label: response to heat
    evidence_type: IDA
    original_reference_id: PMID:8104187
    review:
      summary: GCLC activity and mRNA are induced by heat shock in K562 cells.
      action: KEEP_AS_NON_CORE
      reason: This reflects transcriptional regulation of GCLC by heat shock 
        rather than a direct heat response function. The core function is GSH 
        synthesis.
      supported_by:
        - reference_id: PMID:8104187
          supporting_text: gamma-Glutamylcysteine synthetase and active 
            transport of glutathione S-conjugate are responsive to heat shock in
            K562 erythroid cells.
  - term:
      id: GO:0009725
      label: response to hormone
    evidence_type: IDA
    original_reference_id: PMID:8104187
    review:
      summary: GCLC activity is reduced by erythropoietin treatment in K562 
        cells.
      action: KEEP_AS_NON_CORE
      reason: This annotation reflects hormonal regulation of GCLC expression 
        rather than a direct hormone response function. The core function is 
        enzymatic.
      supported_by:
        - reference_id: PMID:8104187
          supporting_text: gamma-Glutamylcysteine synthetase and active 
            transport of glutathione S-conjugate are responsive to heat shock in
            K562 erythroid cells.
references:
  - id: GO_REF:0000002
    title: Gene Ontology annotation through association of InterPro records with
      GO terms
    findings: []
  - id: GO_REF:0000033
    title: Annotation inferences using phylogenetic trees
    findings: []
  - id: GO_REF:0000043
    title: Gene Ontology annotation based on UniProtKB/Swiss-Prot keyword 
      mapping
    findings: []
  - id: GO_REF:0000107
    title: Automatic transfer of experimentally verified manual GO annotation 
      data to orthologs using Ensembl Compara
    findings: []
  - id: GO_REF:0000117
    title: Electronic Gene Ontology annotations created by ARBA machine learning
      models
    findings: []
  - id: GO_REF:0000120
    title: Combined Automated Annotation using Multiple IEA Methods
    findings: []
  - id: PMID:10395918
    title: 'Regulation of gamma-glutamylcysteine synthetase regulatory subunit (GLCLR)
      gene expression: identification of the major transcriptional start site in HT29
      cells.'
    findings:
      - statement: SNP increases GSH levels 2-fold and GCS activity 6-fold
      - statement: Coordinate increase in GCSl and GCSh subunit levels
  - id: PMID:10439045
    title: Overexpression of gamma-glutamylcysteine synthetase suppresses tumor 
      necrosis factor-induced apoptosis and activation of nuclear transcription 
      factor-kappa B and activator protein-1.
    findings:
      - statement: GCS overexpression blocks TNF-induced NF-kappa B activation
      - statement: GCS overexpression suppresses TNF-induced apoptosis and 
          caspase-3 activation
      - statement: Cellular redox status controlled by glutathione affects 
          pleiotropic TNF actions
  - id: PMID:11972604
    title: Oxidant stress induces gamma-glutamylcysteine synthetase and 
      glutathione synthesis in human bronchial epithelial NCI-H292 cells.
    findings:
      - statement: Menadione-induced oxidative stress increases gamma-GCS 
          activity and mRNA
      - statement: Adaptive response mediated by transcriptional upregulation
  - id: PMID:12598062
    title: Association of polymorphism in glutamate-cysteine ligase catalytic 
      subunit gene with coronary vasomotor dysfunction and myocardial 
      infarction.
    findings:
      - statement: GCLC -129T polymorphism has lower promoter activity in 
          response to oxidants
      - statement: Associated with impaired endothelium-dependent coronary 
          vasodilation
      - statement: Risk factor for myocardial infarction
  - id: PMID:12663448
    title: A novel missense mutation in the gamma-glutamylcysteine synthetase 
      catalytic subunit gene causes both decreased enzymatic activity and 
      glutathione production.
    findings:
      - statement: R127C mutation causes decreased enzymatic activity and GSH 
          production
      - statement: Mutation lies within a cleft near the binding site
      - statement: Causes hemolytic anemia (CNSHA7)
  - id: PMID:16183645
    title: Knockdown of glutamate-cysteine ligase by small hairpin RNA reveals 
      that both catalytic and modulatory subunits are essential for the survival
      of primary neurons.
    findings:
      - statement: shRNA knockdown of GCLC or GCLM causes neuronal apoptosis
      - statement: Both subunits essential for neuronal survival
      - statement: Rescue by gamma-glutamylcysteine or GSH ethyl ester
  - id: PMID:2294991
    title: Gamma-glutamylcysteine synthetase deficiency and hemolytic anemia.
    findings:
      - statement: GCLC deficiency causes hemolytic anemia
      - statement: Decreased GSH in lymphoblasts and fibroblasts
      - statement: Clinical expression may be pleomorphic
  - id: PMID:24639
    title: Inactivation of human gamma-glutamylcysteine synthetase by cystamine.
      Demonstration and quantification of enzyme-ligand complexes.
    findings:
      - statement: Detection of enzyme-Mg2+ complexes
      - statement: Detection of enzyme-ATP-glutamate complexes
      - statement: Magnesium ion confers protection against cystamine 
          inactivation
  - id: PMID:28514442
    title: Architecture of the human interactome defines protein communities and
      disease networks.
    findings:
      - statement: High-throughput detection of GCLC-GCLM interaction
  - id: PMID:33961781
    title: Dual proteome-scale networks reveal cell-specific remodeling of the 
      human interactome.
    findings:
      - statement: Detection of GCLC-GCLM interaction in proteome-scale study
  - id: PMID:40205054
    title: Multimodal cell maps as a foundation for structural and functional 
      genomics.
    findings:
      - statement: Detection of GCLC-GCLM interaction
  - id: PMID:8104187
    title: gamma-Glutamylcysteine synthetase and active transport of glutathione
      S-conjugate are responsive to heat shock in K562 erythroid cells.
    findings:
      - statement: Heat shock increases gamma-GCS activity 1.7-fold
      - statement: Erythropoietin decreases gamma-GCS activity to 64% of control
      - statement: mRNA induction correlates with enzymatic activity changes
  - id: PMID:9675072
    title: Expression and purification of human gamma-glutamylcysteine 
      synthetase.
    findings:
      - statement: Co-expression and purification of human GCLC-GCLM holoenzyme
      - statement: Km values determined - glutamate 1.8 mM, cysteine 0.1 mM, ATP
          0.4 mM
      - statement: Specific activity greater than 1500 units/mg
      - statement: Feedback inhibited by glutathione
  - id: PMID:9841880
    title: Identification of an important cysteine residue in human 
      glutamate-cysteine ligase catalytic subunit by site-directed mutagenesis.
    findings:
      - statement: Cys553 important for GCLC-GCLM heterodimer formation
      - statement: C553G mutation reduces holoenzyme activity
      - statement: Eight conserved cysteine residues analyzed
  - id: Reactome:R-HSA-174367
    title: GCL ligates L-Glu to L-Cys
    findings:
      - statement: Cytosolic reaction catalyzed by GCL complex
  - id: Reactome:R-HSA-5602892
    title: Defective GCLC does not ligate L-Glu to L-Cys
    findings:
      - statement: Disease pathway for GCLC mutations
  - id: Reactome:R-HSA-9760122
    title: AcK-NFE2L2-dependent GCLC gene expression
    findings:
      - statement: NRF2-dependent transcriptional regulation of GCLC
  - id: file:human/GCLC/GCLC-deep-research-falcon.md
    title: Deep research report on GCLC
    findings: []
core_functions:
  - molecular_function:
      id: GO:0004357
      label: glutamate-cysteine ligase activity
    description: GCLC is the catalytic subunit of glutamate-cysteine ligase, 
      catalyzing the ATP-dependent ligation of L-glutamate and L-cysteine to 
      form gamma-L-glutamyl-L-cysteine. This is the rate-limiting step in de 
      novo glutathione biosynthesis. The enzyme requires Mg2+ as a cofactor and 
      is feedback inhibited by GSH. Km values are 1.8 mM for glutamate, 0.1 mM 
      for cysteine, and 0.4 mM for ATP.
    supported_by:
      - reference_id: PMID:9675072
        supporting_text: gamma-Glutamylcysteine synthetase (gamma-GCS) catalyzes
          the ATP-dependent ligation of L-glutamate and L-cysteine to form 
          L-gamma-glutamyl-L-cysteine; this is the first and rate-limiting step 
          in glutathione biosynthesis
      - reference_id: PMID:12663448
        supporting_text: 'Gamma-glutamylcysteine synthetase (gamma-GCS) catalyzes
          the first and rate-limiting step in glutathione (GSH) biosynthesis: the
          adenosine triphosphate (ATP)-dependent ligation of glutamate and cysteine'
tags:
  - ferroptosis

GCLC

Gene Description

Existing Annotations Review

Core Functions

References

Tags

📚 Additional Documentation

Deep Research Falcon

Question

Gene Research for Functional Annotation

⚠️ CRITICAL: Gene/Protein Identification Context

Target Gene/Protein Identity (from UniProt):

MANDATORY VERIFICATION STEPS:

If Gene Symbol is Ambiguous or You Cannot Find Relevant Literature:

Research Target:

Output

Gene Research for Functional Annotation

⚠️ CRITICAL: Gene/Protein Identification Context

Target Gene/Protein Identity (from UniProt):

MANDATORY VERIFICATION STEPS:

If Gene Symbol is Ambiguous or You Cannot Find Relevant Literature:

Research Target:

Citations

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