Peroxiredoxin AHP1 (alkyl hydroperoxide reductase 1; cytoplasmic thiol peroxidase III, cTPx III; 'type II TPx') is a Prx5-subfamily peroxiredoxin of Saccharomyces cerevisiae and one of the two most highly expressed yeast thiol peroxidases. It reduces organic (alkyl) hydroperoxides in preference to hydrogen peroxide, using electrons from thioredoxin (TRX1/TRX2) but not glutathione; the peroxidatic Cys62 forms an intersubunit disulfide that thioredoxin reduces. AHP1 is a cytosolic protein that protects cells against organic peroxides, and ahp1 mutants are also sensitive to several metals and to glutathione depletion. AHP1 disruption lowers Mn2+ tolerance, and Mn2+ transport measurements led to the proposal that AHP1 contributes to cellular Mn2+ homeostasis, although the mechanism is unknown. It relays alkyl hydroperoxide signals to the transcription factor Cad1/Yap2 and is a prominent target of oxidative-stress-dependent urmylation (URM1 conjugation). Its C-terminus (AHL) matches the PTS1 consensus, and its Candida homologue PMP20 is peroxisomal, but a peroxisomal pool of yeast AHP1 has not been established.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0005515 protein binding | IPI PMID:23831759 Mapping the functional yeast ABC transporter interactome. | REMOVE | Summary: Membrane yeast two-hybrid screen of ABC transporters reported AHP1 interacting with PXA2. Bare protein binding gives no functional information and the interaction has not been followed up. Reason: Uninformative 'protein binding' term from a large-scale MYTH screen; no informative MF can be derived. Supporting Evidence: PMID:23831759 we used membrane yeast two-hybrid technology to map the protein interactome of all of the nonmitochondrial ABC transporters |
| GO:0005737 cytoplasm | IBA GO_REF:0000033 | ACCEPT | Summary: PAINT inference of cytoplasmic activity for the PRX5-like clade; matches the experimental cytoplasmic localisation of AHP1 (cTPx III). Reason: Directly supported in S. cerevisiae by cytoplasmic localization of Ahp1/cTPx III (PMID:10681558) and cytosolic SWAT-GFP localization (PMID:26928762); SGD:S000004099 (AHP1) is itself an experimental seed of PTN001625584. Propagation Review Root cause: NO FAILURE CORE Sources checked: PANTHER:PTN001625584 SUPPORTS TRANSFER PRX5-like clade node; cytoplasmic localization is conserved and directly demonstrated for S. cerevisiae Ahp1. SGD:S000004099 SUPPORTS TRANSFER Target's own experimental cytoplasmic localization (PMID:10681558) grounds the clade annotation. UniProtKB:P30044 SUPPORTS TRANSFER Human PRDX5 cytoplasmic pool supports clade-wide cytoplasmic localization. Supporting Evidence: file:yeast/AHP1/AHP1-uniprot.txt SUBCELLULAR LOCATION: Cytoplasm {ECO:0000269|PubMed:10681558}. PMID:10681558 cTPx III (TSA II/AHPC1) |
| GO:0005737 cytoplasm | IDA PMID:10681558 Distinct physiological functions of thiol peroxidase isoenzy... | ACCEPT | Summary: Park et al. 2000 placed AHP1 (cTPx III) in the cytoplasm; the isoforms were named after their subcellular localisation. Reason: Direct subcellular localization by Park et al. 2000 (PMID:10681558) places Ahp1 (cTPx III) in the cytoplasm, where it functions as a major cytosolic thiol peroxidase. Supporting Evidence: PMID:10681558 cTPx III (TSA II/AHPC1) file:yeast/AHP1/AHP1-uniprot.txt SUBCELLULAR LOCATION: Cytoplasm {ECO:0000269|PubMed:10681558}. |
| GO:0005737 cytoplasm | IEA GO_REF:0000044 | ACCEPT | Summary: Electronic mapping to cytoplasm; correct for AHP1 (experimentally cytoplasmic). Reason: UniProt SubCell mapping from the experimentally curated cytoplasmic localization (PMID:10681558). Supporting Evidence: file:yeast/AHP1/AHP1-uniprot.txt SUBCELLULAR LOCATION: Cytoplasm {ECO:0000269|PubMed:10681558}. |
| GO:0005739 mitochondrion | IBA GO_REF:0000033 | MARK AS OVER ANNOTATED | Summary: PAINT mitochondrion inference for the PRX5 clade, driven by mammalian PRDX5 whose mitochondrial form uses an N-terminal targeting extension. AHP1 starts directly with the Prx domain (MSDLVNKKFP...), has no predicted presequence, has been localised to the cytoplasm, and the mitochondrial thiol peroxidase role in yeast is filled by PRX1. Likely over-propagated to AHP1. Reason: Mammalian PRDX5 mitochondrial import requires an N-terminal mitochondrial targeting sequence that S. cerevisiae Ahp1 lacks; Ahp1 is experimentally localized to the cytoplasm/cytosol (PMID:10681558, PMID:26928762), and mitochondrial thiol peroxidase activity in budding yeast is performed by Prx1. Under the root-organelle policy (projects/ORGANELLES.md, rule 3), an unsupported synthesis row on a root organelle term is marked MARK_AS_OVER_ANNOTATED, consistent with the S. pombe pmp20 review on PTN000046537. Propagation Review Root cause: PROPAGATION BAD Failure modes: COMPARTMENT OR COMPLEX MISMATCH Sources checked: PANTHER:PTN000046537 SUPPORTS SOURCE BUT NOT TARGET Ancestral PRX5 clade node; mitochondrial localization depends on an N-terminal targeting extension absent from S. cerevisiae Ahp1. FB:FBgn0038570 SUPPORTS SOURCE BUT NOT TARGET Drosophila Prx5 mitochondrial localization does not transfer to the unextended cytosolic S. cerevisiae Ahp1 protein. RGD:71007 SUPPORTS SOURCE BUT NOT TARGET Rat Prdx5 mitochondrial localization depends on a mammalian N-terminal targeting peptide absent in Ahp1. UniProtKB:P30044 · PRDX5 (human) SUPPORTS SOURCE BUT NOT TARGET Mitochondrial PRDX5 isoform depends on an N-terminal targeting extension that AHP1 lacks. Supporting Evidence: file:yeast/AHP1/AHP1-uniprot.txt SUBCELLULAR LOCATION: Cytoplasm {ECO:0000269|PubMed:10681558}. PMID:10681558 cTPx III (TSA II/AHPC1) |
| GO:0005777 peroxisome | IBA GO_REF:0000033 | MARK AS OVER ANNOTATED | Summary: PAINT peroxisome inference for the PRX5 clade (seeded by mammalian PRDX5). Although AHP1 ends in -AHL (matching the PTS1 consensus) and its Candida homologue PMP20 is peroxisomal, experimental localisation of S. cerevisiae AHP1 is cytoplasmic/cytosolic and no peroxisomal pool has been demonstrated. Reason: Experimental localization of S. cerevisiae Ahp1 places the protein in the cytoplasm and cytosol (PMID:10681558, PMID:26928762), and no peroxisomal pool has been established in budding yeast despite the C-terminal -AHL tripeptide and homology to Candida boidinii Pmp20 (PMID:10391912). Under the root-organelle policy (projects/ORGANELLES.md, rule 3), a synthesis row on a root organelle term whose organelle claim is not experimentally supported in the target is marked MARK_AS_OVER_ANNOTATED (rather than REMOVE, as a minor or condition-dependent peroxisomal pool has not been excluded), matching the S. pombe pmp20 review on PTN000046537. Propagation Review Root cause: PROPAGATION BAD Failure modes: COMPARTMENT OR COMPLEX MISMATCH Sources checked: PANTHER:PTN000046537 SUPPORTS SOURCE BUT NOT TARGET Ancestral PRX5 clade node; peroxisomal localization is supported in mammalian PRDX5 but has not been demonstrated for S. cerevisiae Ahp1, which localizes to the cytoplasm/cytosol. RGD:71007 SUPPORTS SOURCE BUT NOT TARGET Rat Prdx5 peroxisomal localization does not establish peroxisomal residence for S. cerevisiae Ahp1. UniProtKB:P30044 SUPPORTS SOURCE BUT NOT TARGET Human PRDX5 peroxisomal localization is supported in human cells, whereas S. cerevisiae Ahp1 is experimentally cytosolic. Supporting Evidence: PMID:10391912 an abundant yeast protein related to PMP20, a peroxisomal protein of Candida file:yeast/AHP1/AHP1-uniprot.txt SUBCELLULAR LOCATION: Cytoplasm {ECO:0000269|PubMed:10681558}. |
| GO:0005829 cytosol | HDA PMID:26928762 One library to make them all: streamlining the creation of y... | ACCEPT | Summary: SWAT-GFP high-throughput localisation placed AHP1 in the cytosol; consistent with low-throughput cytoplasmic localisation. Reason: High-throughput SWAT-GFP imaging places Ahp1 in the cytosol (PMID:26928762), corroborating the low-throughput cytoplasmic localization of cTPx III (PMID:10681558). Supporting Evidence: PMID:26928762 we developed a SWAp-Tag (SWAT) method that enables one parental library to be modified easily and efficiently file:yeast/AHP1/AHP1-uniprot.txt SUBCELLULAR LOCATION: Cytoplasm {ECO:0000269|PubMed:10681558}. |
| GO:0005886 plasma membrane | HDA PMID:16622836 The plasma membrane proteome of Saccharomyces cerevisiae and... | MARK AS OVER ANNOTATED | Summary: AHP1 was identified among ~90 proteins of a stripped plasma membrane fraction (Delom et al. 2006). AHP1 is a very abundant soluble cytosolic protein (~16,000 molecules/cell) without transmembrane segments or lipid anchors, so detection in a membrane fraction is most likely co-purification; no functional plasma-membrane role is known. Reason: Ahp1 is an abundant soluble cytosolic peroxiredoxin (~16,228 molecules/cell) lacking transmembrane domains or lipid anchors; its detection in a proteomic survey of stripped plasma membranes (PMID:16622836) reflects co-purification of an abundant cytosolic protein rather than plasma-membrane residence. Supporting Evidence: PMID:16622836 Nearly 90 proteins were identified and clustered, based on their pI, molecular weight, abundance and/or hydrophobicity. file:yeast/AHP1/AHP1-uniprot.txt Present with 16228 molecules/cell in log phase SD |
| GO:0008379 obsolete thioredoxin peroxidase activity | IBA GO_REF:0000033 | MODIFY | Summary: GO:0008379 thioredoxin peroxidase activity is obsolete; the activity is now GO:0140824 thioredoxin-dependent peroxiredoxin activity. AHP1 is a well-characterised thioredoxin-dependent alkyl hydroperoxide peroxidase (Verdoucq 1999; Jeong 1999; Park 2000). Reason: GO:0008379 is obsolete; replace with the current term GO:0140824 (thioredoxin-dependent peroxiredoxin activity), which is directly demonstrated for recombinant Ahp1 in vitro (PMID:10391912, PMID:9888818, PMID:10681558) and already annotated on the gene. Propagation Review Root cause: NO FAILURE CORE Sources checked: PANTHER:PTN001625584 SUPPORTS TRANSFER PRX5-like clade node; thioredoxin-dependent peroxiredoxin activity is conserved and directly assayed for S. cerevisiae Ahp1. SGD:S000004099 SUPPORTS TRANSFER Target's own experimental peroxidase activity (PMID:10681558) grounds the clade annotation. UniProtKB:P30044 SUPPORTS TRANSFER Human PRDX5 thioredoxin-dependent peroxiredoxin activity supports clade conservation. Proposed replacements: thioredoxin-dependent peroxiredoxin activity Supporting Evidence: PMID:10391912 We demonstrate that both recombinant proteins present a thioredoxin-dependent peroxidase activity in vitro. PMID:9888818 The formed disulfide can then be reduced by thioredoxin, but not by glutathione. PMID:10681558 Three novel isoforms showed a distinct thiol peroxidase activity supported by thioredoxin |
| GO:0008379 obsolete thioredoxin peroxidase activity | IDA PMID:10681558 Distinct physiological functions of thiol peroxidase isoenzy... | MODIFY | Summary: GO:0008379 thioredoxin peroxidase activity is obsolete; the activity is now GO:0140824 thioredoxin-dependent peroxiredoxin activity. AHP1 is a well-characterised thioredoxin-dependent alkyl hydroperoxide peroxidase (Verdoucq 1999; Jeong 1999; Park 2000). Reason: GO:0008379 is obsolete; replace with the current term GO:0140824 (thioredoxin-dependent peroxiredoxin activity), which is directly assayed in PMID:10681558 and already carried on the gene. Proposed replacements: thioredoxin-dependent peroxiredoxin activity Supporting Evidence: PMID:10391912 We demonstrate that both recombinant proteins present a thioredoxin-dependent peroxidase activity in vitro. PMID:9888818 The formed disulfide can then be reduced by thioredoxin, but not by glutathione. PMID:10681558 Three novel isoforms showed a distinct thiol peroxidase activity supported by thioredoxin |
| GO:0008379 obsolete thioredoxin peroxidase activity | IEA GO_REF:0000002 | MODIFY | Summary: GO:0008379 thioredoxin peroxidase activity is obsolete; the activity is now GO:0140824 thioredoxin-dependent peroxiredoxin activity. AHP1 is a well-characterised thioredoxin-dependent alkyl hydroperoxide peroxidase (Verdoucq 1999; Jeong 1999; Park 2000). Reason: GO:0008379 is obsolete; replace with the current term GO:0140824 (thioredoxin-dependent peroxiredoxin activity), which is directly supported by in vitro assays (PMID:10391912, PMID:9888818, PMID:10681558). Proposed replacements: thioredoxin-dependent peroxiredoxin activity Supporting Evidence: PMID:10391912 We demonstrate that both recombinant proteins present a thioredoxin-dependent peroxidase activity in vitro. PMID:9888818 The formed disulfide can then be reduced by thioredoxin, but not by glutathione. PMID:10681558 Three novel isoforms showed a distinct thiol peroxidase activity supported by thioredoxin |
| GO:0008379 obsolete thioredoxin peroxidase activity | IMP PMID:10681558 Distinct physiological functions of thiol peroxidase isoenzy... | MODIFY | Summary: GO:0008379 thioredoxin peroxidase activity is obsolete; the activity is now GO:0140824 thioredoxin-dependent peroxiredoxin activity. AHP1 is a well-characterised thioredoxin-dependent alkyl hydroperoxide peroxidase (Verdoucq 1999; Jeong 1999; Park 2000). Reason: GO:0008379 is obsolete; replace with the current term GO:0140824 (thioredoxin-dependent peroxiredoxin activity), which is directly demonstrated for Ahp1 (PMID:10681558). Proposed replacements: thioredoxin-dependent peroxiredoxin activity Supporting Evidence: PMID:10391912 We demonstrate that both recombinant proteins present a thioredoxin-dependent peroxidase activity in vitro. PMID:9888818 The formed disulfide can then be reduced by thioredoxin, but not by glutathione. PMID:10681558 Three novel isoforms showed a distinct thiol peroxidase activity supported by thioredoxin |
| GO:0010038 response to metal ion | IMP PMID:12270680 Alkyl hydroperoxide reductase 1 protects Saccharomyces cerev... | KEEP AS NON CORE | Summary: ahp1 disruptants are sensitive to Cu, Co, Cr, arsenite/arsenate, Hg, Zn and diethyl maleate; the authors attribute this to reduction of metal-generated peroxides. A downstream consequence of the peroxidase activity rather than a distinct function. Reason: ahp1 null mutants are hypersensitive to multiple transition metals and metalloids (PMID:12270680), reflecting detoxification of metal-induced organic peroxides; kept as a non-core downstream stress phenotype of its core peroxiredoxin activity. Supporting Evidence: PMID:12270680 We report that Ahp1p protects yeast against toxicity induced by copper, cobalt, chromium, arsenite, arsenate, mercury, zinc and diethyl maleate |
| GO:0016491 oxidoreductase activity | IEA GO_REF:0000002 | MODIFY | Summary: InterPro mapping to generic oxidoreductase activity; true but uninformative. AHP1 activity is thioredoxin-dependent hydroperoxide reduction (EC 1.11.1.24). Reason: Correct but less specific than the experimentally established is_a descendant GO:0140824 (thioredoxin-dependent peroxiredoxin activity, EC 1.11.1.24; PMID:10391912, PMID:9888818), which the gene already carries. Proposed replacements: thioredoxin-dependent peroxiredoxin activity Supporting Evidence: file:yeast/AHP1/AHP1-uniprot.txt EC=1.11.1.24 {ECO:0000269|PubMed:10391912, ECO:0000269|PubMed:9888818}; |
| GO:0034599 cellular response to oxidative stress | IBA GO_REF:0000033 | ACCEPT | Summary: AHP1 protects cells against organic peroxides (null mutants hypersensitive) and contributes, with the other four Prxs, to oxidative and nitrosative stress resistance (quintuple-null analysis). Reason: Directly supported in S. cerevisiae by hypersensitivity of ahp1 null mutants to organic peroxides (PMID:12270680) and of peroxiredoxin-null mutants to oxidative and nitrosative stress (PMID:15051715); SGD:S000004099 is itself an experimental seed of PTN001625584. Propagation Review Root cause: NO FAILURE CORE Sources checked: PANTHER:PTN001625584 SUPPORTS TRANSFER PRX5-like clade node; cellular response to oxidative stress is conserved and directly demonstrated in S. cerevisiae Ahp1. SGD:S000004099 SUPPORTS TRANSFER Target's own experimental oxidative-stress resistance evidence (PMID:15051715) grounds the clade annotation. UniProtKB:P30044 SUPPORTS TRANSFER Human PRDX5 oxidative-stress protection supports clade conservation. Supporting Evidence: PMID:12270680 revealed a high sensitivity of null mutants to organic peroxides PMID:15051715 We generated and characterized a yeast mutant lacking all five peroxiredoxins. PMID:15051715 peroxiredoxin-null yeast cells were more susceptible to oxidative and nitrosative stress |
| GO:0034599 cellular response to oxidative stress | IEA GO_REF:0000002 | ACCEPT | Summary: AHP1 protects cells against organic peroxides (null mutants hypersensitive) and contributes, with the other four Prxs, to oxidative and nitrosative stress resistance (quintuple-null analysis). Reason: Consistent with the IBA and IGI rows and supported by ahp1 null mutant sensitivity to organic peroxides (PMID:12270680, PMID:15051715). Supporting Evidence: PMID:12270680 revealed a high sensitivity of null mutants to organic peroxides PMID:15051715 We generated and characterized a yeast mutant lacking all five peroxiredoxins. PMID:15051715 peroxiredoxin-null yeast cells were more susceptible to oxidative and nitrosative stress |
| GO:0034599 cellular response to oxidative stress | IGI PMID:15051715 Peroxiredoxin-null yeast cells are hypersensitive to oxidati... | ACCEPT | Summary: AHP1 protects cells against organic peroxides (null mutants hypersensitive) and contributes, with the other four Prxs, to oxidative and nitrosative stress resistance (quintuple-null analysis). Reason: Genetic interaction across the five yeast peroxiredoxins shows overlapping protection against oxidative and nitrosative stress (PMID:15051715), complementing the single-mutant organic-peroxide sensitivity of ahp1 (PMID:12270680). Supporting Evidence: PMID:12270680 revealed a high sensitivity of null mutants to organic peroxides PMID:15051715 We generated and characterized a yeast mutant lacking all five peroxiredoxins. PMID:15051715 peroxiredoxin-null yeast cells were more susceptible to oxidative and nitrosative stress |
| GO:0034599 cellular response to oxidative stress | IGI PMID:15051715 Peroxiredoxin-null yeast cells are hypersensitive to oxidati... | ACCEPT | Summary: AHP1 protects cells against organic peroxides (null mutants hypersensitive) and contributes, with the other four Prxs, to oxidative and nitrosative stress resistance (quintuple-null analysis). Reason: Genetic interaction across the five yeast peroxiredoxins shows overlapping protection against oxidative and nitrosative stress (PMID:15051715), complementing the single-mutant organic-peroxide sensitivity of ahp1 (PMID:12270680). Supporting Evidence: PMID:12270680 revealed a high sensitivity of null mutants to organic peroxides PMID:15051715 We generated and characterized a yeast mutant lacking all five peroxiredoxins. PMID:15051715 peroxiredoxin-null yeast cells were more susceptible to oxidative and nitrosative stress |
| GO:0034599 cellular response to oxidative stress | IGI PMID:15051715 Peroxiredoxin-null yeast cells are hypersensitive to oxidati... | ACCEPT | Summary: AHP1 protects cells against organic peroxides (null mutants hypersensitive) and contributes, with the other four Prxs, to oxidative and nitrosative stress resistance (quintuple-null analysis). Reason: Genetic interaction across the five yeast peroxiredoxins shows overlapping protection against oxidative and nitrosative stress (PMID:15051715), complementing the single-mutant organic-peroxide sensitivity of ahp1 (PMID:12270680). Supporting Evidence: PMID:12270680 revealed a high sensitivity of null mutants to organic peroxides PMID:15051715 We generated and characterized a yeast mutant lacking all five peroxiredoxins. PMID:15051715 peroxiredoxin-null yeast cells were more susceptible to oxidative and nitrosative stress |
| GO:0034599 cellular response to oxidative stress | IGI PMID:15051715 Peroxiredoxin-null yeast cells are hypersensitive to oxidati... | ACCEPT | Summary: AHP1 protects cells against organic peroxides (null mutants hypersensitive) and contributes, with the other four Prxs, to oxidative and nitrosative stress resistance (quintuple-null analysis). Reason: Genetic interaction across the five yeast peroxiredoxins shows overlapping protection against oxidative and nitrosative stress (PMID:15051715), complementing the single-mutant organic-peroxide sensitivity of ahp1 (PMID:12270680). Supporting Evidence: PMID:12270680 revealed a high sensitivity of null mutants to organic peroxides PMID:15051715 We generated and characterized a yeast mutant lacking all five peroxiredoxins. PMID:15051715 peroxiredoxin-null yeast cells were more susceptible to oxidative and nitrosative stress |
| GO:0042744 hydrogen peroxide catabolic process | IBA GO_REF:0000033 | ACCEPT | Summary: PAINT inference of H2O2 catabolism for the PRX5 clade. AHP1 reduces H2O2 with thioredoxin (Km 14-150 uM) although it prefers alkyl hydroperoxides; the process term fits the module's thiol-peroxidase step, while AHP1's distinctive role is organic hydroperoxide reduction. Reason: Purified S. cerevisiae Ahp1 catalyses thioredoxin-dependent reduction of H2O2 in vitro (KM = 14 uM; PMID:10391912, PMID:9888818) in addition to its preferred alkyl hydroperoxide substrates, supporting the clade-level H2O2 catabolic process annotation. Propagation Review Root cause: NO FAILURE CORE Sources checked: PANTHER:PTN001625584 SUPPORTS TRANSFER PRX5-like clade node; thioredoxin-dependent H2O2 reduction is conserved and biochemically confirmed for S. cerevisiae Ahp1. UniProtKB:P30044 SUPPORTS TRANSFER Human PRDX5 H2O2 catabolic activity supports clade conservation. Supporting Evidence: PMID:9888818 type I preferentially reduces H2O2 rather than alkyl hydroperoxides, whereas type II shows the reverse specificity file:yeast/AHP1/AHP1-uniprot.txt KM=14 uM for H(2)O(2) {ECO:0000269|PubMed:10391912}; |
| GO:0045454 cell redox homeostasis | IBA GO_REF:0000033 | ACCEPT | Summary: Thioredoxin-coupled peroxide reduction by AHP1 (cTPx III) contributes to cellular redox homeostasis; supported by thioredoxin-dependent activity and null-mutant analysis (Park et al. 2000). Reason: Directly supported in S. cerevisiae by thioredoxin-coupled hydroperoxide reduction and null-mutant redox sensitivity (PMID:10681558, PMID:9888818); SGD:S000004099 is itself an experimental seed of PTN001625584. Propagation Review Root cause: NO FAILURE CORE Sources checked: PANTHER:PTN001625584 SUPPORTS TRANSFER PRX5-like clade node; cell redox homeostasis via thioredoxin-coupled peroxidase activity is conserved in S. cerevisiae Ahp1. SGD:S000004099 SUPPORTS TRANSFER Target's own experimental redox homeostasis evidence (PMID:10681558) grounds the clade annotation. Supporting Evidence: PMID:10681558 Three novel isoforms showed a distinct thiol peroxidase activity supported by thioredoxin PMID:9888818 The formed disulfide can then be reduced by thioredoxin, but not by glutathione. |
| GO:0045454 cell redox homeostasis | IDA PMID:10681558 Distinct physiological functions of thiol peroxidase isoenzy... | ACCEPT | Summary: Thioredoxin-coupled peroxide reduction by AHP1 (cTPx III) contributes to cellular redox homeostasis; supported by thioredoxin-dependent activity and null-mutant analysis (Park et al. 2000). Reason: Direct characterization of cTPx III (Ahp1) demonstrates thioredoxin-coupled thiol peroxidase activity maintaining cellular redox balance (PMID:10681558, PMID:9888818). Supporting Evidence: PMID:10681558 Three novel isoforms showed a distinct thiol peroxidase activity supported by thioredoxin PMID:9888818 The formed disulfide can then be reduced by thioredoxin, but not by glutathione. |
| GO:0045454 cell redox homeostasis | IMP PMID:10681558 Distinct physiological functions of thiol peroxidase isoenzy... | ACCEPT | Summary: Thioredoxin-coupled peroxide reduction by AHP1 (cTPx III) contributes to cellular redox homeostasis; supported by thioredoxin-dependent activity and null-mutant analysis (Park et al. 2000). Reason: Mutant analysis of cTPx III (Ahp1) alongside the other yeast thiol peroxidases establishes its role in maintaining cellular redox homeostasis (PMID:10681558). Supporting Evidence: PMID:10681558 Three novel isoforms showed a distinct thiol peroxidase activity supported by thioredoxin PMID:9888818 The formed disulfide can then be reduced by thioredoxin, but not by glutathione. |
| GO:0050821 protein stabilization | IDA NOT PMID:15163410 Two enzymes in one; two yeast peroxiredoxins display oxidati... | ACCEPT | Summary: NOT protein stabilization: in Jang et al. 2004 the chaperone (holdase) activity was found for the typical 2-Cys Prxs TSA1/TSA2 (cPrxI/II), not for the other yeast Prxs; AHP1 is a Prx5-type enzyme that does not form the high-MW chaperone complexes. Curator's negative annotation from full text accepted. Reason: Jang et al. 2004 (PMID:15163410) showed that oxidative-stress-induced molecular chaperone (holdase) switching in yeast is specific to the typical 2-Cys peroxiredoxins Tsa1 and Tsa2 (cPrxI/II) and absent in Ahp1; the curator's NOT annotation is accepted. Supporting Evidence: PMID:15163410 We show here that two cytosolic yeast Prxs, cPrxI and II, which display diversity in structure and apparent molecular weights (MW), can act alternatively as peroxidases and molecular chaperones. |
| GO:0098869 cellular oxidant detoxification | IEA GO_REF:0000120 | ACCEPT | Summary: Combined-IEA mapping to cellular oxidant detoxification from peroxiredoxin activity; Ahp1 directly detoxifies cellular hydroperoxides (both alkyl hydroperoxides and H2O2) via the thioredoxin system. Reason: Inferred by GO_REF:0000120 from Ahp1's peroxiredoxin activity (GO:0008379, GO:0140824). Ahp1 directly reduces cellular hydroperoxides—preferentially organic (alkyl) hydroperoxides as well as H2O2 (PMID:9888818, PMID:10391912, PMID:12270680)—and in GO's ontology GO:0042744 (hydrogen peroxide catabolic process, under GO:0042743/GO:0072593) is not an is_a/part_of descendant of GO:0098869 (under detoxification). Accepted as a core biological process alongside GO:0042744 and GO:0045454, matching ECOLI/ahpC, BACSU/ahpC, HELPY/ahpC, and yeast/HYR1. Supporting Evidence: PMID:12270680 revealed a high sensitivity of null mutants to organic peroxides |
| GO:0140824 thioredoxin-dependent peroxiredoxin activity | EXP PMID:10391912 In vivo characterization of a thioredoxin h target protein d... | ACCEPT | Summary: Verdoucq et al. 1999 trapped YLR109 (AHP1) as a thioredoxin target and showed recombinant protein has thioredoxin-dependent peroxidase activity in vitro. Core function. Reason: Direct biochemical demonstration that recombinant S. cerevisiae Ahp1 catalyses thioredoxin-dependent peroxide reduction in vitro (PMID:10391912). Supporting Evidence: PMID:10391912 We demonstrate that both recombinant proteins present a thioredoxin-dependent peroxidase activity in vitro. |
| GO:0140824 thioredoxin-dependent peroxiredoxin activity | EXP PMID:9888818 Purification and characterization of a second type thioredox... | ACCEPT | Summary: Jeong et al. 1999 purified type II TPx (AHP1, 176 aa, Cys62/Cys120), showed thioredoxin- (not glutathione-) dependent reduction with preference for alkyl hydroperoxides, and that Cys62 is essential. Core function. Reason: Direct biochemical characterization of purified S. cerevisiae Ahp1 (type II TPx) demonstrating thioredoxin-dependent, glutathione-independent reduction of alkyl hydroperoxides and H2O2 via Cys62 (PMID:9888818). Supporting Evidence: PMID:9888818 type I preferentially reduces H2O2 rather than alkyl hydroperoxides, whereas type II shows the reverse specificity PMID:9888818 The formed disulfide can then be reduced by thioredoxin, but not by glutathione. |
| GO:0140824 thioredoxin-dependent peroxiredoxin activity | IEA GO_REF:0000120 | ACCEPT | Summary: Rhea/EC 1.11.1.24 mapping to thioredoxin-dependent peroxiredoxin activity; correct and experimentally confirmed. Reason: Electronic mapping from EC 1.11.1.24 / RHEA:62620 matches the directly assayed thioredoxin-dependent peroxiredoxin activity of Ahp1 (PMID:10391912, PMID:9888818). Supporting Evidence: file:yeast/AHP1/AHP1-uniprot.txt EC=1.11.1.24 {ECO:0000269|PubMed:10391912, ECO:0000269|PubMed:9888818}; |
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Experiment: Image endogenously C-terminally untagged (N-terminal GFP) AHP1 in oleate-grown cells and test Pex5-dependent peroxisomal import; compare an AHL deletion mutant.
Thiol-specific peroxiredoxin; reduces hydroperoxides to protect against oxidative damage; function in vivo requires covalent conjugation to Urm1p
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