Clp1 (also called Flp1) is the single Cdc14-family dual-specificity phosphoprotein phosphatase of the fission yeast Schizosaccharomyces pombe (537 aa; PTP-superfamily catalytic domain with the nucleophilic Cys286, followed by a disordered C-terminal tail carrying the Sid2 RxxS phosphosites and a Sal3-dependent nuclear localization signal). Although classified as a tyrosine phosphatase by fold, it physiologically removes phospho-Ser/Thr-Pro marks deposited by the cyclin-dependent kinase Cdc2 (Cdk1). During interphase Clp1 is sequestered in the nucleolus and at the spindle pole body; at mitotic entry it is released and distributes to the nucleoplasm, kinetochores, the mitotic spindle and midzone, the SPBs and the Mid1-tethered contractile ring, then returns to the nucleolus once cytokinesis is complete. Its activity is further gated by inhibitory Cdk1 phosphorylation that it reverses autocatalytically in anaphase, and the septation initiation network (SIN) kinase Sid2 phosphorylates its C-terminal RxxS sites to create a 14-3-3 (Rad24) binding site that holds Clp1 in the cytoplasm until the ring has constricted. Through these pools Clp1 antagonizes Cdk1 and coordinates late mitosis with cell division: it dephosphorylates and destabilizes the mitotic inducer Cdc25, restraining the G2/M transition and hastening Cdk1 inactivation at mitotic exit; it dephosphorylates the kinesin-6 Klp9, the microtubule bundler Ase1 and the XMAP215 protein Dis1 to drive anaphase B spindle elongation, and Nsk1 and the monopolin subunit Mde4 to support accurate chromosome segregation and biorientation; at the division site it dephosphorylates the F-BAR protein Cdc15, the formin Cdc12 and paxillin Pxl1 to promote contractile-ring assembly and stability; and, acting with the SIN and its scaffold Cdc11, it forms the cytokinesis checkpoint that delays the next nuclear division while a damaged ring is repaired. Unlike Saccharomyces cerevisiae Cdc14 it is not essential for mitotic exit or viability. Clp1 also leaves the nucleolus in interphase upon genotoxic or oxidative stress, phosphorylated by the checkpoint kinases Cds1/Chk1, the MAP kinase Pmk1 and Cdk1, and dephosphorylates the stress transcription factor Pcr1 to limit the oxidative-stress transcriptional response.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0000226 microtubule cytoskeleton organization | IBA GO_REF:0000033 | KEEP AS NON CORE | Summary: PAINT-inferred role in microtubule cytoskeleton organization. In fission yeast this is well grounded: at anaphase B onset Clp1 dephosphorylates the kinesin-6 Klp9, the bundler Ase1 and the XMAP215 protein Dis1 so that Klp9 is recruited to the antiparallel midzone and the anaphase spindle elongates at the normal rate [PMID:19686686, PMID:34080538]. Reason: The phylogenetic placement is sound (the node is seeded by S. cerevisiae Cdc14 and C. elegans cdc-14, and Clp1 has direct evidence of the same kind), but spindle organization is one downstream, substrate-specific consequence of the enzyme's core activity of reversing Cdk1 phosphorylation. It is retained as a genuine but non-core process; the specific fission-yeast evidence is captured by the GO:1902846 rows. Supporting Evidence: PMID:19686686 At the onset of anaphase B, clp1p (also known as flp1p (Cueille et al., 2001), homolog of Cdc14) dephosphorylates klp9p and ase1p, allowing them to physically bind to each other at the spindle midzone to initiate spindle elongation. PMID:34080538 Consequently, the spindle elongation velocity in anaphase B was reduced upon clp1 deletion |
| GO:0000278 mitotic cell cycle | IEA GO_REF:0000117 | ACCEPT | Summary: ARBA-predicted broad term. Clp1 is a mitotic cell-cycle regulator: it controls the G2/M transition, is released from the nucleolus at mitotic entry, dephosphorylates Cdk1 substrates in anaphase and couples cytokinesis to the nuclear cycle [PMID:11448769]. Reason: Unquestionably true, if far less specific than the experimental rows (GO:0010972, GO:0031536, GO:0044878, GO:1902846) that capture the actual processes. Supporting Evidence: PMID:11448769 We have identified the S. pombe Cdc14p homolog, Clp1p, and show that it is not required for mitotic exit but rather functions together with the SIN in coordinating cytokinesis with the nuclear-division cycle. PMID:11448769 In addition to its roles in anaphase, Clp1p regulates the G2/M transition since cells deleted for clp1 enter mitosis precociously and cells overexpressing Clp1p delay mitotic entry. Unlike Cdc14p, Clp1p appears to antagonize Cdk activity by preventing dephosphorylation of Cdc2p on tyrosine. |
| GO:0000776 kinetochore | IDA PMID:15525536 The S. pombe Cdc14-like phosphatase Clp1p regulates chromoso... | ACCEPT | Summary: Trautmann et al. 2004 showed that Clp1 localizes to kinetochores in prometaphase after its release from the nucleolus, where it functions with Aurora kinase (Ark1) in chromosome biorientation. Reason: Direct localization evidence stated in the abstract (cache is abstract-only); kinetochore localization is corroborated by Chen et al. 2008 and by the identification of kinetochore substrates such as Nsk1 and Mde4. Supporting Evidence: PMID:15525536 Here, we report that Clp1p/Flp1p localizes to kinetochores in prometaphase and functions in chromosome segregation, since deletion of clp1/flp1 causes cosegregation of sister chromatids, when sister kinetochores are prone to mono-orientation. |
| GO:0000776 kinetochore | IDA PMID:18951025 The SIN kinase Sid2 regulates cytoplasmic retention of the S... | ACCEPT | Summary: Chen et al. 2008 imaged endogenous-promoter Clp1-GFP and confirmed that, after nucleolar release at mitotic entry, it localizes to kinetochores and the actomyosin ring in early mitosis. Reason: Direct live-cell localization; consistent with PMID:15525536 and the kinetochore substrates Nsk1 (PMID:21965289, PMID:22065639) and Mde4 (PMID:19523829). Supporting Evidence: PMID:18951025 Like wild-type Clp1-GFP, Clp1-6A-GFP localized in interphase to the SPB and nucleolus, was released from the nucleolus as cells enter mitosis, localized to the kinetochores and actomyosin ring in early mitosis (Figure S2A). |
| GO:0004721 phosphoprotein phosphatase activity | IDA PMID:18951025 The SIN kinase Sid2 regulates cytoplasmic retention of the S... | ACCEPT | Summary: Recombinant Clp1 (and the Sid2-site mutant Clp1-6A) shows in vitro phosphatase activity; the in vitro assay was used to show that the 6A mutations do not compromise catalytic function. Reason: Correct but less specific than the GO:0004722 rows; the assay demonstrates phosphoprotein phosphatase activity of the purified enzyme. Kept as a parent-level statement of the core catalytic activity. Supporting Evidence: PMID:18951025 Bacterially expressed Clp1-6A retained wild-type in vitro phosphatase activity suggesting that the mutations did not grossly affect the structure of the protein (Figure 1G). |
| GO:0004721 phosphoprotein phosphatase activity | IEA GO_REF:0000117 | ACCEPT | Summary: ARBA-predicted phosphoprotein phosphatase activity, consistent with the Cdc14-family catalytic domain (Cys286 nucleophile) and abundant in vitro and in vivo evidence. Reason: Correct electronic annotation for the core catalytic activity; the more specific GO:0004722 rows carry the experimental detail. Supporting Evidence: PMID:15128870 The Schizosaccaromyces pombe protein Flp1p belongs to a conserved family of serine-threonine-phosphatases. |
| GO:0004722 protein serine/threonine phosphatase activity | EXP PMID:19523829 Phosphorylation state defines discrete roles for monopolin i... | ACCEPT | Summary: Recombinant Clp1 removed the mitotic phosphorylation-dependent mobility shift of the monopolin subunit Mde4, and Mde4 was trapped by the catalytically dead Clp1-C286S allele; Clp1 dephosphorylates Cdk1 sites on Mde4 to allow monopolin loading onto the anaphase spindle. Reason: Direct biochemical demonstration of Ser/Thr (Cdk1-site) phosphatase activity toward a physiological substrate; note the paper also shows that other phosphatases can dephosphorylate Mde4 in vivo in clp1Ξ. Supporting Evidence: PMID:19523829 Treatment with Clp1 eliminated the migration shift of Mde4-13Myc (Figure 1D), confirming that Mde4 is phosphorylated in vivo, and that Clp1 can dephosphorylate Mde4 in vitro. |
| GO:0004722 protein serine/threonine phosphatase activity | EXP PMID:28178520 Identification of a Sgo2-Dependent but Mad2-Independent Path... | ACCEPT | Summary: Meadows et al. 2017 showed that Clp1 dephosphorylates the C terminus of the kinesin-6 Klp9 (Cdk1 sites) at anaphase onset, which is required for Klp9 to bind the chromosomal passenger complex at the spindle midzone; Klp9 and the CPC fail to concentrate at the midzone in clp1(C286S). Reason: Ser/Thr phosphatase activity toward Cdk1 phosphosites on Klp9, consistent with PMID:19686686. Core activity. Supporting Evidence: PMID:28178520 Taken together, our data indicate that de-phosphorylation of the C terminus of Klp9 by Clp1 phosphatase promotes interaction of CPC components with Klp9 at the spindle midzone rather than interaction of Klp9 with Ase1 to influence the rate of spindle elongation. PMID:28178520 Consistently, we find that both Klp9 and the CPC fail to concentrate at the anaphase spindle midzone in clp1(C286S) cells, which express a catalytically inactive allele of the Clp1 (CDC14) phosphatase (Wolfe et al., 2006). |
| GO:0004722 protein serine/threonine phosphatase activity | EXP PMID:29343550 Cdk1-dependent phosphoinhibition of a formin-F-BAR interacti... | ACCEPT | Summary: Recombinant MBP-Clp1, but not the C286S mutant, increased the gel mobility of Cdk1-phosphorylated formin Cdc12, showing Clp1 dephosphorylates Cdk1 sites on Cdc12 and thereby permits maximal Cdc12 accumulation at the contractile ring. Reason: Direct in vitro Ser/Thr phosphatase activity toward a cytokinetic substrate; core activity. Supporting Evidence: PMID:29343550 Consistent with Cdk1 phosphorylating Cdc12 in vivo, Cdc12-HA3 showed increased gel mobility when incubated with recombinant MBP-Clp1 in comparison with Cdc12-HA3 not incubated with protein or incubated with an inactive form of Clp1 (Figure 1D). PMID:29343550 At least some Cdk1 phosphosites on Cdc12 are dephosphorylated by Clp1, a member of the Cdc14 phosphatase family, thereby allowing maximal Cdc12 accumulation at the CR. |
| GO:0004722 protein serine/threonine phosphatase activity | EXP PMID:34133210 Cdk1 phosphorylation of fission yeast paxillin inhibits its ... | ACCEPT | Summary: Snider et al. 2021 showed that the Cdk1-phosphorylated paxillin Pxl1 remains hyperphosphorylated in clp1β cells, so Clp1 (together with PP1/Dis2) contributes to Pxl1 dephosphorylation at mitotic exit. Reason: Ser/Thr phosphatase activity towards a Cdk1 substrate, inferred from the phosphostate of Pxl1 in clp1β; consistent with the many other Cdk1-site substrates. Supporting Evidence: PMID:34133210 We determined that both the Cdc14 phosphatase Clp1 and the PP1 phosphatase Dis2 contribute to Pxl1 dephosphorylation at mitotic exit, but PP2B/calcineurin does not. PMID:34133210 The slower-migrating bands corresponding to phosphorylated Pxl1 were increased in clp1β compared to clp1+ (Figure 3B), consistent with Clp1 contributing to Pxl1 dephosphorylation. |
| GO:0004722 protein serine/threonine phosphatase activity | IBA GO_REF:0000033 | ACCEPT | Summary: PAINT-inferred core catalytic activity of the Cdc14 family: a cysteine-based dual-specificity fold that physiologically removes Cdk1-deposited phospho-Ser/Thr-Pro. Clp1 itself dephosphorylates Cdc25, Cdc15, Klp9, Ase1, Nsk1, Mde4, Cdc11, Cdc12, Pxl1 and others. Reason: Phylogenetic placement is sound and the target has extensive direct evidence (it appears legitimately in its own WITH/FROM). This is the core molecular function. Supporting Evidence: PMID:23297348 Over 100 Clp1-interacting proteins were consistently identified, over 70 of these were enriched in Clp1-C286S-TAP (potential substrates) and we and others detected Cdk1 phosphorylation sites in over half (44/73) of these potential substrates. |
| GO:0004722 protein serine/threonine phosphatase activity | IDA PMID:15128870 A role for the Cdc14-family phosphatase Flp1p at the end of ... | ACCEPT | Summary: Esteban et al. 2004 showed that the mitotic inducer Cdc25 is a substrate of Flp1/Clp1 in vitro and that Flp1 is required for rapid Cdc25 degradation at the end of mitosis. Reason: Direct in vitro dephosphorylation of a key physiological substrate (abstract-only cache; the curator read the full text). Core activity. Supporting Evidence: PMID:15128870 Here we show that Flp1p is required for rapid degradation of the mitotic inducer Cdc25p at the end of mitosis, and that Cdc25p is a substrate of Flp1p in vitro. Down-regulation of Cdc25p activity by Flp1p may ensure a prompt inactivation of mitotic CDK complexes to trigger cell division. |
| GO:0004722 protein serine/threonine phosphatase activity | IDA PMID:16950131 Phospho-regulation of the Cdc14/Clp1 phosphatase delays late... | ACCEPT | Summary: Wolfe et al. 2006 showed that Cdk1 phosphorylates and inhibits Clp1, and that as Cdk1 activity falls in anaphase Clp1 autocatalytically removes these phosphates to stimulate its own activity. Reason: Direct demonstration of Ser/Thr phosphatase activity (autodephosphorylation of Cdk1 sites) and of its cell-cycle regulation. Supporting Evidence: PMID:16950131 Cdk1 phosphorylates and inhibits the catalytic activity of the Cdc14 family member, Clp1/Flp1. As Cdk1 activity declines during anaphase progression, Clp1/Flp1 autocatalytically reverses these phosphorylation events to stimulate its own activity. |
| GO:0004722 protein serine/threonine phosphatase activity | IDA PMID:18378776 The Clp1/Cdc14 phosphatase contributes to the robustness of ... | ACCEPT | Summary: Clifford et al. 2008 showed that Clp1, tethered at the contractile ring by Mid1, is required for maximal anaphase dephosphorylation of the F-BAR protein Cdc15, and that recombinant Clp1 dephosphorylates Cdc15 in immunocomplexes. Reason: Direct in vitro and in vivo (clp1Ξ, clp1-C286S) evidence for Ser/Thr phosphatase activity toward a contractile-ring substrate. Supporting Evidence: PMID:18378776 Further supporting the idea that Cdc15 is a Clp1 target, recombinant Clp1 dephosphorylated the partially phosphorylated Cdc15 in immunocomplexes purified from nda3-KM311βarrested cells PMID:18378776 These results indicate that Clp1 phosphatase activity is required for maximal Cdc15 dephosphorylation during mitosis. |
| GO:0004722 protein serine/threonine phosphatase activity | IDA PMID:19686686 Phospho-regulated interaction between kinesin-6 Klp9p and mi... | ACCEPT | Summary: Fu et al. 2009 showed that recombinant Clp1 dephosphorylates Cdk1-phosphorylated Klp9 and Ase1 in vitro, allowing motor and MAP to interact at the spindle midzone and drive anaphase B spindle elongation. Reason: Direct in vitro Ser/Thr phosphatase activity toward two physiological Cdk1 substrates; core activity. Supporting Evidence: PMID:19686686 The cdc2p-phosphorylated klp9p and ase1p products showed significant, but not complete, dephosphorylation by clp1p PMID:19686686 At the onset of anaphase B, clp1p (also known as flp1p (Cueille et al., 2001), homolog of Cdc14) dephosphorylates klp9p and ase1p, allowing them to physically bind to each other at the spindle midzone to initiate spindle elongation. |
| GO:0004722 protein serine/threonine phosphatase activity | IDA PMID:21965289 Nsk1 ensures accurate chromosome segregation by promoting as... | ACCEPT | Summary: Buttrick et al. 2011 identified Nsk1 as a Clp1 substrate: Nsk1 dephosphorylation at anaphase onset is greatly delayed in the substrate-trapping clp1(C286S) mutant, Clp1(C286S) co-immunoprecipitates Nsk1, and dephosphorylation is needed for Nsk1 to relocalize to the kinetochore-SPB junction. Reason: Direct evidence of Ser/Thr phosphatase activity toward a kinetochore substrate. Supporting Evidence: PMID:21965289 In these cells, the proportion of faster-migrating Nsk1 increases only very slowly after release into anaphase, suggesting that Clp1 dephosphorylates Nsk1 (Figure 5, A and B). PMID:21965289 Following dephosphorylation by Clp1 (Cdc14-like) phosphatase and at least one other phosphatase, Nsk1 localizes to the interface between kinetochores and the inner face of the spindle pole body during anaphase. |
| GO:0004722 protein serine/threonine phosphatase activity | IDA PMID:22065639 Cdk1 phosphorylation of the kinetochore protein Nsk1 prevent... | ACCEPT | Summary: Chen et al. 2011 showed that purified MBP-Clp1, but not MBP-Clp1-C286S, dephosphorylates Cdk1-phosphorylated Nsk1 in vitro, and that Nsk1 is hyperphosphorylated in clp1Ξ prometaphase cells. Reason: Direct in vitro dephosphorylation with a catalytic-dead control; core activity. Supporting Evidence: PMID:22065639 After washing out Cdk1, purified MBP-Clp1 but not catalytically inactive MBP-Clp1-C286S dephosphorylated Nsk1 |
| GO:0004722 protein serine/threonine phosphatase activity | IDA PMID:23297348 Comprehensive proteomics analysis reveals new substrates and... | ACCEPT | Summary: Chen et al. 2013 used Clp1-TAP and substrate-trapping Clp1-C286S-TAP proteomics to identify >70 candidate substrates, most carrying Cdk1 sites, and confirmed in vitro dephosphorylation of Cdc11, Shk1, MBF regulators, Klp6, Sap1 and Sep1 by recombinant Clp1 but not C286S. Reason: Comprehensive biochemical demonstration of Ser/Thr (Cdk1-site) phosphatase activity; core activity. Supporting Evidence: PMID:23297348 We confirmed association and dephosphorylation of multiple candidate substrates, including a key scaffolding component of the septation initiation network called Cdc11, an essential kinase of the conserved morphogenesis-related NDR kinase network named Shk1, and multiple Mlu1-binding factor transcriptional regulators. PMID:23297348 Over 100 Clp1-interacting proteins were consistently identified, over 70 of these were enriched in Clp1-C286S-TAP (potential substrates) and we and others detected Cdk1 phosphorylation sites in over half (44/73) of these potential substrates. |
| GO:0004722 protein serine/threonine phosphatase activity | IMP PMID:34080538 Kinesin-6 Klp9 orchestrates spindle elongation by regulating... | ACCEPT | Summary: Krueger et al. 2021 showed that in clp1Ξ cells Dis1 remains in its phosphorylated, pole-restricted state and Klp9 recruitment to the midzone is reduced, so Clp1 dephosphorylates both Dis1 and Klp9 at the metaphase-anaphase B transition. Reason: Mutant-phenotype inference of Ser/Thr phosphatase activity toward Cdk1 sites on Dis1 and Klp9, consistent with the direct in vitro data of PMID:19686686. Supporting Evidence: PMID:34080538 Upon clp1 deletion, Dis1-EGFP was only detected at spindle poles, and not on spindle microtubules during anaphase B (Figure 5BβD), resulting in a decreased Dis1-EGFP intensity along the spindle PMID:34080538 Moreover, clp1 deletion resulted in a significant reduction of the Klp9-mCherry intensity at the spindle midzone (Figure 5B, D, and F, Figure 5βsource data 1). |
| GO:0004725 protein tyrosine phosphatase activity | IEA GO_REF:0000120 | MODIFY | Summary: Automatic EC 3.1.3.48 / RHEA:10684 mapping to protein tyrosine phosphatase activity based on the PTP-superfamily catalytic motif. All characterized Clp1 substrates (Cdc25, Cdc15, Klp9, Ase1, Nsk1, Mde4, Cdc11, Cdc12, Pxl1, Pcr1) are phospho-Ser/Thr-Pro sites deposited by Cdk1; no physiological phosphotyrosine substrate is known, and Clp1 acts on Cdc2 Tyr15 only indirectly, by promoting Cdc25 degradation. Reason: 'Protein tyrosine phosphatase activity' alone misrepresents the enzyme. Cdc14 phosphatases are dual-specificity enzymes whose in vivo activity is directed at Cdk1 pSer/pThr-Pro sites; the fission-yeast literature explicitly describes Flp1/Clp1 as a serine-threonine, proline-directed phosphatase. The appropriate replacement for the EC-derived activity is GO:0008138 protein tyrosine/serine/threonine phosphatase activity (as used for S. cerevisiae Cdc14), with GO:0004722 remaining the physiologically relevant activity. Proposed replacements: protein tyrosine/serine/threonine phosphatase activity Supporting Evidence: PMID:15128870 The Schizosaccaromyces pombe protein Flp1p belongs to a conserved family of serine-threonine-phosphatases. PMID:11448769 In addition to its roles in anaphase, Clp1p regulates the G2/M transition since cells deleted for clp1 enter mitosis precociously and cells overexpressing Clp1p delay mitotic entry. Unlike Cdc14p, Clp1p appears to antagonize Cdk activity by preventing dephosphorylation of Cdc2p on tyrosine. file:SCHPO/clp1/clp1-deep-research-falcon.md The available studies do not establish an endogenous phosphotyrosine substrate for Clp1 |
| GO:0005515 protein binding | IPI PMID:15525536 The S. pombe Cdc14-like phosphatase Clp1p regulates chromoso... | MODIFY | Summary: IPI with the Aurora kinase Ark1 (SPCC320.13c): genetic, cytological and biochemical experiments indicate that Clp1 functions together with Aurora kinase at kinetochores to repair mono-oriented sister kinetochores. Reason: Generic GO:0005515 conveys no functional information. The partner is a protein kinase (Aurora/Ark1) and the interaction is functionally meaningful (Clp1 acts with Ark1 at kinetochores), so GO:0019901 protein kinase binding is the informative, evidence-backed replacement; the interaction is not disputed. Proposed replacements: protein kinase binding Supporting Evidence: PMID:15525536 Genetic, cytological, and biochemical experiments suggest that Clp1p/Flp1p functions together with Aurora kinase at kinetochores. Together, these results suggest that Clp1p/Flp1p has a role in repairing mono-orientation of sister kinetochores. |
| GO:0005515 protein binding | IPI PMID:16085489 The 14-3-3 protein rad24p modulates function of the cdc14p f... | MODIFY | Summary: IPI with the 14-3-3 protein Rad24 (P42656): a Sid2-phosphorylated form of Clp1 binds Rad24, which retains Clp1 in the cytoplasm during cytokinesis and cytokinesis-checkpoint arrest. Reason: Generic GO:0005515 is uninformative; the partner is a 14-3-3 protein and the binding is the mechanism of SIN-dependent cytoplasmic retention of Clp1, so GO:0071889 14-3-3 protein binding is the informative replacement. UniProt records the Clp1-Rad24 interaction with three experiments (IntAct EBI-704737/EBI-704791). Proposed replacements: 14-3-3 protein binding Supporting Evidence: PMID:16085489 Here, we show that a phosphorylated form of Clp1p binds the 14-3-3 protein Rad24p and is retained in the cytoplasm in a Rad24p-dependent manner in response to cytokinesis defects. This physical interaction depends on the function of the SIN component, Sid2p. |
| GO:0005515 protein binding | IPI PMID:18378776 The Clp1/Cdc14 phosphatase contributes to the robustness of ... | REMOVE | Summary: IPI with the anillin-related scaffold Mid1 (SPCC4B3.15): Mid1 was recovered in Clp1-TAP purifications, an internal region of Mid1 (aa 331-534) binds the Clp1 catalytic domain directly, and Mid1 is required for Clp1 recruitment to the contractile ring. Reason: Generic GO:0005515 is uninformative and no evidence-backed, more specific molecular-function term describes the anillin/Mid1 scaffold relationship. The biologically informative content of this interaction (Mid1 tethering Clp1 at the ring) is already captured by the GO:0110085 mitotic actomyosin contractile ring IDA row from the same paper. Removal does not assert that the interaction is false. Supporting Evidence: PMID:18378776 Yeast two-hybrid analysis and in vitro binding assays showed that an internal region of Mid1 (aa 331β534) interacted directly with the N-terminal catalytic domain of Clp1 PMID:18378776 Although Cdc15-CFP formed rings in mid1Ξ cells, Clp1-YFP could not be detected in these rings (0/102 cells). |
| GO:0005515 protein binding | IPI PMID:18951025 The SIN kinase Sid2 regulates cytoplasmic retention of the S... | MODIFY | Summary: IPI with the 14-3-3 protein Rad24 (SPAC8E11.02c): Rad24 binding to Clp1 depends on Sid2 phosphorylation of Clp1 RxxS sites, and loss of these sites (clp1-6A) disrupts the interaction and causes premature return of Clp1 to the nucleolus. Reason: Generic GO:0005515 is uninformative; the partner is a 14-3-3 protein and the interaction is the mechanism of SIN-dependent cytoplasmic retention, so GO:0071889 14-3-3 protein binding is the informative replacement. Proposed replacements: 14-3-3 protein binding Supporting Evidence: PMID:18951025 Mutation of the Sid2 phosphorylation sites on Clp1 disrupts the Clp1-Rad24 interaction and causes Clp1 to return prematurely to the nucleolus during cytokinesis. |
| GO:0005515 protein binding | IPI PMID:19523829 Phosphorylation state defines discrete roles for monopolin i... | REMOVE | Summary: IPI with the monopolin subunit Mde4 (SPBC6B1.04), recovered with the substrate-trapping Clp1-C286S allele but not wild-type Clp1, i.e. a phosphorylation-dependent enzyme-substrate interaction. Reason: Generic GO:0005515 is uninformative. This is an enzyme-substrate relationship: the informative representation is the GO:0004722 phosphatase activity annotation from the same paper with Mde4 as the has_input in a GO-CAM, not a binding term on Clp1. Removal does not assert that the interaction is false. Supporting Evidence: PMID:19523829 Mde4-GFP co-immunoprecipitated with the substrate-trapping mutant, Clp1-C286S-13Myc, but not with wild-type Clp1-13Myc (Figure 1B), suggesting that the interaction between Clp1-C286S and Mde4 is mediated by phosphorylation on Mde4. |
| GO:0005634 nucleus | HDA PMID:16823372 ORFeome cloning and global analysis of protein localization ... | ACCEPT | Summary: Genome-wide ORFeome YFP-tagging localization survey (Matsuyama et al. 2006) placed Clp1 in the nucleus; consistent with its nucleolar sequestration in interphase and nucleoplasmic/kinetochore/spindle distribution in mitosis. Reason: High-throughput localization consistent with all targeted studies; the nucleus is the correct parent for the nucleolar, nucleoplasmic, kinetochore and spindle sites. Supporting Evidence: PMID:16823372 Next, we determined the localization of 4,431 proteins, corresponding to approximately 90% of the fission yeast proteome, by tagging each ORF with the yellow fluorescent protein. |
| GO:0005654 nucleoplasm | IDA PMID:22918952 Multiple protein kinases influence the redistribution of fis... | ACCEPT | Summary: Broadus et al. 2012 showed by live imaging with the nucleolar marker Gar2 that Clp1-GFP redistributes from the nucleolus to the nucleoplasm during interphase upon hydroxyurea or H2O2 treatment, driven by Cds1/Chk1, Pmk1 and Cdk1 phosphorylation. Reason: Direct localization evidence; nucleoplasmic Clp1 is also where it acts on mitotic and stress substrates. Supporting Evidence: PMID:22918952 As previously reported, HU induced relocalization of Clp1-GFP to the nucleoplasm (Figure 1, A and B; Diaz-Cuervo and Bueno, 2008). PMID:22918952 Specifically, the Rad3 checkpoint effector kinases Cds1 and/or Chk1, the cell wall integrity mitogen-activated protein kinase Pmk1, and the cell cycle kinase Cdk1 directly phosphorylate Clp1 to promote genotoxic stress-induced nucleoplasmic accumulation. |
| GO:0005654 nucleoplasm | IMP PMID:23297348 Comprehensive proteomics analysis reveals new substrates and... | ACCEPT | Summary: Chen et al. 2013 identified the importin-beta Sal3 as the sole karyopherin for Clp1: Clp1-GFP was absent from the nucleus at all cell-cycle stages in sal3Ξ, and a C-terminal basic region (R524/K527/K529/K532/R534) is the NLS. Reason: Mutant evidence that Clp1 is actively imported into the nucleus and shuttles through the nucleoplasm to reach nucleolar, kinetochore and spindle sites. Supporting Evidence: PMID:23297348 However, Clp1-GFP was absent from the nucleus in all stages of the cell cycle in sal3 Ξ cells, in contrast to wild-type cells PMID:23297348 Thus, Sal3 is required for Clp1 nuclear import. |
| GO:0005730 nucleolus | IBA GO_REF:0000033 | ACCEPT | Summary: PAINT-inferred nucleolar localization, a conserved feature of Cdc14 phosphatases: Clp1 is sequestered in the nucleolus during interphase and released at mitotic entry (earlier than S. cerevisiae Cdc14). Reason: Phylogenetic inference with direct fission-yeast evidence (Clp1 is legitimately in its own WITH/FROM); the nucleolus is the interphase storage site and central to the enzyme's regulation. Supporting Evidence: PMID:11448769 As cells enter mitosis, Clp1p relocalizes from the nucleolus to the spindle and site of cell division. |
| GO:0005730 nucleolus | IDA PMID:11448769 Fission yeast Clp1p phosphatase regulates G2/M transition an... | ACCEPT | Summary: Direct imaging of Clp1-GFP shows nucleolar localization during interphase, with release at mitotic entry (and, for PMID:22918952, upon genotoxic stress), and SIN/Rad24-dependent exclusion until cytokinesis is completed. Reason: Direct localization evidence reproduced across many studies; nucleolar sequestration is the principal mode of Clp1 regulation. Supporting Evidence: PMID:11448769 As cells enter mitosis, Clp1p relocalizes from the nucleolus to the spindle and site of cell division. |
| GO:0005730 nucleolus | IDA PMID:16085489 The 14-3-3 protein rad24p modulates function of the cdc14p f... | ACCEPT | Summary: Direct imaging of Clp1-GFP shows nucleolar localization during interphase, with release at mitotic entry (and, for PMID:22918952, upon genotoxic stress), and SIN/Rad24-dependent exclusion until cytokinesis is completed. Reason: Direct localization evidence reproduced across many studies; nucleolar sequestration is the principal mode of Clp1 regulation. Supporting Evidence: PMID:16085489 In response to cytokinetic defects, Clp1p, normally nucleolar in interphase, is retained in the cytoplasm until completion of cell division in a SIN-dependent manner. |
| GO:0005730 nucleolus | IDA PMID:18951025 The SIN kinase Sid2 regulates cytoplasmic retention of the S... | ACCEPT | Summary: Direct imaging of Clp1-GFP shows nucleolar localization during interphase, with release at mitotic entry (and, for PMID:22918952, upon genotoxic stress), and SIN/Rad24-dependent exclusion until cytokinesis is completed. Reason: Direct localization evidence reproduced across many studies; nucleolar sequestration is the principal mode of Clp1 regulation. Supporting Evidence: PMID:18951025 Like wild-type Clp1-GFP, Clp1-6A-GFP localized in interphase to the SPB and nucleolus, was released from the nucleolus as cells enter mitosis, localized to the kinetochores and actomyosin ring in early mitosis (Figure S2A). |
| GO:0005730 nucleolus | IDA PMID:22918952 Multiple protein kinases influence the redistribution of fis... | ACCEPT | Summary: Direct imaging of Clp1-GFP shows nucleolar localization during interphase, with release at mitotic entry (and, for PMID:22918952, upon genotoxic stress), and SIN/Rad24-dependent exclusion until cytokinesis is completed. Reason: Direct localization evidence reproduced across many studies; nucleolar sequestration is the principal mode of Clp1 regulation. Supporting Evidence: PMID:22918952 As previously reported, HU induced relocalization of Clp1-GFP to the nucleoplasm (Figure 1, A and B; Diaz-Cuervo and Bueno, 2008). |
| GO:0005730 nucleolus | IEA GO_REF:0000120 | ACCEPT | Summary: Electronic annotation from the UniProt subcellular-location vocabulary (Nucleus, nucleolus). Reason: Correct electronic annotation, supported by extensive direct evidence. Supporting Evidence: PMID:11448769 As cells enter mitosis, Clp1p relocalizes from the nucleolus to the spindle and site of cell division. |
| GO:0005737 cytoplasm | IBA GO_REF:0000033 | ACCEPT | Summary: PAINT-inferred cytoplasmic localization. In fission yeast a Sid2-phosphorylated, Rad24-bound pool of Clp1 is held in the cytoplasm from anaphase until cytokinesis is complete, where it maintains the contractile ring and the cytokinesis checkpoint. Reason: Phylogenetic inference backed by direct evidence in the target itself; cytoplasmic Clp1 has a defined function (contractile-ring maintenance, SIN coupling). Supporting Evidence: PMID:16085489 Here, we show that a phosphorylated form of Clp1p binds the 14-3-3 protein Rad24p and is retained in the cytoplasm in a Rad24p-dependent manner in response to cytokinesis defects. This physical interaction depends on the function of the SIN component, Sid2p. PMID:18951025 In telophase cells where the spindle has broken down but cells have not completed cytokinesis, wild-type Clp1 remained out of the nucleolus in the cytoplasm and faintly at the contractile ring until cytokinesis was completed. |
| GO:0005816 spindle pole body | IBA GO_REF:0000033 | ACCEPT | Summary: PAINT-inferred spindle pole body localization: Clp1-GFP is at the SPB throughout interphase and mitosis, and SPB-localized SIN kinase Sid2 phosphorylates it. Reason: Phylogenetic inference with direct evidence in the target; SPB localization is where Clp1 meets the SIN and its substrate Cdc11. Supporting Evidence: PMID:18951025 Like wild-type Clp1-GFP, Clp1-6A-GFP localized in interphase to the SPB and nucleolus, was released from the nucleolus as cells enter mitosis, localized to the kinetochores and actomyosin ring in early mitosis (Figure S2A). |
| GO:0005816 spindle pole body | IEA GO_REF:0000120 | ACCEPT | Summary: Electronic annotation from the UniProt subcellular-location vocabulary (spindle pole body). Reason: Correct electronic annotation with direct supporting evidence (GO:0044732 rows). Supporting Evidence: PMID:18951025 Like wild-type Clp1-GFP, Clp1-6A-GFP localized in interphase to the SPB and nucleolus, was released from the nucleolus as cells enter mitosis, localized to the kinetochores and actomyosin ring in early mitosis (Figure S2A). |
| GO:0006974 DNA damage response | IMP PMID:22918952 Multiple protein kinases influence the redistribution of fis... | KEEP AS NON CORE | Summary: Broadus et al. 2012 showed that genotoxic stress (hydroxyurea, H2O2) but not heat or osmotic stress causes Clp1 to leave the nucleolus, through direct phosphorylation by the Rad3-dependent checkpoint kinases Cds1/Chk1, Pmk1 and Cdk1; phosphosite mutants that block this relocalization were characterized, and earlier work showed Clp1 release is needed for a normal checkpoint response to HU. Reason: The gene product does respond to genotoxic stress in a checkpoint-kinase-dependent manner, so the term is correct, but the paper leaves the downstream role open (the authors suggest Clp1 may reset checkpoint-substrate phosphostates redundantly with other phosphatases). This is a stress-specific, non-core function relative to the mitotic-exit/cytokinesis roles. Supporting Evidence: PMID:22918952 Specifically, the Rad3 checkpoint effector kinases Cds1 and/or Chk1, the cell wall integrity mitogen-activated protein kinase Pmk1, and the cell cycle kinase Cdk1 directly phosphorylate Clp1 to promote genotoxic stress-induced nucleoplasmic accumulation. PMID:22918952 In contrast, Clp1-GFP did not relocalize to the nucleoplasm in either thermally or osmotically stressed cells (Figure 1, AβC) suggesting that nucleolar release is not a general response to cellular stress. PMID:22918952 Alternatively, Clp1 may be involved in resetting the phosphostate of DNA replication/damage checkpoint substrates after resolution of a genotoxic insult in combination with other phosphatases, and its role may be masked by their presence. |
| GO:0007096 regulation of exit from mitosis | IBA GO_REF:0000033 | ACCEPT | Summary: PAINT-inferred role in regulating exit from mitosis. Clp1 antagonizes Cdk1 in anaphase by dephosphorylating and destabilizing Cdc25 (breaking the Cdc25-Cdc2 feedback loop) and by reversing Cdk1 phosphorylation on Klp9, Ase1, Nsk1, Cdc15, Cdc11 and Pxl1; unlike S. cerevisiae Cdc14 it is not essential for mitotic exit. Reason: Sound placement: the regulatory role is conserved even though its necessity differs between yeasts. Clp1 legitimately appears in its own WITH/FROM. Core function. Supporting Evidence: PMID:23297348 Clp1 promotes mitotic exit by antagonizing the auto-amplification loop of Cdk1 by dephosphorylating Cdc25 PMID:15128870 Here we show that Flp1p is required for rapid degradation of the mitotic inducer Cdc25p at the end of mitosis, and that Cdc25p is a substrate of Flp1p in vitro. Down-regulation of Cdc25p activity by Flp1p may ensure a prompt inactivation of mitotic CDK complexes to trigger cell division. |
| GO:0007096 regulation of exit from mitosis | IEA GO_REF:0000117 | ACCEPT | Summary: ARBA-predicted role in regulation of exit from mitosis, consistent with the Cdc14-family function and the fission-yeast evidence (Cdc25 dephosphorylation, autodephosphorylation, reversal of Cdk1 substrates). Reason: Correct electronic annotation supported by experimental rows (GO:0031536). Supporting Evidence: PMID:23297348 Clp1 promotes mitotic exit by antagonizing the auto-amplification loop of Cdk1 by dephosphorylating Cdc25 |
| GO:0010972 negative regulation of G2/M transition of mitotic cell cycle | IMP PMID:11448769 Fission yeast Clp1p phosphatase regulates G2/M transition an... | ACCEPT | Summary: Trautmann et al. 2001: clp1Ξ cells enter mitosis precociously and Clp1 overexpression delays mitotic entry; Clp1 antagonizes Cdk activity by preventing Cdc2 Tyr15 dephosphorylation (later shown to be via Cdc25 dephosphorylation and degradation). Reason: Direct mutant/overexpression phenotypes establish Clp1 as a negative regulator of the G2/M transition acting on the Cdc25/Wee1-Cdc2 switch; a genuine function distinct from its anaphase roles. Supporting Evidence: PMID:11448769 In addition to its roles in anaphase, Clp1p regulates the G2/M transition since cells deleted for clp1 enter mitosis precociously and cells overexpressing Clp1p delay mitotic entry. Unlike Cdc14p, Clp1p appears to antagonize Cdk activity by preventing dephosphorylation of Cdc2p on tyrosine. |
| GO:0031031 positive regulation of septation initiation signaling | IGI PMID:15265986 The Clp1p/Flp1p phosphatase ensures completion of cytokinesi... | ACCEPT | Summary: IGI with the SIN GAP subunit Cdc16 (SPAC6F6.08c): ectopic SIN activation (cdc16 inactivation) bypasses the requirement for Clp1 for both the cytokinesis-checkpoint G2 delay and completion of cytokinesis, placing Clp1 upstream of / feeding into SIN activity. Clp1 also dephosphorylates the SIN scaffold Cdc11 at Cdk1 sites (PMID:23297348). Reason: Genetic epistasis with cdc16 and the Cdc11 substrate data support a positive input of Clp1 into SIN signaling (Clp1 antagonizes Cdk1, which inhibits the SIN). Core to the cytokinesis-coupling function. Supporting Evidence: PMID:15265986 In addition, we show that Clp1p/Flp1p does not function simply to inhibit further rounds of nuclear division, but also allows damaged actomyosin rings to be maintained to facilitate completion of cell division. Ectopic activation of the SIN significantly bypasses the requirement of Clp1p/Flp1p for G2 delay as well as for completion of cytokinesis. PMID:23297348 We confirmed association and dephosphorylation of multiple candidate substrates, including a key scaffolding component of the septation initiation network called Cdc11, an essential kinase of the conserved morphogenesis-related NDR kinase network named Shk1, and multiple Mlu1-binding factor transcriptional regulators. |
| GO:0031536 positive regulation of exit from mitosis | EXP PMID:34133210 Cdk1 phosphorylation of fission yeast paxillin inhibits its ... | ACCEPT | Summary: Snider et al. 2021 showed that Clp1 (with PP1/Dis2) reverses Cdk1 phosphorylation of paxillin Pxl1 at mitotic exit, part of the general Cdc14 function of reversing Cdk1 substrate phosphorylation to promote exit. Reason: Direct evidence that Clp1 performs a dephosphorylation step of mitotic exit; consistent with its role as the Cdk1-antagonizing phosphatase. Supporting Evidence: PMID:34133210 We determined that both the Cdc14 phosphatase Clp1 and the PP1 phosphatase Dis2 contribute to Pxl1 dephosphorylation at mitotic exit, but PP2B/calcineurin does not. |
| GO:0031536 positive regulation of exit from mitosis | IGI PMID:16950131 Phospho-regulation of the Cdc14/Clp1 phosphatase delays late... | ACCEPT | Summary: Wolfe et al. 2006 (IGI recorded with nda3, the beta-tubulin allele used to synchronise cells) showed that Clp1 activity is inhibited by Cdk1 phosphorylation before anaphase and that Clp1 autodephosphorylation as Cdk1 declines stimulates its activity and the timing of late mitotic events. Reason: Abstract-only cache; the curator read the full text. The abstract clearly supports a positive role for Clp1 activity in late mitotic events (mitotic exit) coupled to Cdk1 inactivation. The nda3 interaction reflects the experimental synchronisation system rather than a pathway partner. Supporting Evidence: PMID:16950131 Cdk1 phosphorylates and inhibits the catalytic activity of the Cdc14 family member, Clp1/Flp1. As Cdk1 activity declines during anaphase progression, Clp1/Flp1 autocatalytically reverses these phosphorylation events to stimulate its own activity. |
| GO:0031536 positive regulation of exit from mitosis | IMP PMID:18418059 The Flp1/Clp1 phosphatase cooperates with HECT-type Pub1/2 p... | ACCEPT | Summary: Esteban et al. 2008: Flp1 is required for the rapid degradation of Cdc25 at the end of mitosis, which prevents Cdc2 Tyr15 dephosphorylation and contributes to timely inactivation of mitotic CDK; flp1 interacts genetically with the HECT ligase pub1. Reason: Mutant evidence that Clp1 promotes Cdk1 inactivation (through Cdc25 turnover) at mitotic exit; core function. Supporting Evidence: PMID:18418059 We show that Flp1p is required for the rapid degradation of Cdc25p while Pub1p is responsible for the long-term destabilization of the mitotic inducer. PMID:18418059 Cdc25p degradation prevents Cdc2p-tyrosine 15 dephosphorylation and, thus, contributes to the timely inactivation of mitotic CDK-associated kinase activity. |
| GO:0032153 cell division site | IDA PMID:11448769 Fission yeast Clp1p phosphatase regulates G2/M transition an... | ACCEPT | Summary: Trautmann et al. 2001 imaged Clp1 relocalizing from the nucleolus to the spindle and the site of cell division as cells enter mitosis. Reason: Direct localization to the division site, later resolved as the Mid1-tethered contractile ring (GO:0110085 rows). Supporting Evidence: PMID:11448769 As cells enter mitosis, Clp1p relocalizes from the nucleolus to the spindle and site of cell division. |
| GO:0032467 positive regulation of cytokinesis | IBA GO_REF:0000033 | ACCEPT | Summary: PAINT-inferred positive regulation of cytokinesis. Clp1 at the contractile ring dephosphorylates Cdc15 and Cdc12, reduces ring-protein mobility, makes the ring resistant to mild perturbation and, via Cdc11 and the SIN, allows damaged rings to be maintained until cytokinesis completes. Reason: Sound phylogenetic placement with strong direct evidence in the target (PMID:15265986, PMID:18378776, PMID:29343550). Core function. Supporting Evidence: PMID:18378776 By generating a mutation in mid1 that selectively disrupts Clp1/Flp1 tethering, we reveal the specific functional consequences of Clp1/Flp1 activity at the CR, including dephosphorylation of the essential CR component Cdc15, reductions in CR protein mobility, and CR resistance to mild perturbation. PMID:15265986 In addition, we show that Clp1p/Flp1p does not function simply to inhibit further rounds of nuclear division, but also allows damaged actomyosin rings to be maintained to facilitate completion of cell division. Ectopic activation of the SIN significantly bypasses the requirement of Clp1p/Flp1p for G2 delay as well as for completion of cytokinesis. |
| GO:0032954 regulation of cytokinetic process | IEA GO_REF:0000117 | ACCEPT | Summary: ARBA-predicted regulation of cytokinetic process, consistent with Clp1's roles in contractile-ring maintenance and the cytokinesis checkpoint. Reason: Correct, if generic, electronic annotation; specifics are in the GO:0032467, GO:1903490, GO:1903501 and GO:0044878 rows. Supporting Evidence: PMID:15265986 Here we show that delays in cytokinesis caused by minor perturbations to different components of the cytokinetic machinery, which normally cause only mild defects, become lethal when Clp1p/Flp1p is inactivated. |
| GO:0033554 cellular response to stress | IEA GO_REF:0000117 | KEEP AS NON CORE | Summary: ARBA-predicted cellular response to stress. Clp1 redistributes from the nucleolus to the nucleoplasm specifically upon genotoxic stress (HU, H2O2) but not heat or osmotic stress, and restrains the oxidative-stress transcriptional response by dephosphorylating Pcr1 (Canete et al. 2023, not in GOA). Reason: Supported in broad terms by the genotoxic/oxidative stress work, but generic and clearly non-core relative to the mitotic-exit and cytokinesis functions. Supporting Evidence: PMID:22918952 In contrast, Clp1-GFP did not relocalize to the nucleoplasm in either thermally or osmotically stressed cells (Figure 1, AβC) suggesting that nucleolar release is not a general response to cellular stress. file:SCHPO/clp1/clp1-deep-research-falcon.md Once released, Clp1 associates with Atf1/Pcr1 and directly dephosphorylates Pcr1, constraining transcription driven by Atf1/Pcr1 and, directly or indirectly, Pap1. |
| GO:0044732 mitotic spindle pole body | HDA PMID:16823372 ORFeome cloning and global analysis of protein localization ... | ACCEPT | Summary: Genome-wide YFP-tagging survey placed Clp1 at the mitotic spindle pole body, matching targeted studies. Reason: High-throughput localization consistent with direct evidence. Supporting Evidence: PMID:16823372 Next, we determined the localization of 4,431 proteins, corresponding to approximately 90% of the fission yeast proteome, by tagging each ORF with the yellow fluorescent protein. |
| GO:0044732 mitotic spindle pole body | IDA PMID:11448769 Fission yeast Clp1p phosphatase regulates G2/M transition an... | ACCEPT | Summary: Direct imaging shows Clp1-GFP at the spindle pole body in interphase and throughout mitosis; the SIN kinase Sid2 at the SPB phosphorylates Clp1 and the SPB scaffold Cdc11 is a Clp1 substrate. Reason: Direct localization; the SPB is where Clp1 is regulated by, and feeds back on, the septation initiation network. Supporting Evidence: PMID:11448769 As cells enter mitosis, Clp1p relocalizes from the nucleolus to the spindle and site of cell division. |
| GO:0044732 mitotic spindle pole body | IDA PMID:16085489 The 14-3-3 protein rad24p modulates function of the cdc14p f... | ACCEPT | Summary: Direct imaging shows Clp1-GFP at the spindle pole body in interphase and throughout mitosis; the SIN kinase Sid2 at the SPB phosphorylates Clp1 and the SPB scaffold Cdc11 is a Clp1 substrate. Reason: Direct localization; the SPB is where Clp1 is regulated by, and feeds back on, the septation initiation network. Supporting Evidence: PMID:16085489 In response to cytokinetic defects, Clp1p, normally nucleolar in interphase, is retained in the cytoplasm until completion of cell division in a SIN-dependent manner. |
| GO:0044732 mitotic spindle pole body | IDA PMID:18951025 The SIN kinase Sid2 regulates cytoplasmic retention of the S... | ACCEPT | Summary: Direct imaging shows Clp1-GFP at the spindle pole body in interphase and throughout mitosis; the SIN kinase Sid2 at the SPB phosphorylates Clp1 and the SPB scaffold Cdc11 is a Clp1 substrate. Reason: Direct localization; the SPB is where Clp1 is regulated by, and feeds back on, the septation initiation network. Supporting Evidence: PMID:18951025 Like wild-type Clp1-GFP, Clp1-6A-GFP localized in interphase to the SPB and nucleolus, was released from the nucleolus as cells enter mitosis, localized to the kinetochores and actomyosin ring in early mitosis (Figure S2A). |
| GO:0044878 mitotic cytokinesis checkpoint signaling | IGI PMID:11448769 Fission yeast Clp1p phosphatase regulates G2/M transition an... | ACCEPT | Summary: IGI with the beta-glucan synthase Bgs1/Cps1 (SPBC19G7.05c; cps1-191 is the classic cytokinesis-checkpoint arrest allele): Clp1 functions together with the SIN so that cells with defective cytokinesis delay further nuclear division until cytokinesis is completed. Reason: Foundational genetic evidence (abstract-only cache; the curator read the full text) that Clp1 is a component of the cytokinesis checkpoint; core function. Supporting Evidence: PMID:11448769 We have identified the S. pombe Cdc14p homolog, Clp1p, and show that it is not required for mitotic exit but rather functions together with the SIN in coordinating cytokinesis with the nuclear-division cycle. PMID:11448769 Clp1p exit from the nucleolus does not depend on the SIN, but the SIN is required for keeping Clp1p out of the nucleolus until completion of cytokinesis. Clp1p, in turn, may promote the activation of the SIN by antagonizing Cdk activity until cytokinesis is complete and thus ensuring that cytokinesis is completed prior to the initiation of the next cell cycle. |
| GO:0044878 mitotic cytokinesis checkpoint signaling | IMP PMID:15265986 The Clp1p/Flp1p phosphatase ensures completion of cytokinesi... | ACCEPT | Summary: Mishra et al. 2004 showed that Clp1 is required for the G2 delay and survival of cells whose cytokinetic machinery is mildly perturbed, and that it also allows damaged actomyosin rings to be maintained; ectopic SIN activation bypasses the requirement. Reason: Direct mutant evidence establishing the physiological relevance of the Clp1-dependent cytokinesis checkpoint; core function. Supporting Evidence: PMID:15265986 Here we show that delays in cytokinesis caused by minor perturbations to different components of the cytokinetic machinery, which normally cause only mild defects, become lethal when Clp1p/Flp1p is inactivated. PMID:15265986 In addition, we show that Clp1p/Flp1p does not function simply to inhibit further rounds of nuclear division, but also allows damaged actomyosin rings to be maintained to facilitate completion of cell division. Ectopic activation of the SIN significantly bypasses the requirement of Clp1p/Flp1p for G2 delay as well as for completion of cytokinesis. |
| GO:0044878 mitotic cytokinesis checkpoint signaling | IMP PMID:16085489 The 14-3-3 protein rad24p modulates function of the cdc14p f... | ACCEPT | Summary: Mishra et al. 2005 showed that the checkpoint requires Clp1 to be retained in the cytoplasm by Sid2-dependent binding to 14-3-3 Rad24 in response to cytokinetic defects; without Rad24, SIN signaling is not maintained and cells lose viability under mild cytokinetic stress. Reason: Direct evidence for the mechanism of Clp1 participation in cytokinesis-checkpoint signaling; core function. Supporting Evidence: PMID:16085489 This checkpoint mechanism requires the function of the Cdc14p-family phosphatase Clp1p/Flp1p and the septation initiation network (SIN). PMID:16085489 Here, we show that a phosphorylated form of Clp1p binds the 14-3-3 protein Rad24p and is retained in the cytoplasm in a Rad24p-dependent manner in response to cytokinesis defects. This physical interaction depends on the function of the SIN component, Sid2p. |
| GO:0072479 response to mitotic cell cycle spindle assembly checkpoint signaling | IMP PMID:15525536 The S. pombe Cdc14-like phosphatase Clp1p regulates chromoso... | UNDECIDED | Summary: Trautmann et al. 2004 report that clp1Ξ causes cosegregation of sister chromatids when kinetochores are prone to mono-orientation and that Clp1 works with Aurora kinase at kinetochores. The cached abstract does not describe an experiment on spindle-assembly-checkpoint signaling. Reason: Only the abstract is cached, and it supports a biorientation/mono-orientation repair role (captured by the GO:0140429 IMP row) rather than a process occurring in response to SAC signaling. The curator read the full text and may have used data (e.g. checkpoint-dependent delay or drug sensitivity) not visible here, so the annotation is neither confirmed nor challenged; it should be re-examined with the full text and may be better represented by a kinetochore-attachment term. Supporting Evidence: PMID:15525536 Here, we report that Clp1p/Flp1p localizes to kinetochores in prometaphase and functions in chromosome segregation, since deletion of clp1/flp1 causes cosegregation of sister chromatids, when sister kinetochores are prone to mono-orientation. |
| GO:0072686 mitotic spindle | IBA GO_REF:0000033 | ACCEPT | Summary: PAINT-inferred mitotic spindle localization; Clp1 decorates the spindle from prometaphase and concentrates at the midzone in anaphase B where it dephosphorylates Klp9 and Ase1. Reason: Phylogenetic inference with direct evidence in the target (legitimately in its own WITH/FROM); the spindle is a site of core activity. Supporting Evidence: PMID:19686686 In contrast, clp1p appeared to concentrate at the spindle midzone during anaphase B in an antagonistic manner |
| GO:0072686 mitotic spindle | IDA PMID:11448769 Fission yeast Clp1p phosphatase regulates G2/M transition an... | ACCEPT | Summary: Direct imaging shows Clp1-GFP on the mitotic spindle after nucleolar release at mitotic entry. Reason: Direct localization; consistent across studies and with the spindle substrates Klp9, Ase1, Dis1 and Mde4. Supporting Evidence: PMID:11448769 As cells enter mitosis, Clp1p relocalizes from the nucleolus to the spindle and site of cell division. |
| GO:0072686 mitotic spindle | IDA PMID:16085489 The 14-3-3 protein rad24p modulates function of the cdc14p f... | ACCEPT | Summary: Direct imaging shows Clp1-GFP on the mitotic spindle after nucleolar release at mitotic entry. Reason: Direct localization; consistent across studies and with the spindle substrates Klp9, Ase1, Dis1 and Mde4. Supporting Evidence: PMID:16085489 In response to cytokinetic defects, Clp1p, normally nucleolar in interphase, is retained in the cytoplasm until completion of cell division in a SIN-dependent manner. |
| GO:0110085 mitotic actomyosin contractile ring | IDA PMID:16085489 The 14-3-3 protein rad24p modulates function of the cdc14p f... | ACCEPT | Summary: Mishra et al. 2005 imaged Clp1 at the actomyosin ring/division site, where its Rad24-dependent cytoplasmic retention supports ring maintenance during cytokinetic stress. Reason: Direct localization (abstract-only cache; corroborated by PMID:18378776 and PMID:18951025). Supporting Evidence: PMID:16085489 In response to cytokinetic defects, Clp1p, normally nucleolar in interphase, is retained in the cytoplasm until completion of cell division in a SIN-dependent manner. |
| GO:0110085 mitotic actomyosin contractile ring | IDA PMID:18378776 The Clp1/Cdc14 phosphatase contributes to the robustness of ... | ACCEPT | Summary: Clifford et al. 2008 showed that Clp1-YFP colocalizes with Cdc15-CFP in rings in 97% of arrested cells and is absent from rings in mid1Ξ (0/102 cells); Mid1 tethers Clp1 at the contractile ring so it can dephosphorylate Cdc15 and stabilize the ring. Reason: Direct localization with a defined recruitment mechanism and function at the ring; core site of activity. Supporting Evidence: PMID:18378776 Although Cdc15-CFP formed rings in mid1Ξ cells, Clp1-YFP could not be detected in these rings (0/102 cells). PMID:18378776 By generating a mutation in mid1 that selectively disrupts Clp1/Flp1 tethering, we reveal the specific functional consequences of Clp1/Flp1 activity at the CR, including dephosphorylation of the essential CR component Cdc15, reductions in CR protein mobility, and CR resistance to mild perturbation. |
| GO:0110085 mitotic actomyosin contractile ring | IDA PMID:18951025 The SIN kinase Sid2 regulates cytoplasmic retention of the S... | ACCEPT | Summary: Chen et al. 2008 imaged Clp1-GFP at the actomyosin ring in early mitosis and faintly at the contractile ring during telophase until cytokinesis completed; the clp1-6A mutant that cannot be retained in the cytoplasm is sensitive to ring perturbation. Reason: Direct localization; core site of activity. Supporting Evidence: PMID:18951025 Like wild-type Clp1-GFP, Clp1-6A-GFP localized in interphase to the SPB and nucleolus, was released from the nucleolus as cells enter mitosis, localized to the kinetochores and actomyosin ring in early mitosis (Figure S2A). PMID:18951025 In telophase cells where the spindle has broken down but cells have not completed cytokinesis, wild-type Clp1 remained out of the nucleolus in the cytoplasm and faintly at the contractile ring until cytokinesis was completed. |
| GO:0120105 mitotic actomyosin contractile ring, intermediate layer | IDA PMID:28914606 Nanoscale architecture of the Schizosaccharomyces pombe cont... | ACCEPT | Summary: Super-resolution (FPALM) mapping of the contractile ring by McDonald et al. 2017 placed Clp1 at a low-to-intermediate elevation (136 nm) in the intermediate stratum, near its scaffold Mid1 and its ring substrates Cdc15, Blt1, Rng2, Cyk3, Myp2 and Orb2. Reason: Direct nanoscale localization consistent with the Mid1-tethering mechanism; a refinement of GO:0110085. Supporting Evidence: PMID:28914606 Furthermore, the Clp1 phosphatase is present at a low-to-intermediate level (136 nm), near its scaffold Mid1 (Clifford et al., 2008) and known and predicted ring substrates Cdc15, Blt1, Rng2, Cyk3, Myp2, and Orb2 (Clifford et al., 2008; Chen et al., 2013). |
| GO:0140429 positive regulation of mitotic sister chromatid biorientation | IGI PMID:22264609 A role for metaphase spindle elongation forces in correction... | MODIFY | Summary: IGI with monopolin Mde4 (SPBC6B1.04). Choi & McCollum 2012 found that clp1Ξ suppresses (reduces) lagging chromosomes in mde4Ξ and swi6Ξ cells whereas nuclear-enriched Clp1-NLS increases them: Clp1 antagonizes correction of merotelic attachments, by dephosphorylating Klp9 and thereby increasing metaphase spindle length and lowering kinetochore tension. Reason: GO:0140429 absorbed the former term GO:0098783 'repair of mitotic merotelic kinetochore attachment defect' (secondary id, merged 2020), which is presumably what this row was originally annotated to. Under the merged 'positive regulation' label the row now asserts the wrong direction: the cached full text states explicitly that Clp1 antagonizes merotelic correction. GO has no negative-regulation counterpart, so the direction-neutral GO:0051988 regulation of attachment of spindle microtubules to kinetochore is proposed, which accurately captures Clp1's Klp9-dependent modulation of kinetochore-microtubule attachment/tension without misstating the sign. The separate IMP row from PMID:15525536 (mono-orientation repair) remains a correct positive-regulation annotation. Proposed replacements: regulation of attachment of spindle microtubules to kinetochore Supporting Evidence: PMID:22264609 Conversely, increasing Clp1 activity in the nucleus using the clp1-NLS allele [13] caused an increase in the lagging chromosome frequency (Figure 1E), showing that Clp1 antagonizes correction of merotelic attachments. PMID:22264609 we discovered that deletion of the Cdc14-family phosphatase gene clp1 significantly reduced the lagging chromosome frequency in both monopolin (mde4Ξ; P<0.01) and heterochromatin (swi6Ξ; P<0.01) mutants PMID:22264609 Cdk1 phosphorylation of Klp9 inhibits its localization to the spindle in early mitosis, and Clp1-mediated dephosphorylation of Klp9 allows it to promote spindle elongation in anaphase [20], but it was not clear whether Klp9 functions in spindle length control in metaphase. |
| GO:0140429 positive regulation of mitotic sister chromatid biorientation | IMP PMID:15525536 The S. pombe Cdc14-like phosphatase Clp1p regulates chromoso... | ACCEPT | Summary: Trautmann et al. 2004: deletion of clp1 causes cosegregation of sister chromatids when sister kinetochores are prone to mono-orientation, and Clp1 acts with Aurora kinase at kinetochores to repair mono-oriented attachments (the former GO:1990598 'repair of mitotic mono-orientation defect', now merged into this term). Reason: Direct mutant evidence (abstract-only cache; corroborated by the Nsk1 and Mde4 kinetochore-substrate papers and the minichromosome-loss data of PMID:21965289) that Clp1 promotes sister-chromatid biorientation. Supporting Evidence: PMID:15525536 Here, we report that Clp1p/Flp1p localizes to kinetochores in prometaphase and functions in chromosome segregation, since deletion of clp1/flp1 causes cosegregation of sister chromatids, when sister kinetochores are prone to mono-orientation. PMID:15525536 Genetic, cytological, and biochemical experiments suggest that Clp1p/Flp1p functions together with Aurora kinase at kinetochores. Together, these results suggest that Clp1p/Flp1p has a role in repairing mono-orientation of sister kinetochores. |
| GO:0140602 nucleolar peripheral inclusion body | IDA PMID:33176152 Acute Heat Stress Leads to Reversible Aggregation of Nuclear... | KEEP AS NON CORE | Summary: Gallardo et al. 2020 showed that acute heat stress drives reversible aggregation of many nuclear and nucleolar proteins, including cell-cycle regulators such as Clp1, into nucleolar rings (NuRs) at the nucleolar periphery, from which they are released on return to permissive temperature. Reason: Abstract-only cache; the curator read the full text. The localization is real but describes reversible sequestration under acute heat stress rather than a site of Clp1 activity, so it is kept as non-core. Supporting Evidence: PMID:33176152 NuRs sequester essential factors required for nuclear mRNA metabolism and nuclear pore complex function, as well as cell-cycle regulators. When cells are switched back to growing temperatures, NuRs disaggregate, and their components relocate to their functional environments in an Hsf1- and Hsp104-dependent manner |
| GO:0140602 nucleolar peripheral inclusion body | IDA PMID:37128864 CDK actively contributes to establishment of the stationary ... | KEEP AS NON CORE | Summary: Hiraoka et al. 2023 examined nuclear reorganization in stationary phase, in which nuclear proteins including Clp1 accumulate in nucleolar peripheral inclusion bodies as cells enter the glucose-depleted quiescent state. Reason: Abstract-only cache (the abstract does not mention Clp1; the curator read the full text). A starvation-specific sequestration site, not a site of activity; non-core. Supporting Evidence: PMID:37128864 Furthermore, Cdc2 accumulates in the nucleolus. Most of these changes are induced by glucose depletion. |
| GO:1902846 positive regulation of mitotic spindle elongation | EXP PMID:28178520 Identification of a Sgo2-Dependent but Mad2-Independent Path... | ACCEPT | Summary: Meadows et al. 2017: Clp1 dephosphorylates Klp9 so that Klp9 and the CPC concentrate at the anaphase midzone; clp1Ξ and clp1(C286S) cells show a normal spindle-pole separation rate but a significantly increased frequency of anaphase B spindle collapse. Reason: Supports a positive role for Clp1 in sustaining anaphase B spindle elongation (fewer collapses), even though this paper found no rate change; the rate effect is documented in PMID:19686686 and PMID:34080538. Supporting Evidence: PMID:28178520 Moreover, we find no difference in the rate of spindle pole separation in Ξclp1 or clp1(C286S) cells (in cells not displaying lagging sister chromatids) compared with that observed in wild-type cells, although the frequency of anaphase B spindle collapse increases significantly (Figure S2B). PMID:28178520 Consistently, we find that both Klp9 and the CPC fail to concentrate at the anaphase spindle midzone in clp1(C286S) cells, which express a catalytically inactive allele of the Clp1 (CDC14) phosphatase (Wolfe et al., 2006). |
| GO:1902846 positive regulation of mitotic spindle elongation | IMP PMID:19686686 Phospho-regulated interaction between kinesin-6 Klp9p and mi... | ACCEPT | Summary: Fu et al. 2009: the phosphatase-inactive clp1off mutant fails to focus Klp9 and Ase1 at the midzone and halves anaphase B spindle elongation velocity (0.35 vs 0.68 um/min); Clp1 dephosphorylation of Klp9 and Ase1 at anaphase B onset allows the motor-MAP interaction that drives elongation. Reason: Direct mutant evidence with a defined mechanism; core function of nuclear Clp1. Supporting Evidence: PMID:19686686 whereas wildtype cells exhibited stereotypical anaphase B velocity (0.68 Β± 0.09 n=11 ΞΌm/min), mutants clp1off and ase1S>D-klp9S>D cells showed significantly decreased spindle velocities (0.35 Β± 0.05 n=9 and 0.48 Β± 0.08 n=12 ΞΌm/min, respectively) PMID:19686686 At the onset of anaphase B, clp1p (also known as flp1p (Cueille et al., 2001), homolog of Cdc14) dephosphorylates klp9p and ase1p, allowing them to physically bind to each other at the spindle midzone to initiate spindle elongation. |
| GO:1903490 positive regulation of mitotic cytokinesis | IMP PMID:15128870 A role for the Cdc14-family phosphatase Flp1p at the end of ... | ACCEPT | Summary: Esteban et al. 2004: Flp1 is required for rapid Cdc25 degradation at the end of mitosis, which promptly inactivates mitotic CDK to trigger cell division and coordinate cytokinesis with other cell-cycle events. Reason: Mutant evidence that Clp1 promotes mitotic cytokinesis by lowering Cdk1 activity at the end of mitosis; consistent with its ring-level substrates (Cdc15, Cdc12) and the cytokinesis-checkpoint role. Supporting Evidence: PMID:15128870 Here we show that Flp1p is required for rapid degradation of the mitotic inducer Cdc25p at the end of mitosis, and that Cdc25p is a substrate of Flp1p in vitro. Down-regulation of Cdc25p activity by Flp1p may ensure a prompt inactivation of mitotic CDK complexes to trigger cell division. |
| GO:1903501 positive regulation of mitotic actomyosin contractile ring assembly | EXP PMID:29343550 Cdk1-dependent phosphoinhibition of a formin-F-BAR interacti... | ACCEPT | Summary: Willet et al. 2018: Cdk1 phosphorylation of the formin Cdc12 inhibits its interaction with the F-BAR protein Cdc15 and opposes ring formation; Clp1 dephosphorylates these Cdk1 sites, allowing maximal Cdc12 accumulation at the contractile ring. Reason: Direct biochemical and localization evidence that Clp1 activity promotes contractile-ring assembly; matches the GO-CAM model 67f85f2b00002096 which places Clp1 phosphatase activity in this process at the ring. Supporting Evidence: PMID:29343550 At least some Cdk1 phosphosites on Cdc12 are dephosphorylated by Clp1, a member of the Cdc14 phosphatase family, thereby allowing maximal Cdc12 accumulation at the CR. PMID:29343550 Consistent with Cdk1 phosphorylating Cdc12 in vivo, Cdc12-HA3 showed increased gel mobility when incubated with recombinant MBP-Clp1 in comparison with Cdc12-HA3 not incubated with protein or incubated with an inactive form of Clp1 (Figure 1D). |
| GO:1990023 mitotic spindle midzone | EXP PMID:28178520 Identification of a Sgo2-Dependent but Mad2-Independent Path... | ACCEPT | Summary: Meadows et al. 2017 examined Clp1-dependent recruitment of Klp9 and the CPC to the anaphase spindle midzone; Clp1 itself concentrates at the midzone in anaphase B (PMID:19686686). Reason: The curator had the full text; the cached text documents Clp1 activity at the midzone (Klp9-CPC recruitment) and the midzone localization itself is directly shown by PMID:19686686. Supporting Evidence: PMID:28178520 Consistently, we find that both Klp9 and the CPC fail to concentrate at the anaphase spindle midzone in clp1(C286S) cells, which express a catalytically inactive allele of the Clp1 (CDC14) phosphatase (Wolfe et al., 2006). |
| GO:1990023 mitotic spindle midzone | IDA PMID:19686686 Phospho-regulated interaction between kinesin-6 Klp9p and mi... | ACCEPT | Summary: Fu et al. 2009 imaged Clp1 concentrating at the spindle midzone during anaphase B, reciprocal to Cdc2/Cdc13, where it dephosphorylates Klp9 and Ase1. Reason: Direct localization to the midzone, the site of the spindle-elongation function. Supporting Evidence: PMID:19686686 In contrast, clp1p appeared to concentrate at the spindle midzone during anaphase B in an antagonistic manner |
| GO:1990023 mitotic spindle midzone | IDA PMID:25963819 Nucleocytoplasmic transport in the midzone membrane domain c... | ACCEPT | Summary: Lucena et al. 2015 analysed the localization and dynamics of GFP-tagged spindle-disassembly regulators, including Clp1, at the midzone membrane domain in wild-type and imp1Ξ cells. Reason: Direct localization consistent with PMID:19686686; the cached text confirms Clp1 was among the GFP-tagged midzone proteins analysed. Supporting Evidence: PMID:25963819 the Clp1 phosphatase (Cueille et al., 2001; Trautmann et al., 2001; Fu et al., 2009), which are known regulators of spindle disassembly in budding yeast. |
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Download this section (compressed HTML)Q: Which of the >70 substrate-trapping (Clp1-C286S) candidates from PMID:23297348 are direct in vivo substrates, and does Clp1 have any physiological phosphotyrosine substrate that would justify retaining a protein tyrosine phosphatase annotation?
Q: How should the opposite-sign effects of Clp1 on kinetochore attachment be represented: it repairs mono-oriented sister kinetochores with Aurora/Ark1 (PMID:15525536) yet antagonizes correction of merotelic attachments by lengthening the metaphase spindle via Klp9 (PMID:22264609), and GO currently offers only a positive-regulation term for biorientation?
Q: What is the downstream effector of nucleoplasmic Clp1 after genotoxic stress (PMID:22918952): does it reset checkpoint-substrate phosphostates redundantly with other phosphatases, or act mainly through stress transcription factors such as Pcr1?
Experiment: Phosphoproteomics (including phosphotyrosine enrichment) comparing wild-type, clp1Ξ and clp1-C286S cells released synchronously from an nda3-KM311 prometaphase block, cross-referenced with the Clp1-C286S substrate-trap interactome, to define the direct in vivo substrate set and test for any Clp1-dependent phosphotyrosine sites.
Hypothesis: Clp1 preferentially dephosphorylates Cdk1 pSer/pThr-Pro sites and has no phosphotyrosine substrates in vivo.
Type: phosphoproteomics
Experiment: Score lagging chromosomes and inter-kinetochore distance in clp1-NLS and clp1Ξ cells combined with phospho-deficient (klp9-3A) and phospho-mimetic (klp9-3D) Klp9 alleles, and with ark1 hypomorphs, to separate the spindle-length (merotelic) pathway from the Aurora-dependent mono-orientation repair pathway.
Hypothesis: Clp1 regulates kinetochore-microtubule attachment fidelity through Klp9-dependent control of metaphase spindle length rather than through a kinetochore-intrinsic substrate.
Type: genetic interaction and live-cell imaging
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