pik1 (SPAC22E12.16c; UniProt Q10366) encodes one of the two essential type III phosphatidylinositol 4-kinases of fission yeast. Pik1 is exclusively at the trans-Golgi network, where it makes the Golgi pool of PI4P. It is activated by the Ca2+-myristoyl switch protein Ncs1 and binds the myosin light chains Cdc4 and Cam2, though Ncs1 is not needed to target it to the Golgi. Earlier models implicated Pik1 in cytokinesis. Its 2023 characterisation showed that disrupting Pik1 lowers PI4P without changing plasma-membrane PI(4,5)P2 or division symmetry: the plasma-membrane PI4P kinase Stt4 makes the PI4P that feeds PI(4,5)P2 and cytokinetic ring anchoring.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0000281 mitotic cytokinesis | EXP NOT PMID:37815455 Characterization of Pik1 function in fission yeast reveals i... | ACCEPT | Summary: NOT annotation: unlike earlier models, disrupting Pik1 does not cause the asymmetric division seen when Stt4 is lost. Pik1 is not involved in cytokinesis. Supporting Evidence: PMID:37815455 Also, that cells with disrupted Pik1 do not divide asymmetrically highlights the specific importance of PM PI(4,5)P2 for cytokinetic ring-PM anchoring. |
| GO:0004430 1-phosphatidylinositol 4-kinase activity | EXP PMID:37815455 Characterization of Pik1 function in fission yeast reveals i... | ACCEPT | Summary: Pik1 is required for Golgi PI4P production. Supporting Evidence: PMID:37815455 Here, we found that Pik1 localizes exclusively to the trans-Golgi and is required for Golgi PI4P production. PMID:37815455 When Pik1 function was disrupted, PM PI4P but not PI(4,5)P2 levels were reduced, a major difference compared with Stt4. |
| GO:0004430 1-phosphatidylinositol 4-kinase activity | IBA GO_REF:0000033 | ACCEPT | Summary: PAINT inference; consistent. Supporting Evidence: PMID:37815455 Here, we found that Pik1 localizes exclusively to the trans-Golgi and is required for Golgi PI4P production. |
| GO:0004430 1-phosphatidylinositol 4-kinase activity | IEA GO_REF:0000120 | ACCEPT | Summary: EC/RHEA mapping; consistent. Supporting Evidence: PMID:37815455 Here, we found that Pik1 localizes exclusively to the trans-Golgi and is required for Golgi PI4P production. |
| GO:0005515 protein binding | IPI PMID:21288895 Structure of a Ca2+-myristoyl switch protein that controls a... | REMOVE | Summary: IPI with Ncs1, the Ca2+-myristoyl switch activator of Pik1. Generic protein binding carries no functional information; the interaction itself is not in doubt and is captured in the complex membership and description. Reason: Uninformative generic protein-binding term. Supporting Evidence: PMID:21288895 We determined NMR structures of the NCS-1 homolog from fission yeast (Ncs1), which activates a phosphatidylinositol 4-kinase. |
| GO:0005515 protein binding | IPI PMID:21693583 A calmodulin-related light chain from fission yeast that fun... | REMOVE | Summary: IPI with the calmodulin-like light chain Cam2, which competes with the ELC for Pik1. Generic protein binding carries no functional information; the interaction itself is not in doubt and is captured in the complex membership and description. Reason: Uninformative generic protein-binding term. Supporting Evidence: PMID:21693583 Binding studies revealed that Cam2p and the ELC compete for Pik1p. |
| GO:0005634 nucleus | IEA GO_REF:0000044 | KEEP AS NON CORE | Summary: UniProt location mapping (nucleus); Pik1 is found only at the trans-Golgi in S. pombe. Reason: Not supported for S. pombe Pik1. Supporting Evidence: PMID:37815455 Here, we found that Pik1 localizes exclusively to the trans-Golgi and is required for Golgi PI4P production. |
| GO:0005634 nucleus | ISO GO_REF:0000024 | KEEP AS NON CORE | Summary: Transfer of nuclear location from S. cerevisiae Pik1, which shuttles to the nucleus. S. pombe Pik1 localises only to the trans-Golgi. Reason: Not supported for S. pombe Pik1. Supporting Evidence: PMID:37815455 Here, we found that Pik1 localizes exclusively to the trans-Golgi and is required for Golgi PI4P production. |
| GO:0005737 cytoplasm | IBA GO_REF:0000033 | ACCEPT | Summary: PAINT inference; Golgi-associated peripheral enzyme recruited from the cytoplasm. Supporting Evidence: PMID:37815455 Here, we found that Pik1 localizes exclusively to the trans-Golgi and is required for Golgi PI4P production. |
| GO:0005794 Golgi apparatus | HDA PMID:16823372 ORFeome cloning and global analysis of protein localization ... | ACCEPT | Summary: ORFeome screen: Golgi; consistent with trans-Golgi localisation. Supporting Evidence: PMID:37815455 Here, we found that Pik1 localizes exclusively to the trans-Golgi and is required for Golgi PI4P production. PMID:16823372 we determined the localization of 4,431 proteins |
| GO:0005794 Golgi apparatus | IEA GO_REF:0000044 | ACCEPT | Summary: UniProt mapping; consistent. Supporting Evidence: PMID:37815455 Here, we found that Pik1 localizes exclusively to the trans-Golgi and is required for Golgi PI4P production. |
| GO:0016020 membrane | IBA GO_REF:0000033 | ACCEPT | Summary: PAINT inference of membrane association. Supporting Evidence: PMID:37815455 Here, we found that Pik1 localizes exclusively to the trans-Golgi and is required for Golgi PI4P production. |
| GO:0016301 kinase activity | IEA GO_REF:0000002 | MODIFY | Summary: Generic InterPro-derived parent of the specific activity, which is already annotated. Reason: Too general. Proposed replacements: 1-phosphatidylinositol 4-kinase activity Supporting Evidence: PMID:37815455 Here, we found that Pik1 localizes exclusively to the trans-Golgi and is required for Golgi PI4P production. |
| GO:0032153 cell division site | EXP NOT PMID:37815455 Characterization of Pik1 function in fission yeast reveals i... | ACCEPT | Summary: NOT annotation: Pik1 is not at the division site; it is exclusively trans-Golgi. Supporting Evidence: PMID:37815455 Here, we found that Pik1 localizes exclusively to the trans-Golgi and is required for Golgi PI4P production. |
| GO:0032588 trans-Golgi network membrane | EXP PMID:37815455 Characterization of Pik1 function in fission yeast reveals i... | ACCEPT | Summary: Pik1 localises to the trans-Golgi. Supporting Evidence: PMID:37815455 Here, we found that Pik1 localizes exclusively to the trans-Golgi and is required for Golgi PI4P production. |
| GO:0046854 phosphatidylinositol phosphate biosynthetic process | EXP PMID:37815455 Characterization of Pik1 function in fission yeast reveals i... | ACCEPT | Summary: Pik1 makes the Golgi pool of PI4P. Supporting Evidence: PMID:37815455 Here, we found that Pik1 localizes exclusively to the trans-Golgi and is required for Golgi PI4P production. |
| GO:0046854 phosphatidylinositol phosphate biosynthetic process | IBA GO_REF:0000033 | ACCEPT | Summary: PAINT inference; consistent. Supporting Evidence: PMID:37815455 Here, we found that Pik1 localizes exclusively to the trans-Golgi and is required for Golgi PI4P production. |
| GO:0046854 phosphatidylinositol phosphate biosynthetic process | IEA GO_REF:0000002 | ACCEPT | Summary: InterPro mapping; consistent. Supporting Evidence: PMID:37815455 Here, we found that Pik1 localizes exclusively to the trans-Golgi and is required for Golgi PI4P production. |
| GO:0048015 phosphatidylinositol-mediated signaling | IBA GO_REF:0000033 | KEEP AS NON CORE | Summary: PAINT inference of PI-mediated signalling; loose description of PI4P production. Supporting Evidence: PMID:37815455 Here, we found that Pik1 localizes exclusively to the trans-Golgi and is required for Golgi PI4P production. |
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