{"gene":"GSR","run_date":"2026-04-28T18:06:53","timeline":{"discoveries":[{"year":1981,"finding":"The three-dimensional crystal structure of human glutathione reductase (GSR) was determined at 2 Å resolution, establishing the enzyme as a homodimer with FAD as a prosthetic group and revealing a redox-active disulfide at the active site.","method":"X-ray crystallography","journal":"Journal of molecular biology","confidence":"High","confidence_rationale":"Tier 1 — original crystal structure at 2 Å resolution, foundational structural determination","pmids":["7334521"],"is_preprint":false},{"year":1982,"finding":"Sequence analysis of the NADPH domain (residues 158–293) and interface domain (residues 365–478) of human erythrocyte glutathione reductase established the complete amino acid sequence (478 residues per chain, Mr ~51,600 per subunit for FAD-free apoenzyme); Tyr-197 was identified as the residue involved in an induced-fit mechanism for NADPH binding.","method":"CNBr fragment isolation, automated solid-phase Edman degradation, trypsin/chymotrypsin digestion of peptides","journal":"European journal of biochemistry","confidence":"High","confidence_rationale":"Tier 1 — complete sequence determination with domain-level functional annotation, foundational biochemistry","pmids":["7060551"],"is_preprint":false},{"year":1983,"finding":"X-ray crystallographic analysis of reaction intermediates established the catalytic mechanism of GSR: NADPH binds with its nicotinamide ring stacking onto the re-face of FAD; electron transfer from NADPH reduces the FAD, which then reduces the redox-active disulfide (Cys-58/Cys-63); Cys-58 attacks the substrate GSSG to form a mixed protein-glutathione disulfide; His-467' is essential for catalysis by facilitating disulfide exchange; and electrons flow NADPH → FAD → protein disulfide → GSSG.","method":"X-ray crystallography of reaction intermediates, active-site alkylation with iodoacetamide","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 — crystal structures of multiple reaction intermediates combined with active-site mutagenesis/modification, mechanism fully established","pmids":["6822532"],"is_preprint":false},{"year":1987,"finding":"Refinement of the human GSR crystal structure to 1.54 Å resolution revealed that: FAD is tightly bound with the flavin ring most rigid (mean B ~8.7 Ų); the entire active center is particularly well ordered; the dimer interface contains a rigid conserved contact area and a flexible region not conserved in E. coli GR; N5 of the flavin can accommodate a proton consistent with its role in proton transfer during catalysis; and no buried cations compensate the pyrophosphate charge of FAD.","method":"X-ray crystallography, restrained least-squares refinement (R-factor 18.6%, 77,690 reflections)","journal":"Journal of molecular biology","confidence":"High","confidence_rationale":"Tier 1 — high-resolution crystal structure with rigorous refinement, providing detailed active-site and cofactor geometry","pmids":["3656429"],"is_preprint":false},{"year":1998,"finding":"Crystal structures at 1.7 Å resolution showed that human GSR (hGR) is irreversibly inactivated by NO-carriers: S-nitrosoglutathione (GSNO) oxidizes the active-site Cys-63 to a cysteine sulfenic acid (R-SOH), while diglutathionyl-dinitroso-iron (DNIC-[GSH]2) oxidizes Cys-63 to a cysteine sulfinic acid (R-SO2H), establishing sulfhydryl oxidation of the active-site cysteine as the mechanism of NO-mediated enzyme inactivation.","method":"X-ray crystallography of inhibitor-enzyme complexes at 1.7 Å resolution","journal":"Nature structural biology","confidence":"High","confidence_rationale":"Tier 1 — high-resolution crystal structures of two distinct NO-carrier adducts with active-site modification chemically characterized","pmids":["9546215"],"is_preprint":false},{"year":2011,"finding":"In C. elegans, GSR-1 (glutathione reductase, ortholog of mammalian GSR) functions together with the selenoprotein TRXR-1 thioredoxin reductase to reduce disulfide bonds in the cuticle during molting; loss of both enzymes leaves cuticle disulfides oxidized and blocks removal of the old cuticle. Exogenously supplied reduced glutathione (GSH) was sufficient to reduce cuticle disulfides and induce apolysis, demonstrating that the GSR-1/TRXR-1 axis drives regulated cuticle reduction.","method":"RNAi knockdown, genetic mutant analysis, exogenous GSH rescue experiment, biochemical measurement of cuticle disulfide redox state","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 2 — genetic epistasis with biochemical readout (disulfide redox state) and chemical rescue, replicated with multiple approaches","pmids":["21199936"],"is_preprint":false},{"year":2013,"finding":"In C. elegans, GSR-1 (sole glutathione reductase, ortholog of mammalian GSR) is essential for survival under juglone (redox cycling agent) stress but not arsenite stress; its loss impairs GSSG recycling, which in turn induces compensatory GSH synthesis (but not vice versa); overexpression of GSR-1 increases stress tolerance; and GSR-1 expression, regulated by transcription factor SKN-1, also affects lifespan, establishing the GSH redox state as a determinant of longevity.","method":"RNAi screen, genetic knockdown and overexpression, glutathione level measurement (GSH/GSSG ratio), survival assays under multiple stressors","journal":"PloS one","confidence":"Medium","confidence_rationale":"Tier 2 — genetic KD/OE with defined phenotypic readouts in multiple stress conditions, single lab","pmids":["23593298"],"is_preprint":false},{"year":2016,"finding":"In C. elegans, gsr-1 encodes two GSR-1 isoforms: one cytoplasmic and one mitochondrial (demonstrated by GFP reporters). Complete loss of gsr-1 causes fully penetrant embryonic lethality characterized by cell division delay and aberrant chromatin distribution at the nuclear periphery. Cytoplasmic but not mitochondrial GSR-1 is sufficient to rescue embryonic lethality, indicating that cytoplasmic glutathione redox homeostasis is the critical function. Maternally supplied GSR-1 supports development but animals are short-lived, sensitive to stress, and show increased mitochondrial fragmentation and reduced mitochondrial DNA content.","method":"GFP reporter localization, loss-of-function mutant analysis, isoform-specific rescue experiments, mitochondrial imaging, stress assays","journal":"Free radical biology & medicine","confidence":"High","confidence_rationale":"Tier 2 — subcellular localization by live imaging linked to functional consequence, isoform-specific rescue establishes compartment-specific role","pmids":["27117030"],"is_preprint":false},{"year":2017,"finding":"In Gsr knockout mice, loss of GSR activity and reduced GSH/GSSG ratio in cochlear cytosol did not impair cochlear antioxidant defense under normal conditions; instead, Gsr deficiency was compensated by increased activities of cytosolic thioredoxin (Trx) and thioredoxin reductase (TrxR) in the inner ear, identifying the thioredoxin system as a functional backup capable of supporting GSSG reduction in the peripheral auditory system.","method":"Gsr homozygous knockout mouse (backcrossed to CBA/CaJ), auditory brainstem response (ABR), histology, enzyme activity assays (GSR, GPX, GCL, TrxR, Trx), oxidative damage markers","journal":"PloS one","confidence":"Medium","confidence_rationale":"Tier 2 — clean KO model with multiple enzymatic readouts, single lab","pmids":["28686716"],"is_preprint":false},{"year":2017,"finding":"GSR expression is elevated in temozolomide (TMZ)-resistant glioblastoma cells compared to sensitive cells; GSR silencing re-sensitized resistant cells to TMZ and cisplatin, while GSR overexpression in sensitive cells conferred chemotherapy resistance. GSR-mediated drug resistance operates through maintenance of redox homeostasis (lower ROS, higher GSH and antioxidant capacity), and modulation of the redox state by L-buthionine sulfoximine or exogenous GSH regulated GSR-dependent resistance.","method":"siRNA silencing and overexpression of GSR in glioblastoma cell lines, drug sensitivity assays, ROS measurement, antioxidant capacity and GSH quantification","journal":"Journal of neurochemistry","confidence":"Medium","confidence_rationale":"Tier 2 — reciprocal KD/OE with defined phenotypic readout and redox mechanistic follow-up, single lab","pmids":["29105080"],"is_preprint":false},{"year":2019,"finding":"In mouse liver, simultaneous deletion of TrxR1 and Gsr (double-null) caused ~100-fold higher DNA damage indices compared to single nulls or wild-type, demonstrating that TrxR1 and Gsr together maintain genomic integrity and that their combined loss creates extreme oxidative stress. Elevated oxidative stress (in TrxR1/Gsr-null livers) correlated with significantly increased malignancy of DEN-induced liver cancers, establishing these two antioxidant systems as cooperative determinants of cancer malignancy.","method":"Conditional and germline knockout mouse genetics, DNA damage quantification, DEN-induced hepatocellular carcinoma model, metabolomics, Nrf2 expression analysis","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 2 — genetic epistasis in clean KO mouse model with multiple quantitative readouts, orthogonal metabolomic and histological validation","pmids":["31097586"],"is_preprint":false},{"year":2013,"finding":"1,25(OH)₂ vitamin D upregulates glutathione reductase (GR) activity and protein expression, as well as glutamate cysteine ligase (GCLC), in U937 monocytes, leading to increased GSH formation and decreased ROS, MCP-1, and IL-8 secretion under high-glucose conditions, establishing a direct regulatory link between vitamin D signaling and the GSR/glutathione antioxidant pathway.","method":"Cell culture with vitamin D treatment, GR activity assay (NADPH oxidation), GCLC protein ELISA, GSH HPLC, ROS measurement, cytokine ELISA","journal":"Biochemical and biophysical research communications","confidence":"Medium","confidence_rationale":"Tier 2 — direct enzyme activity and protein level measurements with defined upstream regulatory molecule, single lab","pmids":["23770363"],"is_preprint":false},{"year":2025,"finding":"GSR deficiency in lung epithelial (A549) and fibroblast (MRC5) cells reduces intracellular GSH levels and elevates ROS, which activates the TGF-β/Smad2 signaling pathway, promoting epithelial-to-mesenchymal transition (EMT), fibroblast activation, and cellular senescence. GSR knockdown also promotes cell migration. Together, these data mechanistically link GSR-mediated glutathione redox homeostasis to TGF-β/Smad2-driven pulmonary fibrosis.","method":"GSR siRNA knockdown in A549 and MRC5 cells, GSH measurement, ROS assay, EMT marker analysis, TGF-β/Smad2 pathway activity, migration and senescence assays, bleomycin mouse model","journal":"Biomolecules","confidence":"Medium","confidence_rationale":"Tier 2 — loss-of-function with pathway identification and multiple orthogonal cellular phenotype readouts, single lab","pmids":["40723921"],"is_preprint":false},{"year":2025,"finding":"In C. elegans, inactivation of the nonsense-mediated mRNA decay (NMD) pathway suppresses the embryonic lethality of gsr-1 (glutathione reductase) mutants via upregulation of cth-1 and cth-2 (cystathionine-γ-lyase isoforms of the transsulfuration pathway), which generate cysteine for alternative GSH synthesis. The thioredoxin system (which can also provide cysteine via cystine reduction) is not required for this suppression, establishing the transsulfuration pathway as a specific compensatory route for GSR-1 loss.","method":"Genetic suppressor screen, NMD pathway mutants, RNAi of cth-1/cth-2, epistasis analysis, embryonic lethality quantification","journal":"bioRxiv (preprint)","confidence":"Medium","confidence_rationale":"Tier 2 — genetic epistasis with pathway specificity validated by NMD and transsulfuration mutants, preprint","pmids":["bio_10.1101_2025.01.09.632117"],"is_preprint":true},{"year":2024,"finding":"In a murine lung tumor model (Kras G12D/Nrf2 D29H), deletion of GSR (but not TXNRD1) suppressed tumor initiation regardless of Nrf2 status, while TXNRD1 (but not GSR) was required for progression of Nrf2-activated tumors. Simultaneous deletion of GSR and TXNRD1 further reduced both initiation and progression, demonstrating that the glutathione and thioredoxin antioxidant systems play distinct, non-redundant roles in lung tumorigenesis.","method":"Conditional knockout of GSR and TXNRD1 alone or combined in KrasG12D/Nrf2D29H lung tumor mouse model, tumor initiation and progression quantification","journal":"bioRxiv (preprint)","confidence":"Medium","confidence_rationale":"Tier 2 — clean conditional KO with genetic epistasis across multiple genotypes, preprint not yet peer-reviewed","pmids":["bio_10.1101_2024.08.20.608800"],"is_preprint":true},{"year":2025,"finding":"Structural comparison of human GSR with AIF, DLD, and TrxR reveals a conserved overall fold (pairwise RMSD <3.2 Å across all four enzymes) with spatially aligned FAD and NAD(P)H cofactor-binding pockets, consistent with a conserved FAD/NAD(P)H-dependent catalytic mechanism involving electron transfer via the flavin cofactor.","method":"Comparative structural analysis using available crystallographic data, RMSD-based superposition","journal":"International journal of biological macromolecules","confidence":"Low","confidence_rationale":"Tier 4 — computational/structural comparison without new experimental functional validation","pmids":["40451368"],"is_preprint":false}],"current_model":"Human GSR (glutathione reductase) is a homodimeric FAD-dependent flavoenzyme that catalyzes the NADPH-dependent reduction of GSSG to GSH via a conserved mechanism in which electrons flow from NADPH through FAD to a redox-active disulfide (Cys-58/Cys-63), with His-467' facilitating disulfide exchange with GSSG; the active-site Cys-63 can be irreversibly oxidized to sulfenic or sulfinic acid by NO-carriers (GSNO, DNIC), inactivating the enzyme; GSR maintains cellular glutathione redox homeostasis and cooperates non-redundantly with the thioredoxin reductase (TrxR1) system to suppress oxidative DNA damage and cancer malignancy, while its deficiency activates TGF-β/Smad2 signaling to promote fibrosis and can be compensated by upregulation of the thioredoxin system or the transsulfuration pathway depending on cellular context."},"narrative":{"teleology":[{"year":1981,"claim":"Determination of the three-dimensional structure of human GSR established it as a homodimeric FAD-containing enzyme with a redox-active disulfide at the active site, providing the structural framework for all subsequent mechanistic studies.","evidence":"X-ray crystallography at 2 Å resolution of human erythrocyte glutathione reductase","pmids":["7334521"],"confidence":"High","gaps":["No reaction intermediates captured at this stage","Catalytic mechanism inferred but not demonstrated structurally"]},{"year":1983,"claim":"Crystallographic trapping of reaction intermediates resolved the full catalytic cycle — NADPH→FAD→Cys-58/Cys-63 disulfide→GSSG — and identified His-467' as essential for disulfide exchange, answering how electrons traverse the enzyme.","evidence":"X-ray crystallography of multiple reaction intermediates combined with active-site iodoacetamide alkylation","pmids":["6822532"],"confidence":"High","gaps":["Kinetic validation of individual electron-transfer steps not performed in this study","Role of conformational dynamics in catalysis not addressed"]},{"year":1987,"claim":"Refinement to 1.54 Å resolution revealed that the FAD cofactor and entire active center are exceptionally well-ordered, with the flavin N5 positioned for proton transfer, providing atomic-level detail of cofactor geometry relevant to the reductive half-reaction.","evidence":"X-ray crystallography with restrained least-squares refinement (R-factor 18.6%, 77,690 reflections)","pmids":["3656429"],"confidence":"High","gaps":["No dynamic or solution-state measurements to complement the crystal data"]},{"year":1998,"claim":"Crystal structures of GSR complexed with NO-carriers revealed that irreversible oxidation of active-site Cys-63 to sulfenic or sulfinic acid constitutes the mechanism of NO-mediated inactivation, identifying a physiologically relevant mode of enzyme regulation.","evidence":"X-ray crystallography at 1.7 Å of GSNO- and DNIC-[GSH]₂-treated GSR","pmids":["9546215"],"confidence":"High","gaps":["In vivo relevance of NO-mediated GSR inactivation not demonstrated","Reversibility or cellular repair of sulfinic acid modification not explored"]},{"year":2011,"claim":"Genetic and biochemical work in C. elegans demonstrated that GSR-1 and thioredoxin reductase TRXR-1 function cooperatively to reduce cuticle disulfides during molting, establishing the first in vivo developmental role for glutathione reductase beyond generic antioxidant defense.","evidence":"RNAi knockdown, genetic mutants, exogenous GSH rescue, cuticle disulfide redox measurement in C. elegans","pmids":["21199936"],"confidence":"High","gaps":["Vertebrate developmental role of GSR not addressed","Specific cuticle substrates of GSR-1-generated GSH not identified"]},{"year":2016,"claim":"Identification of cytoplasmic and mitochondrial GSR-1 isoforms in C. elegans, with only cytoplasmic GSR-1 rescuing embryonic lethality, demonstrated that cytoplasmic glutathione redox homeostasis is the essential compartment-specific function, while mitochondrial GSR-1 contributes to organelle integrity and stress resistance.","evidence":"GFP reporters, isoform-specific rescue, mitochondrial imaging, stress assays in gsr-1 null C. elegans","pmids":["27117030"],"confidence":"High","gaps":["Whether compartment-specific essentiality is conserved in mammals not tested","Molecular targets of cytoplasmic GSH that mediate embryonic viability not identified"]},{"year":2017,"claim":"Gsr knockout mice revealed that the thioredoxin system compensates for GSR loss in the cochlea under basal conditions, demonstrating functional redundancy between the two major disulfide reductase systems in vivo in mammals.","evidence":"Gsr homozygous knockout mouse, ABR, enzyme activity assays for GSR/TrxR/Trx, oxidative damage markers","pmids":["28686716"],"confidence":"Medium","gaps":["Compensation tested only in cochlea; generalizability to other tissues unknown","Whether compensation holds under stress not tested in this study"]},{"year":2019,"claim":"Simultaneous deletion of TrxR1 and Gsr in mouse liver caused a ~100-fold increase in DNA damage and dramatically enhanced cancer malignancy, demonstrating that the two antioxidant systems are non-redundant guardians of genomic integrity and tumor suppression.","evidence":"Conditional double knockout in mouse liver, DNA damage quantification, DEN-induced hepatocellular carcinoma model, metabolomics","pmids":["31097586"],"confidence":"High","gaps":["Specific DNA lesion types caused by combined loss not characterized","Whether increased malignancy reflects increased initiation, progression, or both not resolved"]},{"year":2017,"claim":"GSR overexpression conferred chemotherapy resistance in glioblastoma cells by maintaining redox homeostasis, while GSR silencing re-sensitized resistant cells, identifying GSR-mediated GSH maintenance as a druggable determinant of temozolomide and cisplatin resistance.","evidence":"Reciprocal siRNA knockdown and overexpression in glioblastoma cell lines, drug sensitivity, ROS, and GSH quantification","pmids":["29105080"],"confidence":"Medium","gaps":["No in vivo tumor model validation","Downstream effectors of GSR-dependent chemoresistance beyond ROS not identified"]},{"year":2025,"claim":"GSR deficiency was shown to activate TGF-β/Smad2 signaling through elevated ROS, promoting EMT, fibroblast activation, senescence, and migration — linking glutathione redox imbalance mechanistically to pulmonary fibrosis pathogenesis.","evidence":"GSR siRNA knockdown in A549 and MRC5 cells, GSH/ROS measurements, EMT markers, TGF-β/Smad2 pathway analysis, bleomycin mouse model","pmids":["40723921"],"confidence":"Medium","gaps":["Whether GSR loss directly activates TGF-β ligand production or sensitizes receptor signaling not distinguished","Rescue by GSH supplementation of the fibrotic phenotype not fully demonstrated"]},{"year":null,"claim":"Key unresolved questions include whether the compartment-specific essentiality of cytoplasmic versus mitochondrial GSR is conserved in mammals, the precise molecular targets of GSR-maintained GSH that mediate embryonic viability and tumor suppression, and whether NO-mediated inactivation of GSR Cys-63 is a regulated signaling event in vivo.","evidence":"","pmids":[],"confidence":"Low","gaps":["No mammalian isoform-specific rescue experiment reported","In vivo physiological relevance of NO-mediated GSR inactivation untested","Structural basis for GSR vs TrxR1 non-redundancy in cancer not defined"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0016491","term_label":"oxidoreductase activity","supporting_discovery_ids":[0,2,3,4]},{"term_id":"GO:0140657","term_label":"ATP-dependent activity","supporting_discovery_ids":[2]}],"localization":[{"term_id":"GO:0005739","term_label":"mitochondrion","supporting_discovery_ids":[7]},{"term_id":"GO:0005829","term_label":"cytosol","supporting_discovery_ids":[7,8]}],"pathway":[{"term_id":"R-HSA-1430728","term_label":"Metabolism","supporting_discovery_ids":[0,2,6,8]},{"term_id":"R-HSA-8953897","term_label":"Cellular responses to stimuli","supporting_discovery_ids":[6,9,10,12]},{"term_id":"R-HSA-1643685","term_label":"Disease","supporting_discovery_ids":[10,12]}],"complexes":[],"partners":["TXNRD1","TRXR-1"],"other_free_text":[]},"mechanistic_narrative":"GSR (glutathione reductase) is a homodimeric FAD-dependent oxidoreductase that catalyzes the NADPH-dependent reduction of oxidized glutathione (GSSG) to GSH, maintaining cellular glutathione redox homeostasis critical for antioxidant defense, genomic integrity, and suppression of fibrotic and tumorigenic signaling. Electrons flow from NADPH through the FAD prosthetic group to a redox-active disulfide (Cys-58/Cys-63), with His-467' facilitating disulfide exchange with GSSG; the active-site Cys-63 can be irreversibly oxidized to sulfenic or sulfinic acid by nitric oxide carriers, inactivating the enzyme [PMID:7334521, PMID:6822532, PMID:9546215]. GSR cooperates non-redundantly with the thioredoxin reductase system to suppress oxidative DNA damage and cancer malignancy, with GSR specifically required for tumor initiation in murine lung cancer models, while its loss can be partially compensated by upregulation of thioredoxin reductase or the transsulfuration pathway depending on tissue context [PMID:31097586, PMID:28686716, PMID:27117030]. GSR deficiency reduces intracellular GSH, elevates ROS, and activates TGF-β/Smad2 signaling to promote epithelial-to-mesenchymal transition, fibroblast activation, and cellular senescence, linking glutathione redox imbalance to pulmonary fibrosis [PMID:40723921]."},"prefetch_data":{"uniprot":{"accession":"P00390","full_name":"Glutathione reductase, mitochondrial","aliases":[],"length_aa":522,"mass_kda":56.3,"function":"Catalyzes the reduction of glutathione disulfide (GSSG) to reduced glutathione (GSH). Constitutes the major mechanism to maintain a high GSH:GSSG ratio in the cytosol","subcellular_location":"Cytoplasm","url":"https://www.uniprot.org/uniprotkb/P00390/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/GSR","classification":"Not Classified","n_dependent_lines":2,"n_total_lines":1208,"dependency_fraction":0.0016556291390728477},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/GSR","total_profiled":1310},"omim":[{"mim_id":"618660","title":"ANEMIA, CONGENITAL, NONSPHEROCYTIC HEMOLYTIC, 10; CNSHA10","url":"https://www.omim.org/entry/618660"},{"mim_id":"617744","title":"IMMUNODEFICIENCY, DEVELOPMENTAL DELAY, AND HYPOHOMOCYSTEINEMIA; IMDDHH","url":"https://www.omim.org/entry/617744"},{"mim_id":"617220","title":"PYRIDINE NUCLEOTIDE-DISULFIDE OXIDOREDUCTASE DOMAIN-CONTAINING PROTEIN 1; PYROXD1","url":"https://www.omim.org/entry/617220"},{"mim_id":"613777","title":"FAD-DEPENDENT OXIDOREDUCTASE DOMAIN-CONTAINING PROTEIN 2; FOXRED2","url":"https://www.omim.org/entry/613777"},{"mim_id":"608984","title":"ATAXIA, SENSORY, 1, AUTOSOMAL DOMINANT; SNAX1","url":"https://www.omim.org/entry/608984"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Supported","locations":[{"location":"Cytosol","reliability":"Supported"},{"location":"Endoplasmic reticulum","reliability":"Additional"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/GSR"},"hgnc":{"alias_symbol":["GRase"],"prev_symbol":[]},"alphafold":{"accession":"P00390","domains":[{"cath_id":"3.50.50.60","chopping":"61-102_139-203_335-398","consensus_level":"high","plddt":98.2546,"start":61,"end":398},{"cath_id":"3.50.50.60","chopping":"207-332","consensus_level":"high","plddt":98.5036,"start":207,"end":332},{"cath_id":"3.30.390.30","chopping":"411-517","consensus_level":"high","plddt":98.6611,"start":411,"end":517}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/P00390","model_url":"https://alphafold.ebi.ac.uk/files/AF-P00390-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-P00390-F1-predicted_aligned_error_v6.png","plddt_mean":91.62},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=GSR","jax_strain_url":"https://www.jax.org/strain/search?query=GSR"},"sequence":{"accession":"P00390","fasta_url":"https://rest.uniprot.org/uniprotkb/P00390.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/P00390/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/P00390"}},"corpus_meta":[{"pmid":"31097586","id":"PMC_31097586","title":"TrxR1, 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activity and GSH/GSSG ratios, but the thioredoxin system compensates by upregulating thioredoxin and thioredoxin reductase activities, indicating functional redundancy between the two antioxidant systems.\",\n      \"method\": \"Gsr homozygous knockout mice (fractionation, enzyme activity assays, oxidative damage markers, ABR hearing thresholds)\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — clean KO with multiple orthogonal biochemical readouts and defined compensatory pathway\",\n      \"pmids\": [\"28686716\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"C. elegans GSR-1 (glutathione reductase ortholog) exists as two isoforms — one cytoplasmic and one mitochondrial — and cytoplasmic but not mitochondrial GSR-1 activity is required for embryonic development; loss of gsr-1 causes embryonic lethality with cell division delay and aberrant chromatin distribution.\",\n      \"method\": \"GFP reporters for localization, loss-of-function mutants, isoform-specific rescue experiments in C. elegans\",\n      \"journal\": \"Free radical biology & medicine\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — genetic rescue with isoform specificity, multiple orthogonal methods in single study\",\n      \"pmids\": [\"27117030\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"In mouse liver, Gsr and TrxR1 form an integrated antioxidant network; double knockout of TrxR1 and Gsr causes 100-fold higher DNA damage compared to either single knockout or wild-type, establishing that these two systems are functionally redundant for preventing oxidative DNA damage in hepatocytes.\",\n      \"method\": \"Conditional/germline knockout mouse models (TrxR1-null, Gsr-null, double-null), DNA damage indices, metabolomic profiling, DEN-induced carcinogenesis model\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — genetic epistasis with double-knockout and multiple phenotypic readouts, replicated across genotypes\",\n      \"pmids\": [\"31097586\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"GSR deficiency reduces intracellular GSH levels and elevates ROS, which activates the TGF-β/Smad2 signaling pathway, promoting epithelial-to-mesenchymal transition (EMT) and fibroblast activation in pulmonary fibrosis.\",\n      \"method\": \"GSR knockdown in A549 and MRC5 cells, GSH/ROS measurements, TGF-β/Smad2 pathway analysis, bleomycin mouse model\",\n      \"journal\": \"Biomolecules\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — KD with defined pathway placement, single lab with multiple readouts\",\n      \"pmids\": [\"40723921\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"In C. elegans, GSR-1 is essential for survival under oxidative (redox cycling) stress; knockdown of gsr-1 does not appreciably affect basal glutathione levels under normal conditions but impairs GSSG recycling capacity under oxidative stress, and gsr-1 is transcriptionally regulated by SKN-1 (Nrf2 ortholog).\",\n      \"method\": \"RNAi knockdown, juglone/arsenite survival assays, GSH/GSSG ratio measurements, overexpression studies, lifespan assays in C. elegans\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — clean KD/OE with defined phenotypic readouts and pathway placement, single lab\",\n      \"pmids\": [\"23593298\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"C. elegans GSR-1 (glutathione reductase) functions together with TRXR-1 (thioredoxin reductase/selenoprotein) to reduce disulfide bonds in the cuticle during molting; exogenous reduced glutathione mimics GSR-1 activity by reducing cuticle disulfides and inducing apolysis.\",\n      \"method\": \"RNAi/genetic knockdown of gsr-1 and trxr-1 in C. elegans, cuticle disulfide state analysis, exogenous GSH rescue experiments, molting phenotype assays\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — orthogonal genetic and biochemical methods, replicated with chemical rescue, published in high-impact journal\",\n      \"pmids\": [\"21199936\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"In C. elegans, the embryonic lethality of gsr-1 loss-of-function mutants is suppressed by inactivation of the nonsense-mediated mRNA decay (NMD) pathway, and this suppression requires cth-1 and cth-2 (cystathionine-γ-lyase isoforms of the transsulfuration pathway) but not the thioredoxin system, indicating that increased cysteine supply via the transsulfuration pathway can compensate for loss of GSR-1.\",\n      \"method\": \"Genetic epistasis in C. elegans, suppressor screen (NMD pathway), double mutant analysis with cth-1/cth-2\",\n      \"journal\": \"bioRxiv\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — genetic epistasis with pathway specificity, preprint not yet peer-reviewed\",\n      \"pmids\": [],\n      \"is_preprint\": true\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"In murine lung tumor models, GSR (glutathione reductase) promotes tumor initiation regardless of Nrf2 status, while TXNRD1 (thioredoxin reductase) is dispensable for initiation but required for progression specifically in Nrf2-activated tumors; simultaneous deletion of both reduces initiation and progression, revealing non-redundant roles for the two antioxidant systems in different stages of tumorigenesis.\",\n      \"method\": \"Conditional deletion of GSR and/or TXNRD1 in KrasG12D/Nrf2D29H murine lung tumor models, tumor initiation and progression quantification\",\n      \"journal\": \"bioRxiv\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — genetic epistasis with clean conditional KO and defined phenotypic stages, preprint not yet peer-reviewed\",\n      \"pmids\": [],\n      \"is_preprint\": true\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"GSR structural analysis reveals a conserved overall fold shared with AIF, DLD, and TrxR, with pairwise RMSD values below 3.2 Å; FAD and NAD(P)H cofactor-binding pockets are spatially aligned across these enzymes, reflecting conserved catalytic mechanism involving FAD/NAD(P)H-dependent disulfide reduction.\",\n      \"method\": \"Structural comparative analysis (crystallographic superposition, RMSD calculation)\",\n      \"journal\": \"International journal of biological macromolecules\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 1 method (structural) but purely comparative/review without new functional mutagenesis validation for GSR specifically\",\n      \"pmids\": [\"40451368\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"GSR (glutathione reductase) is a FAD/NAD(P)H-dependent flavoenzyme that catalyzes the reduction of oxidized glutathione (GSSG) to reduced glutathione (GSH), maintaining cellular redox homeostasis; it exists in cytoplasmic and mitochondrial isoforms (with cytoplasmic activity being essential for embryonic development), acts in parallel with the thioredoxin reductase system (which can compensate for GSR loss in some tissues), is transcriptionally regulated by NRF2/SKN-1, and its deficiency causes elevated ROS that activates the TGF-β/Smad2 pathway to drive pathological processes such as fibrosis and increased oxidative DNA damage.\"\n}\n```\n\n--- ROUND 2 (R2/R3, augmented corpus) ---\n\nI'll classify each paper, then extract discoveries only from KEEP papers.\n\n**Classification:**\n\nKEEP (canonical human/mammalian GSR - glutathione reductase):\n- [1] PMID:31097586 - TrxR1, Gsr mouse liver cancer study ✓\n- [2] PMID:21199936 - C. elegans GSR-1 (ortholog) ✓\n- [3] PMID:33746607 - GPX4-GSS/GSR axis in ferroptosis ✓\n- [4] PMID:23593298 - C. elegans GSR-1 (ortholog) ✓\n- [10] PMID:28686716 - Mouse GSR knockout cochlea ✓\n- [13] PMID:27117030 - C. elegans gsr-1 (ortholog) ✓\n- [25] PMID:40723921 - GSR deficiency pulmonary fibrosis ✓\n- [31] PMID:40451368 - Structural review of GSR ✓\n- gene2pubmed [7] PMID:3656429 - Crystal structure human GR ✓\n- gene2pubmed [13] PMID:6822532 - Catalytic mechanism GR x-ray ✓\n- gene2pubmed [16] PMID:7334521 - 3D structure GR ✓\n- gene2pubmed [18] PMID:7060551 - Sequence NADPH/interface domains ✓\n- gene2pubmed [25] PMID:9546215 - NO-carrier inhibition of hGR ✓\n- gene2pubmed [28] PMID:923580 - Isolation, redox-active peptide ✓\n- gene2pubmed [29] PMID:29105080 - GSR drug resistance glioblastoma ✓\n- gene2pubmed [19] PMID:23770363 - Vitamin D upregulates GR ✓\n- gene2pubmed [40] preprint bio_10.1101_2025.01.09.632117 - transsulfuration suppresses gsr-1 lethality ✓\n- gene2pubmed [44] preprint bio_10.1101_2024.08.20.608800 - GSR in lung tumor ✓\n\nEXCLUDE:\n- [7] PMID:6234165 - E. coli gsr gene (phosphotransferase carbohydrate utilization) - collision\n- [8] PMID:6302202 - E. coli gsr (phosphotransferase) - collision\n- [9] PMID:38189256 - GSR database (16S rRNA) - collision\n- [11] PMID:3007037 - Chromosomal mapping cat GSR - not mechanistic\n- [12] PMID:12582847 - Catharanthus roseus GSR mutants (plant, glycophytic salinity response) - collision\n- [14] PMID:6302201 - E. coli gsr mutations - collision\n- [15] PMID:35361806 - Computational SNP analysis only\n- [16] PMID:31285952 - FISH/cytogenetic, not mechanistic\n- [17] PMID:8754577 - Gunshot residue (GSR acronym) - collision\n- [18] PMID:8661695 - Chromosome mapping shrew - not mechanistic\n- [19] PMID:20587944 - Gutter-shaped root (GSR) in mice - collision\n- [20] PMID:10808271 - Gutter-shaped root (GSR) - collision\n- [21] PMID:2013231 - Silver fox gene mapping - not mechanistic\n- [22] PMID:40246119 - Pigeon GSR SNP/racing - not mechanistic\n- [23] PMID:8771715 - Yeast gsrm2 gene (ribosomal context, different protein) - collision\n- [24] PMID:37038483 - Osteoporosis SNP association - not mechanistic\n- [26] PMID:41203147 - circGsr-0002 (circular RNA, alt-locus product) - EXCLUDE case B\n- [27] PMID:36089843 - Gunshot residue - collision\n- [28] PMID:41313200 - Biomarker expression study - not mechanistic\n- [29] PMID:2127665 - Streptomyces gsr antibiotic resistance gene - collision\n- [30] PMID:41558219 - GSR-ST deep learning framework - collision\n- [32] PMID:41387654 - Biomarker/expression study - not mechanistic\n- [33] PMID:41934218 - GRASE polyurethane enzyme - collision\n- [34-39, 41-43, 45] - MRI/GRASE imaging, FOG, fMRI, bacterial GSR, plant GSR - collisions\n- [5] PMID:31479834 - Enzymatic activity measurement (correlational, not mechanistic)\n- [6] PMID:22089180 - SNP association - not mechanistic\n- gene2pubmed [1] PMID:16169070 - General Y2H screen\n- gene2pubmed [2] PMID:12477932 - cDNA sequencing resource\n- gene2pubmed [3] PMID:15592455 - Global phosphoproteomics\n- gene2pubmed [4] PMID:22939629 - General proteomics\n- gene2pubmed [5] PMID:21873635 - GO annotation\n- gene2pubmed [6] PMID:19056867 - Urinary exosome proteomics\n- gene2pubmed [8] PMID:15489334 - MGC cDNA resource\n- gene2pubmed [9] PMID:26344197 - Metazoan complex map\n- gene2pubmed [10] PMID:8889548 - cDNA library normalization\n- gene2pubmed [11] PMID:16009940 - ISG15 conjugation targets\n- gene2pubmed [12] PMID:14744259 - 14-3-3 affinity purification\n- gene2pubmed [14] PMID:22863883 - General interactome method\n- gene2pubmed [15] PMID:34800366 - Mitochondrial proteome\n- gene2pubmed [17] PMID:21988832 - Liver protein interaction network\n- gene2pubmed [20] PMID:32807901 - UFMylation/p53 (GSR mentioned incidentally)\n- gene2pubmed [21] PMID:11710935 - Aging skin antioxidant (correlational)\n- gene2pubmed [22] PMID:19913121 - GWAS lipids\n- gene2pubmed [23] PMID:19527700 - Antioxidant enzymes depression (correlational)\n- gene2pubmed [24] PMID:32344865 - BioID/TurboID methods\n- gene2pubmed [26] PMID:19322201 - HuR ubiquitination\n- gene2pubmed [27] PMID:23533145 - Prostate exosome proteomics\n- gene2pubmed [30] PMID:23376485 - Podocyte exosome proteomics\n\n```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 1981,\n      \"finding\": \"The three-dimensional crystal structure of human glutathione reductase (GSR) was determined at 2 Å resolution, establishing the enzyme as a homodimer with FAD as a prosthetic group and revealing a redox-active disulfide at the active site.\",\n      \"method\": \"X-ray crystallography\",\n      \"journal\": \"Journal of molecular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — original crystal structure at 2 Å resolution, foundational structural determination\",\n      \"pmids\": [\"7334521\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1982,\n      \"finding\": \"Sequence analysis of the NADPH domain (residues 158–293) and interface domain (residues 365–478) of human erythrocyte glutathione reductase established the complete amino acid sequence (478 residues per chain, Mr ~51,600 per subunit for FAD-free apoenzyme); Tyr-197 was identified as the residue involved in an induced-fit mechanism for NADPH binding.\",\n      \"method\": \"CNBr fragment isolation, automated solid-phase Edman degradation, trypsin/chymotrypsin digestion of peptides\",\n      \"journal\": \"European journal of biochemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — complete sequence determination with domain-level functional annotation, foundational biochemistry\",\n      \"pmids\": [\"7060551\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1983,\n      \"finding\": \"X-ray crystallographic analysis of reaction intermediates established the catalytic mechanism of GSR: NADPH binds with its nicotinamide ring stacking onto the re-face of FAD; electron transfer from NADPH reduces the FAD, which then reduces the redox-active disulfide (Cys-58/Cys-63); Cys-58 attacks the substrate GSSG to form a mixed protein-glutathione disulfide; His-467' is essential for catalysis by facilitating disulfide exchange; and electrons flow NADPH → FAD → protein disulfide → GSSG.\",\n      \"method\": \"X-ray crystallography of reaction intermediates, active-site alkylation with iodoacetamide\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — crystal structures of multiple reaction intermediates combined with active-site mutagenesis/modification, mechanism fully established\",\n      \"pmids\": [\"6822532\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1987,\n      \"finding\": \"Refinement of the human GSR crystal structure to 1.54 Å resolution revealed that: FAD is tightly bound with the flavin ring most rigid (mean B ~8.7 Ų); the entire active center is particularly well ordered; the dimer interface contains a rigid conserved contact area and a flexible region not conserved in E. coli GR; N5 of the flavin can accommodate a proton consistent with its role in proton transfer during catalysis; and no buried cations compensate the pyrophosphate charge of FAD.\",\n      \"method\": \"X-ray crystallography, restrained least-squares refinement (R-factor 18.6%, 77,690 reflections)\",\n      \"journal\": \"Journal of molecular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — high-resolution crystal structure with rigorous refinement, providing detailed active-site and cofactor geometry\",\n      \"pmids\": [\"3656429\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1998,\n      \"finding\": \"Crystal structures at 1.7 Å resolution showed that human GSR (hGR) is irreversibly inactivated by NO-carriers: S-nitrosoglutathione (GSNO) oxidizes the active-site Cys-63 to a cysteine sulfenic acid (R-SOH), while diglutathionyl-dinitroso-iron (DNIC-[GSH]2) oxidizes Cys-63 to a cysteine sulfinic acid (R-SO2H), establishing sulfhydryl oxidation of the active-site cysteine as the mechanism of NO-mediated enzyme inactivation.\",\n      \"method\": \"X-ray crystallography of inhibitor-enzyme complexes at 1.7 Å resolution\",\n      \"journal\": \"Nature structural biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — high-resolution crystal structures of two distinct NO-carrier adducts with active-site modification chemically characterized\",\n      \"pmids\": [\"9546215\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"In C. elegans, GSR-1 (glutathione reductase, ortholog of mammalian GSR) functions together with the selenoprotein TRXR-1 thioredoxin reductase to reduce disulfide bonds in the cuticle during molting; loss of both enzymes leaves cuticle disulfides oxidized and blocks removal of the old cuticle. Exogenously supplied reduced glutathione (GSH) was sufficient to reduce cuticle disulfides and induce apolysis, demonstrating that the GSR-1/TRXR-1 axis drives regulated cuticle reduction.\",\n      \"method\": \"RNAi knockdown, genetic mutant analysis, exogenous GSH rescue experiment, biochemical measurement of cuticle disulfide redox state\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — genetic epistasis with biochemical readout (disulfide redox state) and chemical rescue, replicated with multiple approaches\",\n      \"pmids\": [\"21199936\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"In C. elegans, GSR-1 (sole glutathione reductase, ortholog of mammalian GSR) is essential for survival under juglone (redox cycling agent) stress but not arsenite stress; its loss impairs GSSG recycling, which in turn induces compensatory GSH synthesis (but not vice versa); overexpression of GSR-1 increases stress tolerance; and GSR-1 expression, regulated by transcription factor SKN-1, also affects lifespan, establishing the GSH redox state as a determinant of longevity.\",\n      \"method\": \"RNAi screen, genetic knockdown and overexpression, glutathione level measurement (GSH/GSSG ratio), survival assays under multiple stressors\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — genetic KD/OE with defined phenotypic readouts in multiple stress conditions, single lab\",\n      \"pmids\": [\"23593298\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"In C. elegans, gsr-1 encodes two GSR-1 isoforms: one cytoplasmic and one mitochondrial (demonstrated by GFP reporters). Complete loss of gsr-1 causes fully penetrant embryonic lethality characterized by cell division delay and aberrant chromatin distribution at the nuclear periphery. Cytoplasmic but not mitochondrial GSR-1 is sufficient to rescue embryonic lethality, indicating that cytoplasmic glutathione redox homeostasis is the critical function. Maternally supplied GSR-1 supports development but animals are short-lived, sensitive to stress, and show increased mitochondrial fragmentation and reduced mitochondrial DNA content.\",\n      \"method\": \"GFP reporter localization, loss-of-function mutant analysis, isoform-specific rescue experiments, mitochondrial imaging, stress assays\",\n      \"journal\": \"Free radical biology & medicine\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — subcellular localization by live imaging linked to functional consequence, isoform-specific rescue establishes compartment-specific role\",\n      \"pmids\": [\"27117030\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"In Gsr knockout mice, loss of GSR activity and reduced GSH/GSSG ratio in cochlear cytosol did not impair cochlear antioxidant defense under normal conditions; instead, Gsr deficiency was compensated by increased activities of cytosolic thioredoxin (Trx) and thioredoxin reductase (TrxR) in the inner ear, identifying the thioredoxin system as a functional backup capable of supporting GSSG reduction in the peripheral auditory system.\",\n      \"method\": \"Gsr homozygous knockout mouse (backcrossed to CBA/CaJ), auditory brainstem response (ABR), histology, enzyme activity assays (GSR, GPX, GCL, TrxR, Trx), oxidative damage markers\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — clean KO model with multiple enzymatic readouts, single lab\",\n      \"pmids\": [\"28686716\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"GSR expression is elevated in temozolomide (TMZ)-resistant glioblastoma cells compared to sensitive cells; GSR silencing re-sensitized resistant cells to TMZ and cisplatin, while GSR overexpression in sensitive cells conferred chemotherapy resistance. GSR-mediated drug resistance operates through maintenance of redox homeostasis (lower ROS, higher GSH and antioxidant capacity), and modulation of the redox state by L-buthionine sulfoximine or exogenous GSH regulated GSR-dependent resistance.\",\n      \"method\": \"siRNA silencing and overexpression of GSR in glioblastoma cell lines, drug sensitivity assays, ROS measurement, antioxidant capacity and GSH quantification\",\n      \"journal\": \"Journal of neurochemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — reciprocal KD/OE with defined phenotypic readout and redox mechanistic follow-up, single lab\",\n      \"pmids\": [\"29105080\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"In mouse liver, simultaneous deletion of TrxR1 and Gsr (double-null) caused ~100-fold higher DNA damage indices compared to single nulls or wild-type, demonstrating that TrxR1 and Gsr together maintain genomic integrity and that their combined loss creates extreme oxidative stress. Elevated oxidative stress (in TrxR1/Gsr-null livers) correlated with significantly increased malignancy of DEN-induced liver cancers, establishing these two antioxidant systems as cooperative determinants of cancer malignancy.\",\n      \"method\": \"Conditional and germline knockout mouse genetics, DNA damage quantification, DEN-induced hepatocellular carcinoma model, metabolomics, Nrf2 expression analysis\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — genetic epistasis in clean KO mouse model with multiple quantitative readouts, orthogonal metabolomic and histological validation\",\n      \"pmids\": [\"31097586\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"1,25(OH)₂ vitamin D upregulates glutathione reductase (GR) activity and protein expression, as well as glutamate cysteine ligase (GCLC), in U937 monocytes, leading to increased GSH formation and decreased ROS, MCP-1, and IL-8 secretion under high-glucose conditions, establishing a direct regulatory link between vitamin D signaling and the GSR/glutathione antioxidant pathway.\",\n      \"method\": \"Cell culture with vitamin D treatment, GR activity assay (NADPH oxidation), GCLC protein ELISA, GSH HPLC, ROS measurement, cytokine ELISA\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — direct enzyme activity and protein level measurements with defined upstream regulatory molecule, single lab\",\n      \"pmids\": [\"23770363\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"GSR deficiency in lung epithelial (A549) and fibroblast (MRC5) cells reduces intracellular GSH levels and elevates ROS, which activates the TGF-β/Smad2 signaling pathway, promoting epithelial-to-mesenchymal transition (EMT), fibroblast activation, and cellular senescence. GSR knockdown also promotes cell migration. Together, these data mechanistically link GSR-mediated glutathione redox homeostasis to TGF-β/Smad2-driven pulmonary fibrosis.\",\n      \"method\": \"GSR siRNA knockdown in A549 and MRC5 cells, GSH measurement, ROS assay, EMT marker analysis, TGF-β/Smad2 pathway activity, migration and senescence assays, bleomycin mouse model\",\n      \"journal\": \"Biomolecules\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — loss-of-function with pathway identification and multiple orthogonal cellular phenotype readouts, single lab\",\n      \"pmids\": [\"40723921\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"In C. elegans, inactivation of the nonsense-mediated mRNA decay (NMD) pathway suppresses the embryonic lethality of gsr-1 (glutathione reductase) mutants via upregulation of cth-1 and cth-2 (cystathionine-γ-lyase isoforms of the transsulfuration pathway), which generate cysteine for alternative GSH synthesis. The thioredoxin system (which can also provide cysteine via cystine reduction) is not required for this suppression, establishing the transsulfuration pathway as a specific compensatory route for GSR-1 loss.\",\n      \"method\": \"Genetic suppressor screen, NMD pathway mutants, RNAi of cth-1/cth-2, epistasis analysis, embryonic lethality quantification\",\n      \"journal\": \"bioRxiv (preprint)\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — genetic epistasis with pathway specificity validated by NMD and transsulfuration mutants, preprint\",\n      \"pmids\": [\"bio_10.1101_2025.01.09.632117\"],\n      \"is_preprint\": true\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"In a murine lung tumor model (Kras G12D/Nrf2 D29H), deletion of GSR (but not TXNRD1) suppressed tumor initiation regardless of Nrf2 status, while TXNRD1 (but not GSR) was required for progression of Nrf2-activated tumors. Simultaneous deletion of GSR and TXNRD1 further reduced both initiation and progression, demonstrating that the glutathione and thioredoxin antioxidant systems play distinct, non-redundant roles in lung tumorigenesis.\",\n      \"method\": \"Conditional knockout of GSR and TXNRD1 alone or combined in KrasG12D/Nrf2D29H lung tumor mouse model, tumor initiation and progression quantification\",\n      \"journal\": \"bioRxiv (preprint)\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — clean conditional KO with genetic epistasis across multiple genotypes, preprint not yet peer-reviewed\",\n      \"pmids\": [\"bio_10.1101_2024.08.20.608800\"],\n      \"is_preprint\": true\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"Structural comparison of human GSR with AIF, DLD, and TrxR reveals a conserved overall fold (pairwise RMSD <3.2 Å across all four enzymes) with spatially aligned FAD and NAD(P)H cofactor-binding pockets, consistent with a conserved FAD/NAD(P)H-dependent catalytic mechanism involving electron transfer via the flavin cofactor.\",\n      \"method\": \"Comparative structural analysis using available crystallographic data, RMSD-based superposition\",\n      \"journal\": \"International journal of biological macromolecules\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 4 — computational/structural comparison without new experimental functional validation\",\n      \"pmids\": [\"40451368\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"Human GSR (glutathione reductase) is a homodimeric FAD-dependent flavoenzyme that catalyzes the NADPH-dependent reduction of GSSG to GSH via a conserved mechanism in which electrons flow from NADPH through FAD to a redox-active disulfide (Cys-58/Cys-63), with His-467' facilitating disulfide exchange with GSSG; the active-site Cys-63 can be irreversibly oxidized to sulfenic or sulfinic acid by NO-carriers (GSNO, DNIC), inactivating the enzyme; GSR maintains cellular glutathione redox homeostasis and cooperates non-redundantly with the thioredoxin reductase (TrxR1) system to suppress oxidative DNA damage and cancer malignancy, while its deficiency activates TGF-β/Smad2 signaling to promote fibrosis and can be compensated by upregulation of the thioredoxin system or the transsulfuration pathway depending on cellular context.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"GSR (glutathione reductase) is a FAD/NAD(P)H-dependent flavoenzyme that catalyzes the reduction of oxidized glutathione (GSSG) to reduced glutathione (GSH), serving as a central regulator of intracellular redox homeostasis. GSR operates in functional redundancy with the thioredoxin reductase system: single loss of GSR is compensated by upregulation of thioredoxin reductase, whereas combined disruption of both systems causes massive oxidative DNA damage in hepatocytes [PMID:28686716, PMID:31097586]. The enzyme exists as cytoplasmic and mitochondrial isoforms, with the cytoplasmic isoform being essential for embryonic viability and proper chromatin segregation during cell division, and is transcriptionally regulated by the Nrf2/SKN-1 pathway [PMID:27117030, PMID:23593298]. GSR deficiency elevates reactive oxygen species, which activates TGF-β/Smad2 signaling to drive epithelial-to-mesenchymal transition and fibroblast activation in pulmonary fibrosis models [PMID:40723921].\",\n  \"teleology\": [\n    {\n      \"year\": 2011,\n      \"claim\": \"Establishing that GSR-1 provides reduced glutathione for extracellular disulfide reduction during molting revealed a non-canonical developmental role for this antioxidant enzyme beyond intracellular redox buffering.\",\n      \"evidence\": \"RNAi/genetic knockdown of gsr-1 and trxr-1 in C. elegans with cuticle disulfide analysis and exogenous GSH rescue\",\n      \"pmids\": [\"21199936\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether mammalian GSR participates in analogous extracellular matrix remodeling is unknown\", \"The specific cuticle disulfide substrates reduced by GSH were not identified\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Demonstrating that GSR-1 is dispensable under basal conditions but essential under oxidative stress, and is transcriptionally controlled by SKN-1/Nrf2, placed GSR within the stress-responsive antioxidant transcriptional network.\",\n      \"evidence\": \"RNAi knockdown and overexpression of gsr-1 in C. elegans with juglone/arsenite survival assays and GSH/GSSG measurements\",\n      \"pmids\": [\"23593298\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct binding of SKN-1 to the gsr-1 promoter was not shown\", \"Whether Nrf2 regulation of GSR is conserved in mammalian tissues was not addressed in this study\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Identifying that GSR-1 exists as cytoplasmic and mitochondrial isoforms and that only cytoplasmic activity is required for embryonic development resolved which subcellular pool is essential for viability.\",\n      \"evidence\": \"GFP reporters, loss-of-function mutants, and isoform-specific rescue in C. elegans\",\n      \"pmids\": [\"27117030\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Why mitochondrial GSR-1 is dispensable for embryogenesis is unexplained\", \"The specific cytoplasmic substrates or processes requiring GSH during cell division are not identified\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Showing that GSR knockout in mice is tolerated due to compensatory upregulation of the thioredoxin system established in vivo functional redundancy between the two major disulfide-reducing pathways in mammals.\",\n      \"evidence\": \"Gsr homozygous knockout mice with enzyme activity assays, GSH/GSSG ratios, and oxidative damage markers in cochlea\",\n      \"pmids\": [\"28686716\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether compensation occurs in all tissues or is tissue-specific was not systematically tested\", \"The signaling mechanism triggering thioredoxin system upregulation upon GSR loss is unknown\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Double knockout of GSR and TrxR1 in mouse liver causing 100-fold elevated DNA damage compared to single knockouts quantified the degree of redundancy and proved that at least one system is required for genome integrity.\",\n      \"evidence\": \"Conditional/germline knockout mice (TrxR1-null, Gsr-null, double-null) with DNA damage indices and metabolomics\",\n      \"pmids\": [\"31097586\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Which specific DNA repair pathways are impaired by dual loss was not determined\", \"Whether double-null hepatocytes undergo apoptosis or tolerate chronic damage long-term was not fully resolved\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Linking GSR deficiency to activation of TGF-β/Smad2 signaling and EMT provided a specific downstream pathological pathway through which loss of GSR-mediated redox control drives tissue fibrosis.\",\n      \"evidence\": \"GSR knockdown in A549 and MRC5 cells with ROS/GSH measurements and bleomycin mouse model\",\n      \"pmids\": [\"40723921\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether ROS directly activates TGF-β ligand release or receptor signaling is unresolved\", \"Independent replication in other fibrosis models is lacking\", \"Whether GSR supplementation or overexpression can reverse established fibrosis was not tested\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Discovery that transsulfuration pathway upregulation (via cth-1/cth-2) can suppress gsr-1 embryonic lethality independently of the thioredoxin system revealed an alternative compensatory route for cysteine and glutathione supply.\",\n      \"evidence\": \"Genetic suppressor screen and double mutant analysis in C. elegans (preprint)\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Not yet peer-reviewed\", \"Whether transsulfuration compensation operates in mammalian GSR deficiency is unknown\", \"The mechanism by which NMD inactivation upregulates cth-1/cth-2 is not defined\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"The tissue-specific contexts in which GSR is non-redundant with thioredoxin reductase, the structural basis for isoform-specific function, and the direct mechanism linking GSR-dependent ROS elevation to TGF-β pathway activation remain open questions.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No crystal structure of human GSR in complex with GSSG and NAD(P)H has been functionally validated with mutagenesis\", \"Tissue-specific essentiality map is incomplete\", \"Whether GSR has non-catalytic scaffolding or signaling roles is unexplored\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0016491\", \"supporting_discovery_ids\": [0, 2, 4, 8]},\n      {\"term_id\": \"GO:0016209\", \"supporting_discovery_ids\": [0, 2, 4]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005829\", \"supporting_discovery_ids\": [1]},\n      {\"term_id\": \"GO:0005739\", \"supporting_discovery_ids\": [1]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-1430728\", \"supporting_discovery_ids\": [0, 2, 4, 5]},\n      {\"term_id\": \"R-HSA-8953897\", \"supporting_discovery_ids\": [0, 2, 3, 4]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [3]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\n      \"TXNRD1\",\n      \"CTH\"\n    ],\n    \"other_free_text\": []\n  }\n}\n```\n\n--- ROUND 2 (R2/R3, augmented corpus) ---\n\n```json\n{\n  \"mechanistic_narrative\": \"GSR (glutathione reductase) is a homodimeric FAD-dependent oxidoreductase that catalyzes the NADPH-dependent reduction of oxidized glutathione (GSSG) to GSH, maintaining cellular glutathione redox homeostasis critical for antioxidant defense, genomic integrity, and suppression of fibrotic and tumorigenic signaling. Electrons flow from NADPH through the FAD prosthetic group to a redox-active disulfide (Cys-58/Cys-63), with His-467' facilitating disulfide exchange with GSSG; the active-site Cys-63 can be irreversibly oxidized to sulfenic or sulfinic acid by nitric oxide carriers, inactivating the enzyme [PMID:7334521, PMID:6822532, PMID:9546215]. GSR cooperates non-redundantly with the thioredoxin reductase system to suppress oxidative DNA damage and cancer malignancy, with GSR specifically required for tumor initiation in murine lung cancer models, while its loss can be partially compensated by upregulation of thioredoxin reductase or the transsulfuration pathway depending on tissue context [PMID:31097586, PMID:28686716, PMID:27117030]. GSR deficiency reduces intracellular GSH, elevates ROS, and activates TGF-β/Smad2 signaling to promote epithelial-to-mesenchymal transition, fibroblast activation, and cellular senescence, linking glutathione redox imbalance to pulmonary fibrosis [PMID:40723921].\",\n  \"teleology\": [\n    {\n      \"year\": 1981,\n      \"claim\": \"Determination of the three-dimensional structure of human GSR established it as a homodimeric FAD-containing enzyme with a redox-active disulfide at the active site, providing the structural framework for all subsequent mechanistic studies.\",\n      \"evidence\": \"X-ray crystallography at 2 Å resolution of human erythrocyte glutathione reductase\",\n      \"pmids\": [\"7334521\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No reaction intermediates captured at this stage\", \"Catalytic mechanism inferred but not demonstrated structurally\"]\n    },\n    {\n      \"year\": 1983,\n      \"claim\": \"Crystallographic trapping of reaction intermediates resolved the full catalytic cycle — NADPH→FAD→Cys-58/Cys-63 disulfide→GSSG — and identified His-467' as essential for disulfide exchange, answering how electrons traverse the enzyme.\",\n      \"evidence\": \"X-ray crystallography of multiple reaction intermediates combined with active-site iodoacetamide alkylation\",\n      \"pmids\": [\"6822532\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Kinetic validation of individual electron-transfer steps not performed in this study\", \"Role of conformational dynamics in catalysis not addressed\"]\n    },\n    {\n      \"year\": 1987,\n      \"claim\": \"Refinement to 1.54 Å resolution revealed that the FAD cofactor and entire active center are exceptionally well-ordered, with the flavin N5 positioned for proton transfer, providing atomic-level detail of cofactor geometry relevant to the reductive half-reaction.\",\n      \"evidence\": \"X-ray crystallography with restrained least-squares refinement (R-factor 18.6%, 77,690 reflections)\",\n      \"pmids\": [\"3656429\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No dynamic or solution-state measurements to complement the crystal data\"]\n    },\n    {\n      \"year\": 1998,\n      \"claim\": \"Crystal structures of GSR complexed with NO-carriers revealed that irreversible oxidation of active-site Cys-63 to sulfenic or sulfinic acid constitutes the mechanism of NO-mediated inactivation, identifying a physiologically relevant mode of enzyme regulation.\",\n      \"evidence\": \"X-ray crystallography at 1.7 Å of GSNO- and DNIC-[GSH]₂-treated GSR\",\n      \"pmids\": [\"9546215\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"In vivo relevance of NO-mediated GSR inactivation not demonstrated\", \"Reversibility or cellular repair of sulfinic acid modification not explored\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Genetic and biochemical work in C. elegans demonstrated that GSR-1 and thioredoxin reductase TRXR-1 function cooperatively to reduce cuticle disulfides during molting, establishing the first in vivo developmental role for glutathione reductase beyond generic antioxidant defense.\",\n      \"evidence\": \"RNAi knockdown, genetic mutants, exogenous GSH rescue, cuticle disulfide redox measurement in C. elegans\",\n      \"pmids\": [\"21199936\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Vertebrate developmental role of GSR not addressed\", \"Specific cuticle substrates of GSR-1-generated GSH not identified\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Identification of cytoplasmic and mitochondrial GSR-1 isoforms in C. elegans, with only cytoplasmic GSR-1 rescuing embryonic lethality, demonstrated that cytoplasmic glutathione redox homeostasis is the essential compartment-specific function, while mitochondrial GSR-1 contributes to organelle integrity and stress resistance.\",\n      \"evidence\": \"GFP reporters, isoform-specific rescue, mitochondrial imaging, stress assays in gsr-1 null C. elegans\",\n      \"pmids\": [\"27117030\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether compartment-specific essentiality is conserved in mammals not tested\", \"Molecular targets of cytoplasmic GSH that mediate embryonic viability not identified\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Gsr knockout mice revealed that the thioredoxin system compensates for GSR loss in the cochlea under basal conditions, demonstrating functional redundancy between the two major disulfide reductase systems in vivo in mammals.\",\n      \"evidence\": \"Gsr homozygous knockout mouse, ABR, enzyme activity assays for GSR/TrxR/Trx, oxidative damage markers\",\n      \"pmids\": [\"28686716\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Compensation tested only in cochlea; generalizability to other tissues unknown\", \"Whether compensation holds under stress not tested in this study\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Simultaneous deletion of TrxR1 and Gsr in mouse liver caused a ~100-fold increase in DNA damage and dramatically enhanced cancer malignancy, demonstrating that the two antioxidant systems are non-redundant guardians of genomic integrity and tumor suppression.\",\n      \"evidence\": \"Conditional double knockout in mouse liver, DNA damage quantification, DEN-induced hepatocellular carcinoma model, metabolomics\",\n      \"pmids\": [\"31097586\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Specific DNA lesion types caused by combined loss not characterized\", \"Whether increased malignancy reflects increased initiation, progression, or both not resolved\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"GSR overexpression conferred chemotherapy resistance in glioblastoma cells by maintaining redox homeostasis, while GSR silencing re-sensitized resistant cells, identifying GSR-mediated GSH maintenance as a druggable determinant of temozolomide and cisplatin resistance.\",\n      \"evidence\": \"Reciprocal siRNA knockdown and overexpression in glioblastoma cell lines, drug sensitivity, ROS, and GSH quantification\",\n      \"pmids\": [\"29105080\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No in vivo tumor model validation\", \"Downstream effectors of GSR-dependent chemoresistance beyond ROS not identified\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"GSR deficiency was shown to activate TGF-β/Smad2 signaling through elevated ROS, promoting EMT, fibroblast activation, senescence, and migration — linking glutathione redox imbalance mechanistically to pulmonary fibrosis pathogenesis.\",\n      \"evidence\": \"GSR siRNA knockdown in A549 and MRC5 cells, GSH/ROS measurements, EMT markers, TGF-β/Smad2 pathway analysis, bleomycin mouse model\",\n      \"pmids\": [\"40723921\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether GSR loss directly activates TGF-β ligand production or sensitizes receptor signaling not distinguished\", \"Rescue by GSH supplementation of the fibrotic phenotype not fully demonstrated\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"Key unresolved questions include whether the compartment-specific essentiality of cytoplasmic versus mitochondrial GSR is conserved in mammals, the precise molecular targets of GSR-maintained GSH that mediate embryonic viability and tumor suppression, and whether NO-mediated inactivation of GSR Cys-63 is a regulated signaling event in vivo.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"No mammalian isoform-specific rescue experiment reported\", \"In vivo physiological relevance of NO-mediated GSR inactivation untested\", \"Structural basis for GSR vs TrxR1 non-redundancy in cancer not defined\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0016491\", \"supporting_discovery_ids\": [0, 2, 3, 4]},\n      {\"term_id\": \"GO:0140657\", \"supporting_discovery_ids\": [2]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005739\", \"supporting_discovery_ids\": [7]},\n      {\"term_id\": \"GO:0005829\", \"supporting_discovery_ids\": [7, 8]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-1430728\", \"supporting_discovery_ids\": [0, 2, 6, 8]},\n      {\"term_id\": \"R-HSA-8953897\", \"supporting_discovery_ids\": [6, 9, 10, 12]},\n      {\"term_id\": \"R-HSA-1643685\", \"supporting_discovery_ids\": [10, 12]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\n      \"TXNRD1\",\n      \"TRXR-1\"\n    ],\n    \"other_free_text\": []\n  }\n}\n```"}