id: P10815
gene_symbol: cdc13
product_type: PROTEIN
status: DRAFT
taxon:
  id: NCBITaxon:284812
  label: Schizosaccharomyces pombe (strain 972 / ATCC 24843)
description: >-
  Cdc13 (p56cdc13) is the major mitotic B-type cyclin (cyclin AB subfamily) of the
  fission yeast Schizosaccharomyces pombe. It is the essential regulatory partner of
  the cyclin-dependent kinase Cdc2 (CDK1); together the Cdc13-Cdc2 complex constitutes
  M-phase-promoting factor (MPF), the principal driver of mitotic entry and progression.
  Cdc13 levels rise steadily through G2 and the complex is activated at the G2/M transition
  (requiring Cdc25 and CAK/Thr167 phosphorylation of Cdc2), then Cdc13 is abruptly
  destroyed at anaphase by APC/C-mediated, destruction-box-dependent proteolysis, behaving
  as a classic cyclin. Cdc13 binding also dictates the catalytic properties, substrate
  selection and subcellular localization of Cdc2: the complex concentrates in the nucleus,
  is enriched at the spindle pole body (SPB, the centrosome equivalent) in G2 via the
  cyclin hydrophobic patch and a Polo-kinase-dependent mechanism, and decorates the
  mitotic spindle and spindle midzone during mitosis. Cdc13-Cdc2 also associates stably
  with ORC-bound replication origins, enforcing the dependence of S phase on an intervening
  mitosis and preventing re-replication, and it contributes to the mitotic DNA damage
  response, chromosome bi-orientation and merotelic-attachment correction. A single
  Cdc13-Cdc2 complex is sufficient to drive both the mitotic and the meiotic cell cycle;
  in meiosis the stability of Cdc13 is specifically controlled (stabilized by Mes1 between
  meiosis I and II to permit MII, then degraded by the Mfr1-activated APC/C at the end of
  meiosis II to license sporulation). Cdc13 is negatively regulated during G1 by the CDK
  inhibitor Rum1, which promotes its proteolysis.
existing_annotations:
- term:
    id: GO:0005815
    label: microtubule organizing center
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  qualifier: is_active_in
  review:
    summary: >-
      Phylogenetic (IBA) annotation to the microtubule organizing center. Cdc13-Cdc2
      is genuinely enriched at the spindle pole body (the fungal MTOC/centrosome
      equivalent) in G2 and mitosis, so the term is correct, though the more specific
      experimentally supported terms (mitotic spindle pole body) are preferred.
    action: KEEP_AS_NON_CORE
    reason: >-
      Localization to the SPB/MTOC is well supported experimentally but is a context for
      the core kinase-regulator function rather than a core function itself; a more
      specific SPB term is available.
    supported_by:
    - reference_id: PMID:32084401
      supporting_text: >-
        the hydrophobic patch targets Cdc13 to the yeast centrosome equivalent, the
        spindle pole body (SPB)
      reference_section_type: ABSTRACT
- term:
    id: GO:0000307
    label: cyclin-dependent protein kinase holoenzyme complex
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  qualifier: part_of
  review:
    summary: >-
      Cdc13 is a B-type cyclin that forms a stable complex with the catalytic subunit
      Cdc2 (CDK1); this complex is the cyclin-dependent protein kinase holoenzyme. The
      IBA assignment is strongly supported by direct experimental evidence.
    action: ACCEPT
    reason: >-
      Direct biochemical evidence shows Cdc13 forms a stable kinase-active complex with
      Cdc2, consistent with the CDK holoenzyme complex.
    supported_by:
    - reference_id: PMID:2569363
      supporting_text: >-
        The products of the cdc13+ and cdc2+ genes form a stable complex that displays
        protein kinase activity in vitro.
      reference_section_type: ABSTRACT
- term:
    id: GO:0016538
    label: cyclin-dependent protein serine/threonine kinase regulator activity
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  qualifier: enables
  review:
    summary: >-
      Core molecular function. As the mitotic B-type cyclin, Cdc13 binds Cdc2 and
      regulates both its catalytic activity and localization, the defining function of a
      cyclin. Strongly supported by both phylogenetic inference and direct experiment.
    action: ACCEPT
    reason: >-
      The cyclin regulatory function of Cdc13 toward the Cdc2 CDK is the central,
      well-established function of this gene product.
    supported_by:
    - reference_id: PMID:2569363
      supporting_text: >-
        These observations suggest that the cdc13+-encoded cyclin acts to regulate both
        the catalytic properties and the localization of the protein kinase of which it
        is a subunit.
      reference_section_type: ABSTRACT
- term:
    id: GO:0007089
    label: traversing start control point of mitotic cell cycle
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  qualifier: involved_in
  review:
    summary: >-
      IBA annotation to passage through Start (G1/S commitment). Cdc13 is the mitotic
      cyclin whose endogenous role is the G2/M transition; in wild-type cells Start and
      G1/S are executed by the G1/S cyclins Cig1, Cig2 and Puc1. Although an engineered
      single Cdc13-Cdc2 complex can drive S phase when it is the only cyclin, this does
      not reflect the normal Start function of Cdc13 and is best treated as an
      over-annotation for the endogenous protein.
    action: MARK_AS_OVER_ANNOTATED
    reason: >-
      The native function of Cdc13 is at G2/M, not at Start; G1/S commitment is normally
      carried out by other cyclins, so the phylogenetically transferred Start annotation
      overstates the endogenous role.
    supported_by:
    - reference_id: PMID:32084401
      supporting_text: >-
        Although, in wild-type cells, the G1/S cyclins Cig1 and Cig2 are expressed in G1
        to execute DNA replication, in this situation, Cdc13 is expressed in G1 and
        compensates for their loss
      reference_section_type: RESULTS
- term:
    id: GO:0005634
    label: nucleus
  evidence_type: IEA
  original_reference_id: GO_REF:0000044
  qualifier: located_in
  review:
    summary: >-
      Electronic annotation to nucleus from UniProt subcellular location mapping. Cdc13
      is a well-established nuclear protein (with the Cdc2 complex localized to a nuclear
      domain distinct from chromatin), so this is correct and redundant with multiple
      experimental nucleus annotations below.
    action: ACCEPT
    reason: Nuclear localization is directly demonstrated experimentally.
    supported_by:
    - reference_id: PMID:2534559
      supporting_text: >-
        both cdc13 and cdc2 are nuclear proteins in S. pombe.
      reference_section_type: ABSTRACT
- term:
    id: GO:0005816
    label: spindle pole body
  evidence_type: IEA
  original_reference_id: GO_REF:0000044
  qualifier: located_in
  review:
    summary: >-
      Electronic annotation to spindle pole body from UniProt mapping. Cdc13-Cdc2 is
      experimentally enriched at the SPB in G2 and mitosis; the mitotic spindle pole body
      term (GO:0044732) is more specific and also annotated experimentally below.
    action: ACCEPT
    reason: SPB localization is directly supported by experimental imaging.
    supported_by:
    - reference_id: PMID:11683390
      supporting_text: >-
        Cdc2-YFP and cdc13-YFP are highly enriched on the spindle pole body of cells in
        late G2 or arrested at S phase.
      reference_section_type: ABSTRACT
- term:
    id: GO:0016538
    label: cyclin-dependent protein serine/threonine kinase regulator activity
  evidence_type: IEA
  original_reference_id: GO_REF:0000120
  qualifier: enables
  review:
    summary: >-
      Automated InterPro-based annotation of the core cyclin regulator activity. This
      duplicates the well-supported IBA/experimental molecular function and is accepted.
    action: ACCEPT
    reason: Redundant with the experimentally supported core kinase-regulator function.
    supported_by:
    - reference_id: PMID:2569363
      supporting_text: >-
        These observations suggest that the cdc13+-encoded cyclin acts to regulate both
        the catalytic properties and the localization of the protein kinase of which it
        is a subunit.
      reference_section_type: ABSTRACT
- term:
    id: GO:0044772
    label: mitotic cell cycle phase transition
  evidence_type: IEA
  original_reference_id: GO_REF:0000002
  qualifier: involved_in
  review:
    summary: >-
      Automated InterPro annotation to mitotic cell cycle phase transition. This is
      correct but general; Cdc13 specifically drives the G2/M transition, which is
      captured by the more precise experimental annotations (GO:0010389, GO:0010971).
    action: MODIFY
    reason: >-
      The general term is correct but a more specific term reflecting the G2/M role is
      preferred and is supported experimentally.
    proposed_replacement_terms:
    - id: GO:0010389
      label: regulation of G2/M transition of mitotic cell cycle
    supported_by:
    - reference_id: PMID:2908246
      supporting_text: >-
        required for the control of the G2 to M transition
      reference_section_type: ABSTRACT
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:9303310
  qualifier: enables
  review:
    summary: >-
      IPI annotation from the Cdc13-Rum1 interaction. Rum1 is the CDK inhibitor that binds
      the Cdc13-Cdc2 complex and promotes Cdc13 proteolysis during G1. The bare protein
      binding term is uninformative per curation guidelines; the biology (being subject to
      regulation by the inhibitor Rum1) is captured by the kinase-regulator function and
      the G1 proteolysis biology rather than by GO:0005515.
    action: MARK_AS_OVER_ANNOTATED
    reason: >-
      Bare protein binding is uninformative; the Rum1 interaction is better represented as
      part of Cdc13 regulation, not as an independent molecular function.
    supported_by:
    - reference_id: PMID:9303310
      supporting_text: >-
        p25rum1 associates with the CDK p34cdc2/p56cdc13 during G1 in normally cycling
        cells and is required for the rapid proteolysis of p56cdc13
      reference_section_type: ABSTRACT
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:9472012
  qualifier: enables
  review:
    summary: >-
      IPI from the Rum1/SIC1 study, again reflecting binding of the Rum1 CDK inhibitor to
      the B-cyclin Cdc2 complex. Bare protein binding is uninformative.
    action: MARK_AS_OVER_ANNOTATED
    reason: >-
      Uninformative bare protein binding; the interaction is between the CDK inhibitor and
      the Cdc13-Cdc2 complex.
    supported_by:
    - reference_id: PMID:9472012
      supporting_text: >-
        p25rum1 and p40SIC1 are specific inhibitors of p34(cdc2/CDC28) kinase complexes
        with B-type cyclins
      reference_section_type: ABSTRACT
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:9614176
  qualifier: enables
  review:
    summary: >-
      IPI from the pheromone-induced G1 arrest study (Rum1-dependent Cdc13 proteolysis).
      Bare protein binding is uninformative and is not retained as a core function.
    action: MARK_AS_OVER_ANNOTATED
    reason: Uninformative bare protein binding term.
    supported_by:
    - reference_id: PMID:9614176
      supporting_text: >-
        Cyclin B proteolysis and the cyclin-dependent kinase inhibitor rum1p are required
        for pheromone-induced G1 arrest in fission yeast.
      reference_section_type: TITLE
- term:
    id: GO:0140602
    label: nucleolar peripheral inclusion body
  evidence_type: IDA
  original_reference_id: PMID:37128864
  qualifier: is_active_in
  review:
    summary: >-
      IDA localization of Cdc2/CDK to a nucleolar inclusion compartment during the
      stationary-phase/CDK study. This reflects a stress/quiescence-associated
      relocalization rather than a site of mitotic function.
    action: KEEP_AS_NON_CORE
    reason: >-
      A condition-specific (stationary phase) localization, not part of the core mitotic
      function.
    supported_by:
    - reference_id: PMID:37128864
      supporting_text: >-
        Cdc2 accumulates in the nucleolus.
      reference_section_type: ABSTRACT
- term:
    id: GO:0005654
    label: nucleoplasm
  evidence_type: IDA
  original_reference_id: PMID:1699136
  qualifier: is_active_in
  review:
    summary: >-
      IDA to nucleoplasm consistent with the nuclear (non-SPB) population of the
      Cdc13-Cdc2 cyclin. Supported by direct localization of two distinct nuclear
      populations of Cdc13.
    action: ACCEPT
    reason: Direct evidence for a nucleoplasmic population of Cdc13.
    supported_by:
    - reference_id: PMID:1699136
      supporting_text: >-
        the presence of two spatially distinct cdc13 cyclin populations in the nucleus of
        S. pombe, one of which is associated with the mitotic spindle poles
      reference_section_type: ABSTRACT
- term:
    id: GO:0044773
    label: mitotic DNA damage checkpoint signaling
  evidence_type: EXP
  original_reference_id: PMID:12023299
  qualifier: involved_in
  review:
    summary: >-
      Experimental evidence that Cdc2-cyclin B kinase activity influences recombinational
      repair of DSBs in G2 and links the checkpoint protein Crb2 to Top3/Rqh1 function.
      This is a genuine but non-core (process-specific) role of the Cdc13-Cdc2 complex.
    action: KEEP_AS_NON_CORE
    reason: >-
      Cdc13-Cdc2 contributes to the G2 DNA damage response, but this is a downstream role
      distinct from its core mitotic-entry function.
    supported_by:
    - reference_id: PMID:12023299
      supporting_text: >-
        the major Schizosaccharomyces pombe CDK, Cdc2-cyclin B, influences recombinational
        repair of radiation-induced DSBs during the G(2) phase at two distinct stages
      reference_section_type: ABSTRACT
- term:
    id: GO:0071957
    label: old mitotic spindle pole body
  evidence_type: IDA
  original_reference_id: PMID:1699136
  qualifier: is_active_in
  review:
    summary: >-
      IDA to the old (pre-existing) SPB, consistent with the SPB-associated population of
      Cdc13. A fine-grained localization within the broader SPB localization.
    action: ACCEPT
    reason: Direct evidence for SPB-associated Cdc13; specific SPB sub-localization.
    supported_by:
    - reference_id: PMID:1699136
      supporting_text: >-
        the presence of two spatially distinct cdc13 cyclin populations in the nucleus of
        S. pombe, one of which is associated with the mitotic spindle poles
      reference_section_type: ABSTRACT
- term:
    id: GO:0071958
    label: new mitotic spindle pole body
  evidence_type: IDA
  original_reference_id: PMID:1699136
  qualifier: is_active_in
  review:
    summary: >-
      IDA to the new (newly duplicated) SPB, complementary to the old-SPB annotation.
      Both reflect the experimentally observed SPB-associated Cdc13 population.
    action: ACCEPT
    reason: Direct evidence for SPB-associated Cdc13; specific SPB sub-localization.
    supported_by:
    - reference_id: PMID:1699136
      supporting_text: >-
        the presence of two spatially distinct cdc13 cyclin populations in the nucleus of
        S. pombe, one of which is associated with the mitotic spindle poles
      reference_section_type: ABSTRACT
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:1655416
  qualifier: enables
  review:
    summary: >-
      IPI to cdc2, reflecting the Cdc13-Cdc2 complex (Thr167 phosphorylation of Cdc2 is
      required for kinase activity and for association with cyclin B). Bare protein binding
      is uninformative; the Cdc2 interaction is the substance of the core kinase-regulator
      function and is captured by GO:0016538.
    action: MARK_AS_OVER_ANNOTATED
    reason: >-
      Uninformative bare protein binding; the Cdc13-Cdc2 interaction is already represented
      by the cyclin kinase-regulator molecular function.
    supported_by:
    - reference_id: PMID:1655416
      supporting_text: >-
        Phosphorylation at Thr167 is required for Schizosaccharomyces pombe p34cdc2
        function.
      reference_section_type: TITLE
- term:
    id: GO:0140602
    label: nucleolar peripheral inclusion body
  evidence_type: IDA
  original_reference_id: PMID:33176152
  qualifier: is_active_in
  review:
    summary: >-
      IDA localization to nucleolar ring/inclusion structures formed upon acute heat
      stress, which reversibly sequester cell-cycle regulators. This is a stress-induced
      aggregation phenomenon, not a constitutive functional site.
    action: KEEP_AS_NON_CORE
    reason: >-
      Heat-stress-induced reversible aggregation; condition-specific localization, not a
      core functional compartment.
    supported_by:
    - reference_id: PMID:33176152
      supporting_text: >-
        NuRs sequester essential factors required for nuclear mRNA metabolism and nuclear
        pore complex function, as well as cell-cycle regulators.
      reference_section_type: ABSTRACT
- term:
    id: GO:0010971
    label: positive regulation of G2/M transition of mitotic cell cycle
  evidence_type: IMP
  original_reference_id: PMID:32084401
  qualifier: involved_in
  review:
    summary: >-
      IMP showing that the Cdc13 hydrophobic patch (and SPB targeting) is required for the
      onset of mitosis and that hydrophobic-patch mutant cells arrest in G2. This directly
      supports a positive role in driving the G2/M transition and is a core function.
    action: ACCEPT
    reason: >-
      Cdc13-Cdc2 is the principal positive driver of the G2/M transition; SPB-targeting
      mutants fail mitotic entry.
    supported_by:
    - reference_id: PMID:32084401
      supporting_text: >-
        disruption of this motif prevents both centrosomal localization of Cdc13 and the
        onset of mitosis but does not prevent S phase
      reference_section_type: ABSTRACT
- term:
    id: GO:0061575
    label: cyclin-dependent protein serine/threonine kinase activator activity
  evidence_type: IMP
  original_reference_id: PMID:32084401
  qualifier: enables
  review:
    summary: >-
      IMP supporting that Cdc13 activates Cdc2/CDK for mitotic substrate phosphorylation,
      with SPB-localized Cdc13-CDK required to reach the high CDK activity needed for
      mitosis. Core molecular function as the activating cyclin subunit.
    action: ACCEPT
    reason: >-
      Cdc13 is the activating B-type cyclin of the mitotic CDK; loss of correct
      localization compromises global mitotic CDK phosphorylation.
    supported_by:
    - reference_id: PMID:32084401
      supporting_text: >-
        Cdc13-CDK localization to the SPB is important for generating the highest levels of
        CDK activity in these compartments needed for mitosis
      reference_section_type: RESULTS
- term:
    id: GO:0044732
    label: mitotic spindle pole body
  evidence_type: IMP
  original_reference_id: PMID:32084401
  qualifier: is_active_in
  review:
    summary: >-
      IMP localization to the mitotic SPB; the hydrophobic patch targets Cdc13 to the SPB
      in G2, and this localization is required for mitotic entry. Well supported.
    action: ACCEPT
    reason: SPB localization of Cdc13-CDK is directly demonstrated and functionally required.
    supported_by:
    - reference_id: PMID:32084401
      supporting_text: >-
        the hydrophobic patch targets Cdc13 to the yeast centrosome equivalent, the
        spindle pole body (SPB)
      reference_section_type: ABSTRACT
- term:
    id: GO:0044732
    label: mitotic spindle pole body
  evidence_type: EXP
  original_reference_id: PMID:32084401
  qualifier: is_active_in
  review:
    summary: >-
      EXP localization to the mitotic SPB (duplicate of the IMP annotation from the same
      study). Cdc13 is enriched at the SPB in G2 and decorates the mitotic spindle.
    action: ACCEPT
    reason: Direct experimental SPB localization of Cdc13.
    supported_by:
    - reference_id: PMID:32084401
      supporting_text: >-
        Wild-type Cdc13 is found in the nucleus, is visibly enriched at the SPB in G2, and
        decorates the mitotic spindle during mitosis
      reference_section_type: RESULTS
- term:
    id: GO:0140429
    label: positive regulation of mitotic sister chromatid biorientation
  evidence_type: EXP
  original_reference_id: PMID:20739936
  qualifier: involved_in
  review:
    summary: >-
      EXP evidence that Cdk1 (Cdc2)-cyclin B phosphorylates the chromosomal passenger
      complex (Survivin) to promote chromosome bi-orientation. A genuine downstream
      mitotic process role of Cdc13-Cdc2.
    action: KEEP_AS_NON_CORE
    reason: >-
      Bi-orientation control is a real role of the Cdc13-Cdc2 kinase but is downstream of
      its core mitotic-entry function.
    supported_by:
    - reference_id: PMID:20739936
      supporting_text: >-
        Cdk1 (also known as Cdc2)-cyclin-B-dependent phosphorylation of Survivin
      reference_section_type: ABSTRACT
- term:
    id: GO:0140013
    label: meiotic nuclear division
  evidence_type: IMP
  original_reference_id: PMID:25891897
  qualifier: involved_in
  review:
    summary: >-
      IMP showing Cdc13 is required for the meiosis I and meiosis II nuclear divisions; a
      single Cdc13-Cdc2 complex is sufficient to drive the meiotic cell cycle. This is a
      genuine (not over-annotated) meiotic role of Cdc13.
    action: ACCEPT
    reason: >-
      Direct genetic evidence establishes Cdc13 as required for both meiotic nuclear
      divisions.
    supported_by:
    - reference_id: PMID:25891897
      supporting_text: >-
        Cdc13 is required for meiosis I and II, and is not required for premeiotic S-phase
        unless this function can be achieved by very low Cdc13 protein levels
      reference_section_type: ABSTRACT
- term:
    id: GO:0005634
    label: nucleus
  evidence_type: IDA
  original_reference_id: PMID:29123917
  qualifier: is_active_in
  review:
    summary: >-
      IDA nuclear localization observed during meiotic prophase imaging of CDK1-Cdc13.
      Consistent with the established nuclear localization of Cdc13-Cdc2.
    action: ACCEPT
    reason: Direct imaging of nuclear/telomere-bouquet-associated Cdc13 in meiosis.
    supported_by:
    - reference_id: PMID:29123917
      supporting_text: >-
        delayed accumulation of CDK1Cdc13 at the SPB
      reference_section_type: RESULTS
- term:
    id: GO:0140445
    label: chromosome, telomeric repeat region
  evidence_type: EXP
  original_reference_id: PMID:29123917
  qualifier: is_active_in
  review:
    summary: >-
      EXP localization of CDK1-Cdc13 near telomeres during the meiotic telomere bouquet;
      heterochromatic/telomeric regions act as a platform that delivers CDK to the SPB.
      A meiosis-specific localization, genuine but non-core.
    action: KEEP_AS_NON_CORE
    reason: >-
      Telomere-proximal localization is a meiosis-prophase-specific context for CDK
      delivery to the SPB, not a core mitotic function site.
    supported_by:
    - reference_id: PMID:29123917
      supporting_text: >-
        CDK1Cdc13 can localise near to the telomeres and therefore to the SPB during the
        later bouquet stage
      reference_section_type: RESULTS
- term:
    id: GO:0005634
    label: nucleus
  evidence_type: EXP
  original_reference_id: PMID:11683390
  qualifier: is_active_in
  review:
    summary: >-
      EXP nuclear localization from in vivo YFP imaging of Cdc13 during mitosis and
      meiosis. Strongly supported core localization.
    action: ACCEPT
    reason: Direct in vivo imaging confirms nuclear localization of Cdc13.
    supported_by:
    - reference_id: PMID:11683390
      supporting_text: >-
        cdc13-YFP is enriched at the nuclear periphery before fluorescence disappears
      reference_section_type: ABSTRACT
- term:
    id: GO:0034399
    label: nuclear periphery
  evidence_type: EXP
  original_reference_id: PMID:11683390
  qualifier: is_active_in
  review:
    summary: >-
      EXP localization to the nuclear periphery; Cdc13-YFP becomes enriched at the nuclear
      periphery in anaphase before being degraded. A genuine cell-cycle-stage-specific
      localization.
    action: KEEP_AS_NON_CORE
    reason: >-
      Nuclear-periphery enrichment is a transient late-mitotic localization, accepted as
      context rather than a core functional compartment.
    supported_by:
    - reference_id: PMID:11683390
      supporting_text: >-
        cdc13-YFP is enriched at the nuclear periphery before fluorescence disappears
      reference_section_type: ABSTRACT
- term:
    id: GO:0044732
    label: mitotic spindle pole body
  evidence_type: EXP
  original_reference_id: PMID:11683390
  qualifier: is_active_in
  review:
    summary: >-
      EXP localization to the mitotic SPB from in vivo imaging; Cdc2-YFP and Cdc13-YFP are
      highly enriched on the SPB in late G2 and accumulate on SPBs and spindle in
      prophase/metaphase. Well supported.
    action: ACCEPT
    reason: Direct in vivo imaging of Cdc13 at the SPB across mitosis.
    supported_by:
    - reference_id: PMID:11683390
      supporting_text: >-
        Cdc2-YFP and cdc13-YFP are highly enriched on the spindle pole body of cells in
        late G2 or arrested at S phase.
      reference_section_type: ABSTRACT
- term:
    id: GO:0072686
    label: mitotic spindle
  evidence_type: EXP
  original_reference_id: PMID:11683390
  qualifier: is_active_in
  review:
    summary: >-
      EXP localization to the mitotic spindle; Cdc13-Cdc2 accumulates on the spindle in
      prophase/metaphase and leaves the spindle before sister-chromatid separation.
    action: ACCEPT
    reason: Direct imaging of Cdc13 decorating the mitotic spindle.
    supported_by:
    - reference_id: PMID:11683390
      supporting_text: >-
        In anaphase, the cdc2p/cdc13p complex leaves the spindle prior to sister chromatid
        separation
      reference_section_type: ABSTRACT
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:26131711
  qualifier: enables
  review:
    summary: >-
      IPI to cdc2 from the study of two Cdc2 pools in the DNA damage response. Bare protein
      binding is uninformative; the Cdc13-Cdc2 interaction is already represented by the
      core cyclin kinase-regulator function.
    action: MARK_AS_OVER_ANNOTATED
    reason: Uninformative bare protein binding; redundant with the Cdc2 kinase-regulator function.
    supported_by:
    - reference_id: PMID:26131711
      supporting_text: >-
        Two Distinct Cdc2 Pools Regulate Cell Cycle Progression and the DNA Damage Response
        in the Fission Yeast S.pombe.
      reference_section_type: TITLE
- term:
    id: GO:0051447
    label: negative regulation of meiotic cell cycle
  evidence_type: IMP
  original_reference_id: PMID:11493649
  qualifier: involved_in
  review:
    summary: >-
      IMP from the Mfr1/APC study. Persistent high Cdc13-Cdc2 activity delays meiotic
      exit/sporulation; timely degradation of Cdc13 by the Mfr1-activated APC/C is required
      to switch off the meiotic cell cycle and license spore formation. Thus Cdc13 activity
      negatively impacts meiotic exit and its destruction is required for progression. A
      genuine, evidence-based meiotic regulatory role (non-core).
    action: KEEP_AS_NON_CORE
    reason: >-
      Cdc13 levels/activity gate meiotic exit; this is a real meiotic regulatory role but
      peripheral to the core G2/M kinase-cyclin function.
    supported_by:
    - reference_id: PMID:11493649
      supporting_text: >-
        An mfr1 null mutant completes meiosis II but remains with high levels of cdc13 and
        cdc2 kinase activity and has considerably delayed spore formation.
      reference_section_type: ABSTRACT
- term:
    id: GO:1990023
    label: mitotic spindle midzone
  evidence_type: IDA
  original_reference_id: PMID:19686686
  qualifier: is_active_in
  review:
    summary: >-
      IDA to the mitotic spindle midzone. Cdc2 (CDK)-Cdc13 phosphorylates the midzone
      kinesin Klp9 and the bundler Ase1 to control anaphase B spindle elongation, placing
      the active kinase at the midzone. A genuine localization/process context.
    action: KEEP_AS_NON_CORE
    reason: >-
      Midzone activity in anaphase B is a downstream role of the Cdc13-Cdc2 kinase, not its
      core mitotic-entry function.
    supported_by:
    - reference_id: PMID:19686686
      supporting_text: >-
        The cyclin-dependent kinase cdc2p phosphorylates and its antagonist phosphatase
        clp1p dephosphorylates klp9p and ase1p to control the position and timing of
        klp9p-ase1p interaction.
      reference_section_type: ABSTRACT
- term:
    id: GO:0044732
    label: mitotic spindle pole body
  evidence_type: IDA
  original_reference_id: PMID:11084332
  qualifier: is_active_in
  review:
    summary: >-
      IDA SPB localization associated with the Cut8/proteasome study of mitotic cyclin
      destruction. Cdc13 SPB localization is independently and strongly supported; here it
      is in the context of where Cdc13 is degraded.
    action: ACCEPT
    reason: SPB localization of Cdc13 is well supported across multiple studies.
    supported_by:
    - reference_id: PMID:11084332
      supporting_text: >-
        destruction of mitotic cyclin and Cut2 in the nucleus is dramatically delayed,
        though polyubiquitination of Cdc13 occurs in cut8 mutant.
      reference_section_type: ABSTRACT
- term:
    id: GO:1990023
    label: mitotic spindle midzone
  evidence_type: IMP
  original_reference_id: PMID:11084332
  qualifier: is_active_in
  review:
    summary: >-
      IMP to spindle midzone from the Cut8 study. Cdc13 localization/degradation is in the
      nucleus and at the SPB; midzone localization of the active kinase is better supported
      by the Klp9/Ase1 phospho-regulation study and is a non-core context.
    action: KEEP_AS_NON_CORE
    reason: >-
      Midzone is a downstream anaphase context for the Cdc13-Cdc2 kinase, not a core
      function site.
    supported_by:
    - reference_id: PMID:11084332
      supporting_text: >-
        destruction of mitotic cyclin and Cut2 in the nucleus is dramatically delayed,
        though polyubiquitination of Cdc13 occurs in cut8 mutant.
      reference_section_type: ABSTRACT
- term:
    id: GO:0000785
    label: chromatin
  evidence_type: IDA
  original_reference_id: PMID:12419251
  qualifier: is_active_in
  review:
    summary: >-
      IDA localization to chromatin. Cdc13-Cdc2 stably associates with ORC-bound
      replication origins (chromatin) in vivo, enforcing the dependence of S phase on an
      intervening mitosis and preventing re-replication. A genuine, functionally important
      chromatin association.
    action: ACCEPT
    reason: >-
      Direct evidence that Cdc13-Cdc2 associates with chromatin (replication origins) via
      ORC.
    supported_by:
    - reference_id: PMID:12419251
      supporting_text: >-
        the mitotic B type cyclin Cdc13/Cdc2 kinase associates with replication origins in
        vivo. This association is dependent on the origin recognition complex (ORC)
      reference_section_type: ABSTRACT
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:15791259
  qualifier: enables
  review:
    summary: >-
      IPI from the Mes1 study (Mes1 binds Slp1/APC activator to block Cdc13 degradation).
      Bare protein binding is uninformative; the biology is captured by the meiotic
      regulation annotations.
    action: MARK_AS_OVER_ANNOTATED
    reason: Uninformative bare protein binding term.
    supported_by:
    - reference_id: PMID:15791259
      supporting_text: >-
        Mes1p is a factor that suppresses the degradation of cyclin Cdc13p at anaphase I
      reference_section_type: ABSTRACT
- term:
    id: GO:0005634
    label: nucleus
  evidence_type: IDA
  original_reference_id: PMID:15791259
  qualifier: is_active_in
  review:
    summary: >-
      IDA nuclear localization observed in the Mes1/Cdc13 meiotic study; consistent with
      the established nuclear localization of Cdc13.
    action: ACCEPT
    reason: Nuclear localization of Cdc13 is well established across studies.
    supported_by:
    - reference_id: PMID:15791259
      supporting_text: >-
        Mes1p is a factor that suppresses the degradation of cyclin Cdc13p at anaphase I
      reference_section_type: ABSTRACT
- term:
    id: GO:0005730
    label: nucleolus
  evidence_type: IDA
  original_reference_id: PMID:8688826
  qualifier: is_active_in
  review:
    summary: >-
      IDA from ultrastructural/immunocytochemical localization of p56cdc13. The study
      mainly shows cytoplasmic and nuclear/perinuclear localization; nucleolar signal is a
      minor compartment and not a core functional site.
    action: KEEP_AS_NON_CORE
    reason: >-
      Nucleolar signal is a minor compartment in the EM/IF study; not a core functional
      site for the mitotic cyclin.
    supported_by:
    - reference_id: PMID:8688826
      supporting_text: >-
        evidencing cytoplasmic localization of p56cdc13, in addition to the nuclear
        localization previously observed
      reference_section_type: ABSTRACT
- term:
    id: GO:0005737
    label: cytoplasm
  evidence_type: IDA
  original_reference_id: PMID:8688826
  qualifier: is_active_in
  review:
    summary: >-
      IDA cytoplasmic localization from improved EM (high-pressure freezing) and
      immunofluorescence, showing a major cytoplasmic pool of p56cdc13 in interphase that
      relocalizes to the nucleus in mitosis. A genuine localization, though the
      functionally dominant compartment is nuclear/SPB.
    action: KEEP_AS_NON_CORE
    reason: >-
      A cytoplasmic interphase pool exists, but the functionally critical mitotic
      localization is nuclear and at the SPB.
    supported_by:
    - reference_id: PMID:8688826
      supporting_text: >-
        evidencing cytoplasmic localization of p56cdc13, in addition to the nuclear
        localization previously observed
      reference_section_type: ABSTRACT
- term:
    id: GO:0034399
    label: nuclear periphery
  evidence_type: IDA
  original_reference_id: PMID:8688826
  qualifier: is_active_in
  review:
    summary: >-
      IDA to nuclear periphery from the EM/IF study; consistent with the documented
      enrichment of Cdc13 at the nuclear periphery during the cell cycle. Non-core
      compartment.
    action: KEEP_AS_NON_CORE
    reason: Transient/contextual perinuclear localization rather than a core function site.
    supported_by:
    - reference_id: PMID:8688826
      supporting_text: >-
        evidencing cytoplasmic localization of p56cdc13, in addition to the nuclear
        localization previously observed
      reference_section_type: ABSTRACT
- term:
    id: GO:0072687
    label: meiotic spindle
  evidence_type: IDA
  original_reference_id: PMID:15791259
  qualifier: is_active_in
  review:
    summary: >-
      IDA localization to the meiotic spindle, consistent with Cdc13's established role in
      meiotic divisions (analogous to its mitotic-spindle association). A genuine meiotic
      localization.
    action: KEEP_AS_NON_CORE
    reason: >-
      Meiotic-spindle localization reflects the genuine meiotic role of Cdc13 but is
      peripheral to its core mitotic function.
    supported_by:
    - reference_id: PMID:15791259
      supporting_text: >-
        Mes1p is a factor that suppresses the degradation of cyclin Cdc13p at anaphase I
      reference_section_type: ABSTRACT
- term:
    id: GO:0140429
    label: positive regulation of mitotic sister chromatid biorientation
  evidence_type: IGI
  original_reference_id: PMID:22264609
  qualifier: involved_in
  review:
    summary: >-
      IGI evidence that Cdk1 (Cdc2)-Cdc13 regulates metaphase spindle elongation forces to
      correct merotelic kinetochore attachments (by phosphorylating/inhibiting Klp9),
      promoting correct bi-orientation. A genuine downstream mitotic role.
    action: KEEP_AS_NON_CORE
    reason: >-
      Merotelic correction/bi-orientation is a real downstream role of the kinase, not the
      core mitotic-entry function.
    supported_by:
    - reference_id: PMID:22264609
      supporting_text: >-
        A role for metaphase spindle elongation forces in correction of merotelic
        kinetochore attachments.
      reference_section_type: TITLE
- term:
    id: GO:0010389
    label: regulation of G2/M transition of mitotic cell cycle
  evidence_type: IMP
  original_reference_id: PMID:2908246
  qualifier: involved_in
  review:
    summary: >-
      IMP from the original cloning/cytology study establishing that cdc13+ is required for
      control of the G2-to-M transition. This is the canonical core biological process of
      Cdc13.
    action: ACCEPT
    reason: >-
      Foundational genetic evidence that Cdc13 controls the G2/M transition; core function.
    supported_by:
    - reference_id: PMID:2908246
      supporting_text: >-
        required for the control of the G2 to M transition
      reference_section_type: ABSTRACT
- term:
    id: GO:0061575
    label: cyclin-dependent protein serine/threonine kinase activator activity
  evidence_type: IGI
  original_reference_id: PMID:2569363
  qualifier: enables
  review:
    summary: >-
      IGI/experimental support that the Cdc13-encoded cyclin activates the Cdc2 protein
      kinase and regulates its catalytic activity and localization. Core molecular
      function.
    action: ACCEPT
    reason: >-
      Cdc13 is the activating cyclin subunit of the Cdc2/CDK1 kinase; the complex is
      kinase-active in vitro and oscillates in activity through the cell cycle.
    supported_by:
    - reference_id: PMID:2569363
      supporting_text: >-
        The products of the cdc13+ and cdc2+ genes form a stable complex that displays
        protein kinase activity in vitro.
      reference_section_type: ABSTRACT
- term:
    id: GO:0005634
    label: nucleus
  evidence_type: IDA
  original_reference_id: PMID:2569363
  qualifier: is_active_in
  review:
    summary: >-
      IDA nuclear localization; Cdc13 and Cdc2 co-localize in the nucleus and Cdc13 is
      required to localize Cdc2 to the nucleus. Strongly supported core localization.
    action: ACCEPT
    reason: Direct co-localization evidence; Cdc13 dictates nuclear localization of the complex.
    supported_by:
    - reference_id: PMID:2569363
      supporting_text: >-
        cdc13 and cdc2 co-localize in the cell nucleus.
      reference_section_type: ABSTRACT
- term:
    id: GO:0005634
    label: nucleus
  evidence_type: HDA
  original_reference_id: PMID:16823372
  qualifier: is_active_in
  review:
    summary: >-
      High-throughput (HDA) nuclear localization from the genome-wide ORFeome
      localization study. Consistent with the strong experimental consensus for nuclear
      Cdc13.
    action: ACCEPT
    reason: Consistent with abundant focused experimental evidence for nuclear localization.
    supported_by:
    - reference_id: PMID:2534559
      supporting_text: >-
        both cdc13 and cdc2 are nuclear proteins in S. pombe.
      reference_section_type: ABSTRACT
- term:
    id: GO:0044732
    label: mitotic spindle pole body
  evidence_type: HDA
  original_reference_id: PMID:16823372
  qualifier: is_active_in
  review:
    summary: >-
      HDA localization to the mitotic SPB from the genome-wide localization study;
      consistent with focused imaging studies of Cdc13 at the SPB.
    action: ACCEPT
    reason: Consistent with focused experimental SPB localization data.
    supported_by:
    - reference_id: PMID:11683390
      supporting_text: >-
        Cdc2-YFP and cdc13-YFP are highly enriched on the spindle pole body of cells in
        late G2 or arrested at S phase.
      reference_section_type: ABSTRACT
- term:
    id: GO:0072686
    label: mitotic spindle
  evidence_type: HDA
  original_reference_id: PMID:16823372
  qualifier: is_active_in
  review:
    summary: >-
      HDA localization to the mitotic spindle from the genome-wide study; consistent with
      focused imaging showing Cdc13 decorating the spindle during mitosis.
    action: ACCEPT
    reason: Consistent with focused experimental mitotic-spindle localization data.
    supported_by:
    - reference_id: PMID:11683390
      supporting_text: >-
        In anaphase, the cdc2p/cdc13p complex leaves the spindle prior to sister chromatid
        separation
      reference_section_type: ABSTRACT
- term:
    id: GO:0005634
    label: nucleus
  evidence_type: IDA
  original_reference_id: PMID:2534559
  qualifier: is_active_in
  review:
    summary: >-
      IDA nuclear localization from the classic subcellular-localization study; both Cdc13
      and Cdc2 are nuclear proteins localized to a nuclear domain distinct from chromatin,
      and Cdc13 is required to localize Cdc2 to the nucleus. Core localization.
    action: ACCEPT
    reason: Foundational direct evidence for nuclear localization of Cdc13.
    supported_by:
    - reference_id: PMID:2534559
      supporting_text: >-
        cdc13 therefore appears to be required to localise cdc2 to the nucleus but not vice
        versa.
      reference_section_type: ABSTRACT
core_functions:
- description: >-
    Acts as the mitotic B-type cyclin regulatory subunit that binds and activates the
    Cdc2 (CDK1) serine/threonine protein kinase, forming M-phase-promoting factor (MPF)
    and dictating the catalytic activity, substrate selection and localization of the
    kinase.
  supported_by:
  - reference_id: PMID:2569363
    supporting_text: >-
      These observations suggest that the cdc13+-encoded cyclin acts to regulate both the
      catalytic properties and the localization of the protein kinase of which it is a
      subunit.
    reference_section_type: ABSTRACT
  molecular_function:
    id: GO:0016538
    label: cyclin-dependent protein serine/threonine kinase regulator activity
- description: >-
    Drives the G2/M transition and mitotic progression; Cdc13-Cdc2 accumulates through G2,
    is activated at mitotic onset, and is required for entry into and completion of
    mitosis.
  supported_by:
  - reference_id: PMID:2908246
    supporting_text: >-
      required for the control of the G2 to M transition
    reference_section_type: ABSTRACT
  - reference_id: PMID:32084401
    supporting_text: >-
      disruption of this motif prevents both centrosomal localization of Cdc13 and the
      onset of mitosis but does not prevent S phase
    reference_section_type: ABSTRACT
  directly_involved_in:
  - id: GO:0010389
    label: regulation of G2/M transition of mitotic cell cycle
- description: >-
    Provides the cyclin activity required for the meiotic nuclear divisions; a single
    Cdc13-Cdc2 complex is sufficient to drive both meiosis I and meiosis II, with its
    stability specifically controlled between the divisions.
  supported_by:
  - reference_id: PMID:25891897
    supporting_text: >-
      Cdc13 is required for meiosis I and II, and is not required for premeiotic S-phase
      unless this function can be achieved by very low Cdc13 protein levels
    reference_section_type: ABSTRACT
  directly_involved_in:
  - id: GO:0140013
    label: meiotic nuclear division
- description: >-
    Targets the Cdc2 kinase to the spindle pole body (the fungal centrosome equivalent)
    via the cyclin hydrophobic patch, concentrating CDK activity needed for phosphorylation
    of SPB/cytoplasmic mitotic substrates and for mitotic entry.
  supported_by:
  - reference_id: PMID:32084401
    supporting_text: >-
      the hydrophobic patch targets Cdc13 to the yeast centrosome equivalent, the spindle
      pole body (SPB)
    reference_section_type: ABSTRACT
  locations:
  - id: GO:0044732
    label: mitotic spindle pole body
proposed_new_terms: []
suggested_questions:
- question: >-
    What is the full repertoire of Cdc13-Cdc2 substrates whose phosphorylation strictly
    requires SPB-localized (hydrophobic-patch-dependent) cyclin-CDK versus the nuclear
    pool, and how does this spatial partitioning order mitotic events?
- question: >-
    How is Cdc13 stability differentially controlled in the mitotic versus meiotic cycle
    (APC/C-Slp1 vs Mes1-protected vs Mfr1-activated APC/C), and what determines the precise
    timing windows?
- question: >-
    To what extent does the ORC-dependent association of Cdc13-Cdc2 with replication
    origins contribute to re-replication control independently of its kinase activity?
suggested_experiments:
- description: >-
    Combine analog-sensitive Cdc2 (cdc2as) with rapid Cdc13 degradation and quantitative
    phosphoproteomics across synchronized mitosis and meiosis to map cyclin-pool-specific
    substrate phosphorylation and define the boundary between core mitotic-entry substrates
    and downstream targets (bi-orientation, midzone, DDR).
- description: >-
    Use endogenously tagged Cdc13 with live-cell super-resolution imaging plus
    degron-controlled removal of SPB, ORC and telomere-bouquet factors to dissect the
    sequence and dependencies of Cdc13 localization (nucleus, SPB, replication origins,
    spindle, midzone) in mitosis and meiosis.
- description: >-
    Reconstitute APC/C-dependent Cdc13 destruction in vitro with Slp1, Mes1 and Mfr1 to
    quantify how these regulators set Cdc13 levels at the meiosis I/II boundary and at
    meiotic exit, correlating with MPF activity and sporulation timing.
references:
- id: file:interpro/panther/PTHR10177/PTHR10177-review.md
  title: 'PANTHER family review PTHR10177: IBA propagation assessment for cdc13'
  findings: []
- id: GO_REF:0000002
  title: Gene Ontology annotation through association of InterPro records with GO terms
  findings: []
- id: GO_REF:0000033
  title: Annotation inferences using phylogenetic trees
  findings: []
- id: GO_REF:0000044
  title: Gene Ontology annotation based on UniProtKB/Swiss-Prot Subcellular Location vocabulary mapping, accompanied by conservative changes to GO terms applied by UniProt
  findings: []
- id: GO_REF:0000120
  title: Combined Automated Annotation using Multiple IEA Methods
  findings: []
- id: PMID:11084332
  title: Cut8, essential for anaphase, controls localization of 26S proteasome, facilitating destruction of cyclin and Cut2.
  findings:
  - statement: >-
      In cut8 mutants, nuclear destruction of mitotic cyclin Cdc13 and Cut2 is delayed
      although Cdc13 is still polyubiquitinated, linking Cut8/proteasome localization to
      cyclin destruction.
    supporting_text: >-
      destruction of mitotic cyclin and Cut2 in the nucleus is dramatically delayed, though
      polyubiquitination of Cdc13 occurs in cut8 mutant.
    reference_section_type: ABSTRACT
- id: PMID:11493649
  title: Fission yeast mfr1 activates APC and coordinates meiotic nuclear division with sporulation.
  findings:
  - statement: >-
      The Mfr1-activated APC/C degrades Cdc13 at the end of meiosis II to coordinate
      meiotic exit with sporulation; persistent Cdc13/Cdc2 activity delays spore formation.
    supporting_text: >-
      An mfr1 null mutant completes meiosis II but remains with high levels of cdc13 and
      cdc2 kinase activity and has considerably delayed spore formation.
    reference_section_type: ABSTRACT
- id: PMID:11683390
  title: In vivo localisation of fission yeast cyclin-dependent kinase cdc2p and cyclin B cdc13p during mitosis and meiosis.
  findings:
  - statement: >-
      Cdc13-Cdc2 is enriched at the SPB in late G2, accumulates on SPBs and the spindle in
      prophase/metaphase, and leaves the spindle in anaphase before sister-chromatid
      separation.
    supporting_text: >-
      Cdc2-YFP and cdc13-YFP are highly enriched on the spindle pole body of cells in late
      G2 or arrested at S phase.
    reference_section_type: ABSTRACT
  - statement: >-
      In anaphase the complex leaves the spindle prior to sister-chromatid separation and
      Cdc13 becomes enriched at the nuclear periphery before disappearing (destruction).
    supporting_text: >-
      In anaphase, the cdc2p/cdc13p complex leaves the spindle prior to sister chromatid
      separation
    reference_section_type: ABSTRACT
- id: PMID:12023299
  title: Cdc2-cyclin B kinase activity links Crb2 and Rqh1-topoisomerase III.
  findings:
  - statement: >-
      Cdc2-cyclin B (Cdc13) kinase activity influences recombinational repair of DSBs in
      G2 at two stages, with effects on Top3 mediated by the checkpoint protein Crb2.
    supporting_text: >-
      the major Schizosaccharomyces pombe CDK, Cdc2-cyclin B, influences recombinational
      repair of radiation-induced DSBs during the G(2) phase at two distinct stages
    reference_section_type: ABSTRACT
- id: PMID:12419251
  title: Stable association of mitotic cyclin B/Cdc2 to replication origins prevents endoreduplication.
  findings:
  - statement: >-
      Cdc13/Cdc2 associates with ORC-bound replication origins in vivo, imposing the
      dependence of S phase on an intervening mitosis and preventing re-replication.
    supporting_text: >-
      the mitotic B type cyclin Cdc13/Cdc2 kinase associates with replication origins in
      vivo. This association is dependent on the origin recognition complex (ORC)
    reference_section_type: ABSTRACT
- id: PMID:15791259
  title: Fission yeast Mes1p ensures the onset of meiosis II by blocking degradation of cyclin Cdc13p.
  findings:
  - statement: >-
      Mes1 blocks APC/C-dependent degradation of Cdc13 at anaphase I, preserving MPF
      activity required for meiosis II.
    supporting_text: >-
      Mes1p is a factor that suppresses the degradation of cyclin Cdc13p at anaphase I
    reference_section_type: ABSTRACT
- id: PMID:1655416
  title: Phosphorylation at Thr167 is required for Schizosaccharomyces pombe p34cdc2 function.
  findings:
  - statement: >-
      Thr167 phosphorylation of Cdc2 is required for kinase function and is implicated in
      association of Cdc2 with cyclin B (Cdc13).
    supporting_text: >-
      Phosphorylation at Thr167 is required for Schizosaccharomyces pombe p34cdc2 function.
    reference_section_type: TITLE
- id: PMID:16823372
  title: ORFeome cloning and global analysis of protein localization in the fission yeast Schizosaccharomyces pombe.
  findings: []
- id: PMID:1699136
  title: Distinct nuclear and spindle pole body population of cyclin-cdc2 in fission yeast.
  findings:
  - statement: >-
      Two spatially distinct nuclear populations of Cdc13 cyclin exist, one associated
      with the mitotic spindle poles, both co-localizing with Cdc2.
    supporting_text: >-
      the presence of two spatially distinct cdc13 cyclin populations in the nucleus of S.
      pombe, one of which is associated with the mitotic spindle poles
    reference_section_type: ABSTRACT
- id: PMID:19686686
  title: Phospho-regulated interaction between kinesin-6 Klp9p and microtubule bundler Ase1p promotes spindle elongation.
  findings:
  - statement: >-
      Cdc2 (Cdc13-CDK) phosphorylates and Clp1 dephosphorylates Klp9 and Ase1 to control
      midzone Klp9-Ase1 interaction and anaphase B spindle elongation.
    supporting_text: >-
      The cyclin-dependent kinase cdc2p phosphorylates and its antagonist phosphatase clp1p
      dephosphorylates klp9p and ase1p to control the position and timing of klp9p-ase1p
      interaction.
    reference_section_type: ABSTRACT
- id: PMID:20739936
  title: Phosphorylation of the CPC by Cdk1 promotes chromosome bi-orientation.
  findings:
  - statement: >-
      Cdk1 (Cdc2)-cyclin B phosphorylates Survivin (CPC) to promote chromosome
      bi-orientation.
    supporting_text: >-
      Cdk1 (also known as Cdc2)-cyclin-B-dependent phosphorylation of Survivin
    reference_section_type: ABSTRACT
- id: PMID:22264609
  title: A role for metaphase spindle elongation forces in correction of merotelic kinetochore attachments.
  findings:
  - statement: >-
      Cdk1 (Cdc2-Cdc13) regulates metaphase spindle elongation forces to correct merotelic
      kinetochore attachments.
    supporting_text: >-
      A role for metaphase spindle elongation forces in correction of merotelic kinetochore
      attachments.
    reference_section_type: TITLE
- id: PMID:2534559
  title: 'Fission yeast cyclin: subcellular localisation and cell cycle regulation.'
  findings:
  - statement: >-
      Cdc13 and Cdc2 are nuclear proteins; Cdc13 is required to localize Cdc2 to the
      nucleus and behaves as a classic cyclin (destroyed at mitosis).
    supporting_text: >-
      cdc13 therefore appears to be required to localise cdc2 to the nucleus but not vice
      versa.
    reference_section_type: ABSTRACT
- id: PMID:2569363
  title: 'The fission yeast cdc2/cdc13/suc1 protein kinase: regulation of catalytic activity and nuclear localization.'
  findings:
  - statement: >-
      Cdc13 and Cdc2 form a stable kinase-active complex; the Cdc13 cyclin regulates both
      the catalytic properties and the localization of the Cdc2 kinase.
    supporting_text: >-
      The products of the cdc13+ and cdc2+ genes form a stable complex that displays
      protein kinase activity in vitro.
    reference_section_type: ABSTRACT
- id: PMID:25891897
  title: A single cyclin-CDK complex is sufficient for both mitotic and meiotic progression in fission yeast.
  findings:
  - statement: >-
      A single Cdc13-Cdc2 complex can drive both the mitotic and the meiotic cell cycle;
      Cdc13 is required for meiosis I and II.
    supporting_text: >-
      Cdc13 is required for meiosis I and II, and is not required for premeiotic S-phase
      unless this function can be achieved by very low Cdc13 protein levels
    reference_section_type: ABSTRACT
- id: PMID:26131711
  title: Two Distinct Cdc2 Pools Regulate Cell Cycle Progression and the DNA Damage Response in the Fission Yeast S.pombe.
  findings:
  - statement: >-
      Two distinct Cdc2 (Cdc13-CDK) pools regulate cell-cycle progression and the DNA
      damage response.
    supporting_text: >-
      Two Distinct Cdc2 Pools Regulate Cell Cycle Progression and the DNA Damage Response
      in the Fission Yeast S.pombe.
    reference_section_type: TITLE
- id: PMID:2908246
  title: Cloning and sequencing of the cyclin-related cdc13+ gene and a cytological study of its role in fission yeast mitosis.
  findings:
  - statement: >-
      cdc13+ is required for the control of the G2-to-M transition and is cyclin-related.
    supporting_text: >-
      required for the control of the G2 to M transition
    reference_section_type: ABSTRACT
- id: PMID:29123917
  title: The telomere bouquet facilitates meiotic prophase progression and exit in fission yeast.
  findings:
  - statement: >-
      During meiotic prophase CDK1-Cdc13 localizes near telomeres and is delivered to the
      SPB; loss of the bouquet delays CDK1-Cdc13 accumulation at the SPB.
    supporting_text: >-
      delayed accumulation of CDK1Cdc13 at the SPB
    reference_section_type: RESULTS
- id: PMID:32084401
  title: The Hydrophobic Patch Directs Cyclin B to Centrosomes to Promote Global CDK Phosphorylation at Mitosis.
  findings:
  - statement: >-
      The Cdc13 hydrophobic patch targets the cyclin to the SPB; this localization is
      required for mitotic entry and for full phosphorylation of SPB/cytoplasmic mitotic
      CDK substrates, but not for S phase.
    supporting_text: >-
      the hydrophobic patch targets Cdc13 to the yeast centrosome equivalent, the spindle
      pole body (SPB), and disruption of this motif prevents both centrosomal localization
      of Cdc13 and the onset of mitosis but does not prevent S phase
    reference_section_type: ABSTRACT
- id: PMID:33176152
  title: Acute Heat Stress Leads to Reversible Aggregation of Nuclear Proteins into Nucleolar Rings in Fission Yeast.
  findings:
  - statement: >-
      Acute heat stress reversibly aggregates nuclear/nucleolar proteins, including
      cell-cycle regulators, into nucleolar rings at the nucleolar periphery.
    supporting_text: >-
      NuRs sequester essential factors required for nuclear mRNA metabolism and nuclear
      pore complex function, as well as cell-cycle regulators.
    reference_section_type: ABSTRACT
- id: PMID:37128864
  title: CDK actively contributes to establishment of the stationary phase state in fission yeast.
  findings:
  - statement: >-
      Upon stationary-phase entry / glucose depletion, Cdc2 (CDK) accumulates in the
      nucleolus and actively contributes to the stationary-phase state.
    supporting_text: >-
      Cdc2 accumulates in the nucleolus.
    reference_section_type: ABSTRACT
- id: PMID:8688826
  title: 'Cyclin B (p56cdc13) localization in the yeast Schizosaccharomyces pombe: an ultrastructural and immunocytochemical study.'
  findings:
  - statement: >-
      EM/immunocytochemistry shows a major cytoplasmic pool of p56cdc13 in interphase in
      addition to nuclear localization, with relocalization to the nucleus in mitosis.
    supporting_text: >-
      evidencing cytoplasmic localization of p56cdc13, in addition to the nuclear
      localization previously observed
    reference_section_type: ABSTRACT
- id: PMID:9303310
  title: p25rum1 promotes proteolysis of the mitotic B-cyclin p56cdc13 during G1 of the fission yeast cell cycle.
  findings:
  - statement: >-
      The CDK inhibitor Rum1 associates with the Cdc2-Cdc13 complex during G1 and is
      required for the rapid proteolysis of Cdc13.
    supporting_text: >-
      p25rum1 associates with the CDK p34cdc2/p56cdc13 during G1 in normally cycling cells
      and is required for the rapid proteolysis of p56cdc13
    reference_section_type: ABSTRACT
- id: PMID:9472012
  title: The Cdk inhibitors p25rum1 and p40SIC1 are functional homologues that play similar roles in the regulation of the cell cycle in fission and budding yeast.
  findings:
  - statement: >-
      Rum1 (and its budding-yeast homolog Sic1) are specific inhibitors of p34cdc2 kinase
      complexes with B-type cyclins such as Cdc13.
    supporting_text: >-
      p25rum1 and p40SIC1 are specific inhibitors of p34(cdc2/CDC28) kinase complexes with
      B-type cyclins
    reference_section_type: ABSTRACT
- id: PMID:9614176
  title: Cyclin B proteolysis and the cyclin-dependent kinase inhibitor rum1p are required for pheromone-induced G1 arrest in fission yeast.
  findings:
  - statement: >-
      Cyclin B (Cdc13) proteolysis and the CDK inhibitor Rum1 are required for
      pheromone-induced G1 arrest.
    supporting_text: >-
      Cyclin B proteolysis and the cyclin-dependent kinase inhibitor rum1p are required for
      pheromone-induced G1 arrest in fission yeast.
    reference_section_type: TITLE