EUG1 encodes a nonessential endoplasmic-reticulum protein disulfide isomerase family member with thioredoxin-like domains and atypical CXXS active-site motifs. Evidence supports an auxiliary ER protein-folding and quality-control role: wild-type Eug1p has weak classical oxidoreductase/isomerase activity, measurable chaperone-like activity, ER retention, and functional overlap with other yeast PDI-family proteins.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
|
GO:0005783
endoplasmic reticulum
|
IBA
GO_REF:0000033 |
ACCEPT |
Summary: Manual review: endoplasmic reticulum is consistent with known biology of EUG1.
Reason: Retained as supported or plausible for this gene and evidence context.
|
|
GO:0006457
protein folding
|
IBA
GO_REF:0000033 |
ACCEPT |
Summary: Manual review: protein folding is consistent with known biology of EUG1.
Reason: Retained as supported or plausible for this gene and evidence context.
|
|
GO:0034976
response to endoplasmic reticulum stress
|
IBA
GO_REF:0000033 |
ACCEPT |
Summary: Manual review: response to endoplasmic reticulum stress is consistent with known biology of EUG1.
Reason: Retained as supported or plausible for this gene and evidence context.
|
|
GO:0003756
protein disulfide isomerase activity
|
IBA
GO_REF:0000033 |
ACCEPT |
Summary: Manual review: protein disulfide isomerase activity is consistent with known biology of EUG1.
Reason: Retained as supported or plausible for this gene and evidence context.
Supporting Evidence:
file:yeast/EUG1/EUG1-deep-research-falcon.md
wild-type Eug1p is a weak oxidoreductase/isomerase
|
|
GO:0003756
protein disulfide isomerase activity
|
IEA
GO_REF:0000120 |
ACCEPT |
Summary: Manual review: protein disulfide isomerase activity is consistent with known biology of EUG1.
Reason: Retained as supported or plausible for this gene and evidence context.
|
|
GO:0005788
endoplasmic reticulum lumen
|
IEA
GO_REF:0000044 |
ACCEPT |
Summary: Manual review: endoplasmic reticulum lumen is consistent with known biology of EUG1.
Reason: Retained as supported or plausible for this gene and evidence context.
|
|
GO:0006457
protein folding
|
IEA
GO_REF:0000117 |
ACCEPT |
Summary: Manual review: protein folding is consistent with known biology of EUG1.
Reason: Retained as supported or plausible for this gene and evidence context.
|
|
GO:0015035
protein-disulfide reductase activity
|
IEA
GO_REF:0000117 |
ACCEPT |
Summary: Manual review: protein-disulfide reductase activity is consistent with known biology of EUG1.
Reason: Retained as supported or plausible for this gene and evidence context.
|
|
GO:0016853
isomerase activity
|
IEA
GO_REF:0000043 |
ACCEPT |
Summary: Manual review: isomerase activity is consistent with known biology of EUG1.
Reason: Retained as supported or plausible for this gene and evidence context.
|
|
GO:0051082
unfolded protein binding
|
IEA
GO_REF:0000117 |
MARK AS OVER ANNOTATED |
Summary: Manual review: unfolded protein binding is too generic or over-extended for EUG1.
Reason: Marked over-annotated because more specific terms capture the biology more accurately.
|
|
GO:0005515
protein binding
|
IPI
PMID:27107014 An inter-species protein-protein interaction network across ... |
MARK AS OVER ANNOTATED |
Summary: Manual review: protein binding is too generic or over-extended for EUG1.
Reason: Marked over-annotated because more specific terms capture the biology more accurately.
|
|
GO:0005783
endoplasmic reticulum
|
HDA
PMID:26928762 One library to make them all: streamlining the creation of y... |
ACCEPT |
Summary: Manual review: endoplasmic reticulum is consistent with known biology of EUG1.
Reason: Retained as supported or plausible for this gene and evidence context.
|
|
GO:0005783
endoplasmic reticulum
|
HDA
PMID:11914276 Subcellular localization of the yeast proteome. |
ACCEPT |
Summary: Manual review: endoplasmic reticulum is consistent with known biology of EUG1.
Reason: Retained as supported or plausible for this gene and evidence context.
|
|
GO:0003756
protein disulfide isomerase activity
|
ISS
PMID:11157982 Functional differences in yeast protein disulfide isomerases... |
ACCEPT |
Summary: Manual review: protein disulfide isomerase activity is consistent with known biology of EUG1.
Reason: Retained as supported or plausible for this gene and evidence context.
|
|
GO:0015035
protein-disulfide reductase activity
|
ISS
PMID:11157982 Functional differences in yeast protein disulfide isomerases... |
ACCEPT |
Summary: Manual review: protein-disulfide reductase activity is consistent with known biology of EUG1.
Reason: Retained as supported or plausible for this gene and evidence context.
|
|
GO:0005515
protein binding
|
IPI
PMID:16002399 Interactions among yeast protein-disulfide isomerase protein... |
MARK AS OVER ANNOTATED |
Summary: Manual review: protein binding is too generic or over-extended for EUG1.
Reason: Marked over-annotated because more specific terms capture the biology more accurately.
|
|
GO:0019153
protein-disulfide reductase (glutathione) activity
|
IDA
PMID:16002399 Interactions among yeast protein-disulfide isomerase protein... |
ACCEPT |
Summary: Manual review: protein-disulfide reductase (glutathione) activity is consistent with known biology of EUG1.
Reason: Retained as supported or plausible for this gene and evidence context.
|
|
GO:0051082
unfolded protein binding
|
IDA
PMID:16002399 Interactions among yeast protein-disulfide isomerase protein... |
MARK AS OVER ANNOTATED |
Summary: Manual review: unfolded protein binding is too generic or over-extended for EUG1.
Reason: Marked over-annotated because more specific terms capture the biology more accurately.
|
|
GO:0003756
protein disulfide isomerase activity
|
IMP
PMID:11157982 Functional differences in yeast protein disulfide isomerases... |
ACCEPT |
Summary: Manual review: protein disulfide isomerase activity is consistent with known biology of EUG1.
Reason: Retained as supported or plausible for this gene and evidence context.
|
|
GO:0003756
protein disulfide isomerase activity
|
IGI
PMID:11157982 Functional differences in yeast protein disulfide isomerases... |
ACCEPT |
Summary: Manual review: protein disulfide isomerase activity is consistent with known biology of EUG1.
Reason: Retained as supported or plausible for this gene and evidence context.
|
|
GO:0003756
protein disulfide isomerase activity
|
IDA
PMID:16002399 Interactions among yeast protein-disulfide isomerase protein... |
ACCEPT |
Summary: Manual review: protein disulfide isomerase activity is consistent with known biology of EUG1.
Reason: Retained as supported or plausible for this gene and evidence context.
|
|
GO:0006457
protein folding
|
IGI
PMID:11157982 Functional differences in yeast protein disulfide isomerases... |
ACCEPT |
Summary: Manual review: protein folding is consistent with known biology of EUG1.
Reason: Retained as supported or plausible for this gene and evidence context.
|
|
GO:0015035
protein-disulfide reductase activity
|
IGI
PMID:11157982 Functional differences in yeast protein disulfide isomerases... |
ACCEPT |
Summary: Manual review: protein-disulfide reductase activity is consistent with known biology of EUG1.
Reason: Retained as supported or plausible for this gene and evidence context.
|
|
GO:0015035
protein-disulfide reductase activity
|
IDA
PMID:16002399 Interactions among yeast protein-disulfide isomerase protein... |
ACCEPT |
Summary: Manual review: protein-disulfide reductase activity is consistent with known biology of EUG1.
Reason: Retained as supported or plausible for this gene and evidence context.
|
Q: Should EUG1 annotations distinguish weak native oxidoreductase activity from engineered CXXC mutant activity when choosing molecular-function terms?
Q: Are recently reported ER interaction-mapping partners suitable for direct GO protein-binding annotations, or should they remain supporting context?
Experiment: Compare wild-type Eug1p and CXXC-engineered variants on native ER client substrates under physiological expression levels.
Experiment: Validate Eug1p ER interaction partners from in situ mapping with reciprocal biochemical assays and client-folding readouts.
The research report should be a detailed narrative explaining the function, biological processes, and localization of the gene product. Citations should be given for all claims.
You should prioritize authoritative reviews and primary scientific literature when conducting research. You can supplement
this with annotations you find in gene/protein databases, but these can be outdated or inaccurate.
We are specifically interested in the primary function of the gene - for enzymes, what reaction is catalyzed, and what is the substrate specificity? For transporters, what is the substrate? For structural proteins or adapters, what is the broader structural role? For signaling molecules, what is the role in the pathway.
We are interested in where in or outside the cell the gene product carries out its function.
We are also interested in the signaling or biochemical pathways in which the gene functions. We are less interested in broad pleiotropic effects, except where these elucidate the precise role.
Include evidence where possible. We are interested in both experimental evidence as well as inference from structure, evolution, or bioinformatic analysis. Precise studies should be prioritized over high-throughput, where available.
Protein disulfide isomerase (PDI) family proteins are thioredoxin-domain oxidoreductases in the endoplasmic reticulum (ER) lumen that catalyze thiol–disulfide exchange reactions during secretory-protein folding, including disulfide bond formation (oxidation), disulfide reduction, and disulfide isomerization (reshuffling of incorrect disulfides) (suzuki2015redoxdiversityin pages 1-2). In budding yeast, Pdi1p is the essential PDI, while several nonessential homologues provide overlapping/auxiliary functions in ER oxidative folding and quality control (xiao2004thecontributionsof pages 2-2, nørgaard2001functionaldifferencesin pages 2-2).
Multiple independent sources explicitly place EUG1 (YDR518W) among the PDI1 homologues localized to the yeast ER (MPD1, MPD2, EUG1, EPS1) and among the yeast PDI family members (xiao2004thecontributionsof pages 2-2, suzuki2015redoxdiversityin pages 1-2). In addition, mechanistic evidence refers to “a yeast PDI homologue, Eug1p” and highlights its unusual active-site chemistry (beynonjones2006mutationalanalysisof pages 1-2). These points confirm that the literature summarized here corresponds to the same target as UniProt P32474 (Eug1p in S. cerevisiae), not an unrelated “EUG1” gene from another organism (xiao2004thecontributionsof pages 2-2, beynonjones2006mutationalanalysisof pages 1-2).
Eug1p is described as a Pdi1p homologue with two thioredoxin-like domains and two non-canonical redox motifs of the form CXXS (rather than CXXC) (nørgaard2001functionaldifferencesin pages 2-2, nørgaard2001functionaldifferencesin pages 1-2). Active-site positions for the two CxxS motifs were reported as residues 62 and 405 (hacioglu2010therolesof pages 3-4). This “CXXS” configuration is repeatedly emphasized as a key reason for Eug1p’s atypically weak oxidoreductase function relative to canonical PDIs (beynonjones2006mutationalanalysisof pages 1-2, nørgaard2001functionaldifferencesin pages 2-2).
Reaction class: Like other PDI-family oxidoreductases, Eug1p participates in thiol–disulfide exchange, which in principle can catalyze oxidation/reduction/isomerization of disulfide bonds in ER client proteins (suzuki2015redoxdiversityin pages 1-2).
Substrate-level evidence: Several experiments use the secretory pathway substrate procarboxypeptidase Y (proCPY/CPY) to probe PDI-family function in vivo and in vitro. In deletion/overexpression backgrounds, loss of PDI homologues slows CPY maturation (xiao2004thecontributionsof pages 5-7, xiao2004thecontributionsof media f566842d). In biochemical assays, engineered Eug1p variants (see below) catalyze oxidative refolding and disulfide reshuffling of proCPY (nørgaard2001mutationofyeast pages 6-6, nørgaard2001mutationofyeast pages 4-6). These experiments provide the most direct “substrate specificity” evidence available in the retrieved corpus: Eug1p-related activity is demonstrated on a complex secretory cargo (proCPY) rather than a single defined peptide substrate (nørgaard2001mutationofyeast pages 4-6).
Multiple sources converge on the conclusion that wild-type Eug1p is a weak oxidoreductase/isomerase in standard PDI assays:
* A study of yeast PDI family functional differences emphasizes that Eug1p contains CXXS motifs and that Eug1p “alone is unable to carry oxidizing equivalents,” consistent with limited oxidase capacity (nørgaard2001functionaldifferencesin pages 2-2).
* A biochemical study concludes that “wild-type Eug1p is a poor isomerase” and that wild-type Eug1p has only a small signal in an insulin reduction assay and does not improve oxidative refolding of proCPY under the tested conditions (nørgaard2001mutationofyeast pages 4-6).
* A comparative analysis reports that isomerase activities of yeast PDI-family proteins including Eug1p were “extremely low,” while also indicating that (except for Mpd1p) PDI-family proteins retain chaperone activity (kimura2004functionaldifferencesbetween pages 1-2).
In contrast to weak oxidoreductase activity, an ER-quality-control role via binding/anti-aggregation (chaperone-like) function is supported by in vitro chaperone metrics: Eug1p exhibited measurable chaperone activity with a reported parameter KD = 4.21×10^-4 M in the referenced assay context (vala2008characterizationoferv2p pages 58-61).
A key mechanistic demonstration is that converting Eug1p active sites from CXXS → CXXC greatly increases PDI-like function:
* Mutation of Eug1p CXXS active sites to CXXC caused a “dramatic increase” in PDI activity; the engineered form gained oxidase/isomerase activity on proCPY-related substrates (including a GS-proCPY assay where wild-type Eug1p showed no activity) (nørgaard2001mutationofyeast pages 6-6).
* Quantitatively, the engineered Eug1pCXXC-CXXC reached approximately 30–50% of native yeast Pdi1p activity in the study’s assays (nørgaard2001mutationofyeast pages 6-6).
* In proCPY refolding kinetics, the authors reported proCPY has 11 free thiols when fully reduced, decreasing rapidly with a plateau around 1.5–2 thiols per proCPY after ~20–30 minutes; wild-type Eug1p did not affect the refolding rate/yield under those test conditions, while CXXC mutants shortened the lag phase and enhanced folding (nørgaard2001mutationofyeast pages 4-6).
Collectively, these results support the interpretation that Eug1p’s primary physiological contribution is likely not bulk oxidation, and that its atypical active sites may tune it toward noncanonical roles (e.g., assisting folding via binding or specialized redox tasks) rather than being a major disulfide oxidase (nørgaard2001mutationofyeast pages 4-6, nørgaard2001functionaldifferencesin pages 2-2).
Eug1p is described as an ER-resident glycoprotein with an N-terminal signal sequence and a C-terminal HDEL ER retention signal, consistent with ER luminal residency (vala2008characterizationoferv2p pages 58-61). This matches broader genetic/functional categorization of EUG1 as one of the yeast ER PDI-family homologues (xiao2004thecontributionsof pages 2-2).
Expression of PDI1 and ER PDI homologues is described as regulated by the unfolded protein response (UPR), and PDI homologues can be upregulated when PDI activity is defective—placing EUG1 within ER stress adaptation/proteostasis circuits (xiao2004thecontributionsof pages 5-7). Functional overlap among ER PDI-family members is also supported by the ability of ER homologues (including EUG1) to rescue a pdi1 mutation when overexpressed (xiao2004thecontributionsof pages 2-2).
In yeast, PDI1 is essential, while EUG1 is nonessential under standard growth conditions (nørgaard2001functionaldifferencesin pages 1-2, vala2008characterizationoferv2p pages 58-61). Nonetheless, EUG1 can participate in partial compensation:
* Overexpressed homologues (EUG1/MPD1/MPD2) can restore viability to a pdi1-deleted strain, but such suppression often requires low endogenous levels of other homologues and is not fully interchangeable (nørgaard2001functionaldifferencesin pages 1-2).
* Specifically, suppression of pdi1 deletion by EUG1 requires endogenous homologues with CXXC motifs, consistent with Eug1p’s inability to provide oxidation alone (nørgaard2001functionaldifferencesin pages 1-2).
Across multiple studies, the folding/maturation of secretory cargo is a sensitive readout of PDI-family function:
* In vivo, CPY maturation can become “extremely slow” in backgrounds lacking supportive PDI-homologue activity under certain conditions (xiao2004thecontributionsof pages 5-7).
* A retrieved figure/table from Xiao et al. (2004) provides pulse–chase evidence and half-time quantification for CPY maturation across mutant backgrounds that alter PDI-family capacity (xiao2004thecontributionsof media f566842d, xiao2004thecontributionsof media a580a63e).
* In another report, cells lacking EUG1 were viable but showed a slight vacuolar sorting defect for soluble vacuolar proteins including CPY; overexpression of EUG1 in a pdi1Δ strain permitted growth but did not correct proCPY accumulation, implying incomplete functional overlap with Pdi1p (vala2008characterizationoferv2p pages 58-61).
Despite strong effects on folding and glycan modification in multiple deletion combinations, one study reports no significant effects on ER-associated degradation (ERAD) across the PDI-deleted strains tested, suggesting that (in that experimental space) PDI-family contributions are more critical for productive folding than for bulk ERAD flux (nørgaard2001functionaldifferencesin pages 1-2).
Beyond secretion/folding readouts:
* Deletion of EUG1 was associated with a reported ~13% decrease in replicative lifespan in one study that surveyed thiol oxidoreductases (hacioglu2010therolesof pages 3-4).
In vitro binding evidence supports interaction between Eug1p and other ER PDI-like proteins:
* Eug1p binds Eps1p with reported KD = 6.06×10^-6 M (vala2008characterizationoferv2p pages 58-61).
* Functional cooperation was suggested by an observation that mixtures of Eps1p + Eug1p enhanced reductive activity in the cited assay context (reported as 122% in the excerpt) (vala2008characterizationoferv2p pages 58-61).
A 2024 bioRxiv preprint introduces YST-PPI, an in situ ER-resident PPI mapping approach using split-fast TEV protease, ER retention signals, and a surface-display cleavage readout quantified by flow cytometry (fan2024characterizinginteractionsof pages 1-4, fan2024characterizinginteractionsof pages 13-17). The authors tested 15 ER resident proteins (including Eug1p) and report a network with >74 interacting pairs above a >10% normalized interaction score threshold, with overall score ranges roughly 1–93% (fan2024characterizinginteractionsof pages 1-4, fan2024characterizinginteractionsof pages 7-10).
Within the subset of interactions validated against BioGRID/STRING, the study lists multiple Eug1p interaction partners, including Sil1p, Yos9p, Scj1p, Cpr5p, Mpd1p, Mpd2p, Kre5p, and interactions among PDI-family members (e.g., Pdi1p–Eug1p) (fan2024characterizinginteractionsof pages 10-13). A specifically mentioned Eug1p interaction score example is Eug1p–Scj1p = 5% (fan2024characterizinginteractionsof pages 10-13). This 2024 dataset contributes an updated view of Eug1p’s ER interaction neighborhood, though it is preprint (not yet peer reviewed) and provides limited mechanistic detail per edge in the extracted snippets (fan2024characterizinginteractionsof pages 10-13).
Direct “EUG1-specific” engineering examples were limited in the retrieved evidence. However, authoritative yeast biomanufacturing literature strongly supports manipulating ER folding and disulfide-handling capacity (PDI/chaperones/oxidases) as a practical strategy to improve recombinant secretion in S. cerevisiae—a context in which EUG1 is part of the endogenous ER folding-factor repertoire.
A highly cited review on metabolic engineering of secretion reports:
* Overexpression of ER chaperones and folding catalysts such as Kar2p and PDI often improves secretion of heterologous proteins, and Kar2p/PDI cooperativity can increase secretion for some clients (e.g., scFv and β-glucosidase examples described) (hou2012metabolicengineeringof pages 10-11).
* Maintaining/engineering disulfide bonds can substantially affect yields: removal of IGF1 cysteines reduced expression by about one-third, and loss of a core disulfide in CD47 reduced expression level and affinity by ~30% (hou2012metabolicengineeringof pages 9-10).
* Broader strain and pathway engineering (including screens connected to ER oxidation/folding machinery) can yield large improvements, including reported ~15-fold and up to ~70-fold secretion improvements in selected/engineered contexts (hou2012metabolicengineeringof pages 11-12).
These real-world findings imply that, while Pdi1p is the primary essential ER oxidoreductase, the broader PDI-family system (including homologues like Eug1p that may contribute binding/isomerase-like capacity or specialized functions) is a relevant target space when tuning ER proteostasis for production (hou2012metabolicengineeringof pages 10-11, xiao2004thecontributionsof pages 2-2).
The strongest, most Eug1p-specific mechanistic conclusion supported by the retrieved literature is:
* Wild-type Eug1p is an ER luminal PDI-family protein whose unusual CXXS active sites severely limit classical PDI oxidase/isomerase activity, and therefore Eug1p is unlikely to be a major provider of oxidizing equivalents for bulk disulfide formation in yeast (nørgaard2001functionaldifferencesin pages 2-2, nørgaard2001mutationofyeast pages 4-6).
* Eug1p instead appears to contribute through auxiliary ER folding functions, potentially including substrate binding/chaperone activity and/or specialized redox roles that do not require a canonical CXXC active site, consistent with measurable chaperone activity and weak oxidoreductase activity (vala2008characterizationoferv2p pages 58-61, kimura2004functionaldifferencesbetween pages 1-2).
* The fact that CXXS→CXXC engineering converts Eug1p into a much more active PDI strongly argues that Eug1p’s native motif is a functional “design choice” rather than an annotation artifact, and that its physiological role may be tuned away from strong oxidase chemistry (nørgaard2001mutationofyeast pages 6-6, nørgaard2001mutationofyeast pages 4-6).
EUG1 is embedded in ER proteostasis through UPR co-regulation with other PDI homologues (xiao2004thecontributionsof pages 5-7), genetic redundancy/conditional suppression behavior with other PDI homologues (nørgaard2001functionaldifferencesin pages 1-2), and a growing interaction network that includes ER chaperones/cochaperones and quality-control proteins (e.g., Sil1p, Yos9p, Scj1p) observed in the 2024 YST-PPI mapping (fan2024characterizinginteractionsof pages 10-13, fan2024characterizinginteractionsof pages 1-4). This supports the view that Eug1p’s contribution may be best interpreted at the level of ER network function rather than a single high-turnover enzymatic role.
The retrieval yielded one clear 2024 Eug1p-relevant source (Fan et al., 2024 bioRxiv) that contributes novel interaction mapping methodology and an ER PPI neighborhood including Eug1p (fan2024characterizinginteractionsof pages 10-13, fan2024characterizinginteractionsof pages 1-4). However, peer-reviewed 2023–2024 Eug1p-specific primary literature was not retrieved in this run, so “latest research” emphasis is necessarily weighted toward (i) foundational functional genetics/biochemistry (2001–2004), (ii) mechanistic review context (2015), and (iii) a 2024 preprint for interaction mapping (nørgaard2001functionaldifferencesin pages 1-2, nørgaard2001mutationofyeast pages 4-6, suzuki2015redoxdiversityin pages 1-2, fan2024characterizinginteractionsof pages 10-13).
| Category | Key finding for EUG1 / Eug1p | Quantitative details | Key source(s) |
|---|---|---|---|
| Identity | Saccharomyces cerevisiae EUG1 (YDR518W; UniProt P32474) encodes an ER-resident protein disulfide-isomerase family member / thioredoxin-domain oxidoreductase homologous to Pdi1p. It is one of four nonessential PDI1 homologues in the yeast ER: MPD1, MPD2, EUG1, EPS1. (xiao2004thecontributionsof pages 1-2, xiao2004thecontributionsof pages 2-2, nørgaard2001functionaldifferencesin pages 2-2) | ~40% sequence identity to Pdi1p reported. (nørgaard2001functionaldifferencesin pages 2-2) | Nørgaard et al., 2001, J Cell Biol 152:553-562, https://doi.org/10.1083/jcb.152.3.553 (nørgaard2001functionaldifferencesin pages 2-2, nørgaard2001functionaldifferencesin pages 1-2); Xiao et al., 2004, J Biol Chem 279:49780-49786, https://doi.org/10.1074/jbc.m409210200 (xiao2004thecontributionsof pages 1-2, xiao2004thecontributionsof pages 2-2) |
| Domain architecture / motifs | Eug1p contains two thioredoxin-like domains and two non-canonical active sites of the CXXS type rather than canonical PDI CXXC/CGHC motifs. Residue positions reported for the two CxxS motifs are 62 and 405. (beynonjones2006mutationalanalysisof pages 1-2, nørgaard2001functionaldifferencesin pages 2-2, hacioglu2010therolesof pages 3-4) | Active-site positions: CxxS at aa 62 and 405. (hacioglu2010therolesof pages 3-4) | Nørgaard et al., 2001, J Cell Biol, https://doi.org/10.1083/jcb.152.3.553 (nørgaard2001functionaldifferencesin pages 2-2, nørgaard2001functionaldifferencesin pages 1-2); Beynon-Jones et al., 2006, FEBS Lett 580:1897-1902, https://doi.org/10.1016/j.febslet.2006.02.055 (beynonjones2006mutationalanalysisof pages 1-2); Hacioglu et al., 2010, Mech Ageing Dev 131:692-699, https://doi.org/10.1016/j.mad.2010.09.006 (hacioglu2010therolesof pages 3-4) |
| Localization / ER retention | Eug1p is reported as an ER-resident glycoprotein with an N-terminal signal sequence and a C-terminal HDEL ER-retention signal; broader literature also consistently places EUG1 among yeast ER PDI-family proteins. (vala2008characterizationoferv2p pages 58-61, xiao2004thecontributionsof pages 1-2, suzuki2015redoxdiversityin pages 1-2) | Length reported as 517 aa. (vala2008characterizationoferv2p pages 58-61) | Vala, 2008, thesis/dissertation excerpt (vala2008characterizationoferv2p pages 58-61); Xiao et al., 2004, J Biol Chem, https://doi.org/10.1074/jbc.m409210200 (xiao2004thecontributionsof pages 1-2); Suzuki & Schmitt, 2015, Biol Chem 396:539-554, https://doi.org/10.1515/hsz-2014-0299 (suzuki2015redoxdiversityin pages 1-2) |
| Primary biochemical role | Current evidence supports Eug1p primarily as a folding assistant / isomerase-like and chaperone-like ER factor, not a strong oxidase. Because its active sites are CXXS, Eug1p alone is considered unable or poorly able to transfer oxidizing equivalents efficiently compared with canonical CXXC PDIs. (nørgaard2001functionaldifferencesin pages 2-2, nørgaard2001mutationofyeast pages 4-6, kimura2004functionaldifferencesbetween pages 1-2) | Wild-type Eug1p described as having very low oxidative/refolding activity and extremely low isomerase activity; chaperone activity is detectable. (vala2008characterizationoferv2p pages 58-61, kimura2004functionaldifferencesbetween pages 1-2) | Nørgaard & Winther, 2001, Biochem J 358:269-274, https://doi.org/10.1042/bj3580269 (nørgaard2001mutationofyeast pages 4-6); Kimura et al., 2004, BBRC 320:359-365, https://doi.org/10.1016/j.bbrc.2004.05.178 (kimura2004functionaldifferencesbetween pages 1-2) |
| Oxidase / oxidative folding activity | Wild-type Eug1p has very low oxidative refolding activity relative to Pdi1p. Overexpression can support growth in some pdi1Δ backgrounds, but this does not restore full Pdi1p-like oxidative folding capacity. (vala2008characterizationoferv2p pages 58-61, nørgaard2001functionaldifferencesin pages 2-2, nørgaard2001functionaldifferencesin pages 1-2) | Oxidative refolding activity reported as 2.16% of Pdi1p in a lysozyme assay. (vala2008characterizationoferv2p pages 58-61) | Vala, 2008 excerpt (vala2008characterizationoferv2p pages 58-61); Nørgaard et al., 2001, J Cell Biol, https://doi.org/10.1083/jcb.152.3.553 (nørgaard2001functionaldifferencesin pages 2-2, nørgaard2001functionaldifferencesin pages 1-2) |
| Reductase / isomerase activity | Wild-type Eug1p shows only a small but significant insulin-reduction signal and is described as a poor isomerase; on some substrates it shows essentially no detectable isomerase activity. (nørgaard2001mutationofyeast pages 4-6, kimura2004functionaldifferencesbetween pages 1-2) | Wild-type Eug1p had no activity on GS-proCPY in the cited assay; isomerase activities of Mpd1p, Mpd2p, and Eug1p were described as extremely low. (nørgaard2001mutationofyeast pages 6-6, kimura2004functionaldifferencesbetween pages 1-2) | Nørgaard & Winther, 2001, Biochem J, https://doi.org/10.1042/bj3580269 (nørgaard2001mutationofyeast pages 6-6, nørgaard2001mutationofyeast pages 4-6); Kimura et al., 2004, BBRC, https://doi.org/10.1016/j.bbrc.2004.05.178 (kimura2004functionaldifferencesbetween pages 1-2) |
| Chaperone activity | Eug1p has experimentally supported chaperone activity despite weak oxidoreductase function, consistent with a role in assisting ER protein folding/quality control. (vala2008characterizationoferv2p pages 58-61, kimura2004functionaldifferencesbetween pages 1-2, hacioglu2010therolesof pages 3-4) | Mastoparan/rhodanase-related binding/activity parameter reported as KD = 4.21×10^-4 M; broader comparison paper states Eug1p retained chaperone activity while Mpd1p did not. (vala2008characterizationoferv2p pages 58-61, kimura2004functionaldifferencesbetween pages 1-2) | Vala, 2008 excerpt (vala2008characterizationoferv2p pages 58-61); Kimura et al., 2004, BBRC, https://doi.org/10.1016/j.bbrc.2004.05.178 (kimura2004functionaldifferencesbetween pages 1-2); Hacioglu et al., 2010, Mech Ageing Dev, https://doi.org/10.1016/j.mad.2010.09.006 (hacioglu2010therolesof pages 3-4) |
| Active-site engineering evidence | Converting Eug1p active sites from CXXS to CXXC dramatically increases PDI-like activity, showing that the native CXXS motif is a major determinant of Eug1p’s weak oxidase/isomerase behavior. (nørgaard2001mutationofyeast pages 6-6, nørgaard2001mutationofyeast pages 4-6, beynonjones2006mutationalanalysisof pages 1-2) | EUG1CXXC-CXXC reached roughly 30–50% of native yeast PDI activity and could complement backgrounds lacking auxiliary PDI-like proteins better than wild-type EUG1. (nørgaard2001mutationofyeast pages 6-6) | Nørgaard & Winther, 2001, Biochem J, https://doi.org/10.1042/bj3580269 (nørgaard2001mutationofyeast pages 6-6, nørgaard2001mutationofyeast pages 4-6); Beynon-Jones et al., 2006, FEBS Lett, https://doi.org/10.1016/j.febslet.2006.02.055 (beynonjones2006mutationalanalysisof pages 1-2) |
| Genetic redundancy with PDI family | EUG1 is nonessential individually. Overexpressed EUG1 can help restore viability to pdi1Δ strains, but this depends on the presence of endogenous homologues with CXXC motifs; thus PDI-family homologues are not functionally interchangeable. Mpd1p is the only homologue reported to carry out all essential Pdi1p functions. (xiao2004thecontributionsof pages 2-2, nørgaard2001functionaldifferencesin pages 2-2, nørgaard2001functionaldifferencesin pages 1-2) | Overexpression of EUG1, MPD1, or MPD2 did not fully complement pdi1Δ; EUG1 suppression required endogenous CXXC-containing homologues. (nørgaard2001functionaldifferencesin pages 2-2, nørgaard2001functionaldifferencesin pages 1-2) | Nørgaard et al., 2001, J Cell Biol, https://doi.org/10.1083/jcb.152.3.553 (nørgaard2001functionaldifferencesin pages 2-2, nørgaard2001functionaldifferencesin pages 1-2); Xiao et al., 2004, J Biol Chem, https://doi.org/10.1074/jbc.m409210200 (xiao2004thecontributionsof pages 2-2) |
| CPY folding / maturation phenotype | Loss of PDI-family support leads to slower carboxypeptidase Y (CPY/proCPY) folding and maturation. EUG1 overexpression permits growth in some contexts but does not fully rescue proCPY accumulation, supporting partial rather than full functional overlap with Pdi1p. (vala2008characterizationoferv2p pages 58-61, xiao2004thecontributionsof pages 5-7, xiao2004thecontributionsof media f566842d) | Xiao et al. Figure 5 quantified half-times for CPY maturation across mutant backgrounds; text states CPY maturation becomes extremely slow when homologues are absent and only a weak Pdi1p isomerase variant is present. Vala excerpt states EUG1 overexpression did not correct proCPY accumulation. (xiao2004thecontributionsof pages 5-7, xiao2004thecontributionsof media f566842d, vala2008characterizationoferv2p pages 58-61) | Xiao et al., 2004, J Biol Chem, https://doi.org/10.1074/jbc.m409210200 (xiao2004thecontributionsof pages 5-7, xiao2004thecontributionsof media f566842d); Vala, 2008 excerpt (vala2008characterizationoferv2p pages 58-61) |
| ERAD phenotype | Across multiple PDI deletion combinations, there were no significant effects on ER-associated degradation (ERAD), suggesting EUG1/PDI-family contributions are more critical for folding/isomerization than for ERAD in the tested contexts. (nørgaard2001functionaldifferencesin pages 1-2) | Qualitative: no significant ERAD effect reported. (nørgaard2001functionaldifferencesin pages 1-2) | Nørgaard et al., 2001, J Cell Biol, https://doi.org/10.1083/jcb.152.3.553 (nørgaard2001functionaldifferencesin pages 1-2) |
| Other phenotypes | Deleting EUG1 causes no gross growth defect under standard conditions, but one study reported a slight vacuolar protein sorting defect and another linked loss of EUG1 to reduced replicative lifespan. (vala2008characterizationoferv2p pages 58-61, hacioglu2010therolesof pages 3-4) | Replicative lifespan reduction of about 13% in eug1Δ cells; slight CPY/proteinase A sorting defect noted. (hacioglu2010therolesof pages 3-4, vala2008characterizationoferv2p pages 58-61) | Hacioglu et al., 2010, Mech Ageing Dev, https://doi.org/10.1016/j.mad.2010.09.006 (hacioglu2010therolesof pages 3-4); Vala, 2008 excerpt (vala2008characterizationoferv2p pages 58-61) |
| Interaction partners: classical biochemical evidence | Eug1p interacts in vitro with Eps1p; functional cooperation among PDI-family proteins has been proposed. (vala2008characterizationoferv2p pages 58-61) | Eug1p–Eps1p KD = 6.06×10^-6 M; Eps1p also binds Pdi1p (7.33×10^-6 M), Mpd1p (3.88×10^-6 M), Kar2p (1.03×10^-6 M), and Cne1p (1.38×10^-5 M). Mixtures of Eps1p + Eug1p showed enhanced reductive activity (122% vs. 0% or 100% for individual proteins, as reported in the excerpt). (vala2008characterizationoferv2p pages 58-61) | Vala, 2008 excerpt (vala2008characterizationoferv2p pages 58-61) |
| Interaction partners: recent 2024 ER-PPI mapping | A 2024 YST-PPI preprint mapped ER-resident interactions in situ and included Eug1p among tested proteins. Reported/validated Eug1p partners included Pdi1p, Sil1p, Yos9p, Scj1p, Cpr5p, Mpd1p, Mpd2p, Kre5p. (fan2024characterizinginteractionsof pages 10-13, fan2024characterizinginteractionsof pages 7-10, fan2024characterizinginteractionsof pages 1-4) | Pairwise scores in the study ranged roughly 1–93% overall; specific values mentioned for Eug1p-related examples include Eug1p–Scj1p = 5%. A validated network of >74 interacting pairs above a >10% cutoff was reported. (fan2024characterizinginteractionsof pages 10-13, fan2024characterizinginteractionsof pages 7-10, fan2024characterizinginteractionsof pages 1-4) | Fan et al., 2024, bioRxiv preprint, published May 2024, https://doi.org/10.1101/2024.05.21.594841 (fan2024characterizinginteractionsof pages 10-13, fan2024characterizinginteractionsof pages 7-10, fan2024characterizinginteractionsof pages 1-4) |
| Interaction-mapping methodology (recent) | YST-PPI measures interactions in situ in the yeast ER using split-TEV / split-fast TEV, ER retention signals, a cleavable surface-display substrate, and flow cytometry readout. This is relevant because Eug1p is an ER lumenal protein whose interactions may be missed by nucleus-based assays. (fan2024characterizinginteractionsof pages 10-13, fan2024characterizinginteractionsof pages 13-17, fan2024characterizinginteractionsof pages 1-4) | Study tested 15 ER resident proteins; reported 91 pairs above negative-control threshold and 74 pairs >10% normalized interaction score. Positive control reached 96%; negative control ~4%. (fan2024characterizinginteractionsof pages 7-10, fan2024characterizinginteractionsof pages 1-4) | Fan et al., 2024, bioRxiv, https://doi.org/10.1101/2024.05.21.594841 (fan2024characterizinginteractionsof pages 10-13, fan2024characterizinginteractionsof pages 7-10, fan2024characterizinginteractionsof pages 13-17, fan2024characterizinginteractionsof pages 1-4) |
| UPR / expression regulation | PDI1 and its ER homologues, including EUG1, are reported to be regulated by the unfolded protein response (UPR) and can be upregulated when PDI activity is defective, placing Eug1p within the ER proteostasis/stress-response network. (xiao2004thecontributionsof pages 5-7) | Qualitative induction/upregulation under ER folding stress. (xiao2004thecontributionsof pages 5-7) | Xiao et al., 2004, J Biol Chem, https://doi.org/10.1074/jbc.m409210200 (xiao2004thecontributionsof pages 5-7) |
Table: This table summarizes identity, biochemical function, localization, genetics, phenotypes, and interaction evidence for Saccharomyces cerevisiae EUG1/Eug1p using only evidence retrieved in the conversation. It is useful as a compact evidence map linking each major claim to specific context IDs and source citations.
Xiao et al. (2004) Table I and Figure 5 provide visual evidence for growth phenotypes across PDI-family deletion backgrounds and CPY maturation pulse–chase/half-time quantification (xiao2004thecontributionsof media f566842d, xiao2004thecontributionsof media a580a63e).
References
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(xiao2004thecontributionsof pages 2-2): Ruoyu Xiao, Bonney Wilkinson, Anton Solovyov, Jakob R. Winther, Arne Holmgren, Johanna Lundström-Ljung, and Hiram F. Gilbert. The contributions of protein disulfide isomerase and its homologues to oxidative protein folding in the yeast endoplasmic reticulum*. Journal of Biological Chemistry, 279:49780-49786, Nov 2004. URL: https://doi.org/10.1074/jbc.m409210200, doi:10.1074/jbc.m409210200. This article has 87 citations and is from a domain leading peer-reviewed journal.
(nørgaard2001functionaldifferencesin pages 2-2): Per Nørgaard, Vibeke Westphal, Christine Tachibana, Lene Alsøe, Bjørn Holst, and Jakob R. Winther. Functional differences in yeast protein disulfide isomerases. The Journal of Cell Biology, 152:553-562, Feb 2001. URL: https://doi.org/10.1083/jcb.152.3.553, doi:10.1083/jcb.152.3.553. This article has 171 citations.
(beynonjones2006mutationalanalysisof pages 1-2): Siân M. Beynon-Jones, Antony N. Antoniou, and Simon J. Powis. Mutational analysis of the oxidoreductase erp57 reveals the importance of the two central residues in the redox motif. FEBS Letters, 580:1897-1902, Mar 2006. URL: https://doi.org/10.1016/j.febslet.2006.02.055, doi:10.1016/j.febslet.2006.02.055. This article has 14 citations and is from a peer-reviewed journal.
(nørgaard2001functionaldifferencesin pages 1-2): Per Nørgaard, Vibeke Westphal, Christine Tachibana, Lene Alsøe, Bjørn Holst, and Jakob R. Winther. Functional differences in yeast protein disulfide isomerases. The Journal of Cell Biology, 152:553-562, Feb 2001. URL: https://doi.org/10.1083/jcb.152.3.553, doi:10.1083/jcb.152.3.553. This article has 171 citations.
(hacioglu2010therolesof pages 3-4): Elise Hacioglu, Isil Esmer, Dmitri E. Fomenko, Vadim N. Gladyshev, and Ahmet Koc. The roles of thiol oxidoreductases in yeast replicative aging. Mechanisms of Ageing and Development, 131:692-699, Nov 2010. URL: https://doi.org/10.1016/j.mad.2010.09.006, doi:10.1016/j.mad.2010.09.006. This article has 15 citations and is from a peer-reviewed journal.
(xiao2004thecontributionsof pages 5-7): Ruoyu Xiao, Bonney Wilkinson, Anton Solovyov, Jakob R. Winther, Arne Holmgren, Johanna Lundström-Ljung, and Hiram F. Gilbert. The contributions of protein disulfide isomerase and its homologues to oxidative protein folding in the yeast endoplasmic reticulum*. Journal of Biological Chemistry, 279:49780-49786, Nov 2004. URL: https://doi.org/10.1074/jbc.m409210200, doi:10.1074/jbc.m409210200. This article has 87 citations and is from a domain leading peer-reviewed journal.
(xiao2004thecontributionsof media f566842d): Ruoyu Xiao, Bonney Wilkinson, Anton Solovyov, Jakob R. Winther, Arne Holmgren, Johanna Lundström-Ljung, and Hiram F. Gilbert. The contributions of protein disulfide isomerase and its homologues to oxidative protein folding in the yeast endoplasmic reticulum*. Journal of Biological Chemistry, 279:49780-49786, Nov 2004. URL: https://doi.org/10.1074/jbc.m409210200, doi:10.1074/jbc.m409210200. This article has 87 citations and is from a domain leading peer-reviewed journal.
(nørgaard2001mutationofyeast pages 6-6): Per NØRGAARD and Jakob R. WINTHER. Mutation of yeast eug1p cxxs active sites to cxxc results in a dramatic increase in protein disulphide isomerase activity. The Biochemical journal, 358 Pt 1:269-74, Aug 2001. URL: https://doi.org/10.1042/bj3580269, doi:10.1042/bj3580269. This article has 47 citations.
(nørgaard2001mutationofyeast pages 4-6): Per NØRGAARD and Jakob R. WINTHER. Mutation of yeast eug1p cxxs active sites to cxxc results in a dramatic increase in protein disulphide isomerase activity. The Biochemical journal, 358 Pt 1:269-74, Aug 2001. URL: https://doi.org/10.1042/bj3580269, doi:10.1042/bj3580269. This article has 47 citations.
(kimura2004functionaldifferencesbetween pages 1-2): Taiji Kimura, Yasuhiro Hosoda, Yukiko Kitamura, Hideshi Nakamura, Tomohisa Horibe, and Masakazu Kikuchi. Functional differences between human and yeast protein disulfide isomerase family proteins. Biochemical and biophysical research communications, 320 2:359-65, Jul 2004. URL: https://doi.org/10.1016/j.bbrc.2004.05.178, doi:10.1016/j.bbrc.2004.05.178. This article has 30 citations and is from a peer-reviewed journal.
(vala2008characterizationoferv2p pages 58-61): ALL Vala. Characterization of erv2p and pdi1p, two thiol oxidoreductases involved in protein disulfide bond formation in the endoplasmic reticulum of saccharomyces cerevisiae. Unknown journal, 2008.
(xiao2004thecontributionsof media a580a63e): Ruoyu Xiao, Bonney Wilkinson, Anton Solovyov, Jakob R. Winther, Arne Holmgren, Johanna Lundström-Ljung, and Hiram F. Gilbert. The contributions of protein disulfide isomerase and its homologues to oxidative protein folding in the yeast endoplasmic reticulum*. Journal of Biological Chemistry, 279:49780-49786, Nov 2004. URL: https://doi.org/10.1074/jbc.m409210200, doi:10.1074/jbc.m409210200. This article has 87 citations and is from a domain leading peer-reviewed journal.
(fan2024characterizinginteractionsof pages 1-4): Xian Fan, Huahua He, Ting Wang, Pan Xu, Faying Zhang, Shantong Hu, Yueli Yun, Meng Mei, Guimin Zhang, and Li Yi. Characterizing interactions of er resident proteins in situ through the yst-ppi method. bioRxiv, May 2024. URL: https://doi.org/10.1101/2024.05.21.594841, doi:10.1101/2024.05.21.594841. This article has 0 citations.
(fan2024characterizinginteractionsof pages 13-17): Xian Fan, Huahua He, Ting Wang, Pan Xu, Faying Zhang, Shantong Hu, Yueli Yun, Meng Mei, Guimin Zhang, and Li Yi. Characterizing interactions of er resident proteins in situ through the yst-ppi method. bioRxiv, May 2024. URL: https://doi.org/10.1101/2024.05.21.594841, doi:10.1101/2024.05.21.594841. This article has 0 citations.
(fan2024characterizinginteractionsof pages 7-10): Xian Fan, Huahua He, Ting Wang, Pan Xu, Faying Zhang, Shantong Hu, Yueli Yun, Meng Mei, Guimin Zhang, and Li Yi. Characterizing interactions of er resident proteins in situ through the yst-ppi method. bioRxiv, May 2024. URL: https://doi.org/10.1101/2024.05.21.594841, doi:10.1101/2024.05.21.594841. This article has 0 citations.
(fan2024characterizinginteractionsof pages 10-13): Xian Fan, Huahua He, Ting Wang, Pan Xu, Faying Zhang, Shantong Hu, Yueli Yun, Meng Mei, Guimin Zhang, and Li Yi. Characterizing interactions of er resident proteins in situ through the yst-ppi method. bioRxiv, May 2024. URL: https://doi.org/10.1101/2024.05.21.594841, doi:10.1101/2024.05.21.594841. This article has 0 citations.
(hou2012metabolicengineeringof pages 10-11): Jin Hou, Keith E.J. Tyo, Zihe Liu, Dina Petranovic, and Jens Nielsen. Metabolic engineering of recombinant protein secretion by saccharomyces cerevisiae. FEMS yeast research, 12 5:491-510, Aug 2012. URL: https://doi.org/10.1111/j.1567-1364.2012.00810.x, doi:10.1111/j.1567-1364.2012.00810.x. This article has 292 citations and is from a peer-reviewed journal.
(hou2012metabolicengineeringof pages 9-10): Jin Hou, Keith E.J. Tyo, Zihe Liu, Dina Petranovic, and Jens Nielsen. Metabolic engineering of recombinant protein secretion by saccharomyces cerevisiae. FEMS yeast research, 12 5:491-510, Aug 2012. URL: https://doi.org/10.1111/j.1567-1364.2012.00810.x, doi:10.1111/j.1567-1364.2012.00810.x. This article has 292 citations and is from a peer-reviewed journal.
(hou2012metabolicengineeringof pages 11-12): Jin Hou, Keith E.J. Tyo, Zihe Liu, Dina Petranovic, and Jens Nielsen. Metabolic engineering of recombinant protein secretion by saccharomyces cerevisiae. FEMS yeast research, 12 5:491-510, Aug 2012. URL: https://doi.org/10.1111/j.1567-1364.2012.00810.x, doi:10.1111/j.1567-1364.2012.00810.x. This article has 292 citations and is from a peer-reviewed journal.
(xiao2004thecontributionsof pages 1-2): Ruoyu Xiao, Bonney Wilkinson, Anton Solovyov, Jakob R. Winther, Arne Holmgren, Johanna Lundström-Ljung, and Hiram F. Gilbert. The contributions of protein disulfide isomerase and its homologues to oxidative protein folding in the yeast endoplasmic reticulum*. Journal of Biological Chemistry, 279:49780-49786, Nov 2004. URL: https://doi.org/10.1074/jbc.m409210200, doi:10.1074/jbc.m409210200. This article has 87 citations and is from a domain leading peer-reviewed journal.
id: P32474
gene_symbol: EUG1
product_type: PROTEIN
status: COMPLETE
taxon:
id: NCBITaxon:559292
label: Saccharomyces cerevisiae
description: >-
EUG1 encodes a nonessential endoplasmic-reticulum protein disulfide isomerase
family member with thioredoxin-like domains and atypical CXXS active-site
motifs. Evidence supports an auxiliary ER protein-folding and quality-control
role: wild-type Eug1p has weak classical oxidoreductase/isomerase activity,
measurable chaperone-like activity, ER retention, and functional overlap with
other yeast PDI-family proteins.
existing_annotations:
- term:
id: GO:0005783
label: endoplasmic reticulum
evidence_type: IBA
original_reference_id: GO_REF:0000033
review:
summary: 'Manual review: endoplasmic reticulum is consistent with known biology of EUG1.'
action: ACCEPT
reason: Retained as supported or plausible for this gene and evidence context.
- term:
id: GO:0006457
label: protein folding
evidence_type: IBA
original_reference_id: GO_REF:0000033
review:
summary: 'Manual review: protein folding is consistent with known biology of EUG1.'
action: ACCEPT
reason: Retained as supported or plausible for this gene and evidence context.
- term:
id: GO:0034976
label: response to endoplasmic reticulum stress
evidence_type: IBA
original_reference_id: GO_REF:0000033
review:
summary: 'Manual review: response to endoplasmic reticulum stress is consistent with known biology of EUG1.'
action: ACCEPT
reason: Retained as supported or plausible for this gene and evidence context.
- term:
id: GO:0003756
label: protein disulfide isomerase activity
evidence_type: IBA
original_reference_id: GO_REF:0000033
review:
summary: 'Manual review: protein disulfide isomerase activity is consistent with known biology of EUG1.'
action: ACCEPT
reason: Retained as supported or plausible for this gene and evidence context.
supported_by:
- reference_id: file:yeast/EUG1/EUG1-deep-research-falcon.md
supporting_text: wild-type Eug1p is a weak oxidoreductase/isomerase
- term:
id: GO:0003756
label: protein disulfide isomerase activity
evidence_type: IEA
original_reference_id: GO_REF:0000120
review:
summary: 'Manual review: protein disulfide isomerase activity is consistent with known biology of EUG1.'
action: ACCEPT
reason: Retained as supported or plausible for this gene and evidence context.
- term:
id: GO:0005788
label: endoplasmic reticulum lumen
evidence_type: IEA
original_reference_id: GO_REF:0000044
review:
summary: 'Manual review: endoplasmic reticulum lumen is consistent with known biology of EUG1.'
action: ACCEPT
reason: Retained as supported or plausible for this gene and evidence context.
- term:
id: GO:0006457
label: protein folding
evidence_type: IEA
original_reference_id: GO_REF:0000117
review:
summary: 'Manual review: protein folding is consistent with known biology of EUG1.'
action: ACCEPT
reason: Retained as supported or plausible for this gene and evidence context.
- term:
id: GO:0015035
label: protein-disulfide reductase activity
evidence_type: IEA
original_reference_id: GO_REF:0000117
review:
summary: 'Manual review: protein-disulfide reductase activity is consistent with known biology of EUG1.'
action: ACCEPT
reason: Retained as supported or plausible for this gene and evidence context.
- term:
id: GO:0016853
label: isomerase activity
evidence_type: IEA
original_reference_id: GO_REF:0000043
review:
summary: 'Manual review: isomerase activity is consistent with known biology of EUG1.'
action: ACCEPT
reason: Retained as supported or plausible for this gene and evidence context.
- term:
id: GO:0051082
label: unfolded protein binding
evidence_type: IEA
original_reference_id: GO_REF:0000117
review:
summary: 'Manual review: unfolded protein binding is too generic or over-extended for EUG1.'
action: MARK_AS_OVER_ANNOTATED
reason: Marked over-annotated because more specific terms capture the biology more accurately.
- term:
id: GO:0005515
label: protein binding
evidence_type: IPI
original_reference_id: PMID:27107014
review:
summary: 'Manual review: protein binding is too generic or over-extended for EUG1.'
action: MARK_AS_OVER_ANNOTATED
reason: Marked over-annotated because more specific terms capture the biology more accurately.
- term:
id: GO:0005783
label: endoplasmic reticulum
evidence_type: HDA
original_reference_id: PMID:26928762
review:
summary: 'Manual review: endoplasmic reticulum is consistent with known biology of EUG1.'
action: ACCEPT
reason: Retained as supported or plausible for this gene and evidence context.
- term:
id: GO:0005783
label: endoplasmic reticulum
evidence_type: HDA
original_reference_id: PMID:11914276
review:
summary: 'Manual review: endoplasmic reticulum is consistent with known biology of EUG1.'
action: ACCEPT
reason: Retained as supported or plausible for this gene and evidence context.
- term:
id: GO:0003756
label: protein disulfide isomerase activity
evidence_type: ISS
original_reference_id: PMID:11157982
review:
summary: 'Manual review: protein disulfide isomerase activity is consistent with known biology of EUG1.'
action: ACCEPT
reason: Retained as supported or plausible for this gene and evidence context.
- term:
id: GO:0015035
label: protein-disulfide reductase activity
evidence_type: ISS
original_reference_id: PMID:11157982
review:
summary: 'Manual review: protein-disulfide reductase activity is consistent with known biology of EUG1.'
action: ACCEPT
reason: Retained as supported or plausible for this gene and evidence context.
- term:
id: GO:0005515
label: protein binding
evidence_type: IPI
original_reference_id: PMID:16002399
review:
summary: 'Manual review: protein binding is too generic or over-extended for EUG1.'
action: MARK_AS_OVER_ANNOTATED
reason: Marked over-annotated because more specific terms capture the biology more accurately.
- term:
id: GO:0019153
label: protein-disulfide reductase (glutathione) activity
evidence_type: IDA
original_reference_id: PMID:16002399
review:
summary: 'Manual review: protein-disulfide reductase (glutathione) activity is consistent with known biology of EUG1.'
action: ACCEPT
reason: Retained as supported or plausible for this gene and evidence context.
- term:
id: GO:0051082
label: unfolded protein binding
evidence_type: IDA
original_reference_id: PMID:16002399
review:
summary: 'Manual review: unfolded protein binding is too generic or over-extended for EUG1.'
action: MARK_AS_OVER_ANNOTATED
reason: Marked over-annotated because more specific terms capture the biology more accurately.
- term:
id: GO:0003756
label: protein disulfide isomerase activity
evidence_type: IMP
original_reference_id: PMID:11157982
review:
summary: 'Manual review: protein disulfide isomerase activity is consistent with known biology of EUG1.'
action: ACCEPT
reason: Retained as supported or plausible for this gene and evidence context.
- term:
id: GO:0003756
label: protein disulfide isomerase activity
evidence_type: IGI
original_reference_id: PMID:11157982
review:
summary: 'Manual review: protein disulfide isomerase activity is consistent with known biology of EUG1.'
action: ACCEPT
reason: Retained as supported or plausible for this gene and evidence context.
- term:
id: GO:0003756
label: protein disulfide isomerase activity
evidence_type: IDA
original_reference_id: PMID:16002399
review:
summary: 'Manual review: protein disulfide isomerase activity is consistent with known biology of EUG1.'
action: ACCEPT
reason: Retained as supported or plausible for this gene and evidence context.
- term:
id: GO:0006457
label: protein folding
evidence_type: IGI
original_reference_id: PMID:11157982
review:
summary: 'Manual review: protein folding is consistent with known biology of EUG1.'
action: ACCEPT
reason: Retained as supported or plausible for this gene and evidence context.
- term:
id: GO:0015035
label: protein-disulfide reductase activity
evidence_type: IGI
original_reference_id: PMID:11157982
review:
summary: 'Manual review: protein-disulfide reductase activity is consistent with known biology of EUG1.'
action: ACCEPT
reason: Retained as supported or plausible for this gene and evidence context.
- term:
id: GO:0015035
label: protein-disulfide reductase activity
evidence_type: IDA
original_reference_id: PMID:16002399
review:
summary: 'Manual review: protein-disulfide reductase activity is consistent with known biology of EUG1.'
action: ACCEPT
reason: Retained as supported or plausible for this gene and evidence context.
references:
- id: GO_REF:0000033
title: Annotation inferences using phylogenetic trees
findings: []
- id: GO_REF:0000043
title: Gene Ontology annotation based on UniProtKB/Swiss-Prot keyword mapping
findings: []
- id: GO_REF:0000044
title: Gene Ontology annotation based on UniProtKB/Swiss-Prot Subcellular Location vocabulary mapping, accompanied by conservative changes to GO terms applied by UniProt
findings: []
- id: GO_REF:0000117
title: Electronic Gene Ontology annotations created by ARBA machine learning models
findings: []
- id: GO_REF:0000120
title: Combined Automated Annotation using Multiple IEA Methods
findings: []
- id: PMID:11157982
title: Functional differences in yeast protein disulfide isomerases.
findings: []
- id: PMID:11914276
title: Subcellular localization of the yeast proteome.
findings: []
- id: PMID:16002399
title: Interactions among yeast protein-disulfide isomerase proteins and endoplasmic reticulum chaperone proteins influence their activities.
findings: []
- id: PMID:26928762
title: 'One library to make them all: streamlining the creation of yeast libraries via a SWAp-Tag strategy.'
findings: []
- id: PMID:27107014
title: An inter-species protein-protein interaction network across vast evolutionary distance.
findings: []
- id: file:yeast/EUG1/EUG1-deep-research-falcon.md
title: Falcon deep research report for EUG1
findings: []
core_functions:
- description: >-
Auxiliary ER protein-folding factor in the protein disulfide isomerase
family. Eug1p has atypical CXXS active sites, weak classical oxidoreductase
activity relative to Pdi1p, and contributes to ER folding/proteostasis
through isomerase-like, reductase-like, and chaperone-like activity.
molecular_function:
id: GO:0003756
label: protein disulfide isomerase activity
directly_involved_in:
- id: GO:0006457
label: protein folding
- id: GO:0034976
label: response to endoplasmic reticulum stress
locations:
- id: GO:0005788
label: endoplasmic reticulum lumen
supported_by:
- reference_id: file:yeast/EUG1/EUG1-deep-research-falcon.md
supporting_text: wild-type Eug1p is a weak oxidoreductase/isomerase
proposed_new_terms: []
suggested_questions:
- question: Should EUG1 annotations distinguish weak native oxidoreductase activity from engineered CXXC mutant activity when choosing molecular-function terms?
- question: Are recently reported ER interaction-mapping partners suitable for direct GO protein-binding annotations, or should they remain supporting context?
suggested_experiments:
- description: Compare wild-type Eug1p and CXXC-engineered variants on native ER client substrates under physiological expression levels.
- description: Validate Eug1p ER interaction partners from in situ mapping with reciprocal biochemical assays and client-folding readouts.