ERG2 encodes the S. cerevisiae endoplasmic-reticulum membrane C-8 sterol isomerase, which moves the B-ring double bond of fecosterol from C8-C9 to C7-C8 to form episterol in the late ergosterol biosynthetic pathway. Erg2p is a single-pass ER membrane protein of the fungal ERG2/sigma-1 receptor family, physically associates with the sterol C-14 reductase Erg24p, and is inhibited by morpholine and piperidine fungicides and by sigma ligands.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0000247 C-8 sterol isomerase activity | IBA GO_REF:0000033 | ACCEPT | Summary: Core C-8 sterol isomerase activity propagated from the fungal ERG2 PAINT node. Reason: PTN001280219 is the fungal ERG2 node in PTHR10868 and is seeded by Candida and S. cerevisiae ERG2 activity annotations. The S. cerevisiae target is one of the experimentally grounded descendants, so its presence in the WITH/FROM list is expected and not circular. Propagation Review Root cause: NO FAILURE CORE Sources checked: PANTHER:PTN001280219 SUPPORTS TRANSFER Fungal ERG2 PAINT node carrying C-8 sterol isomerase activity and ergosterol biosynthesis; it supports the inherited yeast ERG2 activity. Supporting Evidence: file:interpro/panther/PTHR10868/PTHR10868-paint.tsv PTHR10868 PTN001280219 GO:0000247 F IBD false CGD:CAL0000177093|SGD:S000004815 taxon:451864 20251127 file:yeast/ERG2/ERG2-uniprot.txt Reaction=fecosterol = episterol; Xref=Rhea:RHEA:33435 |
| GO:0000247 C-8 sterol isomerase activity | IDA DOI:10.1016/S0031-9422(00)80523-3 | ACCEPT | Summary: Direct legacy biochemical evidence supports Erg2p C-8 sterol isomerase activity. Reason: The 1984 Baloch et al. DOI resolves to an inhibitor study of ergosterol biosynthesis in S. cerevisiae and Ustilago maydis and is used by UniProt as direct evidence for the fecosterol-to-episterol ERG2 reaction. The assignment is independently corroborated by direct ERG2 inhibitor-binding experiments and by Rhea. Supporting Evidence: file:yeast/ERG2/ERG2-uniprot.txt Reaction=fecosterol = episterol; Xref=Rhea:RHEA:33435 PMID:8988026 The yeast gene ERG2 encodes a sterol C8-C7 isomerase |
| GO:0000247 C-8 sterol isomerase activity | IEA GO_REF:0000116 | ACCEPT | Summary: Rhea-to-GO transfer captures the same fecosterol-to-episterol reaction as the direct and PAINT activity rows. Reason: UniProt maps S. cerevisiae ERG2 to RHEA:33435, fecosterol = episterol, which is the late pathway double-bond isomerization catalyzed by fungal ERG2 proteins. Supporting Evidence: file:yeast/ERG2/ERG2-uniprot.txt Reaction=fecosterol = episterol; Xref=Rhea:RHEA:33435 |
| GO:0000247 C-8 sterol isomerase activity | IMP PMID:18459942 Identification of essential amino acid residues in a sterol ... | ACCEPT | Summary: Yeast erg2 mutant experiments in a plant 8,7 sterol isomerase study support the native ERG2 activity. Reason: Rahier et al. used a S. cerevisiae erg2 mutant lacking 8,7 sterol isomerase activity as the complementation background for the maize enzyme, and constructed corresponding S. cerevisiae 8,7SI mutants that were assayed by sterol analysis. This directly depends on the assignment of native ERG2 as the yeast C-8 sterol isomerase. Supporting Evidence: PMID:18459942 yeast erg2 mutant lacking 8,7SI activity PMID:18459942 Saccharomyces cerevisiae 8,7SI |
| GO:0005515 protein binding | IPI PMID:16300994 A systematic study of yeast sterol biosynthetic protein-prot... | REMOVE | Summary: Split-ubiquitin assays support an Erg2p-Erg24p interaction, but the bare protein-binding term should be removed as uninformative for ERG2. Reason: Mo and Bard reported that Erg2p and Erg24p appear to interact in an ER sterol-enzyme network, so removing this row is not a claim that the interaction is false. Rather, GO:0005515 conveys only a generic physical association rather than Erg2p's C-8 sterol isomerase function, and the evidence does not support a more specific Erg2p molecular activity. Supporting Evidence: PMID:16300994 Erg24p and Erg2p, two enzymes that are sensitive to morpholine antifungals, appear to interact with one another file:yeast/ERG2/ERG2-uniprot.txt P32352; P32462: ERG24; NbExp=3 |
| GO:0005515 protein binding | IPI PMID:37968396 The social and structural architecture of the yeast protein ... | REMOVE | Summary: The recent affinity-enrichment interaction row corroborates the Erg2p-Erg24p association, but GO:0005515 should be removed as uninformative for ERG2. Reason: Michaelis et al. generated a high-throughput GFP affinity-enrichment mass spectrometry yeast interactome that SGD uses for an Erg2p-Erg24p IPI. This supports a physical association in the sterol-enzyme network, so removing this row is not a claim that the interaction is false. The evidence does not support a distinct catalytic, adaptor, or regulatory molecular activity for Erg2p. Supporting Evidence: PMID:37968396 high-throughput method using highly reproducible affinity enrichment file:yeast/ERG2/ERG2-uniprot.txt P32352; P32462: ERG24; NbExp=3 |
| GO:0005783 endoplasmic reticulum | HDA PMID:26928762 One library to make them all: streamlining the creation of y... | ACCEPT | Summary: SWAp-Tag high-throughput microscopy places Erg2p in the endoplasmic reticulum. Reason: The SWAp-Tag resource created amino-terminal GFP fusions for endomembrane proteins, and SGD curates ERG2 to the ER from this dataset. The row is also consistent with independent C-terminal GFP microscopy and UniProt's curated ER-membrane location. Supporting Evidence: PMID:26928762 all proteins with known or predicted localization to the yeast endomembrane system are tagged file:yeast/ERG2/ERG2-uniprot.txt SUBCELLULAR LOCATION: Endoplasmic reticulum membrane |
| GO:0005783 endoplasmic reticulum | IBA GO_REF:0000033 | ACCEPT | Summary: Broad eukaryotic ERG2/SIGMAR1-family PAINT transfer to the endoplasmic reticulum is valid for yeast ERG2. Reason: PTN001328958 is broader than the fungal ERG2 node and is seeded by animal SIGMAR1 as well as fungal ERG2 entries, but it propagates only the shared endoplasmic-reticulum compartment. The animal-specific Sigma-receptor signaling and postsynaptic-density assertions in PTHR10868 are on separate descendant nodes and do not propagate to this fungal target. Propagation Review Root cause: NO FAILURE CORE Sources checked: PANTHER:PTN001328958 SUPPORTS TRANSFER Eukaryotic ERG2/SIGMAR1-family ER-localization node; the transferred compartment is corroborated by direct yeast ER/ER-membrane localization. Supporting Evidence: file:interpro/panther/PTHR10868/PTHR10868-paint.tsv PTHR10868 PTN001328958 GO:0005783 C IBD false MGI:MGI:1195268|RGD:68364|SGD:S000004815|UniProtKB:Q99720 taxon:2759 20260528 file:yeast/ERG2/ERG2-uniprot.txt SUBCELLULAR LOCATION: Endoplasmic reticulum membrane |
| GO:0005783 endoplasmic reticulum | NAS PMID:21946531 Steroid-transforming enzymes in fungi. | ACCEPT | Summary: The statement-level fungal steroid-enzyme review is consistent with ERG2 functioning in the ER ergosterol pathway. Reason: The NAS row is weaker than direct yeast microscopy, but fungal ergosterol enzymes are reviewed as steroid-transforming enzymes with discussed cellular localization, and the ER assignment agrees with multiple direct and electronic ERG2 rows. Supporting Evidence: PMID:21946531 The substrate specificities of these enzymes, their cellular localisation, their association with protein super-families, and their potential applications are discussed file:yeast/ERG2/ERG2-uniprot.txt SUBCELLULAR LOCATION: Endoplasmic reticulum membrane |
| GO:0005789 endoplasmic reticulum membrane | EXP PMID:15716577 The spatial organization of lipid synthesis in the yeast Sac... | ACCEPT | Summary: C-terminal GFP microscopy places Erg2p in the endoplasmic-reticulum membrane system. Reason: Natter et al. imaged lipid-metabolism proteins at high resolution with C-terminal GFP tags and found that many tagged lipid enzymes localize to the ER. SGD and UniProt use this study for ERG2's ER-membrane localization, which is also the expected site for Erg2p's membrane sterol isomerase reaction. Supporting Evidence: PMID:15716577 The majority of tagged enzymes localized to the endoplasmic reticulum (91) file:yeast/ERG2/ERG2-uniprot.txt SUBCELLULAR LOCATION: Endoplasmic reticulum membrane |
| GO:0005789 endoplasmic reticulum membrane | IEA GO_REF:0000044 | ACCEPT | Summary: UniProt subcellular-location transfer places Erg2p at the endoplasmic reticulum membrane. Reason: UniProt assigns S. cerevisiae Erg2p to the endoplasmic reticulum membrane based on the C-terminal GFP localization study, matching Erg2p's site of action in the late ergosterol pathway. Supporting Evidence: file:yeast/ERG2/ERG2-uniprot.txt SUBCELLULAR LOCATION: Endoplasmic reticulum membrane |
| GO:0005829 cytosol | RCA GO_REF:0000123 | MODIFY | Summary: The imported YeastPathways superpathway incorrectly projects the ERG2 reaction into the cytosol. Reason: YeastPathways_ERGOSTEROL-SYN-PWY-1 correctly connects ERG2/RXN3O-203 to ergosterol biosynthesis, but its imported GO-CAM activity has generic GO:0003674 molecular_function and GO:0005829 cytosol. Direct microscopy, UniProt, PAINT, and the curated SGD Yeast ergosterol GO-CAM all place Erg2p in the ER or ER membrane, so the compartment should be corrected to the ER membrane. Propagation Review Root cause: SOURCE BAD Failure modes: COMPARTMENT OR COMPLEX MISMATCH Sources checked: SGD_PWY:ERGOSTEROL-SYN-PWY-1 SOURCE BAD Imported YeastPathways RXN3O-203 assigns ERG2 to GO:0005829 cytosol; direct localization and the curated Yeast ergosterol GO-CAM place Erg2p in the ER/ER membrane. Proposed replacements: endoplasmic reticulum membrane Supporting Evidence: file:gocams/index.tsv SGD:S000004815 ERG2 Scer YeastPathways_ERGOSTEROL-SYN-PWY-1 superpathway of ergosterol biosynthesis I - imported from: Saccharomyces Genome Database NCBITaxon:559292 gomodel:RXN3O-203 GO:0003674 molecular_function GO:0006696 ergosterol biosynthetic process GO:0005829 cytosol file:gocams/index.tsv SGD:S000004815 ERG2 Scer 61f34dd300001044 Yeast ergosterol NCBITaxon:559292 gomodel:61f34dd300001044/6205c24300000137 GO:0000247 C-8 sterol isomerase activity GO:0006696 ergosterol biosynthetic process GO:0005783 endoplasmic reticulum |
| GO:0005829 cytosol | RCA GO_REF:0000123 | MODIFY | Summary: The imported YeastPathways ergosterol-biosynthesis-I model incorrectly projects the ERG2 reaction into the cytosol. Reason: YeastPathways_PWY-6075-1 correctly connects ERG2/RXN3O-203 to ergosterol biosynthesis, but its imported GO-CAM activity has generic GO:0003674 molecular_function and GO:0005829 cytosol. Direct microscopy, UniProt, PAINT, and the curated SGD Yeast ergosterol GO-CAM all place Erg2p in the ER or ER membrane, so the compartment should be corrected to the ER membrane. Propagation Review Root cause: SOURCE BAD Failure modes: COMPARTMENT OR COMPLEX MISMATCH Sources checked: SGD_PWY:PWY-6075-1 SOURCE BAD Imported YeastPathways RXN3O-203 assigns ERG2 to GO:0005829 cytosol; direct localization and the curated Yeast ergosterol GO-CAM place Erg2p in the ER/ER membrane. Proposed replacements: endoplasmic reticulum membrane Supporting Evidence: file:gocams/index.tsv SGD:S000004815 ERG2 Scer YeastPathways_PWY-6075-1 ergosterol biosynthesis I - imported from: Saccharomyces Genome Database NCBITaxon:559292 gomodel:RXN3O-203 GO:0003674 molecular_function GO:0006696 ergosterol biosynthetic process GO:0005829 cytosol file:gocams/index.tsv SGD:S000004815 ERG2 Scer 61f34dd300001044 Yeast ergosterol NCBITaxon:559292 gomodel:61f34dd300001044/6205c24300000137 GO:0000247 C-8 sterol isomerase activity GO:0006696 ergosterol biosynthetic process GO:0005783 endoplasmic reticulum |
| GO:0005829 cytosol | RCA GO_REF:0000123 | MODIFY | Summary: The imported YeastPathways ergosterol model incorrectly projects the ERG2 reaction into the cytosol. Reason: YeastPathways_PWY3O-31704 correctly connects ERG2/RXN3O-203 to ergosterol biosynthesis, but its imported GO-CAM activity has generic GO:0003674 molecular_function and GO:0005829 cytosol. Direct microscopy, UniProt, PAINT, and the curated SGD Yeast ergosterol GO-CAM all place Erg2p in the ER or ER membrane, so the compartment should be corrected to the ER membrane. Propagation Review Root cause: SOURCE BAD Failure modes: COMPARTMENT OR COMPLEX MISMATCH Sources checked: SGD_PWY:PWY3O-31704 SOURCE BAD Imported YeastPathways RXN3O-203 assigns ERG2 to GO:0005829 cytosol; direct localization and the curated Yeast ergosterol GO-CAM place Erg2p in the ER/ER membrane. Proposed replacements: endoplasmic reticulum membrane Supporting Evidence: file:gocams/index.tsv SGD:S000004815 ERG2 Scer YeastPathways_PWY3O-31704 ergosterol biosynthesis - imported from: Saccharomyces Genome Database NCBITaxon:559292 gomodel:RXN3O-203 GO:0003674 molecular_function GO:0006696 ergosterol biosynthetic process GO:0005829 cytosol file:gocams/index.tsv SGD:S000004815 ERG2 Scer 61f34dd300001044 Yeast ergosterol NCBITaxon:559292 gomodel:61f34dd300001044/6205c24300000137 GO:0000247 C-8 sterol isomerase activity GO:0006696 ergosterol biosynthetic process GO:0005783 endoplasmic reticulum |
| GO:0006696 ergosterol biosynthetic process | IBA GO_REF:0000033 | ACCEPT | Summary: Fungal ERG2 PAINT transfer correctly assigns yeast ERG2 to ergosterol biosynthesis. Reason: PTN001280219 carries ergosterol biosynthesis from fission-yeast and budding-yeast ERG2 seeds. S. cerevisiae ERG2 directly executes the fecosterol-to-episterol reaction in the late ergosterol pathway. Propagation Review Root cause: NO FAILURE CORE Sources checked: PANTHER:PTN001280219 SUPPORTS TRANSFER Fungal ERG2 PAINT node carrying C-8 sterol isomerase activity and ergosterol biosynthesis; it supports the inherited yeast pathway row. Supporting Evidence: file:interpro/panther/PTHR10868/PTHR10868-paint.tsv PTHR10868 PTN001280219 GO:0006696 P IBD false PomBase:SPAC20G8.07c|SGD:S000004815 taxon:451864 20170228 file:yeast/ERG2/ERG2-uniprot.txt DISRUPTION PHENOTYPE: Abolishes the production of ergosterol |
| GO:0006696 ergosterol biosynthetic process | IDA DOI:10.1016/S0031-9422(00)80523-3 | ACCEPT | Summary: Direct legacy biochemical evidence places the Erg2p isomerase reaction in ergosterol biosynthesis. Reason: The legacy Baloch et al. DOI is the direct UniProt source for Erg2p catalyzing fecosterol-to-episterol as step 2 of the zymosterol-to-ergosterol pathway. Supporting Evidence: file:yeast/ERG2/ERG2-uniprot.txt PATHWAY: Steroid metabolism; ergosterol biosynthesis |
| GO:0006696 ergosterol biosynthetic process | IMP PMID:18459942 Identification of essential amino acid residues in a sterol ... | ACCEPT | Summary: Yeast erg2 mutant/rescue sterol-profile experiments support ERG2 involvement in ergosterol biosynthesis. Reason: Rahier et al. used an erg2 mutant lacking 8,7 sterol isomerase activity and showed that a cloned maize 8,7SI restored endogenous ergosterol synthesis, supporting the native yeast enzyme's placement in the ergosterol pathway. Supporting Evidence: PMID:18459942 Zm8,7SI restored endogenous ergosterol synthesis |
| GO:0006696 ergosterol biosynthetic process | RCA GO_REF:0000123 | ACCEPT | Summary: The imported YeastPathways superpathway correctly includes ERG2 in ergosterol biosynthesis. Reason: The YeastPathways_ERGOSTEROL-SYN-PWY-1 GO-CAM has a bad default cytosol compartment for RXN3O-203, but its process projection is biologically correct: Erg2p catalyzes a reaction in ergosterol biosynthesis. Propagation Review Root cause: NO FAILURE CORE Sources checked: SGD_PWY:ERGOSTEROL-SYN-PWY-1 SUPPORTS TRANSFER The imported YeastPathways model correctly places ERG2/RXN3O-203 in ergosterol biosynthetic process. Supporting Evidence: file:gocams/index.tsv SGD:S000004815 ERG2 Scer YeastPathways_ERGOSTEROL-SYN-PWY-1 superpathway of ergosterol biosynthesis I - imported from: Saccharomyces Genome Database NCBITaxon:559292 gomodel:RXN3O-203 GO:0003674 molecular_function GO:0006696 ergosterol biosynthetic process GO:0005829 cytosol |
| GO:0006696 ergosterol biosynthetic process | RCA GO_REF:0000123 | ACCEPT | Summary: The imported YeastPathways ergosterol-biosynthesis-I model correctly includes ERG2 in ergosterol biosynthesis. Reason: The YeastPathways_PWY-6075-1 GO-CAM has a bad default cytosol compartment for RXN3O-203, but its process projection is biologically correct: Erg2p catalyzes a reaction in ergosterol biosynthesis. Propagation Review Root cause: NO FAILURE CORE Sources checked: SGD_PWY:PWY-6075-1 SUPPORTS TRANSFER The imported YeastPathways model correctly places ERG2/RXN3O-203 in ergosterol biosynthetic process. Supporting Evidence: file:gocams/index.tsv SGD:S000004815 ERG2 Scer YeastPathways_PWY-6075-1 ergosterol biosynthesis I - imported from: Saccharomyces Genome Database NCBITaxon:559292 gomodel:RXN3O-203 GO:0003674 molecular_function GO:0006696 ergosterol biosynthetic process GO:0005829 cytosol |
| GO:0006696 ergosterol biosynthetic process | RCA GO_REF:0000123 | ACCEPT | Summary: The imported YeastPathways ergosterol model correctly includes ERG2 in ergosterol biosynthesis. Reason: The YeastPathways_PWY3O-31704 GO-CAM has a bad default cytosol compartment for RXN3O-203, but its process projection is biologically correct: Erg2p catalyzes a reaction in ergosterol biosynthesis. Propagation Review Root cause: NO FAILURE CORE Sources checked: SGD_PWY:PWY3O-31704 SUPPORTS TRANSFER The imported YeastPathways model correctly places ERG2/RXN3O-203 in ergosterol biosynthetic process. Supporting Evidence: file:gocams/index.tsv SGD:S000004815 ERG2 Scer YeastPathways_PWY3O-31704 ergosterol biosynthesis - imported from: Saccharomyces Genome Database NCBITaxon:559292 gomodel:RXN3O-203 GO:0003674 molecular_function GO:0006696 ergosterol biosynthetic process GO:0005829 cytosol |
| GO:0016126 sterol biosynthetic process | IEA GO_REF:0000041 | ACCEPT | Summary: UniPathway transfer to sterol biosynthesis is a true parent of the ergosterol-specific pathway rows. Reason: The UniPathway mapping is broader than the fungal PAINT, direct, and YeastPathways ergosterol rows, but it is not misleading: ergosterol is the major yeast sterol, and Erg2p catalyzes a late sterol-ring isomerization needed for ergosterol production. Supporting Evidence: file:yeast/ERG2/ERG2-uniprot.txt PATHWAY: Steroid metabolism; ergosterol biosynthesis |
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Download this section (compressed HTML)Q: Given the low substrate specificity of the post-zymosterol enzymes, does Erg2 act in vivo on zymosterol as well as fecosterol when Erg6 is absent?
Q: Does Erg2 share any ligand-binding or chaperone-like property with its mammalian homolog SIGMAR1 beyond isomerase activity?
C-8 sterol isomerase; catalyzes isomerization of delta-8 double bond to delta-7 position at an intermediate step in ergosterol biosynthesis; transcriptionally down-regulated when ergosterol is in excess; mutation is functionally complemented by human EBP
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