SPAC17G8.11c (SPAC17G8.11c; imt3; UniProt Q10323) encodes one of three redundant Golgi inositol phosphoceramide mannosyltransferases (imt1-imt3; SUR1/CSH1 homologues) that mannosylate IPC to MIPC, the terminal and most abundant complex sphingolipid of fission yeast. Single imt mutants are viable, but the triple disruptant lacks MIPC and accumulates IPC. It then shows defects in cell and vacuole morphology, ergosterol distribution and endocytic sorting of a plasma-membrane amino acid transporter.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0000030 mannosyltransferase activity | IBA GO_REF:0000033 | MODIFY | Summary: PAINT inference of generic mannosyltransferase activity; the specific IPC mannosyltransferase activity is the role. Reason: Correct but general. In S. pombe, MIPC is lost in the imt1 imt2 imt3 triple disruptant (PMID:20388730), and UniProt's curated function, tied to that paper (ECO:0000269), states that the protein adds mannose to IPC; the PAINT node is seeded by the S. cerevisiae Sur1/Csh1 IPC mannosyltransferases. The specific descendant is inositol phosphorylceramide mannosyltransferase activity (GO:0103064), not yet carried by the gene. Previously KEEP_AS_NON_CORE, which the rules do not allow for a correct-but-general term with a supported descendant. The S. pombe evidence is genetic and redundant among the three paralogs, not a direct enzyme assay of Imt3. Propagation Review Root cause: TERM SCOPING PROBLEM Sources checked: PANTHER:PTN001285482 · PTN001285482 SUPPORTS TRANSFER Node seeded by S. cerevisiae Sur1/Csh1 and fungal orthologs; S. pombe Imt3 sits inside the IPC mannosyltransferase clade, so the activity is inherited, but the propagated term stops at the generic mannosyltransferase parent. Proposed replacements: inositol phosphorylceramide mannosyltransferase activity Supporting Evidence: file:SCHPO/SPAC17G8.11c/SPAC17G8.11c-uniprot.txt Catalyzes the addition of mannosyl to inositol phosphoceramide (IPC). PMID:20388730 MIPC was not detected and IPC levels were increased in the triple disruptant, indicating that the three SUR1 homologues are involved in the synthesis of MIPC. |
| GO:0005783 endoplasmic reticulum | HDA PMID:16823372 ORFeome cloning and global analysis of protein localization ... | KEEP AS NON CORE | Summary: ORFeome screen ER signal; Imt proteins are Golgi enzymes. Reason: Not the active location. Supporting Evidence: PMID:16823372 we determined the localization of 4,431 proteins |
| GO:0005789 endoplasmic reticulum membrane | IEA GO_REF:0000044 | KEEP AS NON CORE | Summary: ER membrane mapping; Golgi is the active location. Reason: Not the active location. Supporting Evidence: PMID:16823372 we determined the localization of 4,431 proteins |
| GO:0005794 Golgi apparatus | HDA PMID:16823372 ORFeome cloning and global analysis of protein localization ... | ACCEPT | Summary: ORFeome screen: Golgi. Supporting Evidence: PMID:16823372 we determined the localization of 4,431 proteins |
| GO:0005794 Golgi apparatus | IEA GO_REF:0000044 | ACCEPT | Summary: Mapping. Reason: GFP-tagged Imt3p (this gene) localises to Golgi apparatus membranes (PMID:20388730), and UniProt's location line lists Golgi network membranes, so the SubCell-mapped Golgi apparatus term holds. Supporting Evidence: PMID:20388730 GFP-tagged Imt1p, Imt2p and Imt3p localized to Golgi apparatus membranes. file:SCHPO/SPAC17G8.11c/SPAC17G8.11c-uniprot.txt Golgi apparatus, trans-Golgi network membrane |
| GO:0005802 trans-Golgi network | IDA PMID:20388730 Mannosylinositol phosphorylceramide is a major sphingolipid ... | ACCEPT | Summary: GFP-Imt proteins localise to Golgi membranes. Supporting Evidence: PMID:20388730 GFP-tagged Imt1p, Imt2p and Imt3p localized to Golgi apparatus membranes. |
| GO:0032588 trans-Golgi network membrane | IDA PMID:20388730 Mannosylinositol phosphorylceramide is a major sphingolipid ... | ACCEPT | Summary: Golgi membrane localisation of GFP-Imt. Supporting Evidence: PMID:20388730 GFP-tagged Imt1p, Imt2p and Imt3p localized to Golgi apparatus membranes. |
| GO:0032588 trans-Golgi network membrane | IEA GO_REF:0000117 | ACCEPT | Summary: Mapping. Reason: UniProt's location line lists the trans-Golgi network membrane. The cached abstract of PMID:20388730 shows GFP-Imt3p on Golgi apparatus membranes but does not resolve trans versus cis cisternae; the IDA row from that paper (full text read by the curator) carries the TGN term, so this ARBA row is consistent with it. Supporting Evidence: file:SCHPO/SPAC17G8.11c/SPAC17G8.11c-uniprot.txt Golgi apparatus, trans-Golgi network membrane PMID:20388730 GFP-tagged Imt1p, Imt2p and Imt3p localized to Golgi apparatus membranes. |
| GO:0033106 cis-Golgi network membrane | IDA PMID:20388730 Mannosylinositol phosphorylceramide is a major sphingolipid ... | ACCEPT | Summary: Golgi membrane localisation of GFP-Imt. Supporting Evidence: PMID:20388730 GFP-tagged Imt1p, Imt2p and Imt3p localized to Golgi apparatus membranes. |
| GO:0033106 cis-Golgi network membrane | IEA GO_REF:0000117 | ACCEPT | Summary: Mapping. Reason: UniProt's location line lists the cis-Golgi network membrane. The cached abstract of PMID:20388730 shows GFP-Imt3p on Golgi apparatus membranes but does not resolve cis versus trans cisternae; the IDA row from that paper (full text read by the curator) carries the cis-Golgi term, so this ARBA row is consistent with it. Supporting Evidence: file:SCHPO/SPAC17G8.11c/SPAC17G8.11c-uniprot.txt Golgi apparatus, cis-Golgi network membrane PMID:20388730 GFP-tagged Imt1p, Imt2p and Imt3p localized to Golgi apparatus membranes. |
| GO:0051999 mannosyl-inositol phosphorylceramide biosynthetic process | IBA GO_REF:0000033 | ACCEPT | Summary: PAINT inference. Reason: The imt1 imt2 imt3 triple disruptant lacks MIPC and accumulates IPC (PMID:20388730), and UniProt's experimental function statement (ECO:0000269) says the protein catalyses addition of mannosyl to IPC. Note the three imt paralogs are redundant, so the genetic evidence is from the combined loss. Supporting Evidence: PMID:20388730 MIPC was not detected and IPC levels were increased in the triple disruptant, indicating that the three SUR1 homologues are involved in the synthesis of MIPC. file:SCHPO/SPAC17G8.11c/SPAC17G8.11c-uniprot.txt Catalyzes the addition of mannosyl to inositol phosphoceramide (IPC). |
| GO:0051999 mannosyl-inositol phosphorylceramide biosynthetic process | IEA GO_REF:0000117 | ACCEPT | Summary: Mapping. Reason: Supported by the triple-disruptant phenotype (no MIPC, IPC accumulates; PMID:20388730) and UniProt's experimental function statement (ECO:0000269|PubMed:20388730) that the protein catalyses mannosyl addition to IPC. Supporting Evidence: PMID:20388730 MIPC was not detected and IPC levels were increased in the triple disruptant, indicating that the three SUR1 homologues are involved in the synthesis of MIPC. file:SCHPO/SPAC17G8.11c/SPAC17G8.11c-uniprot.txt Catalyzes the addition of mannosyl to inositol phosphoceramide (IPC). |
| GO:0051999 mannosyl-inositol phosphorylceramide biosynthetic process | IGI PMID:20388730 Mannosylinositol phosphorylceramide is a major sphingolipid ... | ACCEPT | Summary: The imt1 imt2 imt3 triple disruptant lacks MIPC and accumulates IPC. Supporting Evidence: PMID:20388730 MIPC was not detected and IPC levels were increased in the triple disruptant, indicating that the three SUR1 homologues are involved in the synthesis of MIPC. |
| GO:0051999 mannosyl-inositol phosphorylceramide biosynthetic process | IMP PMID:20388730 Mannosylinositol phosphorylceramide is a major sphingolipid ... | ACCEPT | Summary: As above. Supporting Evidence: PMID:20388730 MIPC was not detected and IPC levels were increased in the triple disruptant, indicating that the three SUR1 homologues are involved in the synthesis of MIPC. |
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