erg2 (SPAC20G8.07c) encodes the C-8 sterol isomerase of Schizosaccharomyces pombe, a single-pass ER-membrane protein of the ERG2/sigma-1-receptor-like family. It moves the B-ring double bond of fecosterol from Delta8 to Delta7 to give episterol, the step between C-24 methylation by erg6 and C-5 desaturation by erg31/erg32 in the late ergosterol pathway. erg2 deletion mutants are viable but make no ergosterol, are sensitive to cycloheximide and staurosporine, and some cells form more than one septum. The fungal ERG2 isomerase is structurally unrelated to the animal EBP Delta8-Delta7 isomerase.
| 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 transfer matches S. pombe Erg2, a single-copy fission-yeast ERG2 ortholog with the same fecosterol-to-episterol C-8 sterol isomerase reaction recorded by UniProt and Rhea. 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 transfer to S. pombe erg2. Supporting Evidence: file:interpro/panther/PTHR10868/PTHR10868-paint.tsv PTHR10868 PTN001280219 GO:0000247 F IBD false CGD:CAL0000177093|SGD:S000004815 taxon:451864 20251127 file:SCHPO/erg2/erg2-uniprot.txt Reaction=fecosterol = episterol; Xref=Rhea:RHEA:33435 |
| GO:0000247 C-8 sterol isomerase activity | IEA GO_REF:0000116 | ACCEPT | Summary: Rhea-to-GO transfer captures the same fecosterol-to-episterol sterol isomerization as the fungal PAINT activity row. Reason: The UniProt catalytic-activity block maps erg2 to RHEA:33435, the fecosterol = episterol reaction. That reaction is the late pathway double-bond isomerization catalyzed by fungal ERG2 proteins, so the Rhea-derived IEA is an appropriate duplicate molecular-function row. Supporting Evidence: file:SCHPO/erg2/erg2-uniprot.txt Reaction=fecosterol = episterol; Xref=Rhea:RHEA:33435 |
| GO:0005783 endoplasmic reticulum | HDA PMID:16823372 ORFeome cloning and global analysis of protein localization ... | ACCEPT | Summary: PomBase high-throughput localization places erg2 in the endoplasmic reticulum. Reason: Matsuyama et al. reported an ORFeome-scale YFP localization dataset for most S. pombe proteins. The cached abstract does not expose the erg2 image-table row, but PomBase's HDA curation, UniProt's PubMed-linked ER membrane location, and the conserved ER-membrane localization of fungal sterol enzymes support retaining the direct endoplasmic-reticulum row. Supporting Evidence: PMID:16823372 we determined the localization of 4,431 proteins file:SCHPO/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 S. pombe 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 shared ER compartment transfers to erg2 without importing animal-specific Sigma-receptor functions. 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:SCHPO/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 Erg2 at the endoplasmic reticulum membrane. Reason: UniProt assigns S. pombe Erg2 to the endoplasmic reticulum membrane based on the PomBase high-throughput localization study, and this is the expected membrane compartment for the late sterol C-8 isomerase reaction. Supporting Evidence: file:SCHPO/erg2/erg2-uniprot.txt SUBCELLULAR LOCATION: Endoplasmic reticulum membrane |
| GO:0006696 ergosterol biosynthetic process | IBA GO_REF:0000033 | ACCEPT | Summary: Fungal ERG2 PAINT transfer correctly assigns erg2 to ergosterol biosynthesis. Reason: PTN001280219 carries ergosterol-biosynthesis from fission-yeast and budding-yeast ERG2 seeds. S. pombe erg2 directly executes a reaction in the late ergosterol pathway, and Iwaki et al. showed that disruption of the predicted ergosterol genes, including erg2, prevents ergosterol synthesis. 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 transfer to S. pombe erg2. Supporting Evidence: file:interpro/panther/PTHR10868/PTHR10868-paint.tsv PTHR10868 PTN001280219 GO:0006696 P IBD false PomBase:SPAC20G8.07c|SGD:S000004815 taxon:451864 20170228 PMID:18310029 Disruption mutants of these genes were unable to synthesize ergosterol |
| GO:0006696 ergosterol biosynthetic process | IMP PMID:18310029 Multiple functions of ergosterol in the fission yeast Schizo... | ACCEPT | Summary: PomBase IMP evidence from the fission-yeast ergosterol mutant series directly supports erg2 involvement in ergosterol biosynthesis. Reason: The cached abstract identifies Erg2p as the predicted C-8 sterol isomerase in the zymosterol-to-ergosterol series and reports that the disruption mutants of the predicted late ergosterol genes were unable to synthesize ergosterol. The exact erg2 sterol profile is in full-text data curated by PomBase; the abstract is nevertheless sufficient to support the process-level row. Supporting Evidence: PMID:18310029 Disruption mutants of these genes were unable to synthesize ergosterol file:SCHPO/erg2/erg2-uniprot.txt DISRUPTION PHENOTYPE: Abolishes the production of ergosterol and leads to the formation of more than one septum in some cells file:SCHPO/erg2/erg2-uniprot.txt PATHWAY: Steroid metabolism; ergosterol biosynthesis |
| 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 row. Reason: The UniPathway mapping is broader than the fungal PAINT and direct PomBase ergosterol rows, but it is not misleading: ergosterol is the major fungal sterol, and erg2 catalyzes a late sterol-ring isomerization needed for ergosterol production. Supporting Evidence: file:SCHPO/erg2/erg2-uniprot.txt PATHWAY: Steroid metabolism; ergosterol biosynthesis |
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Download this section (compressed HTML)Q: Is S. pombe Erg2 inhibited by morpholine fungicides (fenpropimorph, tridemorph) as budding-yeast Erg2 is, and does it share the sigma-1-receptor-like ligand-binding pocket?
Experiment: Assay fecosterol -> episterol isomerisation in microsomes from wild-type and erg2-deleted S. pombe, and test fenpropimorph sensitivity of the activity.
Hypothesis: S. pombe Erg2 is a morpholine-sensitive C-8 sterol isomerase like budding-yeast Erg2.
Type: enzyme assay
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