Glutathione reductase (EC 1.8.1.7) of Saccharomyces cerevisiae, a homodimeric FAD-containing flavoprotein disulfide oxidoreductase of the class-I pyridine nucleotide-disulfide oxidoreductase family. Glr1 uses NADPH to reduce glutathione disulfide (GSSG) to two molecules of reduced glutathione, maintaining a highly reducing GSH:GSSG ratio. Alternative translation initiation produces a mitochondrial isoform (with an N-terminal presequence) and a cytosolic isoform; GFP studies also detect nuclear signal and a minor Pex5-dependent peroxisomal pool. Glr1 is the main cytosolic GSSG-reducing system, with thioredoxin Trx2 and glutaredoxin Grx2 as backups and Ycf1-mediated vacuolar sequestration of excess GSSG. GLR1 expression is Yap1-dependent and rises in stationary phase; glr1 mutants are sensitive to H2O2. Because the intermembrane-space and cytosolic glutathione pools exchange through porins, the cytosolic glutathione reductase system is the main determinant of the intermembrane-space glutathione redox potential, while the mitochondrial Glr1 isoform keeps matrix glutathione reduced and is required for resistance to hyperoxia.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0004362 glutathione-disulfide reductase (NADPH) activity | IBA GO_REF:0000033 | ACCEPT | Summary: PAINT IBA for glutathione-disulfide reductase (NADPH) activity from the GSR clade (mouse, rat, S. pombe, C. albicans); Glr1 is the yeast glutathione reductase. Supporting Evidence: file:yeast/GLR1/GLR1-uniprot.txt Reaction=2 glutathione + NADP(+) = glutathione disulfide + NADPH + file:yeast/GLR1/GLR1-uniprot.txt SIMILARITY: Belongs to the class-I pyridine nucleotide-disulfide |
| GO:0004362 glutathione-disulfide reductase (NADPH) activity | IDA PMID:19049979 Characterization of a novel dithiocarbamate glutathione redu... | ACCEPT | Summary: Seefeldt et al. 2009 used yeast glutathione reductase as the enzyme in inhibitor kinetics (2-AAPA), i.e. direct assay of GSSG reduction by the yeast enzyme. UniProt cites this paper for EC 1.8.1.7. Supporting Evidence: PMID:19049979 The enzyme catalyzes the reduction of GSSG to GSH to maintain a high GSH:GSSG ratio. file:yeast/GLR1/GLR1-uniprot.txt Reaction=2 glutathione + NADP(+) = glutathione disulfide + NADPH + |
| GO:0004362 glutathione-disulfide reductase (NADPH) activity | IDA PMID:7737505 Isolation, characterization and overexpression of the yeast ... | ACCEPT | Summary: Collinson & Dawes 1995 cloned GLR1; multicopy GLR1 increased glutathione reductase activity six-fold. Supporting Evidence: PMID:7737505 Yeast cells transformed with a multicopy plasmid containing the genomic clone overproduced GR activity sixfold. |
| GO:0004362 glutathione-disulfide reductase (NADPH) activity | IEA GO_REF:0000120 | ACCEPT | Summary: InterPro IPR006322/RHEA:11740/EC 1.8.1.7 mapping; correct. Supporting Evidence: file:yeast/GLR1/GLR1-uniprot.txt Reaction=2 glutathione + NADP(+) = glutathione disulfide + NADPH + |
| GO:0004362 glutathione-disulfide reductase (NADPH) activity | RCA GO_REF:0000123 | ACCEPT | Summary: YeastPathways glutathione-glutaredoxin redox reactions (GLUT-REDOX2-PWY) assign Glr1 the NADPH-dependent GSSG reduction (EC 1.8.1.7); correct. Supporting Evidence: file:yeast/GLR1/GLR1-uniprot.txt Reaction=2 glutathione + NADP(+) = glutathione disulfide + NADPH + PMID:8951820 Utilization of GSH results in its conversion to the oxidized form (GSSG), and it is recycled to GSH by the action of glutathione reductase (GLR) using the reducing power of NADPH. |
| GO:0004362 glutathione-disulfide reductase (NADPH) activity | RCA GO_REF:0000123 | ACCEPT | Summary: YeastPathways glutathione-glutaredoxin system (PWY3O-592) assignment of the same reaction; correct. Supporting Evidence: file:yeast/GLR1/GLR1-uniprot.txt Reaction=2 glutathione + NADP(+) = glutathione disulfide + NADPH + |
| GO:0005634 nucleus | HDA PMID:14562095 Global analysis of protein localization in budding yeast. | KEEP AS NON CORE | Summary: Huh et al. 2003 GFP survey reported Glr1-GFP in cytoplasm and nucleus. A nuclear pool of a soluble ~50 kDa dimer is plausible (diffusion or active import) and would maintain nuclear GSH, but no nuclear-specific function is described. Reason: Observed nuclear signal without a defined nuclear role; cytosol and mitochondria are the established sites of function. Supporting Evidence: PMID:14562095 We classify these proteins, representing 75% of the yeast proteome, into 22 distinct subcellular localization categories |
| GO:0005634 nucleus | IDA PMID:23613772 N-terminal acetylation by NatC is not a general determinant ... | KEEP AS NON CORE | Summary: Aksnes et al. 2013 imaged chromosomally GFP-tagged Glr1 and observed cytosolic and nuclear localisation, unchanged in naa30 cells. Reason: Nuclear presence is observed but no nuclear-specific function is established. Supporting Evidence: PMID:23613772 The cytosolic and nuclear localization of Glr1 in wild type cells (A) was maintained in naa30Ξ cells (B). |
| GO:0005634 nucleus | IEA GO_REF:0000044 | KEEP AS NON CORE | Summary: UniProt subcellular-location mapping (SL-0191 Nucleus) derived from the GFP studies; same caveat. Reason: Nuclear presence without established nuclear function. Supporting Evidence: PMID:23613772 The cytosolic and nuclear localization of Glr1 in wild type cells (A) was maintained in naa30Ξ cells (B). |
| GO:0005737 cytoplasm | EXP PMID:23613772 N-terminal acetylation by NatC is not a general determinant ... | ACCEPT | Summary: GFP imaging of Glr1 shows cytosolic localisation (Aksnes et al. 2013); the cytosolic isoform maintains the cytosolic GSH:GSSG ratio. Supporting Evidence: PMID:23613772 The cytosolic and nuclear localization of Glr1 in wild type cells (A) was maintained in naa30Ξ cells (B). file:yeast/GLR1/GLR1-uniprot.txt a high GSH:GSSG ratio in the cytosol. |
| GO:0005737 cytoplasm | HDA PMID:14562095 Global analysis of protein localization in budding yeast. | ACCEPT | Summary: Huh et al. 2003 GFP survey: cytoplasmic Glr1-GFP; correct. Supporting Evidence: PMID:14562095 We classify these proteins, representing 75% of the yeast proteome, into 22 distinct subcellular localization categories file:yeast/GLR1/GLR1-uniprot.txt SUBCELLULAR LOCATION: Cytoplasm |
| GO:0005737 cytoplasm | IEA GO_REF:0000044 | ACCEPT | Summary: UniProt subcellular-location mapping (SL-0086 Cytoplasm); correct. Supporting Evidence: file:yeast/GLR1/GLR1-uniprot.txt SUBCELLULAR LOCATION: Cytoplasm |
| GO:0005739 mitochondrion | HDA PMID:14562095 Global analysis of protein localization in budding yeast. | ACCEPT | Summary: Huh et al. 2003 GFP survey also scored mitochondrial Glr1-GFP. GLR1 encodes two isoforms by alternative translation initiation; the longer product carries an N-terminal mitochondrial targeting sequence and the shorter one is cytosolic. Glutathione reductase activity is measured in purified mitochondria. Supporting Evidence: PMID:14562095 We classify these proteins, representing 75% of the yeast proteome, into 22 distinct subcellular localization categories file:yeast/GLR1/GLR1-uniprot.txt Event=Alternative initiation; Named isoforms=2; PMID:36164978 Measuring the activity of glutathione reductase clearly demonstrates that native Glr1 is active in both peroxisomes and mitochondria |
| GO:0005739 mitochondrion | HDA PMID:14576278 The proteome of Saccharomyces cerevisiae mitochondria. | ACCEPT | Summary: Detected in the high-purity mitochondrial proteome (Sickmann et al. 2003). GLR1 encodes two isoforms by alternative translation initiation; the longer product carries an N-terminal mitochondrial targeting sequence and the shorter one is cytosolic. Glutathione reductase activity is measured in purified mitochondria. Supporting Evidence: PMID:14576278 From >20 million MS spectra, 750 different proteins were identified, indicating an involvement of mitochondria in numerous cellular processes. PMID:36164978 Measuring the activity of glutathione reductase clearly demonstrates that native Glr1 is active in both peroxisomes and mitochondria |
| GO:0005739 mitochondrion | HDA PMID:16823961 Toward the complete yeast mitochondrial proteome: multidimen... | ACCEPT | Summary: Detected in the PROMITO mitochondrial proteome (Reinders et al. 2006). GLR1 encodes two isoforms by alternative translation initiation; the longer product carries an N-terminal mitochondrial targeting sequence and the shorter one is cytosolic. Glutathione reductase activity is measured in purified mitochondria. Supporting Evidence: PMID:16823961 A total of 851 different proteins (PROMITO dataset) were identified by use of multidimensional LC-MS/MS PMID:36164978 Measuring the activity of glutathione reductase clearly demonstrates that native Glr1 is active in both peroxisomes and mitochondria |
| GO:0005739 mitochondrion | HDA PMID:24769239 Quantitative variations of the mitochondrial proteome and ph... | ACCEPT | Summary: Detected in quantitative proteomics of isolated mitochondria (Renvoise et al. 2014). GLR1 encodes two isoforms by alternative translation initiation; the longer product carries an N-terminal mitochondrial targeting sequence and the shorter one is cytosolic. Glutathione reductase activity is measured in purified mitochondria. Supporting Evidence: PMID:24769239 we performed an overall quantitative proteomic and phosphoproteomic study of isolated mitochondria extracted from yeast grown on fermentative (glucose or galactose) and respiratory (lactate) media PMID:36164978 Measuring the activity of glutathione reductase clearly demonstrates that native Glr1 is active in both peroxisomes and mitochondria |
| GO:0005739 mitochondrion | IBA GO_REF:0000033 | ACCEPT | Summary: PAINT IBA for mitochondrion (with/from S. pombe Pgr1, Aspergillus and C. elegans GSR); fungal glutathione reductases are dual cytosolic/mitochondrial. Correct for Glr1. Supporting Evidence: file:yeast/GLR1/GLR1-uniprot.txt Event=Alternative initiation; Named isoforms=2; PMID:36164978 Measuring the activity of glutathione reductase clearly demonstrates that native Glr1 is active in both peroxisomes and mitochondria |
| GO:0005739 mitochondrion | IEA GO_REF:0000044 | ACCEPT | Summary: UniProt subcellular-location mapping (SL-0173 Mitochondrion); correct. Supporting Evidence: PMID:36164978 Measuring the activity of glutathione reductase clearly demonstrates that native Glr1 is active in both peroxisomes and mitochondria |
| GO:0005777 peroxisome | IDA PMID:36164978 Systematic multi-level analysis of an organelle proteome rev... | KEEP AS NON CORE | Summary: Yifrach et al. 2022 found Glr1 in peroxisomes by microscopy and fractionation with activity assays, targeted via a Pex5 N-terminal-domain interaction rather than a PTS1; glr1 deletion raises GSSG. A genuine but minor third location. Reason: Peroxisomal pool demonstrated, but cytosol and mitochondria are the principal sites of Glr1 function. Supporting Evidence: PMID:36164978 Measuring the activity of glutathione reductase clearly demonstrates that native Glr1 is active in both peroxisomes and mitochondria |
| GO:0005777 peroxisome | IEA GO_REF:0000044 | KEEP AS NON CORE | Summary: UniProt subcellular-location mapping (SL-0204 Peroxisome) from the 2022 study; correct, non-core. Reason: Minor peroxisomal pool. Supporting Evidence: PMID:36164978 Measuring the activity of glutathione reductase clearly demonstrates that native Glr1 is active in both peroxisomes and mitochondria |
| GO:0005829 cytosol | IBA GO_REF:0000033 | ACCEPT | Summary: PAINT IBA for cytosol from the GSR clade (with/from includes GLR1); correct. Supporting Evidence: file:yeast/GLR1/GLR1-uniprot.txt a high GSH:GSSG ratio in the cytosol. |
| GO:0005829 cytosol | IDA PMID:23613772 N-terminal acetylation by NatC is not a general determinant ... | ACCEPT | Summary: GFP imaging shows cytosolic Glr1; correct. Supporting Evidence: PMID:23613772 The cytosolic and nuclear localization of Glr1 in wild type cells (A) was maintained in naa30Ξ cells (B). |
| GO:0005829 cytosol | RCA GO_REF:0000123 | ACCEPT | Summary: YeastPathways GLUT-REDOX2-PWY places GSSG reduction in the cytosol; correct for the cytosolic isoform. Supporting Evidence: file:yeast/GLR1/GLR1-uniprot.txt a high GSH:GSSG ratio in the cytosol. PMID:23242256 we identify Trx2 and Grx2 as efficient backup systems to glutathione reductase for cytosolic GSSG reduction. |
| GO:0005829 cytosol | RCA GO_REF:0000123 | ACCEPT | Summary: YeastPathways glutathione-glutaredoxin system (PWY3O-592) cytosolic assignment; correct. Supporting Evidence: file:yeast/GLR1/GLR1-uniprot.txt a high GSH:GSSG ratio in the cytosol. |
| GO:0006749 glutathione metabolic process | IBA GO_REF:0000033 | ACCEPT | Summary: PAINT IBA for glutathione metabolic process; Glr1 regenerates GSH from GSSG, a step of glutathione metabolism (GO has no more specific term for GSSG reduction). Supporting Evidence: PMID:8951820 Utilization of GSH results in its conversion to the oxidized form (GSSG), and it is recycled to GSH by the action of glutathione reductase (GLR) using the reducing power of NADPH. file:yeast/GLR1/GLR1-uniprot.txt Reaction=2 glutathione + NADP(+) = glutathione disulfide + NADPH + |
| GO:0006749 glutathione metabolic process | IEA GO_REF:0000002 | ACCEPT | Summary: InterPro IPR006322 (glutathione reductase, eukaryote/bacterial) mapping to glutathione metabolic process; correct. Supporting Evidence: file:yeast/GLR1/GLR1-uniprot.txt Reaction=2 glutathione + NADP(+) = glutathione disulfide + NADPH + |
| GO:0006749 glutathione metabolic process | IMP PMID:23242256 Multiple glutathione disulfide removal pathways mediate cyto... | ACCEPT | Summary: Morgan et al. 2013 used genetically encoded glutathione redox probes in glr1 and other mutants to show Glr1 is the main cytosolic GSSG-reducing system, with Trx2 and Grx2 as backups. Supporting Evidence: PMID:23242256 we identify Trx2 and Grx2 as efficient backup systems to glutathione reductase for cytosolic GSSG reduction. |
| GO:0006749 glutathione metabolic process | RCA GO_REF:0000123 | ACCEPT | Summary: YeastPathways GLUT-REDOX2-PWY assignment; correct. Supporting Evidence: PMID:8951820 Utilization of GSH results in its conversion to the oxidized form (GSSG), and it is recycled to GSH by the action of glutathione reductase (GLR) using the reducing power of NADPH. |
| GO:0006749 glutathione metabolic process | RCA GO_REF:0000123 | ACCEPT | Summary: YeastPathways PWY3O-592 assignment; correct. Supporting Evidence: PMID:8951820 Utilization of GSH results in its conversion to the oxidized form (GSSG), and it is recycled to GSH by the action of glutathione reductase (GLR) using the reducing power of NADPH. |
| GO:0010731 protein glutathionylation | IGI PMID:20074363 Thioredoxins function as deglutathionylase enzymes in the ye... | MARK AS OVER ANNOTATED | Summary: Greetham et al. 2010 co-overexpressed the glutaredoxin system (Grx1 plus Glr1) and observed increased protein glutathionylation (GSSP), concluding that glutaredoxins are not general deglutathionylases; Glr1 was included to recycle GSSG and lowered GSSG levels. Glr1 does not catalyse protein glutathionylation; any effect on GSSP is indirect via the glutathione redox state, and the readout is attributed to Grx1. Reason: Indirect effect of a co-overexpressed system; the protein performing (de)glutathionylation is not Glr1. Supporting Evidence: PMID:20074363 overexpression of the glutaredoxin system resulted in an approximate 66% increases in GSSP levels, confirming that glutaredoxins do not act as general deglutathionylases in vivo. PMID:20074363 GSSG levels were significantly lowered by the glutaredoxin system presumably due to the activity of Glr1. |
| GO:0016491 oxidoreductase activity | IEA GO_REF:0000002 | TOO GENERAL | Summary: InterPro pyridine nucleotide-disulfide oxidoreductase domain mapping to oxidoreductase activity; true but uninformative. Reason: Very general parent of glutathione-disulfide reductase activity. Supporting Evidence: file:yeast/GLR1/GLR1-uniprot.txt SIMILARITY: Belongs to the class-I pyridine nucleotide-disulfide |
| GO:0016668 oxidoreductase activity, acting on a sulfur group of donors, NAD(P) as acceptor | IEA GO_REF:0000002 | KEEP AS NON CORE | Summary: InterPro IPR012999 mapping to oxidoreductase acting on a sulfur group of donors, NAD(P) as acceptor; correct parent of glutathione-disulfide reductase activity. Reason: Parent of GO:0004362. Supporting Evidence: file:yeast/GLR1/GLR1-uniprot.txt SIMILARITY: Belongs to the class-I pyridine nucleotide-disulfide |
| GO:0034599 cellular response to oxidative stress | IBA GO_REF:0000033 | KEEP AS NON CORE | Summary: PAINT IBA for cellular response to oxidative stress; GSSG recycling supports antioxidant defence, but this is a response-level description. Reason: Physiological context of GSSG reduction; core BP is cell redox homeostasis. Supporting Evidence: PMID:8951820 a yeast strain deleted for GLR1, encoding glutathione reductase, shows an elevated sensitivity to H2O2 challenge during stationary phase. |
| GO:0034599 cellular response to oxidative stress | IMP PMID:8951820 Stationary-phase induction of GLR1 expression is mediated by... | KEEP AS NON CORE | Summary: Grant et al. 1996: glr1 deletion increases H2O2 sensitivity in stationary phase; GLR1 induction is Yap1-dependent. Reason: Phenotype downstream of loss of GSSG recycling. Supporting Evidence: PMID:8951820 a yeast strain deleted for GLR1, encoding glutathione reductase, shows an elevated sensitivity to H2O2 challenge during stationary phase. |
| GO:0045454 cell redox homeostasis | IBA GO_REF:0000033 | ACCEPT | Summary: PAINT IBA for cell redox homeostasis; Glr1 maintains the high cellular GSH:GSSG ratio. Correct. Supporting Evidence: file:yeast/GLR1/GLR1-uniprot.txt a high GSH:GSSG ratio in the cytosol. PMID:19049979 The enzyme catalyzes the reduction of GSSG to GSH to maintain a high GSH:GSSG ratio. |
| GO:0045454 cell redox homeostasis | IEA GO_REF:0000002 | ACCEPT | Summary: InterPro IPR046952 mapping to cell redox homeostasis; correct. Supporting Evidence: file:yeast/GLR1/GLR1-uniprot.txt a high GSH:GSSG ratio in the cytosol. |
| GO:0045454 cell redox homeostasis | IMP PMID:23242256 Multiple glutathione disulfide removal pathways mediate cyto... | ACCEPT | Summary: Redox-probe measurements in mutants show Glr1 is the primary system keeping cytosolic GSSG low (Morgan et al. 2013). Supporting Evidence: PMID:23242256 we identify Trx2 and Grx2 as efficient backup systems to glutathione reductase for cytosolic GSSG reduction. |
| GO:0050660 flavin adenine dinucleotide binding | IBA GO_REF:0000033 | KEEP AS NON CORE | Summary: PAINT IBA for FAD binding; Glr1 binds one FAD per subunit. Cofactor binding. Reason: Cofactor binding underlying the reductase activity. Supporting Evidence: file:yeast/GLR1/GLR1-uniprot.txt Note=Binds 1 FAD per subunit. |
| GO:0050660 flavin adenine dinucleotide binding | IEA GO_REF:0000002 | KEEP AS NON CORE | Summary: InterPro FAD/NAD(P)-binding domain mapping; correct cofactor binding. Reason: Cofactor binding underlying the reductase activity. Supporting Evidence: file:yeast/GLR1/GLR1-uniprot.txt Note=Binds 1 FAD per subunit. |
| GO:0050661 NADP binding | IEA GO_REF:0000002 | KEEP AS NON CORE | Summary: InterPro IPR006322 mapping to NADP binding; NADPH is the electron donor. Substrate binding. Reason: Substrate binding subsumed by GO:0004362. Supporting Evidence: file:yeast/GLR1/GLR1-uniprot.txt Reaction=2 glutathione + NADP(+) = glutathione disulfide + NADPH + |
| GO:0098869 cellular oxidant detoxification | IEA GO_REF:0000108 | KEEP AS NON CORE | Summary: Inferred by the GO inter-ontology rule from glutathione-disulfide reductase activity. Glr1 does not itself reduce oxidants such as peroxides, but regenerates GSH used by glutathione-dependent peroxidases and glutaredoxins, so it contributes indirectly to oxidant detoxification. Reason: Indirect contribution via GSH supply; the direct process is cell redox homeostasis. Supporting Evidence: PMID:8951820 Utilization of GSH results in its conversion to the oxidized form (GSSG), and it is recycled to GSH by the action of glutathione reductase (GLR) using the reducing power of NADPH. |
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Q: Does the peroxisomal Glr1 pool derive from the cytosolic or mitochondrial translation product?
Cytosolic and mitochondrial glutathione oxidoreductase; converts oxidized glutathione to reduced glutathione; cytosolic Glr1p is the main determinant of the glutathione redox state of the mitochondrial intermembrane space; mitochondrial Glr1p has a role in resistance to hyperoxia; also detected in peroxisomes; protein abundance increases in response to DNA replication stress
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