post-anaphase microtubule array

GO:1990295 · Cytoskeleton · Other · Proposed

A cytoskeletal part that consists of an array of microtubules and associated molecules that forms at the end of anaphase, and in which microtubules are nucleated from an equatorial microtubule organizing center. [GO:1990295]

Multipanel Figure 2 shows the S. pombe post-anaphase microtubule array. A-C and E follow equatorial polygons and longitudinal extensions; D is a schematic, F-G show Ase1 localization and timing, and H-I compare wild type with ase1 deletion. Later projections in B overlap equatorial and longitudinal signals. The scale bar in C is 2 micrometers and the other marked bars are 5 micrometers; these are not fixed array dimensions. FLUORESCENCE · *Schizosaccharomyces pombe* (`NCBITaxon:4896`) · Kimberly Bellingham-Johnstun, Zoe L. Tyree, Jessica Martinez-Baird, Annelise Thorn, Caroline Laplante; CC BY, via PubMed Central · CC_BY_4_0 · source: PMC PMC10047812.1 cells-12-00917-f002 · `DOI:10.3390/cells12060917`

Synonyms: PAA; post-anaphase array

Part of: GO:0015630 — microtubule cytoskeleton (no local record)

Has part: equatorial microtubule organizing center (GO:0000923)

UniProt location names: UniProt Consortium, CC BY 4.0. Reference label and route sources.

Components

Component	Type	Part of / acts on	Grounding	Genes	Essential	Role
Alpha tubulin	Protein	part of	`InterPro:IPR002452`	tub1, atb2, alp2	UNKNOWN	Alpha-tubulin class of the microtubule polymer forming the equatorial and longitudinal array. `DOI:10.3390/cells12060917` Figure 2 directly follows GFP-Atb2 in the equatorial polygon and longitudinal extensions. `GO:0005874` The microtubule definition supplies alpha/beta polymer composition, not a PAA-specific dimension or deletion phenotype.
Beta tubulin	Protein	part of	`InterPro:IPR002453`		UNKNOWN	Beta-tubulin class paired with alpha tubulin in the array microtubule polymer. `GO:1990295` The whole-array identity explicitly consists of microtubules and associated molecules. `GO:0005874` Alpha/beta tubulin composition is inherited from the microtubule definition. No beta-tubulin isoform-specific localization experiment is inferred. `DOI:10.3390/cells12060917` Figure 2 establishes the microtubule array to which the generic polymer composition applies.
Microtubule-associated protein, MAP65/Ase1/PRC1	Protein	part of	`InterPro:IPR007145`	ase1	DISPENSABLE	Resident crosslinker supporting normal equatorial microtubule organization in the S. pombe array; deletion leaves an altered array. `DOI:10.3390/cells12060917` Ase1 appears after equatorial microtubules and before longitudinal extensions. Deletion leaves a dimmer equatorial array and more longitudinal extensions, supporting organization rather than absolute assembly necessity.
equatorial microtubule organizing center	Protein complex	part of	`GO:0000923`		UNKNOWN	Equatorial nucleating subassembly included within the whole-array boundary; its finer composition is curated in the separate center record. `GO:1990295` The native GO class has-part GO:0000923; the relation is not inverted into universal eMTOC part-of PAA. `DOI:10.1016/j.cub.2010.10.006` Equator-selective Mto1 targeting defects prevent PAA nucleation while preserving spindle-pole targeting. `DOI:10.3390/cells12060917` Equatorial Mto1 recruitment precedes PAA formation in live-cell time series.

Organism-specific protein examples

Named proteins in which each component's role was established, with the organism the evidence comes from. The component above is the taxon-agnostic family; these are the specific entries behind it.

Alpha tubulin

Accession	Protein	Gene	Organism	Entry
`UniProtKB:P04689`	Tubulin alpha-2 chain	tub1	Schizosaccharomyces pombe 972h- (`NCBITaxon:284812`)	REVIEWED
Role and evidence (2 references) Reference-sequence exemplar for species-level experiments; no assertion that this exact reference stock was imaged. `DOI:10.3390/cells12060917` GFP-Atb2 labels PAA microtubules in the Figure 2 localization and dynamics experiments. atb2 is a native alias of tub1; this is not a census of all alpha-tubulin isoforms. `https://www.uniprot.org/uniprotkb/P04689/entry` Native accession, reviewed status, protein label, primary gene and source taxon verified on 2026-10-08. Localization comes from the primary experiments, not the sequence lookup.

Microtubule-associated protein, MAP65/Ase1/PRC1

Accession	Protein	Gene	Organism	Entry
`UniProtKB:Q9HDY1`	Anaphase spindle elongation protein 1	ase1	Schizosaccharomyces pombe 972h- (`NCBITaxon:284812`)	REVIEWED
Role and evidence (2 references) Reference-sequence exemplar for species-level experiments; no assertion that this exact reference stock was imaged. `DOI:10.3390/cells12060917` Figure 2F-G follows Ase1 localization at the equatorial array; deletion comparisons in H-I retain PAA microtubules with altered organization. `https://www.uniprot.org/uniprotkb/Q9HDY1/entry` Native accession, reviewed status, protein label, primary gene and source taxon verified on 2026-10-08. Localization comes from the primary experiments, not the sequence lookup.

Canonical examples

NCBITaxon:4896 Schizosaccharomyces pombe — Late-mitotic/cytokinetic arrays studied by live-cell microscopy and genetic perturbations. No fungal-wide prevalence or exact reference-strain identity of all experimental stocks is asserted. [DOI:10.3390/cells12060917]

Functions

nucleus localization GO:0051647 — Limits nuclear migration toward the division plane after anaphase, opposing the displacement produced by mitotic spindle-pole microtubules before septation in S. pombe.
- DOI:10.1091/mbc.E23-01-0034 PAA-deficient cells position nuclei closer to the division plane; longitudinal PAA microtubules dynamically contact and deform the nuclear envelope. Later newborn-cell centering is a distinct interphase-network mechanism.
Contribution to effective contractile-ring stiffness — The PAA is implicated in the effective stiffness inferred from ring-ablation recoil in S. pombe, conditional on unchanged initial ring tension.
- DOI:10.3390/cells12060917 Selective mto1-427 PAA impairment increases fitted recoil amplitude. Stiffness interpretation assumes unchanged initial tension; incomplete mutant plateaus and single-plane imaging limit the fitted parameters. This is not a direct stiffness measurement or a universal anchoring requirement.

Mechanism graphs

Equatorial nucleation and array organization (ASSEMBLY)

S. pombe recruitment, nucleation and array organization, bounded by live imaging and genetic perturbations. Contractile-ring Myp2/F-actin is external docking context, not whole-ring membership. Temporal order and recruitment dependencies do not establish a purified binding pathway; Ase1 is not essential for array formation.

Subject	Predicate	Object	Evidence
Contractile-ring Myp2 and F-actin context	supports	equatorial microtubule organizing center	`DOI:10.1016/j.cub.2010.10.006` Myp2 loss and actin disruption impair equatorial Mto1 recruitment. Association assays do not exclude intermediate proteins.
equatorial microtubule organizing center	supports	microtubule nucleation by microtubule organizing center	`DOI:10.1016/j.cub.2010.10.006` The selective mto1-427 targeting defect prevents PAA nucleation while retaining spindle-pole targeting. Separate Alp4 readouts from Mto1 truncations are not attributed to this allele.
microtubule nucleation by microtubule organizing center	generates	post-anaphase microtubule array	`DOI:10.3390/cells12060917` Live-cell time series follow equatorial Mto1 recruitment and subsequent microtubule production.
Alpha tubulin	contributes_to	post-anaphase microtubule array	`DOI:10.3390/cells12060917` Figure 2 follows GFP-Atb2 in equatorial and longitudinal PAA microtubules.
Beta tubulin	contributes_to	post-anaphase microtubule array	`GO:0005874` Composition of the microtubule class applies to the microtubules in GO:1990295; this is not a beta-isoform-specific experimental result.
Microtubule-associated protein, MAP65/Ase1/PRC1	supports	Equatorial microtubule organization	`DOI:10.3390/cells12060917` Equatorial Ase1 localization and altered arrays after ase1 deletion support this organizational role.
Equatorial microtubule organization	organizes	post-anaphase microtubule array	`DOI:10.3390/cells12060917` Ase1-deleted cells retain a dimmer equatorial array and more longitudinal extensions; no all-or-none assembly requirement is asserted.

Opposing microtubule networks position the nucleus (FUNCTION)

Post-anaphase/telophase nuclear positioning before septation in S. pombe. The basket/contact mechanism is inferred from localization, envelope deformation and network-selective perturbations, not a resolved attachment interface or calibrated force measurement. Later newborn-cell interphase simulations are not a model of this PAA network.

Subject	Predicate	Object	Evidence
post-anaphase microtubule array	supports	Longitudinal-array contact with the nuclear envelope	`DOI:10.1091/mbc.E23-01-0034` Live-cell colocalization and nuclear-envelope deformations support a dynamic basket/contact interpretation.
Longitudinal-array contact with the nuclear envelope	supports	Limited nuclear migration toward the division plane	`DOI:10.1091/mbc.E23-01-0034` PAA-selective perturbations permit nuclei nearer the division plane; the precise attachment molecules and force magnitudes are not established.
Limited nuclear migration toward the division plane	contributes_to	nucleus localization	`DOI:10.1091/mbc.E23-01-0034` The PAA-dependent direction opposes the mitotic spindle-pole network rather than completing newborn-cell centering.
Mitotic spindle-pole microtubule network	supports	Nuclear displacement away from the cell end	`DOI:10.1091/mbc.E23-01-0034` Contact imaging and mSPB-selective mto1(1-1085) perturbation support this opposing network contribution.
Nuclear displacement away from the cell end	contributes_to	nucleus localization	`DOI:10.1091/mbc.E23-01-0034` The two networks jointly constrain the post-anaphase position; full mto1 deletion and MBC treatment are not PAA-selective tests.

Discussions

CURATION_TODO (RESOLVED): Keep the whole array distinct from its organizing center and other microtubule networks. Parsed checks over 906 existing records and hidden/ignored-inclusive name, accession and citation searches found no whole-array duplicate. GO:1990295 exactly denotes the array, with parent GO:0110165, part-of GO:0015630 and has-part GO:0000923. The has-part existential is not inverted into universal center part-of array. OTHER describes the multi-filament system, not a single filament or fixed stoichiometric complex. ePAA and lPAA are equatorial and longitudinal portions, not early/late arrays or exact whole-array synonyms. Spindle, interphase arrays, individual microtubules and microtubule ends remain distinct.
CURATION_TODO (RESOLVED): Distinguish array constituents, the nucleating subassembly and external ring context. Alpha/beta tubulin and resident Ase1 belong to the array. Its organizing center is included at subassembly level, without duplicating every center protein. Myp2 and F-actin are upstream ring context; recruitment dependence alone does not make the whole ring a PAA constituent. Mto1/Myp2 spatial offsets and dosage responses constrain simple direct coassembly without excluding indirect association. Unknown tubulin or center assembly essentiality is not replaced by a cell-viability phenotype. Ase1 deletion leaves an altered array, so this constituent is DISPENSABLE for assembly.
CURATION_TODO (OPEN): Extend PAA-specific composition only after checking localization and assembly evidence. This is not an exhaustive protein inventory. Mal3 is used as a plus-tip reporter in supplementary Figure S2, which has not been directly inspected; no Mal3 class is added from that lead alone. A beta-tubulin family assignment is not an isoform-specific localization assay, so no Nda3 protein example is supplied. InterPro families define classes, not universal PAA residence of every family member. Direct PAA-specific evidence is needed before adding other motors or microtubule-associated proteins.
KNOWLEDGE_GAP (OPEN): Resolve the physical PAA-nuclear-envelope interface and transmitted forces. Contact imaging, envelope deformation and selective perturbations support a mechanical basket interpretation, but do not identify a purified interface or calibrated forces. Protection from septal cutting, DNA-damage avoidance and precise inheritance benefits remain hypotheses; no nuclei were cut by the ring after PAA loss under the reported conditions. Later newborn-cell simulations model interphase microtubules and growth, not PAA. MBC affects multiple networks and can leave residual PAA signal.
CURATION_TODO (RESOLVED): Keep inferred effective stiffness separate from direct measurements and universal cytokinesis requirements. Ablations used rings approximately 20-50 percent constricted, single-plane imaging and recoil fits. Interpreting increased recoil as reduced effective stiffness assumes unchanged initial tension. Mutant recoil often failed to plateau or moved out of plane; fitted amplitudes and timescales are lower bounds. Selective mto1-427 PAA impairment did not measurably alter anchoring, constriction or cytokinetic timing under the tested conditions. Complete mto1 deletion affects additional networks and cannot establish a PAA-only healing or timing defect. These experiments do not exclude stress-specific roles.
CURATION_TODO (RESOLVED): Preserve taxon, source-access and quantitative limits. Only S. pombe is a canonical example; reference-sequence taxon 284812 does not identify every experimental stock. Main Results, Discussion and Methods of the two 2023 papers and Results/Discussion of the 2010 targeting paper were read. Separate strain supplements, actual movies, raw data and inline equation graphics remain uninspected. No clade-wide prevalence, fixed whole-array copy number, universal dimension, exact Complex Portal composition, trait link or pathway relation is inferred. The hosted figure is the unchanged CC BY 4.0 original; restricted-license imagery from the nuclear-position study is not hosted.

Evidence

GO:1990295 Native non-obsolete identity, definition, exact aliases and outgoing mereology verified through OAK on 2026-10-08.
DOI:10.3390/cells12060917 PMID 36980258; native PMC10047812.1 Results, Discussion, main Methods and figure captions read. Figure 2 inspected unchanged and verified against native media checksums.
DOI:10.1091/mbc.E23-01-0034 PMID 37099380; published PMC10398876.1 Results, Discussion, main Methods and embedded captions read. Separate movies, strain supplements, raw data and inline equation graphics were not inspected.
DOI:10.1016/j.cub.2010.10.006 PMID 20970338; native PMC2989437.1 Results and Discussion read, not detailed supplemental methods. Selective targeting separates PAA and spindle-pole networks.

Curation history

2026-10-08T00:45:29Z codex · CREATED_RECORD — Scaffolded by scripts/new_record.py
2026-10-08T00:48:28Z codex · EXPANDED_RECORD — Added four source-bounded component classes, two protein examples, two functions, two mechanistic graphs and a checksum-verified CC BY 4.0 figure; preserved identity, taxon and inference limits.

Source: data/structures/cytoskeleton/post_anaphase_microtubule_array.yaml