Cut7 is the sole kinesin-5 (BimC/Eg5 family) motor protein of the fission yeast Schizosaccharomyces pombe. It is an essential, microtubule-dependent ATPase that assembles into bipolar homotetramers, crosslinks antiparallel interpolar microtubules and slides them apart to generate outward pushing force. This activity drives separation of the duplicated spindle pole bodies and establishes and maintains the bipolarity of the mitotic (and meiotic) spindle; in cut7 mutants spindle pole bodies fail to separate and two unconnected half-spindles form, blocking chromosome segregation. Cut7 concentrates at the spindle pole bodies throughout nuclear division and associates with spindle (polar) microtubules in a stage-specific manner, including the anaphase B midzone. Its outward force opposes the inward pulling force of the minus-end-directed kinesin-14 motors Pkl1 and Klp2. The N-terminal motor domain has very slow, microtubule-stimulated ATPase activity and is plus-end-directed, although full-length oligomeric Cut7 can reverse stepping direction depending on motor crowding on the microtubule lattice.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0072686 mitotic spindle | IBA GO_REF:0000033 | ACCEPT | Summary: Cut7 acts on the mitotic spindle, where it crosslinks and slides antiparallel interpolar microtubules to establish bipolarity. The phylogenetic inference is strongly corroborated by direct localization and functional data. Reason: Consistent with experimental localization to spindle microtubules and the essential role of Cut7 in mitotic spindle bipolarity; a core cellular-component annotation. Supporting Evidence: PMID:1538784 cut7 protein concentrates on or near the spindle pole bodies throughout mitotic and meiotic nuclear division and associates with mitotic spindle microtubules in a stage-specific manner, associating with the mid-anaphase B midzone. |
| GO:0005876 spindle microtubule | IBA GO_REF:0000033 | ACCEPT | Summary: Cut7 binds and acts on spindle microtubules. Direct cryo-EM and localization data confirm microtubule binding and stage-specific association with spindle microtubules, supporting this phylogenetic annotation. Reason: Spindle microtubule is the physical substrate of Cut7 motor activity; corroborated by direct experimental evidence. Supporting Evidence: PMID:1538784 associates with mitotic spindle microtubules in a stage-specific manner, associating with the mid-anaphase B midzone. |
| GO:0051231 spindle elongation | IBA GO_REF:0000033 | ACCEPT | Summary: Cut7 contributes to spindle elongation by sliding antiparallel microtubules apart. Anaphase B elongation velocity is reduced in cut7-deletion backgrounds, supporting a role in elongation in addition to bipolar spindle assembly. The more specific experimental term mitotic spindle elongation (spindle phase three) is also annotated. Reason: Phylogenetic inference consistent with experimental data; spindle elongation is a real Cut7 contribution, though secondary to bipolar spindle assembly. Supporting Evidence: PMID:28513584 1e), suggesting that Cut7 participates in anaphase spindle elongation in addition to its established function in spindle bipolarity. |
| GO:0008574 plus-end-directed microtubule motor activity | IBA GO_REF:0000033 | ACCEPT | Summary: Plus-end-directed microtubule motor activity is the core molecular function of Cut7 and is the physiologically relevant in-vivo direction (under the crowded conditions of the spindle). This is directly demonstrated experimentally as well as inferred phylogenetically. Reason: Core molecular function; directly demonstrated in vitro and consistent with kinesin-5 family phylogeny. Supporting Evidence: PMID:30659798 Density corresponding to the C-terminal neck linker, which connects the Cut7MD to the rest of the protein, is clearly visible docking along the length of the motor domain and directed toward the MT plus end. |
| GO:0090307 mitotic spindle assembly | IBA GO_REF:0000033 | ACCEPT | Summary: Mitotic spindle assembly (bipolar spindle assembly) is the central biological process for Cut7. Loss of Cut7 produces monopolar spindles and blocks spindle formation. The phylogenetic annotation is strongly supported by experimental evidence. Reason: Core biological process; supported by mutant phenotype and force-balance studies. Supporting Evidence: PMID:24239120 Upon inactivation of cut7p at the non-permissive 35Β°C, the metaphase spindle immediately shortened until the spindle became a focused monopolar structure. |
| GO:0000073 initial mitotic spindle pole body separation | IBA GO_REF:0000033 | ACCEPT | Summary: Cut7 is essential for the initial separation of duplicated spindle pole bodies, the defining step of bipolar spindle establishment. This is a core process supported by multiple lines of experimental evidence and by phylogeny. Reason: Core biological process; directly supported by experimental (EXP) annotation and the original mutant phenotype. Supporting Evidence: PMID:30659798 Cut7, the sole kinesin-5 in fission yeast, was among the first mitotic kinesins to be identified and is essential for spindle pole body separation. |
| GO:0005634 nucleus | IBA GO_REF:0000033 | KEEP AS NON CORE | Summary: The nucleus annotation reflects that fission yeast undergoes a closed mitosis with an intranuclear spindle; Cut7 acts on the spindle within the nuclear envelope rather than having an independent nuclear function. This is a generic compartment term that is technically correct but uninformative compared to the spindle/spindle pole body annotations. Reason: Correct but non-specific; Cut7 function is on the intranuclear spindle, better captured by spindle/SPB terms. Supporting Evidence: PMID:16823372 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:0000073 initial mitotic spindle pole body separation | IEA GO_REF:0000117 | ACCEPT | Summary: Electronic (ARBA) annotation recapitulating the well-established, experimentally supported role of Cut7 in initial spindle pole body separation. Redundant with the curated EXP annotation but correct. Reason: Correct electronic inference consistent with strong experimental support. Supporting Evidence: PMID:30659798 Cut7, the sole kinesin-5 in fission yeast, was among the first mitotic kinesins to be identified and is essential for spindle pole body separation. |
| GO:0003777 microtubule motor activity | IEA GO_REF:0000120 | ACCEPT | Summary: Microtubule motor activity is a core, experimentally demonstrated molecular function of Cut7. The electronic InterPro/automated inference is correct, although the more specific plus-end-directed microtubule motor activity term is preferred. Reason: Correct parent molecular-function term; also supported by direct IDA evidence and the kinesin motor domain. Supporting Evidence: PMID:30659798 Kinesin-5s are microtubule-dependent motors that drive spindle pole separation during mitosis. |
| GO:0005524 ATP binding | IEA GO_REF:0000002 | ACCEPT | Summary: Cut7 contains a canonical kinesin motor domain with a P-loop ATP-binding site (UniProt BINDING 159..166) and is a microtubule-stimulated ATPase. ATP binding is a core part of its mechanochemical cycle. Reason: Core molecular function supported by domain architecture and biochemical assays. Supporting Evidence: PMID:30659798 there is strong density in the nucleotide binding pocket corresponding to bound Mg-AMPPNP. |
| GO:0005816 spindle pole body | IEA GO_REF:0000044 | ACCEPT | Summary: Spindle pole body localization is a core, directly observed feature of Cut7, which concentrates on or near the SPBs throughout nuclear division. The electronic Subcellular-Location-derived annotation matches the curated IDA mitotic spindle pole body annotation. Reason: Correct; corroborated by direct localization evidence. Supporting Evidence: PMID:1538784 cut7 protein concentrates on or near the spindle pole bodies throughout mitotic and meiotic nuclear division. |
| GO:0007018 microtubule-based movement | IEA GO_REF:0000002 | KEEP AS NON CORE | Summary: Microtubule-based movement is a broad process term consistent with Cut7's motor activity sliding antiparallel microtubules. It is correct but general; the specific spindle assembly/elongation terms better capture the biology. Reason: Correct but generic process term; the more specific mitotic spindle terms are the core annotations. Supporting Evidence: PMID:28513584 Kinesin-5 family members are plus-end directed motors organized as homo-tetramers that crosslink antiparallel MTs and slide them apart, pushing on the spindle poles. |
| GO:0008017 microtubule binding | IEA GO_REF:0000002 | ACCEPT | Summary: Microtubule binding is a core molecular function of Cut7, demonstrated directly by cryo-EM of the motor domain bound to microtubules and by biochemical assays showing the N-terminus binds microtubules. The electronic InterPro inference is correct. Reason: Core molecular function; supported by structural and biochemical IDA evidence. Supporting Evidence: PMID:27834216 Biochemical assays confirm that the Cut7 N terminus increases Cut7 occupancy by binding directly to microtubules. |
| GO:0015630 microtubule cytoskeleton | IEA GO_REF:0000117 | KEEP AS NON CORE | Summary: Microtubule cytoskeleton is a broad localization term consistent with Cut7's association with spindle microtubules. Correct but general relative to the specific spindle/SPB/spindle-midzone annotations. Reason: Correct but non-specific compartment; more precise spindle terms are preferred. Supporting Evidence: PMID:16823372 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:0005515 protein binding | IPI PMID:26258632 Mad1 promotes chromosome congression by anchoring a kinesin ... | MARK AS OVER ANNOTATED | Summary: This IPI records a physical interaction between Cut7 and the spindle-assembly-checkpoint protein Mad1 (P87169 / SPBC3D6.04c). The interaction is experimentally sound, but bare "protein binding" is uninformative per curation guidelines. The biology (Mad1 anchoring Cut7 to kinetochores for chromosome congression) is better captured by the kinetochore localization and chromosome-migration annotations from the same study. Reason: The underlying Mad1 interaction is valid, but the generic "protein binding" term adds no functional information and should not be treated as a core function. Supporting Evidence: PMID:26258632 fission yeast Mad1 binds the plus-end-directed kinesin-5 motor protein Cut7 (Eg5 homologue), which is generally thought to promote spindle bipolarity. |
| GO:0016887 ATP hydrolysis activity | IC GO_REF:0000111 | ACCEPT | Summary: Cut7 is a microtubule-stimulated ATPase; its motor domain hydrolyzes ATP (measured Vmax ~1.14 ATP/s on fission yeast microtubules) to power motility. The curator-inferred ATP hydrolysis activity is well supported by direct biochemical measurement. Reason: Core enzymatic activity underlying motor function; supported by ATPase assays. Supporting Evidence: PMID:30659798 Characteristic of kinesin-5s [1], Cut7MD has a very slow ATPase activity in vitro, which may be important in the context of its spindle function. |
| GO:0005827 polar microtubule | IDA PMID:32327557 Kinesin-14 family proteins and microtubule dynamics define S... | ACCEPT | Summary: Cut7 acts on polar (interpolar) microtubules, the antiparallel microtubules emanating from opposite spindle poles that it crosslinks and slides apart to drive pole separation. This directly observed localization is a core cellular-component annotation. Reason: Directly captures the antiparallel interpolar microtubules that are the functional substrate of Cut7; supported by IDA. Supporting Evidence: PMID:32327557 Spindle bipolarity is achieved when interdigitating MTs are crosslinked and organized into antiparallel arrays by the kinesin-5 family protein Cut7 (Hagan and Yanagida, 1992; Kapitein et al., 2005; Sharp et al., 1999), inducing the separation of spindle poles. |
| GO:0061804 mitotic spindle formation (spindle phase one) | IMP PMID:24239120 Antagonistic spindle motors and MAPs regulate metaphase spin... | ACCEPT | Summary: Cut7 is required for phase-one mitotic spindle formation (the initial assembly and bipolarization of the spindle). Acute inactivation collapses the spindle into a monopolar structure, demonstrating Cut7 as the active outward-force producer that forms the bipolar spindle. Reason: Core process; directly supported by temperature-sensitive inactivation phenotype during spindle formation. Supporting Evidence: PMID:24239120 cut7p can be viewed as an active force producer, sliding interpolar MTs apart as the outward pushing force experienced by the spindle. |
| GO:0090306 meiotic spindle assembly | IMP PMID:32327557 Kinesin-14 family proteins and microtubule dynamics define S... | KEEP AS NON CORE | Summary: Cut7 is required for meiotic (MI) bipolar spindle assembly: zygotes lacking Cut7 (and Pkl1) fail to form a functional MI spindle and remain monopolar. This is a genuine but secondary context relative to the primary mitotic role; meiosis is a specialized division. Reason: Real, experimentally supported contribution, but a context-specific (meiotic) manifestation of the same core spindle-assembly function rather than a distinct core role. Supporting Evidence: PMID:32327557 fission yeast zygotes deficient in Cut7 and Pkl1 failed to assemble a functional MI spindle, and instead persisted to stay in a monopolar state. |
| GO:0090619 meiotic spindle pole | IDA PMID:32327557 Kinesin-14 family proteins and microtubule dynamics define S... | KEEP AS NON CORE | Summary: Cut7 localizes to meiotic spindle poles, consistent with its constant concentration from mitosis to meiosis I and its role in meiotic spindle bipolarity. A correct, context-specific (meiotic) localization. Reason: Correct directly observed meiotic localization, but mitotic spindle poles are the primary functional context. Supporting Evidence: PMID:32327557 the concentration of the kinesin-5 family protein Cut7 remains constant. |
| GO:0061805 mitotic spindle elongation (spindle phase three) | IMP PMID:28513584 Kinesin-5-independent mitotic spindle assembly requires the ... | ACCEPT | Summary: Cut7 contributes to anaphase B (phase three) spindle elongation in addition to its core role in bipolar spindle assembly; cut7 deletion reduces anaphase B elongation velocity. This is a genuine but secondary function (kinesin-6 Klp9 is the major anaphase B motor). Reason: Experimentally supported phase-three elongation contribution; a real, if secondary, Cut7 function. Supporting Evidence: PMID:28513584 1e), suggesting that Cut7 participates in anaphase spindle elongation in addition to its established function in spindle bipolarity. |
| GO:0008569 minus-end-directed microtubule motor activity | IDA PMID:27834216 Schizosaccharomyces pombe kinesin-5 switches direction using... | KEEP AS NON CORE | Summary: Full-length Cut7 can step toward microtubule minus ends in vitro; direction is set by motor crowding, with low occupancy favoring minus-end-directed stepping. This is an experimentally demonstrated but emergent, context-dependent property. The physiologically relevant in-vivo direction (in the crowded spindle) is plus-end-directed, so minus-end-directed motor activity is retained as non-core. Reason: Directly observed in vitro and not to be removed, but it is a context-dependent property rather than the core in-vivo function; do not overrule the experimental annotation. Supporting Evidence: PMID:27834216 the key determinant of stepping direction is the degree of motor crowding on the microtubule lattice, with greater crowding converting the motor from minus end-directed to plus end-directed stepping. |
| GO:0008574 plus-end-directed microtubule motor activity | IDA PMID:27834216 Schizosaccharomyces pombe kinesin-5 switches direction using... | ACCEPT | Summary: Plus-end-directed stepping is directly demonstrated for crowded full-length Cut7 and is the physiologically relevant in-vivo direction. This is the core motor function of Cut7. Reason: Core molecular function directly demonstrated in vitro. Supporting Evidence: PMID:27834216 greater crowding converting the motor from minus end-directed to plus end-directed stepping. |
| GO:0000073 initial mitotic spindle pole body separation | EXP PMID:1538784 Kinesin-related cut7 protein associates with mitotic and mei... | ACCEPT | Summary: The original characterization of cut7 mutants showed failure of microtubule interdigitation, formation of two unconnected half-spindles, and failure of pole-body separation/chromosome separation, establishing Cut7 as essential for initial spindle pole body separation. This is a core, foundational annotation. Reason: Core process; directly supported by the defining loss-of-function phenotype. Supporting Evidence: PMID:1538784 In bimC and cut7 mutants, microtubule interdigitation does not appear to take place, instead two unconnected half spindles form and chromosome separation fails. |
| GO:0090619 meiotic spindle pole | IDA PMID:1538784 Kinesin-related cut7 protein associates with mitotic and mei... | KEEP AS NON CORE | Summary: Cut7 concentrates on/near spindle pole bodies during meiotic as well as mitotic nuclear division, supporting meiotic spindle pole localization. Correct directly observed localization but a specialized (meiotic) context relative to the core mitotic role. Reason: Correct directly observed meiotic localization; mitosis is the primary context. Supporting Evidence: PMID:1538784 cut7 protein concentrates on or near the spindle pole bodies throughout mitotic and meiotic nuclear division. |
| GO:0003777 microtubule motor activity | IDA PMID:30659798 Cryo-EM Structure (4.5-Γ ) of Yeast Kinesin-5-Microtubule Com... | ACCEPT | Summary: Cryo-EM and ATPase assays directly demonstrate that the Cut7 motor domain binds microtubules and hydrolyzes ATP in a microtubule-stimulated manner, with a plus-end docked neck linker. Microtubule motor activity is a core molecular function. Reason: Core molecular function; directly demonstrated by structural and biochemical data. Supporting Evidence: PMID:30659798 the core motor-microtubule interaction is tightly conserved, reflected in similar Cut7 ATPase activities on each microtubule type. |
| GO:0005515 protein binding | IPI PMID:30659798 Cryo-EM Structure (4.5-Γ ) of Yeast Kinesin-5-Microtubule Com... | MARK AS OVER ANNOTATED | Summary: These IPI annotations record physical interactions detected in the cryo-EM study (the WITH/FROM partners are fission yeast tubulin genes). The interactions are valid, but bare "protein binding" is uninformative; the functional content is captured by microtubule binding and microtubule motor activity from the same work. Reason: Valid interaction evidence, but the generic "protein binding" term adds no functional information beyond the microtubule-binding/motor annotations. Supporting Evidence: PMID:30659798 The Cut7MD binds to the outside surface of Sp_tub MTs with helix-Ξ±4 of Cut7MD centered on the Ξ±Ξ²-tubulin intradimer interface. |
| GO:0008017 microtubule binding | IDA PMID:30659798 Cryo-EM Structure (4.5-Γ ) of Yeast Kinesin-5-Microtubule Com... | ACCEPT | Summary: Direct cryo-EM visualization shows the Cut7 motor domain bound to the microtubule surface via canonical kinesin elements (helix-Ξ±4 at the intradimer interface). Microtubule binding is a core molecular function. Reason: Core molecular function directly demonstrated by structural data. Supporting Evidence: PMID:30659798 Cut7MD contacts Sp_tub MTs using canonical kinesin structural elements: helix-Ξ±4 at the intradimer interface, with additional contacts formed with Ξ²-tubulin. |
| GO:0000776 kinetochore | IDA PMID:26258632 Mad1 promotes chromosome congression by anchoring a kinesin ... | KEEP AS NON CORE | Summary: Cut7 is recruited by Mad1 to the kinetochores of misaligned chromosomes, where it promotes chromosome gliding toward the spindle equator. This is a context-specific (misaligned-chromosome) moonlighting localization distinct from the core bipolar-spindle function at SPBs/interpolar microtubules. Reason: Directly observed but context-specific (Mad1-dependent congression) localization, not the core spindle-assembly site of action. Supporting Evidence: PMID:26258632 Mad1 recruits Cut7 to kinetochores of misaligned chromosomes and promotes chromosome gliding towards the spindle equator. |
| GO:0099606 microtubule plus-end directed mitotic chromosome migration | IGI PMID:26258632 Mad1 promotes chromosome congression by anchoring a kinesin ... | KEEP AS NON CORE | Summary: When anchored to kinetochores by Mad1, Cut7 drives plus-end-directed gliding of misaligned chromosomes toward the spindle equator (chromosome congression). This is a genuine but specialized, Mad1-dependent role distinct from the canonical bipolar-spindle function. Reason: Experimentally supported (genetic interaction with Mad1) but a context-specific congression role rather than the core function. Supporting Evidence: PMID:26258632 We demonstrate that Mad1 recruits Cut7 to kinetochores of misaligned chromosomes and promotes chromosome gliding towards the spindle equator. |
| GO:0051256 mitotic spindle midzone assembly | IGI PMID:18418055 Protein complexes at the microtubule organizing center regul... | ACCEPT | Summary: Genetic-interaction evidence (cut7-22 temperature-sensitive allele combined with MTOC and pkl1 alleles) supports Cut7's role in assembling the bipolar spindle/midzone, where it antagonizes the kinesin-14 Pkl1. cut7-22 bipolarity defects are rescued by stabilizing microtubules or deleting pkl1. Reason: Supported by genetic interactions establishing Cut7's role in bipolar spindle/midzone assembly and its antagonism with Pkl1. Supporting Evidence: PMID:18418055 Altering the Alp4/gamma-tubulin interaction, conserved residues in helix 11 or deletion of pkl1 each are sufficient to rescue bipolarity in our cut7-22(ts) strain. |
| GO:0044732 mitotic spindle pole body | IDA PMID:1538784 Kinesin-related cut7 protein associates with mitotic and mei... | ACCEPT | Summary: Cut7 directly localizes to the mitotic spindle pole body throughout nuclear division. This is a core cellular-component annotation: the SPB is the structure whose separation Cut7 drives. Reason: Core localization directly observed; the SPB is central to Cut7 function. Supporting Evidence: PMID:1538784 cut7 protein concentrates on or near the spindle pole bodies throughout mitotic and meiotic nuclear division. |
| GO:0051256 mitotic spindle midzone assembly | IMP PMID:2145514 Novel potential mitotic motor protein encoded by the fission... | ACCEPT | Summary: The discovery study showed that cut7 mutations block spindle formation, with failure of microtubule interdigitation at the spindle midzone region. Cut7 crosslinks/slides the antiparallel midzone microtubules, supporting a role in spindle midzone assembly. Reason: Supported by the defining loss-of-function spindle-formation phenotype; consistent with the midzone crosslinking/sliding function. Supporting Evidence: PMID:2145514 We have identified two loci which, when mutated, block spindle formation. |
| GO:0072687 meiotic spindle | IDA PMID:1538784 Kinesin-related cut7 protein associates with mitotic and mei... | KEEP AS NON CORE | Summary: Cut7 associates with the meiotic spindle as well as the mitotic spindle. A correct directly observed localization, retained as non-core because the mitotic spindle is the primary functional context. Reason: Correct directly observed meiotic localization; mitosis is the primary context. Supporting Evidence: PMID:1538784 Kinesin-related cut7 protein associates with mitotic and meiotic spindles in fission yeast. |
| GO:1990023 mitotic spindle midzone | IDA PMID:1538784 Kinesin-related cut7 protein associates with mitotic and mei... | ACCEPT | Summary: Cut7 associates with the spindle midzone in a stage-specific manner, including the mid-anaphase B midzone, consistent with its crosslinking/sliding of antiparallel interpolar microtubules. A core directly observed localization. Reason: Directly observed midzone localization matching the antiparallel-microtubule crosslinking/sliding function. Supporting Evidence: PMID:1538784 associates with mitotic spindle microtubules in a stage-specific manner, associating with the mid-anaphase B midzone. |
| GO:0005634 nucleus | HDA PMID:16823372 ORFeome cloning and global analysis of protein localization ... | KEEP AS NON CORE | Summary: High-throughput YFP localization places Cut7 in the nucleus, reflecting the intranuclear closed mitosis of fission yeast where the spindle assembles inside the nuclear envelope. Correct but generic; the spindle/SPB terms capture the actual site of function. Reason: Correct but non-specific compartment derived from a global screen; spindle/SPB terms are preferred. Supporting Evidence: PMID:16823372 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:0015630 microtubule cytoskeleton | HDA PMID:16823372 ORFeome cloning and global analysis of protein localization ... | KEEP AS NON CORE | Summary: High-throughput localization to the microtubule cytoskeleton, consistent with Cut7's association with spindle microtubules. Correct but general relative to the specific spindle terms. Reason: Correct but non-specific compartment from a global screen. Supporting Evidence: PMID:16823372 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 | HDA PMID:16823372 ORFeome cloning and global analysis of protein localization ... | ACCEPT | Summary: High-throughput YFP localization to the mitotic spindle pole body, corroborating the directly observed IDA SPB localization. A core localization. Reason: Consistent with and corroborates the directly observed SPB localization. Supporting Evidence: PMID:1538784 cut7 protein concentrates on or near the spindle pole bodies throughout mitotic and meiotic nuclear division. |
| GO:0005875 microtubule associated complex | IC GO_REF:0000111 | KEEP AS NON CORE | Summary: Curator-inferred (from microtubule motor activity) membership in a microtubule-associated complex. Cut7 forms a bipolar homotetramer that crosslinks microtubules, so this is reasonable, though it is a broad term; the kinesin-5 tetramer itself is the relevant complex. Reason: Reasonable curator inference but a generic complex term; the specific homotetramer is the functionally relevant assembly. Supporting Evidence: PMID:30659798 These roles are enabled by the quaternary structure of kinesin-5s, which forms dumbbell shaped antiparallel tetramers that support spindle MT cross linking and sliding. |
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Download this section (compressed HTML)Q: What is the in-vivo stepping direction and processivity of full-length tetrameric Cut7 on the spindle, and how is the crowding-dependent directional switch observed in vitro regulated within the spindle midzone?
Q: Beyond Mad1 and tubulin, what is the full set of functionally relevant Cut7 protein interactions, and which of the generic "protein binding" annotations can be replaced with informative molecular-function or complex terms?
Q: How is Cut7 activity regulated by cell-cycle phosphorylation (e.g., the predicted CDC2/ Cdk1 site at Thr1011), and does this control its localization or motor output?
Experiment: Single-molecule and microtubule-gliding/sliding assays with purified full-length Cut7 tetramers on defined antiparallel microtubule overlaps to quantify directionality, crosslinking and sliding velocity under physiological crowding.
Experiment: Live-cell imaging of endogenously tagged Cut7 combined with fast (microfluidic) inactivation of temperature-sensitive alleles to dissect its distinct contributions to phase-one spindle formation versus anaphase B (phase-three) elongation.
Experiment: Phospho-site mutant analysis (e.g., Thr1011A/Thr1011D) and Cdk1 inhibition to test whether cell-cycle phosphorylation regulates Cut7 spindle localization, tetramer assembly, or motor activity.
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