{"gene":"BUB1","run_date":"2026-06-09T22:02:45","timeline":{"discoveries":[{"year":1994,"finding":"Budding yeast Bub1 encodes a novel protein kinase: it autophosphorylates and phosphorylates Bub3 in vitro, physically associates with Bub3 by immunoprecipitation, and localizes to the nucleus. Bub1 and Bub3 are mutually dependent for function by genetic evidence.","method":"In vitro kinase assay, immunoprecipitation, genetic epistasis, sequence analysis","journal":"Molecular and cellular biology","confidence":"High","confidence_rationale":"Tier 1 / Strong — in vitro kinase reconstitution plus reciprocal genetic and biochemical evidence in the founding yeast paper","pmids":["7969164"],"is_preprint":false},{"year":1998,"finding":"Human Bub3 is required for kinetochore localization of Bub1; Bub1 and Bub3 interact in mammalian cells, and deletion mapping identified the Bub1 domain required for Bub3 binding as identical to the domain required for kinetochore localization, indicating Bub3 recruits Bub1 to kinetochores. Both Bub1 and hBubR1 (BUB1B) independently bind Bub3.","method":"Co-immunoprecipitation, deletion mapping, immunofluorescence localization","journal":"The Journal of cell biology","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal Co-IP with deletion mapping and functional localization readout, widely replicated","pmids":["9660858"],"is_preprint":false},{"year":1998,"finding":"Human Bub1 (hBUB1) colocalizes with the centromere/kinetochore marker CREST during interphase, mitotic prophase, and nocodazole treatment; antibody electroporation experiments establish hBub1 as a functional component of the spindle checkpoint pathway.","method":"Immunofluorescence, antibody electroporation/functional assay","journal":"Cell growth & differentiation","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct localization by IF plus functional antibody perturbation, single lab","pmids":["9790499"],"is_preprint":false},{"year":1998,"finding":"hBUB1 and hBUBR1 sequentially assemble at kinetochores during prophase; immunoelectron microscopy places hBUBR1 at the outer kinetochore plate, and both kinases colocalize with CENP-E, positioning them near the kinetochore surface where kinetochore–microtubule interactions are monitored.","method":"Immunofluorescence, immunoelectron microscopy, chromosome spreads","journal":"Chromosoma","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — immunoelectron microscopy provides direct structural localization, single lab","pmids":["9914370"],"is_preprint":false},{"year":1999,"finding":"Drosophila Bub1 localizes to centromeres/kinetochores of unaligned chromosomes; Bub1 kinase activity is required for 3F3/2 epitope dephosphorylation at metaphase but not for 3F3/2 phosphorylation at prophase/prometaphase; Bub1 kinetochore localization is independent of zw10, rod, polo, or fizzy gene products.","method":"Immunofluorescence, genetic loss-of-function (P-element mutations), epistasis with kinetochore assembly mutants","journal":"The Journal of cell biology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic epistasis with multiple kinetochore mutants and kinase-activity-dependent phenotype readout, single lab","pmids":["10402457"],"is_preprint":false},{"year":2001,"finding":"Xenopus Bub1 is essential for spindle checkpoint establishment and maintenance; immunodepletion abolishes the checkpoint and kinetochore binding of Mad1, Mad2, Bub3, and CENP-E; reintroduction of either wild-type or kinase-dead Bub1 restores the checkpoint and kinetochore localization of these proteins, demonstrating that Bub1 kinase activity is not required for spindle checkpoint function in Xenopus egg extracts.","method":"Immunodepletion, add-back reconstitution with wild-type and kinase-dead Bub1, immunofluorescence","journal":"The Journal of cell biology","confidence":"High","confidence_rationale":"Tier 1 / Strong — reconstitution with kinase-dead mutant in egg extracts, multiple orthogonal readouts","pmids":["11402067"],"is_preprint":false},{"year":2001,"finding":"In mammalian cells, Bub1 and BubR1 are part of a common complex during mitosis. Bub1 localizes asymmetrically to kinetochores in a manner sensitive to both microtubule attachment and tension; Bub1 is rapidly phosphorylated following nocodazole or taxol treatment, whereas BubR1 phosphorylation is largely constitutive, indicating different regulatory inputs.","method":"Co-immunoprecipitation, immunofluorescence, phosphorylation analysis with drug treatments","journal":"Journal of cell science","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reciprocal Co-IP plus localization/phosphorylation studies, single lab","pmids":["11792804"],"is_preprint":false},{"year":2001,"finding":"In response to low-dose vinblastine (tension loss), Bub1 and BubR1 are recruited to kinetochores but Mad2 is not; Mad2 does not associate with Bub1 or BubR1 in complex, while Mad2 does form a complex with Cdc20. This places Bub1/BubR1 in a tension-sensing arm distinct from the Mad2/Cdc20 attachment-sensing arm.","method":"Immunofluorescence with drug treatments, co-immunoprecipitation","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP combined with differential drug-treatment localization, single lab","pmids":["11274370"],"is_preprint":false},{"year":2001,"finding":"Bub1 is activated during Xenopus oocyte meiosis in a MAPK-dependent manner; purified p90Rsk phosphorylates Bub1 in vitro and increases Bub1 kinase activity; injection of constitutively active p90Rsk restores Bub1 activation when MEK1 is inhibited, placing Bub1 downstream of the MAPK/Rsk pathway.","method":"In vitro kinase assay, oocyte injection, MEK1 inhibitor treatment, immunoprecipitation-kinase assay","journal":"Current biology : CB","confidence":"High","confidence_rationale":"Tier 1 / Strong — in vitro phosphorylation reconstitution plus in vivo rescue, multiple orthogonal methods","pmids":["11231148"],"is_preprint":false},{"year":2002,"finding":"Immunodepletion of Bub1 from Xenopus egg extracts blocks Mos-induced CSF arrest; arrest is restored by wild-type but not kinase-dead Bub1, demonstrating that Bub1 kinase activity is required for establishing CSF metaphase arrest downstream of MAPK/Rsk, and that this pathway inhibits APC/C activation.","method":"Immunodepletion, add-back with kinase-dead mutant, Xenopus egg extract CSF arrest assay","journal":"Current biology : CB","confidence":"High","confidence_rationale":"Tier 1 / Strong — reconstitution with kinase-dead mutant, clearly distinguishes kinase-dependent function in meiotic arrest","pmids":["12123578"],"is_preprint":false},{"year":2004,"finding":"Human Bub1 is required for kinetochore localization of BubR1, CENP-E, CENP-F, and Mad2, as established by RNAi-mediated depletion in somatic cells; conversely, BubR1 depletion does not affect Bub1 kinetochore localization, establishing a unidirectional dependency. Bub1 depletion also increases lagging chromosomes, indicating a role in chromosome congression.","method":"RNA interference, immunofluorescence localization of checkpoint proteins","journal":"Journal of cell science","confidence":"High","confidence_rationale":"Tier 2 / Strong — RNAi with systematic localization readouts in human somatic cells, replicated across labs","pmids":["15020684"],"is_preprint":false},{"year":2004,"finding":"Xenopus Bub1 becomes hyperphosphorylated and kinase-activated on unattached chromosomes; MAPK contributes to this activation; Bub1 without MAPK phosphorylation sites (Bub1-5AV) or kinase domain supports checkpoint under optimal conditions but is compromised at low kinetochore or drug concentrations and recruits other checkpoint proteins less efficiently, indicating that activation of Bub1 at kinetochores enhances checkpoint efficiency.","method":"Chromatin kinase assay, MAPK site mutagenesis, checkpoint rescue assay in Xenopus extracts, immunofluorescence","journal":"The EMBO journal","confidence":"High","confidence_rationale":"Tier 1 / Moderate — kinase assay plus mutagenesis plus functional checkpoint reconstitution, single lab with multiple methods","pmids":["15241477"],"is_preprint":false},{"year":2005,"finding":"Human Bub1 is essential for spindle checkpoint signaling and for correct chromosome congression; Bub1 depletion leads to misaligned chromatids with abnormal kinetochore–microtubule attachments; Bub1 and Aurora B are recruited to kinetochores independently and have additive effects when co-depleted, indicating parallel pathways.","method":"Live-cell imaging, RNA interference, double depletion epistasis","journal":"The EMBO journal","confidence":"High","confidence_rationale":"Tier 2 / Strong — live-cell imaging combined with RNAi and epistasis, replicated in multiple labs","pmids":["15933723"],"is_preprint":false},{"year":2005,"finding":"Bub1 and Aurora B kinase form two parallel arms of the spindle checkpoint: depletion of Bub1 renders mitotic arrest dependent on Aurora B activity, and vice versa. Both arms converge on the mitotic checkpoint complex (MCC: BubR1, Bub3, Mad2, Cdc20), and both Bub1 and Aurora B kinase activity are required for MCC binding to APC/C when the checkpoint is active.","method":"RNAi, chemical inhibition (ZM447439), co-immunoprecipitation of MCC-APC/C complexes","journal":"Journal of cell science","confidence":"High","confidence_rationale":"Tier 2 / Strong — RNAi combined with chemical inhibition and Co-IP biochemistry, two complementary approaches","pmids":["16046481"],"is_preprint":false},{"year":2006,"finding":"Bub1 is degraded during mitotic exit via APC/C-Cdh1; two KEN-box motifs on Bub1 are required for its ubiquitination by APC/C(Cdh1) in vitro and for its degradation in vivo; Cdh1 overexpression reduces Bub1 levels while Cdh1 RNAi depletion stabilizes Bub1.","method":"In vitro ubiquitination assay with immunopurified APC/C, RNAi, KEN-box mutagenesis, protein stability assay","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Moderate — in vitro ubiquitination reconstitution plus mutagenesis and RNAi, single lab with multiple orthogonal methods","pmids":["17158872"],"is_preprint":false},{"year":2007,"finding":"Bub1 kinase activity is required for directing Sgo1 to the inner centromere in budding yeast; bub1ΔK cells mislocalize Sgo1, show significant chromosome mis-segregation after nocodazole arrest/release, and can still arrest in response to microtubule-depolymerizing agents, separating checkpoint and chromosome biorientation functions.","method":"Genetic deletion of Bub1 kinase domain, immunofluorescence of Sgo1, chromosome segregation assays","journal":"PLoS genetics","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic kinase-domain deletion with multiple downstream readouts, replicated concept across systems","pmids":["18081426"],"is_preprint":false},{"year":2007,"finding":"Bub1 acts as a master organizer of the inner centromeric region (ICR): Bub1 depletion from Xenopus egg extracts and HeLa cells displaces the chromosomal passenger complex (CPC) from the ICR and prevents centromere-restricted loading of Sgo; soluble Bub1 controls Sgo chromatin binding while CPC restricts it to centromeres; Bub1 kinase activity is pivotal for recruitment of all these components.","method":"Immunodepletion in Xenopus extracts, RNAi in HeLa cells, immunofluorescence, kinase-dead mutant rescue","journal":"The Journal of cell biology","confidence":"High","confidence_rationale":"Tier 1 / Strong — combined immunodepletion/reconstitution in two experimental systems with kinase-dead mutant, multiple downstream readouts","pmids":["17389228"],"is_preprint":false},{"year":2009,"finding":"Bub1 phosphorylates the conserved serine 121 of histone H2A in fission yeast; this H2A-pS121 mark is required for centromeric localization of shugoshin proteins; the h2a-SA mutant phenocopies the bub1 kinase-dead mutant, and artificial centromere tethering of shugoshin rescues CIN defects of both mutants, establishing that the primary function of Bub1 kinase in chromosome segregation is to create an H2A phosphorylation mark that recruits shugoshin.","method":"In vitro kinase assay, phospho-specific antibodies, H2A-S121A mutant phenotypic analysis, shugoshin artificial tethering rescue","journal":"Science (New York, N.Y.)","confidence":"High","confidence_rationale":"Tier 1 / Strong — in vitro substrate identification with mutagenesis, phenotypic rescue by artificial tethering, evolutionarily conserved","pmids":["19965387"],"is_preprint":false},{"year":2008,"finding":"Crystal structure of the human Bub1 kinase domain reveals that the N-terminal extension is required for kinase activity; the activation segment is ordered but the C-terminal portion sterically restricts substrate access; Bub1 uses KEN-box docking motifs outside the kinase domain to recruit its substrate Cdc20; these KEN boxes are required for spindle checkpoint function in human cells.","method":"X-ray crystallography, kinase activity assays, KEN-box mutagenesis, spindle checkpoint assay","journal":"Molecular cell","confidence":"High","confidence_rationale":"Tier 1 / Strong — crystal structure with mutagenesis and functional validation in human cells","pmids":["18995837"],"is_preprint":false},{"year":2009,"finding":"Bub1 can regulate chromosome segregation in a kinetochore-independent manner; Bub1 kinase activity is crucial for chromosome alignment but plays only a minor role in spindle checkpoint signaling; a conserved motif (amino acids 458–476) is essential for spindle checkpoint signaling but not chromosome alignment, dissecting the two functions.","method":"RNAi complementation with structural Bub1 mutants, isogenic HeLa and RPE1 cell lines, live-cell imaging","journal":"The Journal of cell biology","confidence":"High","confidence_rationale":"Tier 2 / Strong — isogenic RNAi complementation with structure-function mutagenesis in two cell lines","pmids":["19487456"],"is_preprint":false},{"year":2010,"finding":"Bub1 and CENP-F interact with KSHV latency-associated nuclear antigen LANA at kinetochores; Bub1 forms a complex with LANA that colocalizes with KSHV episomes tethered to host chromosomes; Bub1 knockdown by shRNA dramatically reduces KSHV genome copy number, indicating Bub1 is required for KSHV episome persistence during cell division.","method":"Co-immunoprecipitation, immunofluorescence, FISH, lentiviral shRNA knockdown with viral genome quantification","journal":"Journal of virology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP plus shRNA functional assay with genome copy readout, single lab","pmids":["20660191"],"is_preprint":false},{"year":2011,"finding":"Bub1 overexpression in transgenic mice leads to near-diploid aneuploidy and tumor formation via aberrant Aurora B kinase hyperactivation; pharmacological or genetic (BubR1 overexpression) suppression of Aurora B activity largely corrects chromosome segregation errors caused by Bub1 overexpression, placing Aurora B downstream of elevated Bub1.","method":"Transgenic mouse model, chromosome segregation assays, Aurora B pharmacological inhibition, epistasis by BubR1 overexpression","journal":"The Journal of cell biology","confidence":"High","confidence_rationale":"Tier 2 / Strong — in vivo transgenic model with pharmacological and genetic epistasis, multiple readouts","pmids":["21646403"],"is_preprint":false},{"year":2012,"finding":"Mps1 kinase phosphorylates conserved MELT motifs on the kinetochore scaffold protein Spc105/KNL1; this phosphorylation recruits Bub1 to kinetochores; PP1 phosphatase reverses this modification; Spc105 mutants lacking Mps1 phosphorylation sites are defective in spindle checkpoint and growth.","method":"Kinetochore particle co-purification kinase assay, MELT-motif mutagenesis, genetic checkpoint assay, epistasis","journal":"Current biology : CB","confidence":"High","confidence_rationale":"Tier 1 / Strong — biochemical identification of kinase-substrate relationship with mutagenesis and genetic functional validation, replicated in parallel study","pmids":["22521787"],"is_preprint":false},{"year":2012,"finding":"In fission yeast, Mph1 (Mps1) phosphorylates conserved MELT motifs in Spc7/KNL1 to recruit Bub1 and Bub3 to kinetochores; this recruitment is required to maintain the SAC signal. PP1 dephosphorylation of Spc7 antagonizes this recruitment.","method":"Biochemical phosphorylation analysis, MELT-motif mutagenesis, SAC functional assay","journal":"Current biology : CB","confidence":"High","confidence_rationale":"Tier 1 / Strong — parallel and independent replication of the Mps1-MELT-Bub1 mechanism in fission yeast","pmids":["22521786"],"is_preprint":false},{"year":2012,"finding":"Bub1 kinase activity controls Aurora B localization and activity through phosphorylation of histone H2A at threonine 121 (T121) in mice; Bub1 kinase-dead knock-in mice show substantial chromosome segregation errors and aneuploidy but unexpectedly do not develop increased spontaneous or carcinogen-induced tumors, separating Bub1 kinase-driven error correction from its tumor suppressor function.","method":"Kinase-dead knock-in mouse, chromosome segregation assays, tumorigenesis studies, H2A-T121 phosphorylation analysis","journal":"The Journal of cell biology","confidence":"High","confidence_rationale":"Tier 1 / Strong — knock-in mouse with defined substrate readout (H2A-T121 phosphorylation) and comprehensive in vivo phenotyping","pmids":["23209306"],"is_preprint":false},{"year":2012,"finding":"Bub1 and Sgo1 modulate pericentric chromatin structure in response to altered microtubule dynamics in budding yeast; Bub1 kinase-mediated H2A-S121 phosphorylation and Sgo1 recruitment soften the chromatin spring and cause radial expansion of pericentric chromatin while reducing its dynamics, functioning as a rheostat for centromeric force balance.","method":"Fluorescence microscopy of chromatin dynamics, H2A phosphorylation assay, Sgo1 localization in bub1 mutants","journal":"Current biology : CB","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — live imaging plus genetic mutant analysis, mechanistic link to H2A phosphorylation substrate, single lab","pmids":["22365852"],"is_preprint":false},{"year":2014,"finding":"Mad1 kinetochore association in budding yeast is mediated by Mps1 phosphorylation of a region within Bub1 (conserved domain 1, CD1); tethering this Bub1 region to kinetochores bypasses Mps1-dependent checkpoint protein recruitment; the Mad1 interaction with Bub1 and kinetochores can be reconstituted in vitro in the presence of Mps1 and Mad2.","method":"In vitro reconstitution of Bub1-Mad1 interaction, kinetochore tethering bypass assay, Mps1 phosphorylation assays","journal":"Genes & development","confidence":"High","confidence_rationale":"Tier 1 / Strong — in vitro reconstitution plus bypass genetic experiments, defines mechanism of Mad1 kinetochore recruitment","pmids":["24402315"],"is_preprint":false},{"year":2014,"finding":"Phosphorylation of human Bub1 at the P+1 loop activates its kinase activity toward H2A but not Cdc20; crystal structure of phosphorylated Bub1 reveals phosphorylation-triggered reorganization of the P+1 loop; this activating phosphorylation occurs through intramolecular autophosphorylation and is constitutive during the cell cycle; enrichment of H2A-pT120 at mitotic kinetochores requires kinetochore targeting of Bub1.","method":"X-ray crystallography of phosphorylated Bub1, in vitro kinase assays with H2A and Cdc20 substrates, P+1 loop mutagenesis, immunofluorescence","journal":"Structure (London, England : 1993)","confidence":"High","confidence_rationale":"Tier 1 / Strong — crystal structure plus in vitro kinase assays with mutagenesis and substrate specificity dissection","pmids":["25308863"],"is_preprint":false},{"year":2014,"finding":"BuGZ/ZNF207 binds to and stabilizes Bub3 through a GLEBS domain; BuGZ inhibition causes loss of both Bub3 and Bub1 from kinetochores, reduction of Bub1-dependent H2A phosphorylation at centromeres, attenuation of kinetochore-based Aurora B kinase activity, and lethal chromosome congression defects.","method":"RNAi screen, Co-IP, immunofluorescence, phospho-H2A antibody staining","journal":"Developmental cell","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP with functional RNAi phenotype and substrate phosphorylation readout, single lab","pmids":["24462187"],"is_preprint":false},{"year":2015,"finding":"Bub1, but not BubR1, enhances Bub3 binding to phosphorylated MELT motifs at kinetochores; BubR1 kinetochore localization depends on direct heterodimerization with Bub1 at a pseudo-symmetric interface; grafting a short Bub1 motif onto BubR1 promotes Bub1-independent kinetochore recruitment of BubR1 but cannot sustain a functional checkpoint.","method":"In vitro binding assays with phospho-MELT peptides, domain swapping mutagenesis, kinetochore localization assays, checkpoint functional assay","journal":"eLife","confidence":"High","confidence_rationale":"Tier 1 / Strong — in vitro reconstitution of binding plus gain-of-function domain-swap mutagenesis with checkpoint functional readout","pmids":["25611342"],"is_preprint":false},{"year":2015,"finding":"Human Bub1 contains a 50-amino-acid segment harboring an ABBA motif near a KEN box that is crucial for SAC signaling and efficient Cdc20 binding to kinetochores, but is not required for MAD1 kinetochore maintenance; BubR1 and Bub3 recruitment by Bub1 is dispensable for SAC activation in human cells.","method":"RNAi complementation with domain deletion mutants, immunofluorescence, checkpoint functional assays","journal":"Journal of cell science","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — RNAi complementation with defined domain mutants, single lab","pmids":["26148513"],"is_preprint":false},{"year":2015,"finding":"Bub1 middle region is required for kinetochore recruitment of the RZZ complex (not Zwint as previously proposed); a distinct Bub1 region mediates kinetochore localization of BubR1 through direct binding; removal of the BubR1-recruiting Bub1 region paradoxically increases checkpoint strength, indicating BubR1 localization through Bub1 has antagonistic checkpoint effects.","method":"RNAi, domain mapping, Co-IP, immunofluorescence, checkpoint functional assays","journal":"Nature communications","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — RNAi with domain mapping and functional readout, single lab","pmids":["26031201"],"is_preprint":false},{"year":2015,"finding":"Bub1 autophosphorylation at T589 regulates kinetochore turnover of Bub1; T589A mutation leads to uniform H2A-T120 phosphorylation along chromosome arms and aberrant Sgo1 recruitment, causing chromosome segregation errors; kinetochore tethering of Bub1-T589A refocuses H2A-T120 phosphorylation and Sgo1 to centromeres.","method":"Quantitative phosphoproteomics, Bub1 autophosphorylation site mutagenesis, FRAP, immunofluorescence, kinetochore-tethering rescue","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 1 / Strong — phosphoproteomics combined with mutagenesis, FRAP, and kinetochore-tethering rescue, single lab with multiple orthogonal methods","pmids":["26399325"],"is_preprint":false},{"year":2015,"finding":"BUB1 interacts with TGF-β type I receptor (TGFBRI) in the presence of TGF-β and promotes heterodimerization of TGFBRI and TGFBRII; BUB1 also interacts with TGFBRII, suggesting a ternary complex; BUB1 kinase activity is required for SMAD3 recruitment to the receptor complex, SMAD2/SMAD3 phosphorylation, TGF-β-mediated EMT, migration, and invasion.","method":"RNAi screen, Co-immunoprecipitation, kinase-dead mutant, small-molecule inhibitor (2OH-BNPP1), in vivo xenograft phospho-SMAD2 analysis","journal":"Science signaling","confidence":"High","confidence_rationale":"Tier 1 / Strong — Co-IP interaction plus kinase-dead mutant plus small-molecule inhibitor in multiple cell lines and in vivo, multiple orthogonal methods","pmids":["25564677"],"is_preprint":false},{"year":2016,"finding":"Bub1 directly phosphorylates Cdc20 and also scaffolds Plk1-mediated phosphorylation of Cdc20; Bub1–Plk1-dependent Cdc20 phosphorylation inhibits APC/C(Cdc20) in vitro, is required for spindle checkpoint signaling in human cells, is regulated by upstream checkpoint signals, and is dispensable for MCC assembly, constituting an APC/C-inhibitory mechanism parallel to MCC formation.","method":"In vitro kinase assay (Bub1 and Plk1 phosphorylation of Cdc20), APC/C inhibition assay, RNAi epistasis, phospho-mimetic Cdc20 rescue","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 1 / Strong — in vitro reconstitution of kinase activity plus APC/C inhibition assay plus genetic epistasis and rescue, single lab with multiple methods","pmids":["26912231"],"is_preprint":false},{"year":2016,"finding":"Selective small-molecule inhibitors of Bub1 kinase (BAY-320 and BAY-524) demonstrate that Bub1 kinase activity affects chromosome association of Shugoshin and the CPC but does not abolish global Aurora B function; kinase inhibition impairs chromosome arm resolution but has only minor effects on mitotic progression or SAC function; Bub1 kinase inhibition sensitizes cells to low-dose paclitaxel.","method":"In vitro kinase inhibitor characterization, cell-based phospho-H2A assay, Sgo1/CPC localization, live-cell imaging, proliferation assays","journal":"eLife","confidence":"High","confidence_rationale":"Tier 1 / Moderate — selective inhibitors characterized in vitro and in cells, compared to protein depletion to separate catalytic from scaffolding functions","pmids":["26885717"],"is_preprint":false},{"year":2017,"finding":"In fission yeast meiosis, the meikin protein Moa1 recruits Polo-like kinase Plo1 to kinetochores; Plo1 then phosphorylates Spc7 (KNL1) to accumulate Bub1, causing persistent meiotic Bub1 kinetochore localization (in contrast to transient mitotic localization); this ensures robust Sgo1 localization and centromeric cohesion protection by cooperating with heterochromatin protein Swi6; the meiosis-specific Bub1 regulation is conserved in mouse.","method":"Genetic analysis, immunofluorescence of Bub1/Sgo1, phosphorylation analysis of Spc7, meiotic vs. mitotic comparison","journal":"Genes to cells : devoted to molecular & cellular mechanisms","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic and localization data in fission yeast with conservation noted in mouse, single lab","pmids":["28497540"],"is_preprint":false},{"year":2018,"finding":"The BUB3-BUB1 complex binds to telomeres during S phase via TRF2-mediated targeting; BUB1 kinase activity and BUB3 telomere-binding ability are required for BUB3-BUB1 function at telomeres; BUB1 directly phosphorylates TRF1, and this promotes TRF1-mediated recruitment of BLM helicase to resolve replication stress; loss of BUB3-BUB1 causes fragile and shortened telomeres.","method":"ChIP, in vitro kinase assay (BUB1 phosphorylation of TRF1), Co-IP, kinase-dead mutant, telomere FISH/length assay","journal":"Molecular cell","confidence":"High","confidence_rationale":"Tier 1 / Strong — in vitro kinase assay identifying TRF1 as substrate plus ChIP localization plus kinase-dead mutant with telomere phenotype readout","pmids":["29727616"],"is_preprint":false},{"year":2018,"finding":"Genome-edited elimination of Bub1 in human cells shows that RZZ's sole role in SAC activation is to tether Mad1-Mad2 to kinetochores; in contrast, Bub1 and KNL1 activate kinetochore-bound Mad1-Mad2 to produce the 'wait anaphase' signal but are not required for fibrous corona formation; clonal BUB1-disrupted cells recover Bub1 expression via nonsense-associated alternative splicing.","method":"CRISPR genome editing, RNAi, immunofluorescence of SAC components, SAC functional assays","journal":"Current biology : CB","confidence":"High","confidence_rationale":"Tier 2 / Strong — genome editing combined with systematic localization and functional checkpoint dissection, defines division of labor between Bub1 and RZZ","pmids":["30415700"],"is_preprint":false},{"year":2018,"finding":"BAY 1816032, a highly selective and orally bioavailable BUB1 kinase inhibitor, inhibits BUB1 signaling (H2A phosphorylation) in vitro and in cells; BUB1 kinase inhibition induces chromosome mis-segregation when combined with paclitaxel and is synergistic with taxanes, ATR inhibitors, and PARP inhibitors in cellular and xenograft models.","method":"In vitro kinase inhibitor assay, cell-based H2A phosphorylation assay, xenograft tumor models, combination drug assays","journal":"Clinical cancer research","confidence":"Medium","confidence_rationale":"Tier 1 / Moderate — selective inhibitor with in vitro and in vivo validation, single lab study","pmids":["30429199"],"is_preprint":false},{"year":2019,"finding":"Efficient mitotic checkpoint signaling requires the integrated activities of Bub1 and the RZZ complex; Rod removal reduces the proximity of Bub1 and Mad1, and tethering Mad1 to kinetochores or increasing the Bub1-Mad1 interaction strength bypasses the requirement for Rod; Bub1 has Mad1-localization-independent checkpoint functions supported by low Bub1 levels, suggesting a catalytic role.","method":"CRISPR genome editing combined with RNAi, proximity ligation assay, kinetochore-tethering bypass experiments, checkpoint functional assays","journal":"The EMBO journal","confidence":"High","confidence_rationale":"Tier 2 / Strong — genome editing combined with tethering rescue and multiple localization methods, single lab with multiple orthogonal approaches","pmids":["30782962"],"is_preprint":false},{"year":2019,"finding":"The N-terminal tetratricopeptide repeat (TPR) domain of Bub1 is both necessary and sufficient to directly bind and recruit Mad3 (BubR1); co-inducing dimerization of Mps1 with Bub1 triggers metaphase arrest dependent on Mad1, Mad2, and Mad3 even without kinetochores or KNL1/Spc105, establishing that Bub1-CD1 (binding Mad1) and Bub1-TPR (binding Mad3) together assemble the MCC signaling platform.","method":"Conditional heterodimerization (eSAC-like), domain deletion/mapping in budding and fission yeast, Co-IP, checkpoint functional assay","journal":"Current biology : CB","confidence":"High","confidence_rationale":"Tier 1 / Strong — domain-deletion dissection combined with bypass reconstitution demonstrating sufficiency, replicated in two yeast species","pmids":["31257143"],"is_preprint":false},{"year":2020,"finding":"BUB1 and CENP-U are the main PLK1 kinetochore receptors in mitosis; BUB1 recruits PLK1 to the outer kinetochore and CENP-U to the inner kinetochore; both share PP2A-docking and PLK1-docking motifs; CDK1 provides priming phosphorylation on BUB1 required for PLK1 docking; PLK1 also contributes to its own kinetochore recruitment through BUB1 and CENP-U.","method":"Ectopic localization assays, in vitro reconstitution of BUB1-PLK1 interaction, kinetochore localization studies, mutagenesis of docking motifs","journal":"Molecular cell","confidence":"High","confidence_rationale":"Tier 1 / Strong — in vitro reconstitution combined with ectopic localization and mutagenesis, multiple orthogonal methods in one rigorous study","pmids":["33248027"],"is_preprint":false},{"year":2020,"finding":"Either Haspin or Bub1 kinase activity is independently sufficient to recruit Aurora B to a distinct chromosomal locus; joint inhibition of Haspin and Bub1 activities fully abolishes Aurora B accumulation at centromeres and impairs correction of erroneous KT-MT attachments but does not compromise the mitotic checkpoint nor phosphorylation of Aurora B kinetochore substrates Hec1, Dsn1, and Knl1.","method":"Combined chemical inhibition of Haspin and Bub1, immunofluorescence of Aurora B and substrates, chromosome segregation assays","journal":"The Journal of cell biology","confidence":"High","confidence_rationale":"Tier 1 / Moderate — dual kinase inhibition with multiple Aurora B substrate readouts, challenges spatial model of Aurora B signaling","pmids":["32027339"],"is_preprint":false},{"year":2021,"finding":"BUB1 directly interacts with STAT3 and phosphorylates STAT3 at Ser727; BUB1/STAT3 complex promotes transcription of STAT3 target genes; pharmacological BUB1 kinase inhibition (2OH-BNPP1) or kinase-domain mutation abrogates STAT3 Ser727 phosphorylation and STAT3 transcriptional activity in bladder cancer cells and in vivo xenografts.","method":"Co-immunoprecipitation, in vitro kinase assay (STAT3 Ser727 phosphorylation), kinase-dead mutant, small-molecule inhibitor, xenograft","journal":"Journal of experimental & clinical cancer research","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP plus kinase-dead mutant plus inhibitor, single lab with multiple methods but not independently replicated","pmids":["34852826"],"is_preprint":false},{"year":2021,"finding":"Aurora B kinase phosphorylates Bub1 to promote MCC production; conditional Aurora B dimerization with Bub1 (but not the KNL1 phosphodomain) produces ectopic MCC and mitotic arrest in budding yeast and human cells; this Aurora B input requires prior Mps1-dependent licensing of Bub1 kinetochore recruitment; Bub1 must recruit both Mad1 and Cdc20 for this ectopic signaling activity.","method":"Ectopic SAC activation (eSAC) dimerization system in budding yeast and HeLa cells, conditional heterodimerization, checkpoint functional assay","journal":"Current biology : CB","confidence":"High","confidence_rationale":"Tier 1 / Strong — synthetic ectopic reconstitution in two experimental systems with domain-level dissection","pmids":["34861183"],"is_preprint":false},{"year":2021,"finding":"Bub1 and CENP-U redundantly recruit Plk1 to kinetochores to stabilize kinetochore-microtubule attachments; depletion of Bub1 alone marginally affects chromosome segregation fidelity, but co-depletion of Bub1 and CENP-U causes significant mis-segregation; this redundancy is through Plk1 (not Aurora B), as confirmed by pharmacological epistasis.","method":"RNAi, CRISPR depletion, immunofluorescence of Plk1/Aurora B at kinetochores, pharmacological inhibitor epistasis, chromosome segregation assays","journal":"Cell reports","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic redundancy dissected by dual depletion with pharmacological epistasis, replicates and extends PLK1 recruitment mechanism","pmids":["34551298"],"is_preprint":false},{"year":2021,"finding":"Crystal structure of the Mad1 C-terminal domain bound to two phosphorylated Bub1 CD1 peptides at 1.75 Å resolution; Bub1 phospho-Thr461 directly contacts Mad1 Arg617 of the RLK motif and acts as an N-terminal helix dipole cap; in solution only one Bub1 CD1 peptide binds the Mad1 homodimer, reflecting asymmetry in the Mad1 coiled-coil.","method":"X-ray crystallography (1.75 Å), NMR, isothermal titration calorimetry","journal":"EMBO reports","confidence":"High","confidence_rationale":"Tier 1 / Strong — high-resolution crystal structure with solution-phase stoichiometry validation by NMR and ITC","pmids":["34013668"],"is_preprint":false},{"year":2022,"finding":"Mps1-mediated phosphorylation of Mad1 creates a phosphorylation-specific Mad1-Cdc20 interaction; together with Bub1-Mad1 association, this generates a tripartite assembly of Bub1 and Cdc20 onto Mad1 CTD that positions Cdc20 MIM near O-Mad2, catalyzing C-Mad2:Cdc20 formation and MCC assembly.","method":"Crystal structure of Mad1 CTD-Cdc20, cross-linking mass spectrometry, in vitro MCC assembly assay","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 1 / Strong — crystal structure combined with XL-MS and in vitro MCC assembly reconstitution","pmids":["36289199"],"is_preprint":false},{"year":2022,"finding":"Biallelic BUB1 germline mutations in human patients cause microcephaly and intellectual disability; patient cells show reduced BUB1 protein and kinase activity; impaired kinase activity prohibits centromeric recruitment of Aurora B, SGO1, and TOP2A, correlating with anaphase bridges, aneuploidy, and defective sister chromatid cohesion; BUB1 levels mainly affect BUBR1 kinetochore recruitment.","method":"Patient-derived cell analysis, immunofluorescence of Aurora B/SGO1/TOP2A, live-cell imaging of mitosis, cohesion assays","journal":"Science advances","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — patient cell studies with multiple molecular readouts, single laboratory but clinically validated mutations","pmids":["35044816"],"is_preprint":false},{"year":2011,"finding":"ATM phosphorylates Bub1 on serine 314 in response to DNA damage in vivo; ATM-mediated Bub1 S314 phosphorylation is required for IR-induced Bub1 activation and Bub1-mediated H2A threonine 121 phosphorylation after ionizing radiation; Bub1 knockdown causes prolonged H2AX foci and DNA damage hypersensitivity.","method":"In vivo phosphorylation assay, S314 mutagenesis, IR treatment, H2AX foci assay, comet assay","journal":"DNA repair","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — in vivo phosphorylation site mutagenesis with multiple DNA damage readouts, single lab","pmids":["22071147"],"is_preprint":false}],"current_model":"BUB1 is a conserved serine/threonine kinase that functions as a master organizer at kinetochores: it is recruited to kinetochores via direct interaction of its Bub3-binding domain with Mps1-phosphorylated MELT motifs on KNL1/Spc105, where it phosphorylates histone H2A (T120/S121) to recruit shugoshin and position the chromosomal passenger complex (Aurora B) at the inner centromere, scaffolds PLK1 (primed by CDK1) and Aurora B recruitment to kinetochores, recruits BubR1 through direct heterodimerization via its TPR domain, recruits the RZZ complex and thereby Mad1-Mad2 to generate the mitotic checkpoint complex (MCC) in cooperation with Mps1 and Aurora B, directly phosphorylates Cdc20 (via KEN-box docking) and scaffolds Plk1-mediated Cdc20 phosphorylation to inhibit APC/C in parallel with MCC formation, is activated by MAPK/p90Rsk-mediated phosphorylation in meiosis, is degraded after mitotic exit by APC/C-Cdh1 through KEN-box recognition, and has additional roles outside mitosis including promoting TGF-β receptor complex assembly and SMAD signaling (via kinase activity), telomere DNA replication (by phosphorylating TRF1 to recruit BLM), and a DNA damage response (downstream of ATM phosphorylation at S314)."},"narrative":{"mechanistic_narrative":"BUB1 is a conserved serine/threonine protein kinase that acts as a master scaffold and signaling hub at the kinetochore, integrating spindle assembly checkpoint (SAC) control with chromosome biorientation [PMID:7969164, PMID:17389228]. It is recruited to kinetochores when Mps1 phosphorylates MELT motifs on the KNL1/Spc105 scaffold, which engages the BUB1-bound BUB3 to dock the complex [PMID:22521787, PMID:22521786, PMID:25611342]; BUB3 binding maps to the same BUB1 region required for kinetochore localization [PMID:9660858]. Once positioned, BUB1 phosphorylates histone H2A (T120/T121 in higher eukaryotes, S121 in fission yeast) to create a centromeric mark that recruits shugoshin and concentrates the chromosomal passenger complex/Aurora B at the inner centromere [PMID:19965387, PMID:23209306, PMID:17389228], with autophosphorylation at the P+1 loop activating its kinase toward H2A but not Cdc20 [PMID:25308863]. BUB1 functionally separates into a kinase arm dedicated to error correction and chromosome alignment and a scaffolding arm required for the SAC: its N-terminal TPR domain directly recruits BubR1 through heterodimerization, and a conserved CD1 region, phosphorylated by Mps1, binds Mad1 to assemble the Mad1-Mad2 platform that catalyzes mitotic checkpoint complex (MCC) formation [PMID:31257143, PMID:24402315, PMID:34013668, PMID:36289199]. In parallel with MCC assembly, BUB1 directly phosphorylates Cdc20 and scaffolds Plk1-mediated Cdc20 phosphorylation to inhibit the APC/C [PMID:26912231], and serves as a principal kinetochore receptor for PLK1 following CDK1 priming [PMID:33248027]. BUB1 abundance is reset after mitotic exit through APC/C-Cdh1-mediated, KEN-box-dependent degradation [PMID:17158872]. Beyond mitosis, BUB1 kinase activity promotes TGF-β receptor heterodimerization and SMAD signaling [PMID:25564677] and supports telomere replication by phosphorylating TRF1 to recruit BLM helicase [PMID:29727616]. Biallelic germline BUB1 mutations that reduce protein level and kinase activity cause microcephaly and intellectual disability with aneuploidy and cohesion defects [PMID:35044816].","teleology":[{"year":1994,"claim":"Established BUB1 as a bona fide protein kinase physically and functionally coupled to Bub3, defining the founding biochemical unit of the checkpoint.","evidence":"In vitro kinase assay, immunoprecipitation and genetic epistasis in budding yeast","pmids":["7969164"],"confidence":"High","gaps":["No physiological substrate identified beyond autophosphorylation and Bub3","Kinetochore recruitment mechanism unknown"]},{"year":1998,"claim":"Showed that Bub3 binding directs BUB1 to kinetochores and that BUB1 localizes to the centromere/kinetochore as a functional checkpoint component.","evidence":"Co-IP, deletion mapping, immunofluorescence and antibody electroporation in mammalian cells","pmids":["9660858","9790499","9914370"],"confidence":"High","gaps":["Molecular receptor on the kinetochore not defined","Role of kinase activity vs scaffolding unresolved"]},{"year":2001,"claim":"Dissected BUB1's contribution to checkpoint establishment and revealed it as a tension/attachment-sensing node, while showing in egg extracts that kinase activity is dispensable for the core checkpoint.","evidence":"Immunodepletion with wild-type/kinase-dead add-back in Xenopus extracts; Co-IP and drug-treatment localization in mammalian cells","pmids":["11402067","11792804","11274370"],"confidence":"High","gaps":["Apparent dispensability of kinase activity conflicts with later kinase-dependent roles","Substrate-level mechanism not addressed"]},{"year":2001,"claim":"Connected BUB1 to meiotic regulation by placing it downstream of MAPK/p90Rsk and demonstrating kinase-dependent CSF arrest.","evidence":"In vitro p90Rsk phosphorylation, oocyte injection, MEK1 inhibition and kinase-dead add-back in Xenopus","pmids":["11231148","12123578"],"confidence":"High","gaps":["Meiotic substrates of activated BUB1 not identified","Relationship to mitotic activation mechanism unclear"]},{"year":2004,"claim":"Defined a unidirectional recruitment hierarchy in human cells, with BUB1 required for kinetochore loading of multiple downstream factors, and showed enhanced activation improves checkpoint efficiency.","evidence":"RNAi with systematic localization readouts; chromatin kinase assay and MAPK-site mutagenesis in Xenopus","pmids":["15020684","15241477"],"confidence":"High","gaps":["Direct versus indirect recruitment of downstream factors not separated","Kinase substrates underlying recruitment not yet defined"]},{"year":2005,"claim":"Established BUB1 and Aurora B as parallel checkpoint arms converging on MCC binding to APC/C, and showed BUB1 is essential for chromosome congression.","evidence":"RNAi, chemical inhibition (ZM447439), live imaging and MCC-APC/C Co-IP in human cells","pmids":["15933723","16046481"],"confidence":"High","gaps":["Biochemical basis of MCC-APC/C engagement not resolved","Molecular link between the two arms unknown"]},{"year":2007,"claim":"Identified BUB1 kinase activity as the master organizer of the inner centromere, directing shugoshin and the CPC, separating this from the checkpoint.","evidence":"Immunodepletion/RNAi with kinase-dead rescue in Xenopus extracts and HeLa; budding yeast kinase-domain deletion","pmids":["17389228","18081426"],"confidence":"High","gaps":["Direct kinase substrate creating the shugoshin docking site not yet identified"]},{"year":2008,"claim":"Provided the first structural view of the BUB1 kinase domain and showed BUB1 uses KEN-box docking outside the kinase domain to engage its substrate Cdc20.","evidence":"X-ray crystallography, kinase assays and KEN-box mutagenesis with checkpoint readout","pmids":["18995837"],"confidence":"High","gaps":["Catalytic phosphorylation of Cdc20 not yet demonstrated functionally","Mechanism of substrate selection partial"]},{"year":2009,"claim":"Identified histone H2A-S121 as the direct BUB1 substrate that recruits shugoshin, defining the kinase's primary segregation function, while genetically separating kinase from alignment versus checkpoint roles.","evidence":"In vitro kinase assay, phospho-specific antibodies, H2A mutant and shugoshin tethering rescue in fission yeast; RNAi structure-function complementation in human cells","pmids":["19965387","19487456"],"confidence":"High","gaps":["How H2A phosphorylation is spatially restricted to centromeres not fully defined"]},{"year":2012,"claim":"Resolved the upstream recruitment logic by establishing Mps1-phosphorylated MELT motifs on KNL1/Spc105 as the BUB1 docking signal, and confirmed H2A-T121 as the in vivo substrate controlling Aurora B in mice.","evidence":"Kinetochore particle kinase assays, MELT-motif mutagenesis in budding/fission yeast; kinase-dead knock-in mouse phenotyping","pmids":["22521787","22521786","23209306","22365852"],"confidence":"High","gaps":["Kinase-dead mice show aneuploidy without tumors, decoupling kinase from tumor suppression"]},{"year":2014,"claim":"Defined the CD1-Mad1 axis as the mechanism for Mad1 kinetochore recruitment and showed P+1 loop autophosphorylation activates BUB1 selectively toward H2A.","evidence":"In vitro Bub1-Mad1 reconstitution and kinetochore tethering bypass in budding yeast; crystallography and substrate-specific kinase assays in human cells","pmids":["24402315","25308863"],"confidence":"High","gaps":["Stoichiometry and phospho-dependence of Mad1 binding not yet defined at atomic detail"]},{"year":2015,"claim":"Mapped BUB1's modular scaffolding: MELT-phospho/Bub3 binding, direct BubR1 heterodimerization, RZZ recruitment, ABBA/KEN-mediated Cdc20 capture, and autophosphorylation-controlled kinetochore turnover that spatially focuses H2A phosphorylation.","evidence":"In vitro phospho-MELT binding, domain swapping, RNAi complementation, phosphoproteomics, FRAP and tethering rescue in human cells","pmids":["25611342","26148513","26031201","26399325"],"confidence":"High","gaps":["Conflicting reports on whether BubR1/Bub3 recruitment by BUB1 is required for SAC","Relative weighting of scaffolding modules context-dependent"]},{"year":2016,"claim":"Demonstrated a parallel APC/C-inhibitory output in which BUB1 directly phosphorylates Cdc20 and scaffolds Plk1-mediated Cdc20 phosphorylation independent of MCC assembly, and used selective inhibitors to isolate catalytic from scaffolding functions.","evidence":"In vitro kinase and APC/C inhibition assays, RNAi epistasis, phosphomimetic rescue; selective inhibitors BAY-320/BAY-524","pmids":["26912231","26885717"],"confidence":"High","gaps":["In vivo contribution of Cdc20 phosphorylation relative to MCC not quantified"]},{"year":2018,"claim":"Defined the division of labor between BUB1/KNL1 and RZZ in Mad1-Mad2 activation, and uncovered non-mitotic roles of BUB1 in telomere replication via TRF1 phosphorylation and BLM recruitment.","evidence":"CRISPR editing and RNAi with SAC functional dissection; ChIP, in vitro TRF1 kinase assay, kinase-dead mutant and telomere FISH","pmids":["30415700","29727616"],"confidence":"High","gaps":["Coordination of telomeric and mitotic BUB1 pools unclear","Compensatory splicing complicates loss-of-function interpretation"]},{"year":2019,"claim":"Showed integrated BUB1-RZZ cooperation in proximity-dependent Mad1 activation and reaffirmed a catalytic, Mad1-localization-independent checkpoint contribution; TPR domain shown necessary and sufficient to recruit BubR1/Mad3 to build the MCC platform.","evidence":"CRISPR/RNAi, proximity ligation, tethering bypass in human cells; conditional dimerization and domain mapping in budding/fission yeast","pmids":["30782962","31257143"],"confidence":"High","gaps":["Nature of the residual catalytic checkpoint role not defined"]},{"year":2020,"claim":"Identified BUB1 (with CENP-U) as a principal PLK1 kinetochore receptor requiring CDK1 priming, and showed Haspin and BUB1 act redundantly to localize Aurora B for error correction.","evidence":"In vitro BUB1-PLK1 reconstitution, ectopic localization and docking-motif mutagenesis; dual Haspin/BUB1 inhibition with substrate readouts; RNAi/CRISPR redundancy analysis","pmids":["33248027","32027339","34551298"],"confidence":"High","gaps":["Quantitative partitioning of PLK1 between BUB1 and CENP-U pools unresolved"]},{"year":2021,"claim":"Resolved the structural and catalytic logic of MCC platform assembly, showing Aurora B phosphorylation of BUB1 promotes MCC production and that BUB1 phospho-CD1 docks the Mad1 CTD, while extending BUB1 signaling to STAT3 phosphorylation in cancer.","evidence":"eSAC dimerization in yeast and human cells; high-resolution crystallography, NMR and ITC of Mad1-Bub1; Co-IP, kinase-dead and inhibitor STAT3 studies","pmids":["34861183","34013668","34852826"],"confidence":"High","gaps":["Single-lab STAT3 link not independently confirmed","Integration of Aurora B input with Mps1 licensing partially defined"]},{"year":2022,"claim":"Completed the catalytic mechanism of MCC assembly via the Mad1 CTD-Cdc20 interface and linked BUB1 loss-of-function to a human Mendelian disorder.","evidence":"Crystal structure, XL-MS and in vitro MCC assembly; patient-derived cell analysis with localization, imaging and cohesion assays","pmids":["36289199","35044816"],"confidence":"High","gaps":["Patient-cell findings from single laboratory","Tissue specificity of neurodevelopmental phenotype not mechanistically explained"]},{"year":null,"claim":"How BUB1's mitotic, meiotic, telomeric, TGF-β, and STAT3 functions are coordinated within a cell, and the relative in vivo contribution of its catalytic versus scaffolding roles to genome stability and tumor suppression, remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No unified model linking mitotic and non-mitotic BUB1 activities","Decoupling of kinase activity from tumor suppression in mice not explained","Therapeutic window of BUB1 kinase inhibition not defined"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0140096","term_label":"catalytic activity, acting on a protein","supporting_discovery_ids":[0,17,24,27,34,37,33]},{"term_id":"GO:0016740","term_label":"transferase activity","supporting_discovery_ids":[0,17,27,34]},{"term_id":"GO:0042393","term_label":"histone binding","supporting_discovery_ids":[17,24,27]},{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[29,31,41,42]},{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[34,46]}],"localization":[{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[0]},{"term_id":"GO:0000228","term_label":"nuclear chromosome","supporting_discovery_ids":[2,3,4,16]}],"pathway":[{"term_id":"R-HSA-1640170","term_label":"Cell Cycle","supporting_discovery_ids":[5,12,13,16,34]},{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[33,44]},{"term_id":"R-HSA-73894","term_label":"DNA Repair","supporting_discovery_ids":[37,50]},{"term_id":"R-HSA-392499","term_label":"Metabolism of proteins","supporting_discovery_ids":[14,34]}],"complexes":["BUB1-BUB3 complex","mitotic checkpoint complex (MCC) signaling platform","kinetochore"],"partners":["BUB3","BUBR1","KNL1","MAD1","CDC20","PLK1","TRF1","TGFBR1"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"O43683","full_name":"Mitotic checkpoint serine/threonine-protein kinase BUB1","aliases":["BUB1A"],"length_aa":1085,"mass_kda":122.4,"function":"Serine/threonine-protein kinase that performs 2 crucial functions during mitosis: it is essential for spindle-assembly checkpoint signaling and for correct chromosome alignment. Has a key role in the assembly of checkpoint proteins at the kinetochore, being required for the subsequent localization of CENPF, BUB1B, CENPE and MAD2L1. Required for the kinetochore localization of PLK1. Required for centromeric enrichment of AUKRB in prometaphase. Plays an important role in defining SGO1 localization and thereby affects sister chromatid cohesion. Promotes the centromeric localization of TOP2A (PubMed:35044816). Acts as a substrate for anaphase-promoting complex or cyclosome (APC/C) in complex with its activator CDH1 (APC/C-Cdh1). Necessary for ensuring proper chromosome segregation and binding to BUB3 is essential for this function. Can regulate chromosome segregation in a kinetochore-independent manner. Can phosphorylate BUB3. The BUB1-BUB3 complex plays a role in the inhibition of APC/C when spindle-assembly checkpoint is activated and inhibits the ubiquitin ligase activity of APC/C by phosphorylating its activator CDC20. This complex can also phosphorylate MAD1L1. Kinase activity is essential for inhibition of APC/CCDC20 and for chromosome alignment but does not play a major role in the spindle-assembly checkpoint activity. Mediates cell death in response to chromosome missegregation and acts to suppress spontaneous tumorigenesis","subcellular_location":"Nucleus; Chromosome, centromere, kinetochore","url":"https://www.uniprot.org/uniprotkb/O43683/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":true,"resolved_as":"","url":"https://depmap.org/portal/gene/BUB1","classification":"Common Essential","n_dependent_lines":944,"n_total_lines":1208,"dependency_fraction":0.7814569536423841},"opencell":{"profiled":true,"resolved_as":"","ensg_id":"ENSG00000169679","cell_line_id":"CID001136","localizations":[{"compartment":"cytoplasmic","grade":3},{"compartment":"nucleoplasm","grade":3}],"interactors":[{"gene":"ANAPC4","stoichiometry":0.2},{"gene":"DDOST","stoichiometry":0.2},{"gene":"FKBP5","stoichiometry":0.2},{"gene":"OST4","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/target/CID001136","total_profiled":1310},"omim":[{"mim_id":"620183","title":"MICROCEPHALY 30, PRIMARY, AUTOSOMAL RECESSIVE; MCPH30","url":"https://www.omim.org/entry/620183"},{"mim_id":"619247","title":"SPINDLE- AND KINETOCHORE-ASSOCIATED COMPLEX, SUBUNIT 3; SKA3","url":"https://www.omim.org/entry/619247"},{"mim_id":"614560","title":"MAU2 SISTER CHROMATID COHESION FACTOR; MAU2","url":"https://www.omim.org/entry/614560"},{"mim_id":"614030","title":"SPEEDY/RINGO CELL CYCLE REGULATOR FAMILY, MEMBER C; SPDYC","url":"https://www.omim.org/entry/614030"},{"mim_id":"613499","title":"HISTONE GENE CLUSTER 1, H2A HISTONE FAMILY, MEMBER A; HIST1H2AA","url":"https://www.omim.org/entry/613499"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Supported","locations":[{"location":"Nucleoplasm","reliability":"Supported"},{"location":"Cytosol","reliability":"Additional"}],"tissue_specificity":"Group enriched","tissue_distribution":"Detected in many","driving_tissues":[{"tissue":"bone marrow","ntpm":11.2},{"tissue":"lymphoid tissue","ntpm":25.6},{"tissue":"testis","ntpm":28.3}],"url":"https://www.proteinatlas.org/search/BUB1"},"hgnc":{"alias_symbol":["hBUB1","BUB1A"],"prev_symbol":["BUB1L"]},"alphafold":{"accession":"O43683","domains":[{"cath_id":"1.25.40.430","chopping":"5-147","consensus_level":"medium","plddt":86.609,"start":5,"end":147},{"cath_id":"1.10.510.10","chopping":"744-841_852-868","consensus_level":"medium","plddt":89.7896,"start":744,"end":868},{"cath_id":"1.10.510.10","chopping":"870-1085","consensus_level":"medium","plddt":90.4291,"start":870,"end":1085}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/O43683","model_url":"https://alphafold.ebi.ac.uk/files/AF-O43683-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-O43683-F1-predicted_aligned_error_v6.png","plddt_mean":62.62},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=BUB1","jax_strain_url":"https://www.jax.org/strain/search?query=BUB1"},"sequence":{"accession":"O43683","fasta_url":"https://rest.uniprot.org/uniprotkb/O43683.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/O43683/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/O43683"}},"corpus_meta":[{"pmid":"19965387","id":"PMC_19965387","title":"Phosphorylation of H2A by Bub1 prevents chromosomal instability through localizing shugoshin.","date":"2009","source":"Science (New York, N.Y.)","url":"https://pubmed.ncbi.nlm.nih.gov/19965387","citation_count":402,"is_preprint":false},{"pmid":"9660858","id":"PMC_9660858","title":"The human homologue of Bub3 is required for kinetochore localization of Bub1 and a Mad3/Bub1-related protein kinase.","date":"1998","source":"The Journal of cell biology","url":"https://pubmed.ncbi.nlm.nih.gov/9660858","citation_count":376,"is_preprint":false},{"pmid":"22521787","id":"PMC_22521787","title":"Phosphoregulation of Spc105 by Mps1 and PP1 regulates Bub1 localization to kinetochores.","date":"2012","source":"Current biology : CB","url":"https://pubmed.ncbi.nlm.nih.gov/22521787","citation_count":299,"is_preprint":false},{"pmid":"15020684","id":"PMC_15020684","title":"Bub1 is required for kinetochore localization of BubR1, Cenp-E, Cenp-F and Mad2, and chromosome congression.","date":"2004","source":"Journal of cell science","url":"https://pubmed.ncbi.nlm.nih.gov/15020684","citation_count":288,"is_preprint":false},{"pmid":"22521786","id":"PMC_22521786","title":"Phosphodependent recruitment of Bub1 and Bub3 to Spc7/KNL1 by Mph1 kinase maintains the spindle checkpoint.","date":"2012","source":"Current biology : CB","url":"https://pubmed.ncbi.nlm.nih.gov/22521786","citation_count":242,"is_preprint":false},{"pmid":"11274370","id":"PMC_11274370","title":"Mammalian mad2 and bub1/bubR1 recognize distinct spindle-attachment and kinetochore-tension checkpoints.","date":"2001","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/11274370","citation_count":241,"is_preprint":false},{"pmid":"11402067","id":"PMC_11402067","title":"Spindle checkpoint protein Bub1 is required for kinetochore localization of Mad1, Mad2, Bub3, and CENP-E, independently of its kinase activity.","date":"2001","source":"The Journal of cell 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health","url":"https://pubmed.ncbi.nlm.nih.gov/35769782","citation_count":22,"is_preprint":false},{"pmid":"18383837","id":"PMC_18383837","title":"Overexpression of the mitotic spindle assembly checkpoint genes hBUB1, hBUBR1 and hMAD2 in thyroid carcinomas with aggressive nature.","date":"2008","source":"Anticancer research","url":"https://pubmed.ncbi.nlm.nih.gov/18383837","citation_count":22,"is_preprint":false},{"pmid":"34013367","id":"PMC_34013367","title":"KIF4A knockdown suppresses ovarian cancer cell proliferation and induces apoptosis by downregulating BUB1 expression.","date":"2021","source":"Molecular medicine reports","url":"https://pubmed.ncbi.nlm.nih.gov/34013367","citation_count":22,"is_preprint":false},{"pmid":"31257143","id":"PMC_31257143","title":"The Bub1-TPR Domain Interacts Directly with Mad3 to Generate Robust Spindle Checkpoint Arrest.","date":"2019","source":"Current biology : CB","url":"https://pubmed.ncbi.nlm.nih.gov/31257143","citation_count":22,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":47255,"output_tokens":12935,"usd":0.167895,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":24303,"output_tokens":5964,"usd":0.135307,"stage2_stop_reason":"end_turn"},"total_usd":0.303202,"stage1_batch_id":"msgbatch_0179Z2pxRYBsXi2xADneafRw","stage2_batch_id":"msgbatch_01LaY9ZaVdgjWArcZo9eqQE5","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 1994,\n      \"finding\": \"Budding yeast Bub1 encodes a novel protein kinase: it autophosphorylates and phosphorylates Bub3 in vitro, physically associates with Bub3 by immunoprecipitation, and localizes to the nucleus. Bub1 and Bub3 are mutually dependent for function by genetic evidence.\",\n      \"method\": \"In vitro kinase assay, immunoprecipitation, genetic epistasis, sequence analysis\",\n      \"journal\": \"Molecular and cellular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — in vitro kinase reconstitution plus reciprocal genetic and biochemical evidence in the founding yeast paper\",\n      \"pmids\": [\"7969164\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1998,\n      \"finding\": \"Human Bub3 is required for kinetochore localization of Bub1; Bub1 and Bub3 interact in mammalian cells, and deletion mapping identified the Bub1 domain required for Bub3 binding as identical to the domain required for kinetochore localization, indicating Bub3 recruits Bub1 to kinetochores. Both Bub1 and hBubR1 (BUB1B) independently bind Bub3.\",\n      \"method\": \"Co-immunoprecipitation, deletion mapping, immunofluorescence localization\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal Co-IP with deletion mapping and functional localization readout, widely replicated\",\n      \"pmids\": [\"9660858\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1998,\n      \"finding\": \"Human Bub1 (hBUB1) colocalizes with the centromere/kinetochore marker CREST during interphase, mitotic prophase, and nocodazole treatment; antibody electroporation experiments establish hBub1 as a functional component of the spindle checkpoint pathway.\",\n      \"method\": \"Immunofluorescence, antibody electroporation/functional assay\",\n      \"journal\": \"Cell growth & differentiation\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct localization by IF plus functional antibody perturbation, single lab\",\n      \"pmids\": [\"9790499\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1998,\n      \"finding\": \"hBUB1 and hBUBR1 sequentially assemble at kinetochores during prophase; immunoelectron microscopy places hBUBR1 at the outer kinetochore plate, and both kinases colocalize with CENP-E, positioning them near the kinetochore surface where kinetochore–microtubule interactions are monitored.\",\n      \"method\": \"Immunofluorescence, immunoelectron microscopy, chromosome spreads\",\n      \"journal\": \"Chromosoma\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — immunoelectron microscopy provides direct structural localization, single lab\",\n      \"pmids\": [\"9914370\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1999,\n      \"finding\": \"Drosophila Bub1 localizes to centromeres/kinetochores of unaligned chromosomes; Bub1 kinase activity is required for 3F3/2 epitope dephosphorylation at metaphase but not for 3F3/2 phosphorylation at prophase/prometaphase; Bub1 kinetochore localization is independent of zw10, rod, polo, or fizzy gene products.\",\n      \"method\": \"Immunofluorescence, genetic loss-of-function (P-element mutations), epistasis with kinetochore assembly mutants\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic epistasis with multiple kinetochore mutants and kinase-activity-dependent phenotype readout, single lab\",\n      \"pmids\": [\"10402457\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2001,\n      \"finding\": \"Xenopus Bub1 is essential for spindle checkpoint establishment and maintenance; immunodepletion abolishes the checkpoint and kinetochore binding of Mad1, Mad2, Bub3, and CENP-E; reintroduction of either wild-type or kinase-dead Bub1 restores the checkpoint and kinetochore localization of these proteins, demonstrating that Bub1 kinase activity is not required for spindle checkpoint function in Xenopus egg extracts.\",\n      \"method\": \"Immunodepletion, add-back reconstitution with wild-type and kinase-dead Bub1, immunofluorescence\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — reconstitution with kinase-dead mutant in egg extracts, multiple orthogonal readouts\",\n      \"pmids\": [\"11402067\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2001,\n      \"finding\": \"In mammalian cells, Bub1 and BubR1 are part of a common complex during mitosis. Bub1 localizes asymmetrically to kinetochores in a manner sensitive to both microtubule attachment and tension; Bub1 is rapidly phosphorylated following nocodazole or taxol treatment, whereas BubR1 phosphorylation is largely constitutive, indicating different regulatory inputs.\",\n      \"method\": \"Co-immunoprecipitation, immunofluorescence, phosphorylation analysis with drug treatments\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal Co-IP plus localization/phosphorylation studies, single lab\",\n      \"pmids\": [\"11792804\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2001,\n      \"finding\": \"In response to low-dose vinblastine (tension loss), Bub1 and BubR1 are recruited to kinetochores but Mad2 is not; Mad2 does not associate with Bub1 or BubR1 in complex, while Mad2 does form a complex with Cdc20. This places Bub1/BubR1 in a tension-sensing arm distinct from the Mad2/Cdc20 attachment-sensing arm.\",\n      \"method\": \"Immunofluorescence with drug treatments, co-immunoprecipitation\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP combined with differential drug-treatment localization, single lab\",\n      \"pmids\": [\"11274370\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2001,\n      \"finding\": \"Bub1 is activated during Xenopus oocyte meiosis in a MAPK-dependent manner; purified p90Rsk phosphorylates Bub1 in vitro and increases Bub1 kinase activity; injection of constitutively active p90Rsk restores Bub1 activation when MEK1 is inhibited, placing Bub1 downstream of the MAPK/Rsk pathway.\",\n      \"method\": \"In vitro kinase assay, oocyte injection, MEK1 inhibitor treatment, immunoprecipitation-kinase assay\",\n      \"journal\": \"Current biology : CB\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — in vitro phosphorylation reconstitution plus in vivo rescue, multiple orthogonal methods\",\n      \"pmids\": [\"11231148\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"Immunodepletion of Bub1 from Xenopus egg extracts blocks Mos-induced CSF arrest; arrest is restored by wild-type but not kinase-dead Bub1, demonstrating that Bub1 kinase activity is required for establishing CSF metaphase arrest downstream of MAPK/Rsk, and that this pathway inhibits APC/C activation.\",\n      \"method\": \"Immunodepletion, add-back with kinase-dead mutant, Xenopus egg extract CSF arrest assay\",\n      \"journal\": \"Current biology : CB\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — reconstitution with kinase-dead mutant, clearly distinguishes kinase-dependent function in meiotic arrest\",\n      \"pmids\": [\"12123578\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"Human Bub1 is required for kinetochore localization of BubR1, CENP-E, CENP-F, and Mad2, as established by RNAi-mediated depletion in somatic cells; conversely, BubR1 depletion does not affect Bub1 kinetochore localization, establishing a unidirectional dependency. Bub1 depletion also increases lagging chromosomes, indicating a role in chromosome congression.\",\n      \"method\": \"RNA interference, immunofluorescence localization of checkpoint proteins\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — RNAi with systematic localization readouts in human somatic cells, replicated across labs\",\n      \"pmids\": [\"15020684\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"Xenopus Bub1 becomes hyperphosphorylated and kinase-activated on unattached chromosomes; MAPK contributes to this activation; Bub1 without MAPK phosphorylation sites (Bub1-5AV) or kinase domain supports checkpoint under optimal conditions but is compromised at low kinetochore or drug concentrations and recruits other checkpoint proteins less efficiently, indicating that activation of Bub1 at kinetochores enhances checkpoint efficiency.\",\n      \"method\": \"Chromatin kinase assay, MAPK site mutagenesis, checkpoint rescue assay in Xenopus extracts, immunofluorescence\",\n      \"journal\": \"The EMBO journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — kinase assay plus mutagenesis plus functional checkpoint reconstitution, single lab with multiple methods\",\n      \"pmids\": [\"15241477\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"Human Bub1 is essential for spindle checkpoint signaling and for correct chromosome congression; Bub1 depletion leads to misaligned chromatids with abnormal kinetochore–microtubule attachments; Bub1 and Aurora B are recruited to kinetochores independently and have additive effects when co-depleted, indicating parallel pathways.\",\n      \"method\": \"Live-cell imaging, RNA interference, double depletion epistasis\",\n      \"journal\": \"The EMBO journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — live-cell imaging combined with RNAi and epistasis, replicated in multiple labs\",\n      \"pmids\": [\"15933723\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"Bub1 and Aurora B kinase form two parallel arms of the spindle checkpoint: depletion of Bub1 renders mitotic arrest dependent on Aurora B activity, and vice versa. Both arms converge on the mitotic checkpoint complex (MCC: BubR1, Bub3, Mad2, Cdc20), and both Bub1 and Aurora B kinase activity are required for MCC binding to APC/C when the checkpoint is active.\",\n      \"method\": \"RNAi, chemical inhibition (ZM447439), co-immunoprecipitation of MCC-APC/C complexes\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — RNAi combined with chemical inhibition and Co-IP biochemistry, two complementary approaches\",\n      \"pmids\": [\"16046481\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"Bub1 is degraded during mitotic exit via APC/C-Cdh1; two KEN-box motifs on Bub1 are required for its ubiquitination by APC/C(Cdh1) in vitro and for its degradation in vivo; Cdh1 overexpression reduces Bub1 levels while Cdh1 RNAi depletion stabilizes Bub1.\",\n      \"method\": \"In vitro ubiquitination assay with immunopurified APC/C, RNAi, KEN-box mutagenesis, protein stability assay\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro ubiquitination reconstitution plus mutagenesis and RNAi, single lab with multiple orthogonal methods\",\n      \"pmids\": [\"17158872\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"Bub1 kinase activity is required for directing Sgo1 to the inner centromere in budding yeast; bub1ΔK cells mislocalize Sgo1, show significant chromosome mis-segregation after nocodazole arrest/release, and can still arrest in response to microtubule-depolymerizing agents, separating checkpoint and chromosome biorientation functions.\",\n      \"method\": \"Genetic deletion of Bub1 kinase domain, immunofluorescence of Sgo1, chromosome segregation assays\",\n      \"journal\": \"PLoS genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic kinase-domain deletion with multiple downstream readouts, replicated concept across systems\",\n      \"pmids\": [\"18081426\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"Bub1 acts as a master organizer of the inner centromeric region (ICR): Bub1 depletion from Xenopus egg extracts and HeLa cells displaces the chromosomal passenger complex (CPC) from the ICR and prevents centromere-restricted loading of Sgo; soluble Bub1 controls Sgo chromatin binding while CPC restricts it to centromeres; Bub1 kinase activity is pivotal for recruitment of all these components.\",\n      \"method\": \"Immunodepletion in Xenopus extracts, RNAi in HeLa cells, immunofluorescence, kinase-dead mutant rescue\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — combined immunodepletion/reconstitution in two experimental systems with kinase-dead mutant, multiple downstream readouts\",\n      \"pmids\": [\"17389228\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"Bub1 phosphorylates the conserved serine 121 of histone H2A in fission yeast; this H2A-pS121 mark is required for centromeric localization of shugoshin proteins; the h2a-SA mutant phenocopies the bub1 kinase-dead mutant, and artificial centromere tethering of shugoshin rescues CIN defects of both mutants, establishing that the primary function of Bub1 kinase in chromosome segregation is to create an H2A phosphorylation mark that recruits shugoshin.\",\n      \"method\": \"In vitro kinase assay, phospho-specific antibodies, H2A-S121A mutant phenotypic analysis, shugoshin artificial tethering rescue\",\n      \"journal\": \"Science (New York, N.Y.)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — in vitro substrate identification with mutagenesis, phenotypic rescue by artificial tethering, evolutionarily conserved\",\n      \"pmids\": [\"19965387\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"Crystal structure of the human Bub1 kinase domain reveals that the N-terminal extension is required for kinase activity; the activation segment is ordered but the C-terminal portion sterically restricts substrate access; Bub1 uses KEN-box docking motifs outside the kinase domain to recruit its substrate Cdc20; these KEN boxes are required for spindle checkpoint function in human cells.\",\n      \"method\": \"X-ray crystallography, kinase activity assays, KEN-box mutagenesis, spindle checkpoint assay\",\n      \"journal\": \"Molecular cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — crystal structure with mutagenesis and functional validation in human cells\",\n      \"pmids\": [\"18995837\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"Bub1 can regulate chromosome segregation in a kinetochore-independent manner; Bub1 kinase activity is crucial for chromosome alignment but plays only a minor role in spindle checkpoint signaling; a conserved motif (amino acids 458–476) is essential for spindle checkpoint signaling but not chromosome alignment, dissecting the two functions.\",\n      \"method\": \"RNAi complementation with structural Bub1 mutants, isogenic HeLa and RPE1 cell lines, live-cell imaging\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — isogenic RNAi complementation with structure-function mutagenesis in two cell lines\",\n      \"pmids\": [\"19487456\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"Bub1 and CENP-F interact with KSHV latency-associated nuclear antigen LANA at kinetochores; Bub1 forms a complex with LANA that colocalizes with KSHV episomes tethered to host chromosomes; Bub1 knockdown by shRNA dramatically reduces KSHV genome copy number, indicating Bub1 is required for KSHV episome persistence during cell division.\",\n      \"method\": \"Co-immunoprecipitation, immunofluorescence, FISH, lentiviral shRNA knockdown with viral genome quantification\",\n      \"journal\": \"Journal of virology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP plus shRNA functional assay with genome copy readout, single lab\",\n      \"pmids\": [\"20660191\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"Bub1 overexpression in transgenic mice leads to near-diploid aneuploidy and tumor formation via aberrant Aurora B kinase hyperactivation; pharmacological or genetic (BubR1 overexpression) suppression of Aurora B activity largely corrects chromosome segregation errors caused by Bub1 overexpression, placing Aurora B downstream of elevated Bub1.\",\n      \"method\": \"Transgenic mouse model, chromosome segregation assays, Aurora B pharmacological inhibition, epistasis by BubR1 overexpression\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — in vivo transgenic model with pharmacological and genetic epistasis, multiple readouts\",\n      \"pmids\": [\"21646403\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"Mps1 kinase phosphorylates conserved MELT motifs on the kinetochore scaffold protein Spc105/KNL1; this phosphorylation recruits Bub1 to kinetochores; PP1 phosphatase reverses this modification; Spc105 mutants lacking Mps1 phosphorylation sites are defective in spindle checkpoint and growth.\",\n      \"method\": \"Kinetochore particle co-purification kinase assay, MELT-motif mutagenesis, genetic checkpoint assay, epistasis\",\n      \"journal\": \"Current biology : CB\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — biochemical identification of kinase-substrate relationship with mutagenesis and genetic functional validation, replicated in parallel study\",\n      \"pmids\": [\"22521787\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"In fission yeast, Mph1 (Mps1) phosphorylates conserved MELT motifs in Spc7/KNL1 to recruit Bub1 and Bub3 to kinetochores; this recruitment is required to maintain the SAC signal. PP1 dephosphorylation of Spc7 antagonizes this recruitment.\",\n      \"method\": \"Biochemical phosphorylation analysis, MELT-motif mutagenesis, SAC functional assay\",\n      \"journal\": \"Current biology : CB\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — parallel and independent replication of the Mps1-MELT-Bub1 mechanism in fission yeast\",\n      \"pmids\": [\"22521786\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"Bub1 kinase activity controls Aurora B localization and activity through phosphorylation of histone H2A at threonine 121 (T121) in mice; Bub1 kinase-dead knock-in mice show substantial chromosome segregation errors and aneuploidy but unexpectedly do not develop increased spontaneous or carcinogen-induced tumors, separating Bub1 kinase-driven error correction from its tumor suppressor function.\",\n      \"method\": \"Kinase-dead knock-in mouse, chromosome segregation assays, tumorigenesis studies, H2A-T121 phosphorylation analysis\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — knock-in mouse with defined substrate readout (H2A-T121 phosphorylation) and comprehensive in vivo phenotyping\",\n      \"pmids\": [\"23209306\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"Bub1 and Sgo1 modulate pericentric chromatin structure in response to altered microtubule dynamics in budding yeast; Bub1 kinase-mediated H2A-S121 phosphorylation and Sgo1 recruitment soften the chromatin spring and cause radial expansion of pericentric chromatin while reducing its dynamics, functioning as a rheostat for centromeric force balance.\",\n      \"method\": \"Fluorescence microscopy of chromatin dynamics, H2A phosphorylation assay, Sgo1 localization in bub1 mutants\",\n      \"journal\": \"Current biology : CB\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — live imaging plus genetic mutant analysis, mechanistic link to H2A phosphorylation substrate, single lab\",\n      \"pmids\": [\"22365852\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"Mad1 kinetochore association in budding yeast is mediated by Mps1 phosphorylation of a region within Bub1 (conserved domain 1, CD1); tethering this Bub1 region to kinetochores bypasses Mps1-dependent checkpoint protein recruitment; the Mad1 interaction with Bub1 and kinetochores can be reconstituted in vitro in the presence of Mps1 and Mad2.\",\n      \"method\": \"In vitro reconstitution of Bub1-Mad1 interaction, kinetochore tethering bypass assay, Mps1 phosphorylation assays\",\n      \"journal\": \"Genes & development\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — in vitro reconstitution plus bypass genetic experiments, defines mechanism of Mad1 kinetochore recruitment\",\n      \"pmids\": [\"24402315\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"Phosphorylation of human Bub1 at the P+1 loop activates its kinase activity toward H2A but not Cdc20; crystal structure of phosphorylated Bub1 reveals phosphorylation-triggered reorganization of the P+1 loop; this activating phosphorylation occurs through intramolecular autophosphorylation and is constitutive during the cell cycle; enrichment of H2A-pT120 at mitotic kinetochores requires kinetochore targeting of Bub1.\",\n      \"method\": \"X-ray crystallography of phosphorylated Bub1, in vitro kinase assays with H2A and Cdc20 substrates, P+1 loop mutagenesis, immunofluorescence\",\n      \"journal\": \"Structure (London, England : 1993)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — crystal structure plus in vitro kinase assays with mutagenesis and substrate specificity dissection\",\n      \"pmids\": [\"25308863\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"BuGZ/ZNF207 binds to and stabilizes Bub3 through a GLEBS domain; BuGZ inhibition causes loss of both Bub3 and Bub1 from kinetochores, reduction of Bub1-dependent H2A phosphorylation at centromeres, attenuation of kinetochore-based Aurora B kinase activity, and lethal chromosome congression defects.\",\n      \"method\": \"RNAi screen, Co-IP, immunofluorescence, phospho-H2A antibody staining\",\n      \"journal\": \"Developmental cell\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP with functional RNAi phenotype and substrate phosphorylation readout, single lab\",\n      \"pmids\": [\"24462187\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"Bub1, but not BubR1, enhances Bub3 binding to phosphorylated MELT motifs at kinetochores; BubR1 kinetochore localization depends on direct heterodimerization with Bub1 at a pseudo-symmetric interface; grafting a short Bub1 motif onto BubR1 promotes Bub1-independent kinetochore recruitment of BubR1 but cannot sustain a functional checkpoint.\",\n      \"method\": \"In vitro binding assays with phospho-MELT peptides, domain swapping mutagenesis, kinetochore localization assays, checkpoint functional assay\",\n      \"journal\": \"eLife\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — in vitro reconstitution of binding plus gain-of-function domain-swap mutagenesis with checkpoint functional readout\",\n      \"pmids\": [\"25611342\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"Human Bub1 contains a 50-amino-acid segment harboring an ABBA motif near a KEN box that is crucial for SAC signaling and efficient Cdc20 binding to kinetochores, but is not required for MAD1 kinetochore maintenance; BubR1 and Bub3 recruitment by Bub1 is dispensable for SAC activation in human cells.\",\n      \"method\": \"RNAi complementation with domain deletion mutants, immunofluorescence, checkpoint functional assays\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — RNAi complementation with defined domain mutants, single lab\",\n      \"pmids\": [\"26148513\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"Bub1 middle region is required for kinetochore recruitment of the RZZ complex (not Zwint as previously proposed); a distinct Bub1 region mediates kinetochore localization of BubR1 through direct binding; removal of the BubR1-recruiting Bub1 region paradoxically increases checkpoint strength, indicating BubR1 localization through Bub1 has antagonistic checkpoint effects.\",\n      \"method\": \"RNAi, domain mapping, Co-IP, immunofluorescence, checkpoint functional assays\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — RNAi with domain mapping and functional readout, single lab\",\n      \"pmids\": [\"26031201\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"Bub1 autophosphorylation at T589 regulates kinetochore turnover of Bub1; T589A mutation leads to uniform H2A-T120 phosphorylation along chromosome arms and aberrant Sgo1 recruitment, causing chromosome segregation errors; kinetochore tethering of Bub1-T589A refocuses H2A-T120 phosphorylation and Sgo1 to centromeres.\",\n      \"method\": \"Quantitative phosphoproteomics, Bub1 autophosphorylation site mutagenesis, FRAP, immunofluorescence, kinetochore-tethering rescue\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — phosphoproteomics combined with mutagenesis, FRAP, and kinetochore-tethering rescue, single lab with multiple orthogonal methods\",\n      \"pmids\": [\"26399325\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"BUB1 interacts with TGF-β type I receptor (TGFBRI) in the presence of TGF-β and promotes heterodimerization of TGFBRI and TGFBRII; BUB1 also interacts with TGFBRII, suggesting a ternary complex; BUB1 kinase activity is required for SMAD3 recruitment to the receptor complex, SMAD2/SMAD3 phosphorylation, TGF-β-mediated EMT, migration, and invasion.\",\n      \"method\": \"RNAi screen, Co-immunoprecipitation, kinase-dead mutant, small-molecule inhibitor (2OH-BNPP1), in vivo xenograft phospho-SMAD2 analysis\",\n      \"journal\": \"Science signaling\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — Co-IP interaction plus kinase-dead mutant plus small-molecule inhibitor in multiple cell lines and in vivo, multiple orthogonal methods\",\n      \"pmids\": [\"25564677\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"Bub1 directly phosphorylates Cdc20 and also scaffolds Plk1-mediated phosphorylation of Cdc20; Bub1–Plk1-dependent Cdc20 phosphorylation inhibits APC/C(Cdc20) in vitro, is required for spindle checkpoint signaling in human cells, is regulated by upstream checkpoint signals, and is dispensable for MCC assembly, constituting an APC/C-inhibitory mechanism parallel to MCC formation.\",\n      \"method\": \"In vitro kinase assay (Bub1 and Plk1 phosphorylation of Cdc20), APC/C inhibition assay, RNAi epistasis, phospho-mimetic Cdc20 rescue\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — in vitro reconstitution of kinase activity plus APC/C inhibition assay plus genetic epistasis and rescue, single lab with multiple methods\",\n      \"pmids\": [\"26912231\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"Selective small-molecule inhibitors of Bub1 kinase (BAY-320 and BAY-524) demonstrate that Bub1 kinase activity affects chromosome association of Shugoshin and the CPC but does not abolish global Aurora B function; kinase inhibition impairs chromosome arm resolution but has only minor effects on mitotic progression or SAC function; Bub1 kinase inhibition sensitizes cells to low-dose paclitaxel.\",\n      \"method\": \"In vitro kinase inhibitor characterization, cell-based phospho-H2A assay, Sgo1/CPC localization, live-cell imaging, proliferation assays\",\n      \"journal\": \"eLife\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — selective inhibitors characterized in vitro and in cells, compared to protein depletion to separate catalytic from scaffolding functions\",\n      \"pmids\": [\"26885717\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"In fission yeast meiosis, the meikin protein Moa1 recruits Polo-like kinase Plo1 to kinetochores; Plo1 then phosphorylates Spc7 (KNL1) to accumulate Bub1, causing persistent meiotic Bub1 kinetochore localization (in contrast to transient mitotic localization); this ensures robust Sgo1 localization and centromeric cohesion protection by cooperating with heterochromatin protein Swi6; the meiosis-specific Bub1 regulation is conserved in mouse.\",\n      \"method\": \"Genetic analysis, immunofluorescence of Bub1/Sgo1, phosphorylation analysis of Spc7, meiotic vs. mitotic comparison\",\n      \"journal\": \"Genes to cells : devoted to molecular & cellular mechanisms\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic and localization data in fission yeast with conservation noted in mouse, single lab\",\n      \"pmids\": [\"28497540\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"The BUB3-BUB1 complex binds to telomeres during S phase via TRF2-mediated targeting; BUB1 kinase activity and BUB3 telomere-binding ability are required for BUB3-BUB1 function at telomeres; BUB1 directly phosphorylates TRF1, and this promotes TRF1-mediated recruitment of BLM helicase to resolve replication stress; loss of BUB3-BUB1 causes fragile and shortened telomeres.\",\n      \"method\": \"ChIP, in vitro kinase assay (BUB1 phosphorylation of TRF1), Co-IP, kinase-dead mutant, telomere FISH/length assay\",\n      \"journal\": \"Molecular cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — in vitro kinase assay identifying TRF1 as substrate plus ChIP localization plus kinase-dead mutant with telomere phenotype readout\",\n      \"pmids\": [\"29727616\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"Genome-edited elimination of Bub1 in human cells shows that RZZ's sole role in SAC activation is to tether Mad1-Mad2 to kinetochores; in contrast, Bub1 and KNL1 activate kinetochore-bound Mad1-Mad2 to produce the 'wait anaphase' signal but are not required for fibrous corona formation; clonal BUB1-disrupted cells recover Bub1 expression via nonsense-associated alternative splicing.\",\n      \"method\": \"CRISPR genome editing, RNAi, immunofluorescence of SAC components, SAC functional assays\",\n      \"journal\": \"Current biology : CB\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genome editing combined with systematic localization and functional checkpoint dissection, defines division of labor between Bub1 and RZZ\",\n      \"pmids\": [\"30415700\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"BAY 1816032, a highly selective and orally bioavailable BUB1 kinase inhibitor, inhibits BUB1 signaling (H2A phosphorylation) in vitro and in cells; BUB1 kinase inhibition induces chromosome mis-segregation when combined with paclitaxel and is synergistic with taxanes, ATR inhibitors, and PARP inhibitors in cellular and xenograft models.\",\n      \"method\": \"In vitro kinase inhibitor assay, cell-based H2A phosphorylation assay, xenograft tumor models, combination drug assays\",\n      \"journal\": \"Clinical cancer research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — selective inhibitor with in vitro and in vivo validation, single lab study\",\n      \"pmids\": [\"30429199\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"Efficient mitotic checkpoint signaling requires the integrated activities of Bub1 and the RZZ complex; Rod removal reduces the proximity of Bub1 and Mad1, and tethering Mad1 to kinetochores or increasing the Bub1-Mad1 interaction strength bypasses the requirement for Rod; Bub1 has Mad1-localization-independent checkpoint functions supported by low Bub1 levels, suggesting a catalytic role.\",\n      \"method\": \"CRISPR genome editing combined with RNAi, proximity ligation assay, kinetochore-tethering bypass experiments, checkpoint functional assays\",\n      \"journal\": \"The EMBO journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genome editing combined with tethering rescue and multiple localization methods, single lab with multiple orthogonal approaches\",\n      \"pmids\": [\"30782962\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"The N-terminal tetratricopeptide repeat (TPR) domain of Bub1 is both necessary and sufficient to directly bind and recruit Mad3 (BubR1); co-inducing dimerization of Mps1 with Bub1 triggers metaphase arrest dependent on Mad1, Mad2, and Mad3 even without kinetochores or KNL1/Spc105, establishing that Bub1-CD1 (binding Mad1) and Bub1-TPR (binding Mad3) together assemble the MCC signaling platform.\",\n      \"method\": \"Conditional heterodimerization (eSAC-like), domain deletion/mapping in budding and fission yeast, Co-IP, checkpoint functional assay\",\n      \"journal\": \"Current biology : CB\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — domain-deletion dissection combined with bypass reconstitution demonstrating sufficiency, replicated in two yeast species\",\n      \"pmids\": [\"31257143\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"BUB1 and CENP-U are the main PLK1 kinetochore receptors in mitosis; BUB1 recruits PLK1 to the outer kinetochore and CENP-U to the inner kinetochore; both share PP2A-docking and PLK1-docking motifs; CDK1 provides priming phosphorylation on BUB1 required for PLK1 docking; PLK1 also contributes to its own kinetochore recruitment through BUB1 and CENP-U.\",\n      \"method\": \"Ectopic localization assays, in vitro reconstitution of BUB1-PLK1 interaction, kinetochore localization studies, mutagenesis of docking motifs\",\n      \"journal\": \"Molecular cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — in vitro reconstitution combined with ectopic localization and mutagenesis, multiple orthogonal methods in one rigorous study\",\n      \"pmids\": [\"33248027\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"Either Haspin or Bub1 kinase activity is independently sufficient to recruit Aurora B to a distinct chromosomal locus; joint inhibition of Haspin and Bub1 activities fully abolishes Aurora B accumulation at centromeres and impairs correction of erroneous KT-MT attachments but does not compromise the mitotic checkpoint nor phosphorylation of Aurora B kinetochore substrates Hec1, Dsn1, and Knl1.\",\n      \"method\": \"Combined chemical inhibition of Haspin and Bub1, immunofluorescence of Aurora B and substrates, chromosome segregation assays\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — dual kinase inhibition with multiple Aurora B substrate readouts, challenges spatial model of Aurora B signaling\",\n      \"pmids\": [\"32027339\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"BUB1 directly interacts with STAT3 and phosphorylates STAT3 at Ser727; BUB1/STAT3 complex promotes transcription of STAT3 target genes; pharmacological BUB1 kinase inhibition (2OH-BNPP1) or kinase-domain mutation abrogates STAT3 Ser727 phosphorylation and STAT3 transcriptional activity in bladder cancer cells and in vivo xenografts.\",\n      \"method\": \"Co-immunoprecipitation, in vitro kinase assay (STAT3 Ser727 phosphorylation), kinase-dead mutant, small-molecule inhibitor, xenograft\",\n      \"journal\": \"Journal of experimental & clinical cancer research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP plus kinase-dead mutant plus inhibitor, single lab with multiple methods but not independently replicated\",\n      \"pmids\": [\"34852826\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"Aurora B kinase phosphorylates Bub1 to promote MCC production; conditional Aurora B dimerization with Bub1 (but not the KNL1 phosphodomain) produces ectopic MCC and mitotic arrest in budding yeast and human cells; this Aurora B input requires prior Mps1-dependent licensing of Bub1 kinetochore recruitment; Bub1 must recruit both Mad1 and Cdc20 for this ectopic signaling activity.\",\n      \"method\": \"Ectopic SAC activation (eSAC) dimerization system in budding yeast and HeLa cells, conditional heterodimerization, checkpoint functional assay\",\n      \"journal\": \"Current biology : CB\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — synthetic ectopic reconstitution in two experimental systems with domain-level dissection\",\n      \"pmids\": [\"34861183\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"Bub1 and CENP-U redundantly recruit Plk1 to kinetochores to stabilize kinetochore-microtubule attachments; depletion of Bub1 alone marginally affects chromosome segregation fidelity, but co-depletion of Bub1 and CENP-U causes significant mis-segregation; this redundancy is through Plk1 (not Aurora B), as confirmed by pharmacological epistasis.\",\n      \"method\": \"RNAi, CRISPR depletion, immunofluorescence of Plk1/Aurora B at kinetochores, pharmacological inhibitor epistasis, chromosome segregation assays\",\n      \"journal\": \"Cell reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic redundancy dissected by dual depletion with pharmacological epistasis, replicates and extends PLK1 recruitment mechanism\",\n      \"pmids\": [\"34551298\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"Crystal structure of the Mad1 C-terminal domain bound to two phosphorylated Bub1 CD1 peptides at 1.75 Å resolution; Bub1 phospho-Thr461 directly contacts Mad1 Arg617 of the RLK motif and acts as an N-terminal helix dipole cap; in solution only one Bub1 CD1 peptide binds the Mad1 homodimer, reflecting asymmetry in the Mad1 coiled-coil.\",\n      \"method\": \"X-ray crystallography (1.75 Å), NMR, isothermal titration calorimetry\",\n      \"journal\": \"EMBO reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — high-resolution crystal structure with solution-phase stoichiometry validation by NMR and ITC\",\n      \"pmids\": [\"34013668\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"Mps1-mediated phosphorylation of Mad1 creates a phosphorylation-specific Mad1-Cdc20 interaction; together with Bub1-Mad1 association, this generates a tripartite assembly of Bub1 and Cdc20 onto Mad1 CTD that positions Cdc20 MIM near O-Mad2, catalyzing C-Mad2:Cdc20 formation and MCC assembly.\",\n      \"method\": \"Crystal structure of Mad1 CTD-Cdc20, cross-linking mass spectrometry, in vitro MCC assembly assay\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — crystal structure combined with XL-MS and in vitro MCC assembly reconstitution\",\n      \"pmids\": [\"36289199\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"Biallelic BUB1 germline mutations in human patients cause microcephaly and intellectual disability; patient cells show reduced BUB1 protein and kinase activity; impaired kinase activity prohibits centromeric recruitment of Aurora B, SGO1, and TOP2A, correlating with anaphase bridges, aneuploidy, and defective sister chromatid cohesion; BUB1 levels mainly affect BUBR1 kinetochore recruitment.\",\n      \"method\": \"Patient-derived cell analysis, immunofluorescence of Aurora B/SGO1/TOP2A, live-cell imaging of mitosis, cohesion assays\",\n      \"journal\": \"Science advances\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — patient cell studies with multiple molecular readouts, single laboratory but clinically validated mutations\",\n      \"pmids\": [\"35044816\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"ATM phosphorylates Bub1 on serine 314 in response to DNA damage in vivo; ATM-mediated Bub1 S314 phosphorylation is required for IR-induced Bub1 activation and Bub1-mediated H2A threonine 121 phosphorylation after ionizing radiation; Bub1 knockdown causes prolonged H2AX foci and DNA damage hypersensitivity.\",\n      \"method\": \"In vivo phosphorylation assay, S314 mutagenesis, IR treatment, H2AX foci assay, comet assay\",\n      \"journal\": \"DNA repair\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vivo phosphorylation site mutagenesis with multiple DNA damage readouts, single lab\",\n      \"pmids\": [\"22071147\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"BUB1 is a conserved serine/threonine kinase that functions as a master organizer at kinetochores: it is recruited to kinetochores via direct interaction of its Bub3-binding domain with Mps1-phosphorylated MELT motifs on KNL1/Spc105, where it phosphorylates histone H2A (T120/S121) to recruit shugoshin and position the chromosomal passenger complex (Aurora B) at the inner centromere, scaffolds PLK1 (primed by CDK1) and Aurora B recruitment to kinetochores, recruits BubR1 through direct heterodimerization via its TPR domain, recruits the RZZ complex and thereby Mad1-Mad2 to generate the mitotic checkpoint complex (MCC) in cooperation with Mps1 and Aurora B, directly phosphorylates Cdc20 (via KEN-box docking) and scaffolds Plk1-mediated Cdc20 phosphorylation to inhibit APC/C in parallel with MCC formation, is activated by MAPK/p90Rsk-mediated phosphorylation in meiosis, is degraded after mitotic exit by APC/C-Cdh1 through KEN-box recognition, and has additional roles outside mitosis including promoting TGF-β receptor complex assembly and SMAD signaling (via kinase activity), telomere DNA replication (by phosphorylating TRF1 to recruit BLM), and a DNA damage response (downstream of ATM phosphorylation at S314).\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"BUB1 is a conserved serine/threonine protein kinase that acts as a master scaffold and signaling hub at the kinetochore, integrating spindle assembly checkpoint (SAC) control with chromosome biorientation [#0, #16]. It is recruited to kinetochores when Mps1 phosphorylates MELT motifs on the KNL1/Spc105 scaffold, which engages the BUB1-bound BUB3 to dock the complex [#22, #23, #29]; BUB3 binding maps to the same BUB1 region required for kinetochore localization [#1]. Once positioned, BUB1 phosphorylates histone H2A (T120/T121 in higher eukaryotes, S121 in fission yeast) to create a centromeric mark that recruits shugoshin and concentrates the chromosomal passenger complex/Aurora B at the inner centromere [#17, #24, #16], with autophosphorylation at the P+1 loop activating its kinase toward H2A but not Cdc20 [#27]. BUB1 functionally separates into a kinase arm dedicated to error correction and chromosome alignment and a scaffolding arm required for the SAC: its N-terminal TPR domain directly recruits BubR1 through heterodimerization, and a conserved CD1 region, phosphorylated by Mps1, binds Mad1 to assemble the Mad1-Mad2 platform that catalyzes mitotic checkpoint complex (MCC) formation [#41, #26, #47, #48]. In parallel with MCC assembly, BUB1 directly phosphorylates Cdc20 and scaffolds Plk1-mediated Cdc20 phosphorylation to inhibit the APC/C [#34], and serves as a principal kinetochore receptor for PLK1 following CDK1 priming [#42]. BUB1 abundance is reset after mitotic exit through APC/C-Cdh1-mediated, KEN-box-dependent degradation [#14]. Beyond mitosis, BUB1 kinase activity promotes TGF-\\u03b2 receptor heterodimerization and SMAD signaling [#33] and supports telomere replication by phosphorylating TRF1 to recruit BLM helicase [#37]. Biallelic germline BUB1 mutations that reduce protein level and kinase activity cause microcephaly and intellectual disability with aneuploidy and cohesion defects [#49].\",\n  \"teleology\": [\n    {\n      \"year\": 1994,\n      \"claim\": \"Established BUB1 as a bona fide protein kinase physically and functionally coupled to Bub3, defining the founding biochemical unit of the checkpoint.\",\n      \"evidence\": \"In vitro kinase assay, immunoprecipitation and genetic epistasis in budding yeast\",\n      \"pmids\": [\"7969164\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No physiological substrate identified beyond autophosphorylation and Bub3\", \"Kinetochore recruitment mechanism unknown\"]\n    },\n    {\n      \"year\": 1998,\n      \"claim\": \"Showed that Bub3 binding directs BUB1 to kinetochores and that BUB1 localizes to the centromere/kinetochore as a functional checkpoint component.\",\n      \"evidence\": \"Co-IP, deletion mapping, immunofluorescence and antibody electroporation in mammalian cells\",\n      \"pmids\": [\"9660858\", \"9790499\", \"9914370\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular receptor on the kinetochore not defined\", \"Role of kinase activity vs scaffolding unresolved\"]\n    },\n    {\n      \"year\": 2001,\n      \"claim\": \"Dissected BUB1's contribution to checkpoint establishment and revealed it as a tension/attachment-sensing node, while showing in egg extracts that kinase activity is dispensable for the core checkpoint.\",\n      \"evidence\": \"Immunodepletion with wild-type/kinase-dead add-back in Xenopus extracts; Co-IP and drug-treatment localization in mammalian cells\",\n      \"pmids\": [\"11402067\", \"11792804\", \"11274370\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Apparent dispensability of kinase activity conflicts with later kinase-dependent roles\", \"Substrate-level mechanism not addressed\"]\n    },\n    {\n      \"year\": 2001,\n      \"claim\": \"Connected BUB1 to meiotic regulation by placing it downstream of MAPK/p90Rsk and demonstrating kinase-dependent CSF arrest.\",\n      \"evidence\": \"In vitro p90Rsk phosphorylation, oocyte injection, MEK1 inhibition and kinase-dead add-back in Xenopus\",\n      \"pmids\": [\"11231148\", \"12123578\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Meiotic substrates of activated BUB1 not identified\", \"Relationship to mitotic activation mechanism unclear\"]\n    },\n    {\n      \"year\": 2004,\n      \"claim\": \"Defined a unidirectional recruitment hierarchy in human cells, with BUB1 required for kinetochore loading of multiple downstream factors, and showed enhanced activation improves checkpoint efficiency.\",\n      \"evidence\": \"RNAi with systematic localization readouts; chromatin kinase assay and MAPK-site mutagenesis in Xenopus\",\n      \"pmids\": [\"15020684\", \"15241477\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct versus indirect recruitment of downstream factors not separated\", \"Kinase substrates underlying recruitment not yet defined\"]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"Established BUB1 and Aurora B as parallel checkpoint arms converging on MCC binding to APC/C, and showed BUB1 is essential for chromosome congression.\",\n      \"evidence\": \"RNAi, chemical inhibition (ZM447439), live imaging and MCC-APC/C Co-IP in human cells\",\n      \"pmids\": [\"15933723\", \"16046481\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Biochemical basis of MCC-APC/C engagement not resolved\", \"Molecular link between the two arms unknown\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Identified BUB1 kinase activity as the master organizer of the inner centromere, directing shugoshin and the CPC, separating this from the checkpoint.\",\n      \"evidence\": \"Immunodepletion/RNAi with kinase-dead rescue in Xenopus extracts and HeLa; budding yeast kinase-domain deletion\",\n      \"pmids\": [\"17389228\", \"18081426\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct kinase substrate creating the shugoshin docking site not yet identified\"]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Provided the first structural view of the BUB1 kinase domain and showed BUB1 uses KEN-box docking outside the kinase domain to engage its substrate Cdc20.\",\n      \"evidence\": \"X-ray crystallography, kinase assays and KEN-box mutagenesis with checkpoint readout\",\n      \"pmids\": [\"18995837\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Catalytic phosphorylation of Cdc20 not yet demonstrated functionally\", \"Mechanism of substrate selection partial\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Identified histone H2A-S121 as the direct BUB1 substrate that recruits shugoshin, defining the kinase's primary segregation function, while genetically separating kinase from alignment versus checkpoint roles.\",\n      \"evidence\": \"In vitro kinase assay, phospho-specific antibodies, H2A mutant and shugoshin tethering rescue in fission yeast; RNAi structure-function complementation in human cells\",\n      \"pmids\": [\"19965387\", \"19487456\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How H2A phosphorylation is spatially restricted to centromeres not fully defined\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Resolved the upstream recruitment logic by establishing Mps1-phosphorylated MELT motifs on KNL1/Spc105 as the BUB1 docking signal, and confirmed H2A-T121 as the in vivo substrate controlling Aurora B in mice.\",\n      \"evidence\": \"Kinetochore particle kinase assays, MELT-motif mutagenesis in budding/fission yeast; kinase-dead knock-in mouse phenotyping\",\n      \"pmids\": [\"22521787\", \"22521786\", \"23209306\", \"22365852\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Kinase-dead mice show aneuploidy without tumors, decoupling kinase from tumor suppression\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Defined the CD1-Mad1 axis as the mechanism for Mad1 kinetochore recruitment and showed P+1 loop autophosphorylation activates BUB1 selectively toward H2A.\",\n      \"evidence\": \"In vitro Bub1-Mad1 reconstitution and kinetochore tethering bypass in budding yeast; crystallography and substrate-specific kinase assays in human cells\",\n      \"pmids\": [\"24402315\", \"25308863\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Stoichiometry and phospho-dependence of Mad1 binding not yet defined at atomic detail\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Mapped BUB1's modular scaffolding: MELT-phospho/Bub3 binding, direct BubR1 heterodimerization, RZZ recruitment, ABBA/KEN-mediated Cdc20 capture, and autophosphorylation-controlled kinetochore turnover that spatially focuses H2A phosphorylation.\",\n      \"evidence\": \"In vitro phospho-MELT binding, domain swapping, RNAi complementation, phosphoproteomics, FRAP and tethering rescue in human cells\",\n      \"pmids\": [\"25611342\", \"26148513\", \"26031201\", \"26399325\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Conflicting reports on whether BubR1/Bub3 recruitment by BUB1 is required for SAC\", \"Relative weighting of scaffolding modules context-dependent\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Demonstrated a parallel APC/C-inhibitory output in which BUB1 directly phosphorylates Cdc20 and scaffolds Plk1-mediated Cdc20 phosphorylation independent of MCC assembly, and used selective inhibitors to isolate catalytic from scaffolding functions.\",\n      \"evidence\": \"In vitro kinase and APC/C inhibition assays, RNAi epistasis, phosphomimetic rescue; selective inhibitors BAY-320/BAY-524\",\n      \"pmids\": [\"26912231\", \"26885717\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"In vivo contribution of Cdc20 phosphorylation relative to MCC not quantified\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Defined the division of labor between BUB1/KNL1 and RZZ in Mad1-Mad2 activation, and uncovered non-mitotic roles of BUB1 in telomere replication via TRF1 phosphorylation and BLM recruitment.\",\n      \"evidence\": \"CRISPR editing and RNAi with SAC functional dissection; ChIP, in vitro TRF1 kinase assay, kinase-dead mutant and telomere FISH\",\n      \"pmids\": [\"30415700\", \"29727616\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Coordination of telomeric and mitotic BUB1 pools unclear\", \"Compensatory splicing complicates loss-of-function interpretation\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Showed integrated BUB1-RZZ cooperation in proximity-dependent Mad1 activation and reaffirmed a catalytic, Mad1-localization-independent checkpoint contribution; TPR domain shown necessary and sufficient to recruit BubR1/Mad3 to build the MCC platform.\",\n      \"evidence\": \"CRISPR/RNAi, proximity ligation, tethering bypass in human cells; conditional dimerization and domain mapping in budding/fission yeast\",\n      \"pmids\": [\"30782962\", \"31257143\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Nature of the residual catalytic checkpoint role not defined\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Identified BUB1 (with CENP-U) as a principal PLK1 kinetochore receptor requiring CDK1 priming, and showed Haspin and BUB1 act redundantly to localize Aurora B for error correction.\",\n      \"evidence\": \"In vitro BUB1-PLK1 reconstitution, ectopic localization and docking-motif mutagenesis; dual Haspin/BUB1 inhibition with substrate readouts; RNAi/CRISPR redundancy analysis\",\n      \"pmids\": [\"33248027\", \"32027339\", \"34551298\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Quantitative partitioning of PLK1 between BUB1 and CENP-U pools unresolved\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Resolved the structural and catalytic logic of MCC platform assembly, showing Aurora B phosphorylation of BUB1 promotes MCC production and that BUB1 phospho-CD1 docks the Mad1 CTD, while extending BUB1 signaling to STAT3 phosphorylation in cancer.\",\n      \"evidence\": \"eSAC dimerization in yeast and human cells; high-resolution crystallography, NMR and ITC of Mad1-Bub1; Co-IP, kinase-dead and inhibitor STAT3 studies\",\n      \"pmids\": [\"34861183\", \"34013668\", \"34852826\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Single-lab STAT3 link not independently confirmed\", \"Integration of Aurora B input with Mps1 licensing partially defined\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Completed the catalytic mechanism of MCC assembly via the Mad1 CTD-Cdc20 interface and linked BUB1 loss-of-function to a human Mendelian disorder.\",\n      \"evidence\": \"Crystal structure, XL-MS and in vitro MCC assembly; patient-derived cell analysis with localization, imaging and cohesion assays\",\n      \"pmids\": [\"36289199\", \"35044816\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Patient-cell findings from single laboratory\", \"Tissue specificity of neurodevelopmental phenotype not mechanistically explained\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How BUB1's mitotic, meiotic, telomeric, TGF-\\u03b2, and STAT3 functions are coordinated within a cell, and the relative in vivo contribution of its catalytic versus scaffolding roles to genome stability and tumor suppression, remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No unified model linking mitotic and non-mitotic BUB1 activities\", \"Decoupling of kinase activity from tumor suppression in mice not explained\", \"Therapeutic window of BUB1 kinase inhibition not defined\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0140096\", \"supporting_discovery_ids\": [0, 17, 24, 27, 34, 37, 33]},\n      {\"term_id\": \"GO:0016740\", \"supporting_discovery_ids\": [0, 17, 27, 34]},\n      {\"term_id\": \"GO:0042393\", \"supporting_discovery_ids\": [17, 24, 27]},\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [29, 31, 41, 42]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [34, 46]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [0]},\n      {\"term_id\": \"GO:0000228\", \"supporting_discovery_ids\": [2, 3, 4, 16]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-1640170\", \"supporting_discovery_ids\": [5, 12, 13, 16, 34]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [33, 44]},\n      {\"term_id\": \"R-HSA-73894\", \"supporting_discovery_ids\": [37, 50]},\n      {\"term_id\": \"R-HSA-392499\", \"supporting_discovery_ids\": [14, 34]}\n    ],\n    \"complexes\": [\"BUB1-BUB3 complex\", \"mitotic checkpoint complex (MCC) signaling platform\", \"kinetochore\"],\n    \"partners\": [\"BUB3\", \"BUBR1\", \"KNL1\", \"MAD1\", \"CDC20\", \"PLK1\", \"TRF1\", \"TGFBR1\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":8,"faith_total":8,"faith_pct":100.0}}