provider: falcon
model: Edison Scientific Literature
cached: false
start_time: '2026-01-31T12:36:05.979281'
end_time: '2026-01-31T12:41:20.151652'
duration_seconds: 314.17
template_file: templates/gene_research_go_focused.md
template_variables:
organism: ARATH
gene_id: BUB3.1
gene_symbol: BUB3.1
uniprot_accession: Q9LJN8
protein_description: 'RecName: Full=Mitotic checkpoint protein BUB3.1; AltName:
Full=Protein BUDDING UNINHIBITED BY BENZYMIDAZOL 3.1;'
gene_info: Name=BUB3.1; OrderedLocusNames=At3g19590; ORFNames=MMB12.5;
organism_full: Arabidopsis thaliana (Mouse-ear cress).
protein_family: Belongs to the WD repeat BUB3 family. .
protein_domains: WD40/YVTN_repeat-like_dom_sf. (IPR015943); WD40_PAC1. (IPR020472);
WD40_repeat_dom_sf. (IPR036322); WD40_rpt. (IPR001680); WD40 (PF00400)
provider_config:
timeout: 600
max_retries: 3
parameters:
allowed_domains: []
temperature: 0.1
citation_count: 16

Question

Gene Research for Functional Annotation

⚠️ CRITICAL: Gene/Protein Identification Context

BEFORE YOU BEGIN RESEARCH: You MUST verify you are researching the CORRECT gene/protein. Gene symbols can be ambiguous, especially for less well-characterized genes from non-model organisms.

Target Gene/Protein Identity (from UniProt):

• UniProt Accession: Q9LJN8
• Protein Description: RecName: Full=Mitotic checkpoint protein BUB3.1; AltName: Full=Protein BUDDING UNINHIBITED BY BENZYMIDAZOL 3.1;
• Gene Information: Name=BUB3.1; OrderedLocusNames=At3g19590; ORFNames=MMB12.5;
• Organism (full): Arabidopsis thaliana (Mouse-ear cress).
• Protein Family: Belongs to the WD repeat BUB3 family. .
• Key Domains: WD40/YVTN_repeat-like_dom_sf. (IPR015943); WD40_PAC1. (IPR020472); WD40_repeat_dom_sf. (IPR036322); WD40_rpt. (IPR001680); WD40 (PF00400)

MANDATORY VERIFICATION STEPS:

1. Check if the gene symbol "BUB3.1" matches the protein description above
2. Verify the organism is correct: Arabidopsis thaliana (Mouse-ear cress).
3. Check if protein family/domains align with what you find in literature
4. If you find literature for a DIFFERENT gene with the same or similar symbol, STOP

If Gene Symbol is Ambiguous or You Cannot Find Relevant Literature:

DO NOT PROCEED WITH RESEARCH ON A DIFFERENT GENE. Instead:
- State clearly: "The gene symbol 'BUB3.1' is ambiguous or literature is limited for this specific protein"
- Explain what you found (e.g., "Found extensive literature on a different gene with the same symbol in a different organism")
- Describe the protein based ONLY on the UniProt information provided above
- Suggest that the protein function can be inferred from domain/family information

Research Target:

Please provide a comprehensive research report on the gene BUB3.1 (gene ID: BUB3.1, UniProt: Q9LJN8) in ARATH.

The research report should be a detailed narrative explaining the function, biological processes, and localization of the gene product. Citations should be given for all claims.

You should prioritize authoritative reviews and primary scientific literature when conducting research. You can supplement
this with annotations you find in gene/protein databases, but these can be outdated or inaccurate.

We are specifically interested in the primary function of the gene - for enzymes, what reaction is catalyzed, and what is the substrate specificity? For transporters, what is the substrate? For structural proteins or adapters, what is the broader structural role? For signaling molecules, what is the role in the pathway.

We are interested in where in or outside the cell the gene product carries out its function.

We are also interested in the signaling or biochemical pathways in which the gene functions. We are less interested in broad pleiotropic effects, except where these elucidate the precise role.

Include evidence where possible. We are interested in both experimental evidence as well as inference from structure, evolution, or bioinformatic analysis. Precise studies should be prioritized over high-throughput, where available.

Output

Question: You are an expert researcher providing comprehensive, well-cited information.

Provide detailed information focusing on:
1. Key concepts and definitions with current understanding
2. Recent developments and latest research (prioritize 2023-2024 sources)
3. Current applications and real-world implementations
4. Expert opinions and analysis from authoritative sources
5. Relevant statistics and data from recent studies

Format as a comprehensive research report with proper citations. Include URLs and publication dates where available.
Always prioritize recent, authoritative sources and provide specific citations for all major claims.

Gene Research for Functional Annotation

⚠️ CRITICAL: Gene/Protein Identification Context

BEFORE YOU BEGIN RESEARCH: You MUST verify you are researching the CORRECT gene/protein. Gene symbols can be ambiguous, especially for less well-characterized genes from non-model organisms.

Target Gene/Protein Identity (from UniProt):

• UniProt Accession: Q9LJN8
• Protein Description: RecName: Full=Mitotic checkpoint protein BUB3.1; AltName: Full=Protein BUDDING UNINHIBITED BY BENZYMIDAZOL 3.1;
• Gene Information: Name=BUB3.1; OrderedLocusNames=At3g19590; ORFNames=MMB12.5;
• Organism (full): Arabidopsis thaliana (Mouse-ear cress).
• Protein Family: Belongs to the WD repeat BUB3 family. .
• Key Domains: WD40/YVTN_repeat-like_dom_sf. (IPR015943); WD40_PAC1. (IPR020472); WD40_repeat_dom_sf. (IPR036322); WD40_rpt. (IPR001680); WD40 (PF00400)

MANDATORY VERIFICATION STEPS:

1. Check if the gene symbol "BUB3.1" matches the protein description above
2. Verify the organism is correct: Arabidopsis thaliana (Mouse-ear cress).
3. Check if protein family/domains align with what you find in literature
4. If you find literature for a DIFFERENT gene with the same or similar symbol, STOP

If Gene Symbol is Ambiguous or You Cannot Find Relevant Literature:

DO NOT PROCEED WITH RESEARCH ON A DIFFERENT GENE. Instead:
- State clearly: "The gene symbol 'BUB3.1' is ambiguous or literature is limited for this specific protein"
- Explain what you found (e.g., "Found extensive literature on a different gene with the same symbol in a different organism")
- Describe the protein based ONLY on the UniProt information provided above
- Suggest that the protein function can be inferred from domain/family information

Research Target:

Please provide a comprehensive research report on the gene BUB3.1 (gene ID: BUB3.1, UniProt: Q9LJN8) in ARATH.

The research report should be a detailed narrative explaining the function, biological processes, and localization of the gene product. Citations should be given for all claims.

You should prioritize authoritative reviews and primary scientific literature when conducting research. You can supplement
this with annotations you find in gene/protein databases, but these can be outdated or inaccurate.

We are specifically interested in the primary function of the gene - for enzymes, what reaction is catalyzed, and what is the substrate specificity? For transporters, what is the substrate? For structural proteins or adapters, what is the broader structural role? For signaling molecules, what is the role in the pathway.

We are interested in where in or outside the cell the gene product carries out its function.

We are also interested in the signaling or biochemical pathways in which the gene functions. We are less interested in broad pleiotropic effects, except where these elucidate the precise role.

Include evidence where possible. We are interested in both experimental evidence as well as inference from structure, evolution, or bioinformatic analysis. Precise studies should be prioritized over high-throughput, where available.

Plan
Objective 1: Verify target identity, organism, family/domains, and paralogs for Arabidopsis thaliana BUB3.1 (UniProt Q9LJN8; At3g19590). Status: completed. Evidence from Arabidopsis studies identifies two close BUB3 paralogs (BUB3.1/At3g19590 and BUB3.2/At1g49910) and a divergent BUB3.3; BUB3.1 is a ~38 kDa WD40-repeat BUB3 family protein with 52% identity to human BUB3, consistent with the UniProt description and WD40 family annotation (PLoS ONE 2009; https://doi.org/10.1371/journal.pone.0006757, Aug 2009) (caillaud2009spindleassemblycheckpoint pages 2-4, paganelli2013…formationdes pages 147-148).
Objective 2: Gather recent and foundational literature with emphasis on 2023–2024 sources. Status: completed. High-quality recent work in 2024 PNAS articles detail a KNL1–SAC axis and BMF3–BUB3.3–CDC20 recruitment, and a 2024 Nature Plants article links BUB3.3 to a kinesin-7 motor; foundational Arabidopsis BUB3.1 studies from 2009–2018 provide functional and localization evidence (https://doi.org/10.1073/pnas.2316583121, Jan 2024; https://doi.org/10.1073/pnas.2322677121, Mar 2024; https://doi.org/10.1038/s41477-024-01824-7, Oct 2024; https://doi.org/10.1371/journal.pone.0006757, Aug 2009; https://doi.org/10.1038/s41477-018-0192-z, Jul 2018) (deng2024acoadaptedknl1 pages 1-2, deng2024thearabidopsisbub1mad3 pages 3-5, tang2024akinetochoreassociatedkinesin7 pages 1-8, caillaud2009spindleassemblycheckpoint pages 2-4, zhang2018roleofthe pages 1-2).
Objective 3: Compile detailed evidence on function, pathways, localization, and plant-specific roles. Status: completed. Evidence assembled below (caillaud2009spindleassemblycheckpoint pages 2-4, paganelli2015threebub1and pages 1-2, zhang2018roleofthe pages 1-2).
Objective 4: Extract statistics/quantitative data and applications/implications. Status: completed. Quantitative n values for localization/interaction assays and identity percentages are included; developmental and cytokinesis implications summarized (caillaud2009spindleassemblycheckpoint pages 2-4, zhang2018roleofthe pages 1-2, deng2024thearabidopsisbub1mad3 pages 11-11).
Objective 5: Synthesize expert analysis from authoritative sources. Status: completed. Integrates PNAS and Nature Plants advances with foundational Arabidopsis work to delineate paralog-specific roles (deng2024acoadaptedknl1 pages 1-2, deng2024thearabidopsisbub1mad3 pages 3-5, tang2024akinetochoreassociatedkinesin7 pages 1-8).
Objective 6: Create a summary artifact table. Status: completed; see embedded artifact (artifact-00).
Objective 7: Write and submit the comprehensive, cited research report. Status: completed.

Comprehensive research report: Arabidopsis thaliana BUB3.1 (At3g19590; UniProt Q9LJN8)

1) Key concepts and definitions
BUB3.1 is an Arabidopsis thaliana WD40-repeat protein of the conserved BUB3 family, encoded at locus At3g19590, and one of multiple BUB3 paralogs in Arabidopsis (BUB3.1, BUB3.2, BUB3.3). Sequence and domain analyses show BUB3.1 is ~38 kDa with multiple WD40 repeats; it shares ~52% identity with human BUB3 and ~22% with budding yeast BUB3, consistent with a conserved scaffold role in the spindle assembly checkpoint (SAC) (PLoS ONE, 2009; URL: https://doi.org/10.1371/journal.pone.0006757, Aug 2009) (caillaud2009spindleassemblycheckpoint pages 2-4, paganelli2013…formationdes pages 147-148). In plants, BUB3 paralogs have diversified: BUB3.1 and BUB3.2 are highly similar (≈88% identity), while BUB3.3 is more divergent and exhibits specialized kinetochore functions (Nature Plants, 2018; URL: https://doi.org/10.1038/s41477-018-0192-z, Jul 2018; PNAS, 2024; URL: https://doi.org/10.1073/pnas.2316583121, Jan 2024) (zhang2018roleofthe pages 1-2, deng2024acoadaptedknl1 pages 2-3, deng2024acoadaptedknl1 pages 1-2).

Functionally, BUB3 proteins are core SAC components that contribute to assembly of a checkpoint effector complex to inhibit APC/C activator CDC20 until all chromosomes are properly attached to spindle microtubules. In Arabidopsis, BUB3.1 interacts with MAD2 and BUBR1/MAD3-like proteins, consistent with a role in mitotic checkpoint complex (MCC)-like signaling (PLoS ONE, 2009; URL: https://doi.org/10.1371/journal.pone.0006757, Aug 2009) (caillaud2009spindleassemblycheckpoint pages 2-4, paganelli2013…formationdes pages 148-150, paganelli2013…formationdes pages 147-148).

2) Primary molecular function, interactions, and plant‑specific roles
- Checkpoint scaffold and MCC context: BUB3.1 displays cell cycle–regulated expression peaking at G2/M and physically interacts with MAD2 and BUBR1/MAD3 family proteins, supporting participation in SAC signaling that restrains anaphase onset (PLoS ONE, 2009; URL: https://doi.org/10.1371/journal.pone.0006757; thesis/compendium 2013) (caillaud2009spindleassemblycheckpoint pages 2-4, paganelli2013…formationdes pages 148-150, paganelli2013…formationdes pages 147-148, paganelli2013…formationdes pages 174-182).
- Plant‑specific cytokinesis function: Unlike the canonical animal paradigm that emphasizes kinetochore-restricted BUB3 functions, Arabidopsis BUB3.1 and its close paralog BUB3.2 additionally interact with the microtubule-bundling protein MAP65-3 and promote phragmoplast microtubule reorganization during cytokinesis. BUB3.1/2 localize to the spindle midzone and phragmoplast midline and facilitate MAP65-3 association with microtubules, directly linking checkpoint components to cytokinetic machinery (Nature Plants, 2018; URL: https://doi.org/10.1038/s41477-018-0192-z, Jul 2018) (zhang2018roleofthe pages 1-2, paganelli2015threebub1and pages 1-2, paganelli2015threebub1and pages 9-10).
- Interaction repertoire: BUB3.1 interacts with MAD2 and BUBR1/MAD3 family proteins by Y2H/BiFC and co-localizes at centromeric foci; tandem affinity purifications and biochemical data identify MAP65-3 as a BUB3.1 partner, with specificity over other MAP65 isoforms (e.g., not MAP65-1), reinforcing a targeted role in midzone/cell plate formation (New Phytologist, 2015; URL: https://doi.org/10.1111/nph.13073, Sep 2015) (paganelli2015threebub1and pages 1-2, paganelli2015threebub1and pages 9-10).

3) Subcellular localization dynamics
- Interphase: BUB3.1-GFP is nuclear with additional cytoplasmic signal (PLoS ONE, 2009; URL: https://doi.org/10.1371/journal.pone.0006757) (caillaud2009spindleassemblycheckpoint pages 2-4, paganelli2013…formationdes pages 147-148).
- Proto-/prometaphase under SAC activation: Upon microtubule destabilization (e.g., propyzamide), BUB3.1 accumulates at unattached kinetochores, similar to MAD2 and BUBR1, consistent with checkpoint activation (PLoS ONE, 2009; URL: https://doi.org/10.1371/journal.pone.0006757) (caillaud2009spindleassemblycheckpoint pages 2-4, paganelli2013…formationdes pages 148-150).
- Anaphase to cytokinesis: BUB3.1 enriches in the spindle midzone during anaphase and strongly at the phragmoplast midline during cytokinesis, before reappearing in daughter nuclei, matching a role in phragmoplast regulation (Nature Plants, 2018; URL: https://doi.org/10.1038/s41477-018-0192-z) (zhang2018roleofthe pages 1-2).

4) Genetic/phenotypic evidence
- BUB3.1 loss and development: Arabidopsis BUB3.1 disruption has been associated with embryo/gametophyte lethality in certain lines, indicating essential roles in reproduction; family-level evidence supports BUB3 roles in development and fertility (PNAS, 2024; URL: https://doi.org/10.1073/pnas.2322677121, Mar 2024) (deng2024thearabidopsisbub1mad3 pages 11-11).
- Cytokinesis function revealed by paralog double mutants: bub3;1 bub3;2 double mutants exhibit uncoordinated phragmoplast expansion, failed cell plate assembly, and hypersensitivity to caffeine, consistent with defective cytokinesis. At the organismal level, seedlings can appear grossly normal, but cellular defects are clear (Nature Plants, 2018; URL: https://doi.org/10.1038/s41477-018-0192-z) (zhang2018roleofthe pages 1-2).
- SAC-related phenotypes in family: MAD3/BUBR1-related mutants (interacting with BUB3.1) show metaphase misalignment, lagging chromosomes, and micronuclei; combined SAC component mutations exacerbate mitotic defects (New Phytologist, 2015; URL: https://doi.org/10.1111/nph.13073) (paganelli2015threebub1and pages 1-2, paganelli2015threebub1and pages 9-10).

5) Plant-specific features vs animals/yeast
Plants repurpose BUB3 paralogs for additional midzone/phragmoplast roles. BUB3.1/2 cooperate with MAP65-3 to reorganize midzone microtubules, a function not described in the same form in animals/yeast, where BUB3 primarily scaffolds kinetochore recruitment via GLEBS interactions on Bub1/BubR1. In Arabidopsis, only BUB3.3 is a persistent kinetochore-localized SAC factor, while BUB3.1/2 primarily support cytokinesis, illustrating paralog specialization in plants (Nature Plants, 2018; URL: https://doi.org/10.1038/s41477-018-0192-z; PNAS, 2024; URL: https://doi.org/10.1073/pnas.2316583121) (zhang2018roleofthe pages 1-2, deng2024acoadaptedknl1 pages 2-3, deng2024acoadaptedknl1 pages 1-2).

6) Recent developments and latest research (2023–2024)
Although these advances focus on BUB3.3 rather than BUB3.1, they define the present understanding of the BUB3 family axis at plant kinetochores and clarify paralog-specific roles relative to BUB3.1:
- KNL1–SAC axis in Arabidopsis: KNL1 independently recruits BUB3.3 and BMF3 to kinetochores; loss of KNL1 disrupts kinetochore localization of SAC components and prevents SAC activation, establishing KNL1 as a core plant kinetochore scaffold for SAC proteins (PNAS, 2024; URL: https://doi.org/10.1073/pnas.2316583121, Jan 2024) (deng2024acoadaptedknl1 pages 1-2, deng2024acoadaptedknl1 pages 2-3).
- BMF3–BUB3.3–CDC20 recruitment: BMF3 requires BUB3.3 to recruit CDC20 to unattached kinetochores; BMF3 carries internal repeats necessary for BUB3.3 binding, and bub3.3 and bmf3 mutants lose kinetochore CDC20 signals, indicating a specialized paralog pathway for MCC-like assembly in plants (PNAS, 2024; URL: https://doi.org/10.1073/pnas.2322677121, Mar 2024) (deng2024thearabidopsisbub1mad3 pages 9-10, deng2024thearabidopsisbub1mad3 pages 7-7, deng2024thearabidopsisbub1mad3 pages 3-5).
- Kinesin-7 cooperation with BUB3.3: A kinetochore-associated kinesin-7 motor (KAK1; CENP-E–like) cooperates with BUB3.3 to promote chromosome congression. KNL1C-BUB3.3 and KAK1-KNL1C fusion experiments rescue respective mutant phenotypes, supporting functional connections among KNL1, BUB3.3, and kinesin-7 (Nature Plants, 2024; URL: https://doi.org/10.1038/s41477-024-01824-7, Oct 2024) (tang2024akinetochoreassociatedkinesin7 pages 1-8). These data underscore that the kinetochore-centric BUB3 activity in Arabidopsis is predominantly mediated by BUB3.3, whereas BUB3.1 serves plant-specific cytokinetic functions.

7) Quantitative data and key statistics
- Sequence identity: BUB3.1 shares ~52% identity with human BUB3 and ~22% with budding yeast BUB3; BUB3.1 and BUB3.2 share ~88% identity, consistent with paralogous conservation (PLoS ONE, 2009; URL: https://doi.org/10.1371/journal.pone.0006757) (caillaud2009spindleassemblycheckpoint pages 2-4, paganelli2013…formationdes pages 147-148).
- Localization/interaction assays: Multiple BiFC and localization experiments report sample sizes typically n = 20–40 cells per assay; kinetochore association is observed under spindle poison (e.g., propyzamide) or proteasome inhibition (MG132) conditions (PLoS ONE, 2009; URL: https://doi.org/10.1371/journal.pone.0006757) (caillaud2009spindleassemblycheckpoint pages 2-4, paganelli2013…formationdes pages 148-150).
- Genetic phenotypes: bub3;1 bub3;2 double mutants show clear cellular cytokinesis defects and stress hypersensitivity (caffeine) despite relatively mild gross morphology (Nature Plants, 2018; URL: https://doi.org/10.1038/s41477-018-0192-z) (zhang2018roleofthe pages 1-2). Family-level SAC mutants (MAD3-related) exhibit increased chromosome misalignment, lagging chromosomes, and micronuclei, quantitatively increasing mitotic error frequency (New Phytologist, 2015; URL: https://doi.org/10.1111/nph.13073) (paganelli2015threebub1and pages 1-2, paganelli2015threebub1and pages 9-10).

8) Current applications and implications
- Development and fertility: Disruption of BUB3 family members can lead to gametophyte/embryo lethality; for BUB3.1, essential roles in reproduction have been reported in specific genetic backgrounds, highlighting potential constraints on cell division fidelity during plant reproduction (PNAS, 2024; URL: https://doi.org/10.1073/pnas.2322677121) (deng2024thearabidopsisbub1mad3 pages 11-11).
- Cytokinesis engineering and stress responses: The BUB3.1/2–MAP65-3 axis provides a plant-specific handle on phragmoplast organization; defects yield sensitivity to agents like caffeine and cytokinesis failure, implicating BUB3.1 in robustness of cell plate formation and thus tissue patterning during growth (Nature Plants, 2018; URL: https://doi.org/10.1038/s41477-018-0192-z) (zhang2018roleofthe pages 1-2).
- Mechanistic framework for crop systems: The 2024 KNL1–SAC studies outline a plant lineage–specific recruitment architecture for kinetochore checkpoints, which may inform targeted manipulation of mitotic fidelity in plant breeding and development. Although these data focus on BUB3.3, they clarify the broader BUB3 family organization in plants and help contextualize BUB3.1’s cytokinesis role (PNAS, 2024; URLs above) (deng2024acoadaptedknl1 pages 1-2, deng2024acoadaptedknl1 pages 2-3).

Expert synthesis and analysis
Collectively, Arabidopsis BUB3.1 conforms to a conserved SAC scaffold with WD40 repeats, but plant evolution diversified BUB3 paralogs: BUB3.3 now anchors core kinetochore SAC functions (recruiting CDC20 via BMF3 and cooperating with KNL1 and KAK1 kinesin-7), whereas BUB3.1 (and BUB3.2) have assumed prominent phragmoplast/midzone roles by partnering with MAP65-3 to execute cytokinesis. This division of labor explains earlier observations of BUB3.1 localization to unattached kinetochores under checkpoint activation, while its dominant developmental impact manifests through cytokinesis. The 2024 advances provide a mechanistic scaffold for kinetochore recruitment in plants and, by demarcating paralog-specific roles, prevent conflation of BUB3.1 cytokinesis functions with BUB3.3 checkpoint recruitment roles (PNAS 2024; Nature Plants 2018, 2024) (deng2024acoadaptedknl1 pages 1-2, deng2024thearabidopsisbub1mad3 pages 3-5, tang2024akinetochoreassociatedkinesin7 pages 1-8, zhang2018roleofthe pages 1-2).

Embedded summary table of evidence
| Category | Key finding (1–2 sentences) | Evidence type | Organism / isoform specificity | Quantitative details | Primary source(s) (URL, year) |
|---|---|---:|---|---:|---|
| Identity / domains / paralogs | BUB3.1 is a WD40-repeat protein (~38 kDa) belonging to the BUB3 family; Arabidopsis has multiple BUB3 paralogs including highly similar BUB3.2 and a more divergent BUB3.3. | Sequence analysis, expression profiling | Arabidopsis thaliana (BUB3.1 At3g19590 vs BUB3.2 At1g49910; BUB3.3 divergent) | BUB3.1 ~38 kDa; BUB3.1 vs BUB3.2 ~88% identity; BUB3.1 vs human BUB3 ~52% identity (n / assays reported) | https://doi.org/10.1371/journal.pone.0006757 (2009) (caillaud2009spindleassemblycheckpoint pages 2-4), (paganelli2013…formationdes pages 147-148) |
| Primary molecular function | Functions as a WD40 scaffold in the spindle assembly checkpoint (forms part of MCC to inhibit CDC20/APC/C), with cell-cycle regulated expression peaking at G2/M. | Localization (GFP), BiFC, cell synchronization, pharmacological SAC activation | BUB3.1 (primary evidence for SAC role) | G2/M expression peak reported; localization/BiFC assays typically n = 20–40 cells in studies | https://doi.org/10.1371/journal.pone.0006757 (2009) (caillaud2009spindleassemblycheckpoint pages 2-4), (paganelli2013…formationdes pages 148-150) |
| Interaction partners | Direct/robust interactions reported with MAD2 and BUBR1/MAD3 family proteins and a plant-specific interaction with MAP65-3 (links SAC to microtubule bundling). | Y2H / split-ubiquitin, BiFC, TAP-MS, co‑IP | BUB3.1 ↔ MAD2, BUBR1/MAD3; BUB3.1 ↔ MAP65-3 (plant-specific) | Interaction assays with BiFC/Y2H reported (n ≈ 20–40); TAP‑MS identified MAP65-3 in complexes | https://doi.org/10.1111/nph.13073 (2015) (paganelli2015threebub1and pages 1-2, paganelli2015threebub1and pages 9-10), https://doi.org/10.1038/s41477-018-0192-z (2018) (zhang2018roleofthe pages 1-2) |
| Subcellular localization dynamics | BUB3.1 is nuclear in interphase, localizes to unattached kinetochores on SAC activation, becomes enriched in the spindle midzone during anaphase and concentrates at the phragmoplast midline during cytokinesis. | Live-cell imaging (GFP fusions), drug treatments (propyzamide), immunolocalization | Observed for BUB3.1 (also reported for BUB3.2 in many assays) | Localization assays reported with sample counts (e.g., n = 20–40); dynamic relocalization across mitotic phases documented | https://doi.org/10.1371/journal.pone.0006757 (2009) (caillaud2009spindleassemblycheckpoint pages 2-4), https://doi.org/10.1038/s41477-018-0192-z (2018) (zhang2018roleofthe pages 1-2), (paganelli2013…formationdes pages 148-150) |
| Mutant / phenotypic evidence | Loss or combined loss of BUB3 paralogs impairs cytokinesis and chromosome segregation: bub3;1 bub3;2 double mutants display uncoordinated phragmoplast expansion, cytokinesis failure and caffeine hypersensitivity; single BUB3.1 disruption reported to affect female gametophyte/embryogenesis in some lines. | Genetic knockouts / double mutants, phenotypic characterization, cytology | Phenotypes reported for bub3;1 bub3;2 double mutants; some BUB3.1 T‑DNA lines show gametophytic/embryo defects | Cellular phenotypes: failed cell plate assembly, misaligned chromosomes, cytokinesis defects; stress sensitivity (caffeine) described | https://doi.org/10.1038/s41477-018-0192-z (2018) (zhang2018roleofthe pages 1-2), https://doi.org/10.1111/nph.13073 (2015) (paganelli2015threebub1and pages 1-2) |
| Plant‑specific roles beyond SAC | BUB3.1/2 promote phragmoplast microtubule reorganization by interacting with MAP65-3, implicating BUB3 paralogs in cytokinesis regulation distinct from canonical kinetochore-only roles in animals/yeast. | Biochemistry (interaction assays), cellular imaging, genetics | Demonstrated for BUB3.1 and BUB3.2 (plant paralogs) | Functional assays show MAP65-3 recruitment/activity promoted by BUB3.1/2; double mutant cytokinesis phenotypes documented | https://doi.org/10.1038/s41477-018-0192-z (2018) (zhang2018roleofthe pages 1-2) |
| 2023–2024 family‑level advances | Recent 2024 work shows a noncanonical BUB3 paralog (BUB3.3) mediates recruitment of CDC20 via BMF3 at kinetochores and highlights coadaptation of KNL1–SAC connections in Arabidopsis; these advances emphasize paralog-specific specialization within the plant BUB3 family (BUB3.3 findings distinct from BUB3.1 roles). | Genetic, biochemical, cryo/cell biological analyses (recent PNAS and PNAS-series studies) | Findings primarily implicate BUB3.3 (not BUB3.1) for CDC20 recruitment; KNL1–SAC coadaptation discussed at family level in Arabidopsis | PNAS 2024 (Deng et al.) demonstrates BMF3 requires BUB3.3 to recruit CDC20 (see DOI); reviews/PNAS work on KNL1 coadaptation in 2024 discuss plant‑specific recruitment mechanisms | https://doi.org/10.1073/pnas.2322677121 (2024) (deng2024thearabidopsisbub1mad3 pages 11-11), https://doi.org/10.1073/pnas.2316583121 (2024) (paganelli2015threebub1and pages 9-10) |

Table: Concise, evidence‑linked summary of Arabidopsis thaliana BUB3.1 (At3g19590; UniProt Q9LJN8) covering identity, functions, partners, localization, mutant phenotypes, plant‑specific roles, and recent 2023–2024 family advances; sources cited for each entry for quick verification.

Verification of gene/protein identity and avoidance of ambiguity
- The literature cited explicitly uses Arabidopsis At3g19590 for BUB3.1 and distinguishes BUB3.2 (At1g49910) and BUB3.3, aligning with the UniProt entry Q9LJN8 and the Arabidopsis organism context. Domain and family annotations (WD40 repeats; BUB3 family) match UniProt-provided domain architecture. No conflicting gene symbol usage from other organisms is invoked in the evidence (Nature Plants 2018; PLoS ONE 2009) (zhang2018roleofthe pages 1-2, caillaud2009spindleassemblycheckpoint pages 2-4).

References with URLs and dates (selection within the evidence set)
- Caillaud MC et al. Spindle Assembly Checkpoint Protein Dynamics Reveal Conserved and Unsuspected Roles in Plant Cell Division. PLoS ONE. Aug 2009. URL: https://doi.org/10.1371/journal.pone.0006757 (caillaud2009spindleassemblycheckpoint pages 2-4).
- Paganelli L et al. Three BUB1 and BUBR1/MAD3-related spindle assembly checkpoint proteins are required for accurate mitosis in Arabidopsis. New Phytologist. Sep 2015. URL: https://doi.org/10.1111/nph.13073 (paganelli2015threebub1and pages 1-2, paganelli2015threebub1and pages 9-10).
- Zhang H et al. Role of the BUB3 protein in phragmoplast microtubule reorganization during cytokinesis. Nature Plants. Jul 2018. URL: https://doi.org/10.1038/s41477-018-0192-z (zhang2018roleofthe pages 1-2).
- Deng X et al. A coadapted KNL1 and spindle assembly checkpoint axis orchestrates precise mitosis in Arabidopsis. PNAS. Jan 2024. URL: https://doi.org/10.1073/pnas.2316583121 (deng2024acoadaptedknl1 pages 1-2, deng2024acoadaptedknl1 pages 2-3).
- Deng X et al. The Arabidopsis BUB1/MAD3 family protein BMF3 requires BUB3.3 to recruit CDC20 to kinetochores in SAC signaling. PNAS. Mar 2024. URL: https://doi.org/10.1073/pnas.2322677121 (deng2024thearabidopsisbub1mad3 pages 9-10, deng2024thearabidopsisbub1mad3 pages 7-9, deng2024thearabidopsisbub1mad3 pages 11-11, deng2024thearabidopsisbub1mad3 pages 7-7, deng2024thearabidopsisbub1mad3 pages 3-5).
- Tang X et al. A kinetochore-associated kinesin-7 motor cooperates with BUB3.3 to regulate mitotic chromosome congression in Arabidopsis thaliana. Nature Plants. Oct 2024. URL: https://doi.org/10.1038/s41477-024-01824-7 (tang2024akinetochoreassociatedkinesin7 pages 1-8).

References

1. (caillaud2009spindleassemblycheckpoint pages 2-4): Marie-Cécile Caillaud, Laetitia Paganelli, Philippe Lecomte, Laurent Deslandes, Michaël Quentin, Yann Pecrix, Manuel Le Bris, Nicolas Marfaing, Pierre Abad, and Bruno Favery. Spindle assembly checkpoint protein dynamics reveal conserved and unsuspected roles in plant cell division. PLoS ONE, 4:e6757, Aug 2009. URL: https://doi.org/10.1371/journal.pone.0006757, doi:10.1371/journal.pone.0006757. This article has 89 citations and is from a peer-reviewed journal.

2. (paganelli2013…formationdes pages 147-148): L Paganelli. … formation des cellules géantes induites par le nématode à galles meloidogyne incognita: caractérisation du complexe de surveillance de la mitose chez arabidopsis. Unknown journal, 2013.

3. (deng2024acoadaptedknl1 pages 1-2): Xingguang Deng, Ying He, Xiaoya Tang, Xianghong Liu, Yuh-Ru Julie Lee, Bo Liu, and Honghui Lin. A coadapted knl1 and spindle assembly checkpoint axis orchestrates precise mitosis in arabidopsis. Proceedings of the National Academy of Sciences of the United States of America, Jan 2024. URL: https://doi.org/10.1073/pnas.2316583121, doi:10.1073/pnas.2316583121. This article has 10 citations and is from a highest quality peer-reviewed journal.

4. (deng2024thearabidopsisbub1mad3 pages 3-5): Xingguang Deng, Felicia Lei Peng, Xiaoya Tang, Yuh-Ru Julie Lee, Hong-Hui Lin, and Bo Liu. The arabidopsis bub1/mad3 family protein bmf3 requires bub3.3 to recruit cdc20 to kinetochores in spindle assembly checkpoint signaling. Proceedings of the National Academy of Sciences of the United States of America, Mar 2024. URL: https://doi.org/10.1073/pnas.2322677121, doi:10.1073/pnas.2322677121. This article has 10 citations and is from a highest quality peer-reviewed journal.

5. (tang2024akinetochoreassociatedkinesin7 pages 1-8): Xiaoya Tang, Ying He, Yihang Tang, Keqi Chen, Honghui Lin, Bo Liu, and Xingguang Deng. A kinetochore-associated kinesin-7 motor cooperates with bub3.3 to regulate mitotic chromosome congression in arabidopsis thaliana. Nature plants, 10:1724-1736, Oct 2024. URL: https://doi.org/10.1038/s41477-024-01824-7, doi:10.1038/s41477-024-01824-7. This article has 7 citations and is from a highest quality peer-reviewed journal.

6. (zhang2018roleofthe pages 1-2): Hongchang Zhang, Xingguang Deng, Baojuan Sun, Sonny Lee Van, Zhensheng Kang, Honghui Lin, Yuh-Ru Julie Lee, and Bo Liu. Role of the bub3 protein in phragmoplast microtubule reorganization during cytokinesis. Nature Plants, 4:485-494, Jul 2018. URL: https://doi.org/10.1038/s41477-018-0192-z, doi:10.1038/s41477-018-0192-z. This article has 39 citations and is from a highest quality peer-reviewed journal.

7. (paganelli2015threebub1and pages 1-2): Laetitia Paganelli, Marie‐Cécile Caillaud, Michaël Quentin, Isabelle Damiani, Benjamin Govetto, Philippe Lecomte, Pavel A. Karpov, Pierre Abad, Marie‐Edith Chabouté, and Bruno Favery. Three bub1 and bubr1/mad3-related spindle assembly checkpoint proteins are required for accurate mitosis in arabidopsis. The New phytologist, 205 1:202-15, Sep 2015. URL: https://doi.org/10.1111/nph.13073, doi:10.1111/nph.13073. This article has 19 citations.

8. (deng2024thearabidopsisbub1mad3 pages 11-11): Xingguang Deng, Felicia Lei Peng, Xiaoya Tang, Yuh-Ru Julie Lee, Hong-Hui Lin, and Bo Liu. The arabidopsis bub1/mad3 family protein bmf3 requires bub3.3 to recruit cdc20 to kinetochores in spindle assembly checkpoint signaling. Proceedings of the National Academy of Sciences of the United States of America, Mar 2024. URL: https://doi.org/10.1073/pnas.2322677121, doi:10.1073/pnas.2322677121. This article has 10 citations and is from a highest quality peer-reviewed journal.

9. (deng2024acoadaptedknl1 pages 2-3): Xingguang Deng, Ying He, Xiaoya Tang, Xianghong Liu, Yuh-Ru Julie Lee, Bo Liu, and Honghui Lin. A coadapted knl1 and spindle assembly checkpoint axis orchestrates precise mitosis in arabidopsis. Proceedings of the National Academy of Sciences of the United States of America, Jan 2024. URL: https://doi.org/10.1073/pnas.2316583121, doi:10.1073/pnas.2316583121. This article has 10 citations and is from a highest quality peer-reviewed journal.

10. (paganelli2013…formationdes pages 148-150): L Paganelli. … formation des cellules géantes induites par le nématode à galles meloidogyne incognita: caractérisation du complexe de surveillance de la mitose chez arabidopsis. Unknown journal, 2013.

11. (paganelli2013…formationdes pages 174-182): L Paganelli. … formation des cellules géantes induites par le nématode à galles meloidogyne incognita: caractérisation du complexe de surveillance de la mitose chez arabidopsis. Unknown journal, 2013.

12. (paganelli2015threebub1and pages 9-10): Laetitia Paganelli, Marie‐Cécile Caillaud, Michaël Quentin, Isabelle Damiani, Benjamin Govetto, Philippe Lecomte, Pavel A. Karpov, Pierre Abad, Marie‐Edith Chabouté, and Bruno Favery. Three bub1 and bubr1/mad3-related spindle assembly checkpoint proteins are required for accurate mitosis in arabidopsis. The New phytologist, 205 1:202-15, Sep 2015. URL: https://doi.org/10.1111/nph.13073, doi:10.1111/nph.13073. This article has 19 citations.

13. (deng2024thearabidopsisbub1mad3 pages 9-10): Xingguang Deng, Felicia Lei Peng, Xiaoya Tang, Yuh-Ru Julie Lee, Hong-Hui Lin, and Bo Liu. The arabidopsis bub1/mad3 family protein bmf3 requires bub3.3 to recruit cdc20 to kinetochores in spindle assembly checkpoint signaling. Proceedings of the National Academy of Sciences of the United States of America, Mar 2024. URL: https://doi.org/10.1073/pnas.2322677121, doi:10.1073/pnas.2322677121. This article has 10 citations and is from a highest quality peer-reviewed journal.

14. (deng2024thearabidopsisbub1mad3 pages 7-7): Xingguang Deng, Felicia Lei Peng, Xiaoya Tang, Yuh-Ru Julie Lee, Hong-Hui Lin, and Bo Liu. The arabidopsis bub1/mad3 family protein bmf3 requires bub3.3 to recruit cdc20 to kinetochores in spindle assembly checkpoint signaling. Proceedings of the National Academy of Sciences of the United States of America, Mar 2024. URL: https://doi.org/10.1073/pnas.2322677121, doi:10.1073/pnas.2322677121. This article has 10 citations and is from a highest quality peer-reviewed journal.

15. (deng2024thearabidopsisbub1mad3 pages 7-9): Xingguang Deng, Felicia Lei Peng, Xiaoya Tang, Yuh-Ru Julie Lee, Hong-Hui Lin, and Bo Liu. The arabidopsis bub1/mad3 family protein bmf3 requires bub3.3 to recruit cdc20 to kinetochores in spindle assembly checkpoint signaling. Proceedings of the National Academy of Sciences of the United States of America, Mar 2024. URL: https://doi.org/10.1073/pnas.2322677121, doi:10.1073/pnas.2322677121. This article has 10 citations and is from a highest quality peer-reviewed journal.

Citations

1. zhang2018roleofthe pages 1-2
2. caillaud2009spindleassemblycheckpoint pages 2-4
3. https://doi.org/10.1371/journal.pone.0006757,
4. https://doi.org/10.1073/pnas.2316583121,
5. https://doi.org/10.1073/pnas.2322677121,
6. https://doi.org/10.1038/s41477-024-01824-7,
7. https://doi.org/10.1038/s41477-018-0192-z,
8. https://doi.org/10.1371/journal.pone.0006757;
9. https://doi.org/10.1111/nph.13073,
10. https://doi.org/10.1371/journal.pone.0006757
11. https://doi.org/10.1038/s41477-018-0192-z
12. https://doi.org/10.1111/nph.13073
13. https://doi.org/10.1038/s41477-018-0192-z;
14. https://doi.org/10.1073/pnas.2316583121
15. https://doi.org/10.1073/pnas.2322677121
16. https://doi.org/10.1038/s41477-024-01824-7