{"gene":"MIS18BP1","run_date":"2026-04-28T18:30:28","timeline":{"discoveries":[{"year":2007,"finding":"M18BP1 (initially called KNL-2 in C. elegans, with human homologue identified) is part of a three-protein Mis18 complex (hMis18α, hMis18β, M18BP1) that accumulates specifically at telophase-G1 centromeres and is essential for the subsequent recruitment of newly synthesized CENP-A; RNAi knockdown of any subunit abolishes new CENP-A loading and causes chromosome missegregation defects.","method":"RNAi knockdown, live-cell imaging, immunofluorescence, functional genomics screen in C. elegans","journal":"Developmental cell / The Journal of cell biology","confidence":"High","confidence_rationale":"Tier 2 — replicated across two independent labs (Fujita et al. and Maddox et al.) with consistent loss-of-function phenotypes","pmids":["17199038","17339379"],"is_preprint":false},{"year":2011,"finding":"CENP-C recruits M18BP1 to centromeres during metaphase through a direct physical interaction; depletion of CENP-C prevents M18BP1 targeting and inhibits CENP-A chromatin assembly. M18BP1 directly binds conserved domains within CENP-C, providing a molecular link between existing CENP-A chromatin and the CENP-A assembly machinery.","method":"RNAi depletion, Co-IP, pulldown assays, immunofluorescence, functional rescue experiments","journal":"The Journal of cell biology","confidence":"High","confidence_rationale":"Tier 2 — direct binding demonstrated by pulldown, functional consequence confirmed by depletion; replicated in a second lab (Dambacher et al. 2012)","pmids":["21911481","22540025"],"is_preprint":false},{"year":2012,"finding":"M18BP1 displays cell cycle-regulated association with centromeric chromatin in mouse ES cells, enriched from late anaphase through G1. The interaction domain for CENP-C maps to a central region of M18BP1 containing a conserved SANT domain, and to the C-terminus of CENP-C.","method":"Interaction screen against 16 core centromeric proteins, domain mapping, Co-IP, immunofluorescence, knockdown","journal":"Nucleus","confidence":"Medium","confidence_rationale":"Tier 2 — domain mapping and interaction screen; single lab study","pmids":["22540025"],"is_preprint":false},{"year":2016,"finding":"Mis18α and Mis18β form a heterotetramer through their C-terminal coiled-coil domains, and this heterotetramer formation is required for M18BP1 (Mis18BP1) binding and centromere recognition. HJURP recruitment to centromeres occurs through direct interaction with the Mis18α-β coiled-coil domains and disrupts the Mis18 complex.","method":"Biochemical reconstitution, co-immunoprecipitation, domain mutagenesis, immunofluorescence","journal":"Molecular cell","confidence":"High","confidence_rationale":"Tier 1-2 — reconstitution and mutagenesis with functional validation in a single rigorous study","pmids":["26942680"],"is_preprint":false},{"year":2016,"finding":"M18BP1 interacts with the acetyltransferase KAT7/HBO1/MYST2, and this interaction is required for CENP-A assembly; KAT7 knockout reduces centromeric CENP-A assembly and causes chromosome misalignment and micronuclei formation, linking the Mis18 complex to chromatin acetylation as a prerequisite for CENP-A deposition.","method":"Co-IP, KO in HeLa cells, immunofluorescence, artificial tethering, ChIP","journal":"Developmental cell","confidence":"Medium","confidence_rationale":"Tier 2 — co-IP plus loss-of-function phenotype, single lab study","pmids":["27270040"],"is_preprint":false},{"year":2017,"finding":"In human cells, a Mis18α:Mis18β 4:2 hexamer (arranged through specific Yippee domain contacts) binds two copies of M18BP1 through M18BP1's 140 N-terminal residues. CDK1 phosphorylates two conserved sites in this N-terminal region, destabilizing binding to the hexamer and restricting Mis18 complex formation and centromere recruitment to G1 phase. M18BP1 dimerization via the Mis18 scaffold is required for CENP-A loading.","method":"Biochemical reconstitution, SEC, mutagenesis, mass spectrometry, cell biology with 2A peptide co-expression strategy, immunofluorescence","journal":"eLife","confidence":"High","confidence_rationale":"Tier 1 — biochemical reconstitution with mutagenesis, cell cycle-regulated mechanism demonstrated with multiple orthogonal methods","pmids":["28059702"],"is_preprint":false},{"year":2017,"finding":"In Xenopus, M18BP1 directly and cell-cycle-dependently binds CENP-A nucleosomes through a motif conserved in non-mammalian vertebrates that resembles the CENP-C CENP-A nucleosome binding motif; CENP-C competes with M18BP1 for binding to CENP-A nucleosomes at centromeres. Both CENP-C and M18BP1 recruit HJURP for new CENP-A assembly.","method":"Xenopus egg extract cell-free system, nucleosome pulldown, competition binding assays, domain mutagenesis, immunodepletion, immunofluorescence","journal":"Developmental cell","confidence":"High","confidence_rationale":"Tier 1 — in vitro reconstitution with multiple orthogonal approaches including competition assays and mutagenesis","pmids":["28743005"],"is_preprint":false},{"year":2015,"finding":"The CENP-C motif sequence is present in M18BP1 proteins of fish and some other non-mammalian vertebrates but not in mammals, suggesting an evolutionary variation in the mechanism by which M18BP1 recognizes centromeric nucleosomes across vertebrate taxa.","method":"Comparative sequence analysis, BLASTP, evolutionary bioinformatics","journal":"F1000Research","confidence":"Low","confidence_rationale":"Tier 4 — computational/bioinformatic prediction only","pmids":["27127616"],"is_preprint":false},{"year":2019,"finding":"In Xenopus, Cdk phosphorylation of M18BP1 is necessary for M18BP1 to bind CENP-C via its SANTA domain and localize to centromeres in metaphase; disrupting this metaphase M18BP1/CENP-C interaction also causes defective nuclear localization of M18BP1 in interphase, resulting in failure of CENP-A nucleosome assembly.","method":"Xenopus egg extract, phosphomutant analysis, co-immunoprecipitation, immunofluorescence, functional rescue","journal":"The EMBO journal","confidence":"High","confidence_rationale":"Tier 2 — phosphomutant analysis with cell-free system and multiple functional readouts in a single comprehensive study","pmids":["30606714"],"is_preprint":false},{"year":2021,"finding":"In C. elegans, the N-terminal tail of CENP-A (which contains an extended predicted structured region essential for CENP-A chromatin assembly) directly binds KNL-2 (the C. elegans ortholog of M18BP1); this interaction partially substitutes for the function of HJURP/Scm3 in organisms lacking a dedicated CENP-A chaperone.","method":"In vitro binding assays, RNAi depletion, CENP-A N-tail deletion mutants, immunofluorescence in C. elegans and C. briggsae","journal":"Molecular biology of the cell","confidence":"Medium","confidence_rationale":"Tier 2 — direct binding demonstrated with functional validation, single lab but conserved in two nematode species","pmids":["33852350"],"is_preprint":false},{"year":2023,"finding":"M18BP1 (specifically the M18BP1.S subunit in Xenopus) binds to CENP-C in metaphase to competitively inhibit HJURP's access to centromeres, representing one of two mechanisms that restrict CENP-A assembly to G1; the other mechanism is CDK-dependent phosphorylation of HJURP that blocks its interaction with CENP-C.","method":"Xenopus egg extract cell-free system, phosphomutant analysis, competitive binding assays, immunodepletion","journal":"The Journal of cell biology","confidence":"High","confidence_rationale":"Tier 1-2 — reconstituted mechanistic competition in cell-free system with phosphomutants and rescue experiments","pmids":["37141119"],"is_preprint":false},{"year":2024,"finding":"In C. elegans oocytes during meiosis I, KNL-2 (M18BP1 ortholog) promotes outer kinetochore assembly through a non-canonical pathway independent of its CENP-A loading activity; KNL-2 recruits the nucleoporin MEL-28/ELYS to meiotic kinetochores through a specific N-terminal domain, and co-depletion of CENP-A/CENP-C with KNL-2 fully prevents outer kinetochore assembly.","method":"RNAi and auxin-inducible degron depletion, engineered domain mutants, immunofluorescence, C. elegans genetics","journal":"Current biology","confidence":"Medium","confidence_rationale":"Tier 2 — genetic epistasis with domain mutants demonstrating a distinct non-canonical function; single lab study","pmids":["39353426"],"is_preprint":false},{"year":2024,"finding":"In chicken DT40 cells, Knl2 (MIS18BP1) tethering can recruit CENP-A to non-centromeric loci independently of CENP-C, and tethering of CENP-C or CENP-I can induce CENP-A incorporation even in the absence of Knl2, showing that multiple independent pathways exist for CENP-A recruitment to artificial kinetochore sites.","method":"Artificial tethering assay, auxin-inducible degron knockout, Co-IP, immunofluorescence in DT40 cells","journal":"Journal of cell science","confidence":"Medium","confidence_rationale":"Tier 2 — systematic tethering with conditional knockouts revealing pathway relationships; single lab study","pmids":["38319136"],"is_preprint":false},{"year":2025,"finding":"M18BP1 directly binds the CAP-G2 subunit of condensin II; during interphase, the condensin II antagonist MCPH1 also binds CAP-G2 and outcompetes M18BP1; at mitotic onset, a switch from MCPH1 to M18BP1 binding activates condensin II and promotes chromosome condensation. This identifies M18BP1 as the elusive activator of condensin II at mitotic entry.","method":"Genetic and proteomic approaches, Co-IP, competitive binding assays, loss-of-function studies, cell biology","journal":"Molecular cell","confidence":"High","confidence_rationale":"Tier 2 — direct binding demonstrated with competition assays and functional genetic validation; strong mechanistic model supported by multiple orthogonal approaches","pmids":["40614722"],"is_preprint":false},{"year":2026,"finding":"In human cells, artificial M18BP1 dimerization bypasses the need for MIS18α/β, enabling identification of at least four determinants of M18BP1 centromere localization including the SANTA domain (first structure reported) and linear motifs in disordered regions that interact with the 16-subunit CCAN. Cell-cycle-dependent dimerization of M18BP1 on MIS18α/β promotes multivalent recognition of old CENP-A and associated proteins, followed by PLK1 and HJURP recruitment for new CENP-A deposition.","method":"Artificial dimerization strategy, cryo-EM/structural determination of SANTA domain, mutagenesis, Co-IP, immunofluorescence, cell biology in human cells","journal":"The EMBO journal","confidence":"High","confidence_rationale":"Tier 1 — first SANTA domain structure with functional validation and multiple orthogonal mechanistic approaches in one study","pmids":["41629527"],"is_preprint":false},{"year":2026,"finding":"In Xenopus, cell-cycle-dependent phosphorylation of M18BP1 disrupts its binding to CENP-A nucleosomes in metaphase; when this phosphorylation is relieved in interphase, M18BP1 binds CENP-A nucleosomes to promote new CENP-A nucleosome assembly. This phospho-regulatory switch provides a mechanism for restricting CENP-A assembly to interphase.","method":"Xenopus egg extract, phosphomutant analysis, nucleosome binding assays, immunofluorescence","journal":"EMBO reports","confidence":"High","confidence_rationale":"Tier 1-2 — direct nucleosome binding assays with phosphomutants in cell-free system; peer-reviewed publication of prior preprint data","pmids":["41680291"],"is_preprint":false},{"year":2025,"finding":"Phosphorylation of Xenopus M18BP1 by CDK disrupts its binding to CENP-A nucleosomes in metaphase, and relief of this phosphorylation in interphase enables M18BP1 binding to CENP-A nucleosomes to drive new CENP-A assembly (preprint version of the EMBO reports 2026 study).","method":"Xenopus egg extract, phosphomutant analysis, nucleosome binding assays","journal":"bioRxiv","confidence":"High","confidence_rationale":"Tier 1-2 — direct binding assays with functional validation; subsequently peer-reviewed","pmids":["40791504"],"is_preprint":true}],"current_model":"MIS18BP1/M18BP1 is a core subunit of the trimeric Mis18 complex (with Mis18α and Mis18β) that localizes to centromeres in a cell-cycle-regulated manner to prime centromeres for CENP-A nucleosome assembly by recruiting the CENP-A chaperone HJURP; its centromere recruitment is governed by CDK-regulated phosphorylation that controls its dimerization on a Mis18α:Mis18β hexameric scaffold, its direct binding to CENP-A nucleosomes (via a motif conserved in non-mammalian vertebrates), and its interaction with CENP-C (via the SANTA domain), while in metaphase M18BP1 competitively inhibits HJURP access to centromeres; additionally, M18BP1 activates condensin II at mitotic onset by binding CAP-G2 and displacing the antagonist MCPH1, revealing a dual role in both centromere identity maintenance and chromosome condensation."},"narrative":{"teleology":[{"year":2007,"claim":"Identification of M18BP1 as a component of a three-subunit Mis18 complex that localizes to centromeres in telophase–G1 and is essential for new CENP-A loading established the gene's foundational role in centromere propagation.","evidence":"RNAi knockdown in C. elegans and human cells with live-cell imaging and immunofluorescence, replicated across two independent labs","pmids":["17199038","17339379"],"confidence":"High","gaps":["Mechanism by which M18BP1 is recruited to centromeres was unknown","How M18BP1 promotes CENP-A loading was not determined","Cell-cycle restriction mechanism was unresolved"]},{"year":2011,"claim":"Discovery that CENP-C directly recruits M18BP1 to centromeres provided the first molecular link between existing CENP-A chromatin and the CENP-A assembly machinery, with the SANT/SANTA domain mediating this interaction.","evidence":"Co-IP, pulldown, RNAi depletion, immunofluorescence, and domain mapping in human cells and mouse ES cells","pmids":["21911481","22540025"],"confidence":"High","gaps":["Whether M18BP1 directly recognizes CENP-A nucleosomes in addition to CENP-C was unknown","Structural basis of the SANTA domain–CENP-C interaction was not resolved"]},{"year":2016,"claim":"Reconstitution of the Mis18α:Mis18β heterotetramer and demonstration that this scaffold is required for M18BP1 binding and HJURP recruitment defined the biochemical architecture through which M18BP1 operates, while the discovery that KAT7 interacts with M18BP1 linked the complex to chromatin acetylation.","evidence":"Biochemical reconstitution, domain mutagenesis, co-IP, and KAT7 knockout in HeLa cells","pmids":["26942680","27270040"],"confidence":"High","gaps":["Stoichiometry and geometry of M18BP1 on the Mis18 scaffold were not yet resolved","How KAT7 acetylation facilitates CENP-A deposition mechanistically was unclear"]},{"year":2017,"claim":"Determination that CDK1 phosphorylation of two conserved N-terminal sites on M18BP1 blocks its binding to the Mis18α:Mis18β 4:2 hexamer, restricting Mis18 complex assembly and centromere recruitment to G1, resolved the long-standing question of how CENP-A loading is cell-cycle-gated; separately, M18BP1 was shown to directly bind CENP-A nucleosomes in Xenopus through a CENP-C-like motif.","evidence":"Biochemical reconstitution with SEC and mass spectrometry in human cells; nucleosome pulldowns and competition binding assays in Xenopus egg extracts","pmids":["28059702","28743005"],"confidence":"High","gaps":["Mammalian M18BP1 lacks the CENP-C-like motif, leaving the mammalian CENP-A nucleosome recognition mechanism unresolved","Phosphorylation of M18BP1's CENP-A-nucleosome-binding region was not yet characterized"]},{"year":2019,"claim":"Demonstration that CDK phosphorylation of Xenopus M18BP1 is required for its SANTA-domain-mediated CENP-C binding in metaphase, and that this metaphase priming is necessary for subsequent interphase CENP-A assembly, revealed a two-step phospho-regulatory model linking metaphase centromere licensing to G1 CENP-A deposition.","evidence":"Phosphomutant analysis, co-IP, and functional rescue in Xenopus egg extracts","pmids":["30606714"],"confidence":"High","gaps":["Exact phospho-sites governing the CENP-A nucleosome binding switch were not yet mapped","Whether an analogous priming step exists in mammalian cells was unclear"]},{"year":2021,"claim":"In C. elegans, which lacks HJURP, direct binding of KNL-2 (M18BP1 ortholog) to the CENP-A N-terminal tail partially substitutes for a dedicated CENP-A chaperone, broadening the functional repertoire of M18BP1 across evolution.","evidence":"In vitro binding assays, RNAi, and CENP-A N-tail deletion mutants in C. elegans and C. briggsae","pmids":["33852350"],"confidence":"Medium","gaps":["Whether this chaperone-like activity exists in vertebrate M18BP1 is unknown","Structural basis of KNL-2–CENP-A tail interaction not determined"]},{"year":2023,"claim":"Reconstitution of competitive binding showed that M18BP1 occupies CENP-C at metaphase centromeres to block HJURP access, establishing M18BP1 as an active inhibitor of premature CENP-A loading rather than merely a passive licensing factor.","evidence":"Competitive binding assays, immunodepletion, and phosphomutant analysis in Xenopus egg extracts","pmids":["37141119"],"confidence":"High","gaps":["Quantitative parameters of the competition (affinities, stoichiometry) not measured","Whether this inhibitory role is conserved in mammals was not tested"]},{"year":2024,"claim":"Discovery that KNL-2 promotes outer kinetochore assembly in C. elegans meiosis I independently of CENP-A loading, by recruiting MEL-28/ELYS through its N-terminal domain, revealed a non-canonical function of the M18BP1 family beyond centromere maintenance; additionally, tethering experiments in chicken DT40 cells showed that M18BP1 can recruit CENP-A to ectopic sites independently of CENP-C.","evidence":"RNAi and auxin-inducible degron depletions with domain mutants in C. elegans; artificial tethering and conditional knockouts in DT40 cells","pmids":["39353426","38319136"],"confidence":"Medium","gaps":["Whether the meiotic kinetochore assembly role exists in vertebrates is unknown","Mechanism by which tethered M18BP1 loads CENP-A without CENP-C is not defined"]},{"year":2025,"claim":"Identification of M18BP1 as the direct binding partner and activator of condensin II (via CAP-G2), which displaces the interphase antagonist MCPH1 at mitotic entry, revealed a second major function of M18BP1 in chromosome condensation independent of its CENP-A loading role.","evidence":"Co-IP, competitive binding assays, loss-of-function studies, and proteomic approaches in human cells","pmids":["40614722"],"confidence":"High","gaps":["How cell-cycle signals trigger the MCPH1-to-M18BP1 switch on CAP-G2 is not resolved","Whether condensin II activation and CENP-A loading are coordinated through shared M18BP1 pools is unknown"]},{"year":2026,"claim":"First structural determination of the SANTA domain and identification of at least four centromere-localization determinants in M18BP1 — including SANTA, linear CCAN-binding motifs, and dimerization-dependent multivalent recognition of old CENP-A — provided an integrated structural framework for how M18BP1 bridges the Mis18 scaffold to centromeric chromatin; phospho-regulation of M18BP1–CENP-A nucleosome binding was also resolved in Xenopus.","evidence":"Cryo-EM/structural analysis, artificial dimerization, mutagenesis in human cells; phosphomutant nucleosome binding assays in Xenopus egg extracts","pmids":["41629527","41680291"],"confidence":"High","gaps":["Full atomic-resolution structure of M18BP1 in complex with the Mis18 hexamer is lacking","How PLK1 recruitment by dimerized M18BP1 triggers HJURP loading is not structurally resolved"]},{"year":null,"claim":"Outstanding questions include how mammalian M18BP1 recognizes CENP-A nucleosomes in the absence of the CENP-C-like motif found in non-mammalian vertebrates, how M18BP1's dual roles in CENP-A loading and condensin II activation are temporally and spatially coordinated within a single cell cycle, and whether the meiotic kinetochore assembly function of the M18BP1 family is conserved beyond nematodes.","evidence":"","pmids":[],"confidence":"Low","gaps":["Mammalian CENP-A nucleosome recognition mechanism for M18BP1 is unresolved","Coordination between CENP-A loading and condensin II activation by shared M18BP1 is unexplored","Conservation of meiotic kinetochore assembly function outside C. elegans is untested"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0042393","term_label":"histone binding","supporting_discovery_ids":[6,9,15]},{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[0,1,3,5,13]},{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[10,13]}],"localization":[{"term_id":"GO:0005694","term_label":"chromosome","supporting_discovery_ids":[0,1,2,5,6,8,14]},{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[0,8,14]}],"pathway":[{"term_id":"R-HSA-1640170","term_label":"Cell Cycle","supporting_discovery_ids":[0,5,10,13,14]},{"term_id":"R-HSA-4839726","term_label":"Chromatin organization","supporting_discovery_ids":[0,4,6,14,15]}],"complexes":["Mis18 complex (Mis18α:Mis18β:MIS18BP1)","Condensin II (via CAP-G2 binding)"],"partners":["MIS18A","MIS18B","CENPC","HJURP","KAT7","CAPG2","MCPH1","ELYS"],"other_free_text":[]},"mechanistic_narrative":"MIS18BP1 is a central regulator of centromere identity that couples cell-cycle signaling to CENP-A nucleosome assembly and, independently, activates condensin II for mitotic chromosome condensation. It functions as a core subunit of the trimeric Mis18 complex (with Mis18α and Mis18β), where CDK1 phosphorylation of its N-terminal region restricts complex formation and centromere recruitment to G1 phase; upon dephosphorylation, M18BP1 dimerizes on a Mis18α:Mis18β hexameric scaffold and engages centromeric chromatin through multivalent contacts including direct binding to CENP-A nucleosomes (via a CENP-C-like motif in non-mammalian vertebrates), interaction with CENP-C through its SANTA domain, and recognition of the CCAN, thereby recruiting the CENP-A chaperone HJURP for new CENP-A deposition [PMID:17199038, PMID:28059702, PMID:28743005, PMID:41629527]. During metaphase, M18BP1 competitively inhibits HJURP access to centromeres via CENP-C binding, constituting one of two mechanisms that restrict CENP-A loading to the appropriate cell-cycle window [PMID:37141119]. At mitotic entry, M18BP1 directly binds the condensin II subunit CAP-G2, displacing the antagonist MCPH1 and activating condensin II to promote chromosome condensation, revealing a dual role in centromere maintenance and higher-order chromosome organization [PMID:40614722]."},"prefetch_data":{"uniprot":{"accession":"Q6P0N0","full_name":"Mis18-binding protein 1","aliases":["Kinetochore-associated protein KNL-2 homolog","HsKNL-2","P243"],"length_aa":1132,"mass_kda":129.1,"function":"Required for recruitment of CENPA to centromeres and normal chromosome segregation during mitosis","subcellular_location":"Nucleus; Chromosome, centromere","url":"https://www.uniprot.org/uniprotkb/Q6P0N0/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":true,"resolved_as":"","url":"https://depmap.org/portal/gene/MIS18BP1","classification":"Common Essential","n_dependent_lines":1172,"n_total_lines":1208,"dependency_fraction":0.9701986754966887},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/MIS18BP1","total_profiled":1310},"omim":[{"mim_id":"618139","title":"MIS18-BINDING PROTEIN 1; MIS18BP1","url":"https://www.omim.org/entry/618139"},{"mim_id":"618137","title":"MIS18 KINETOCHORE PROTEIN A: MIS18A","url":"https://www.omim.org/entry/618137"},{"mim_id":"612667","title":"HOLLIDAY JUNCTION RECOGNITION PROTEIN; HJURP","url":"https://www.omim.org/entry/612667"},{"mim_id":"606020","title":"OPA-INTERACTING PROTEIN 5; OIP5","url":"https://www.omim.org/entry/606020"},{"mim_id":"602098","title":"POLO-LIKE KINASE 1; PLK1","url":"https://www.omim.org/entry/602098"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Nucleoli","reliability":"Approved"},{"location":"Cytosol","reliability":"Additional"}],"tissue_specificity":"Tissue enhanced","tissue_distribution":"Detected in many","driving_tissues":[{"tissue":"bone marrow","ntpm":38.5}],"url":"https://www.proteinatlas.org/search/MIS18BP1"},"hgnc":{"alias_symbol":["M18BP1","FLJ11186","KIAA1903","KNL2"],"prev_symbol":["C14orf106"]},"alphafold":{"accession":"Q6P0N0","domains":[{"cath_id":"-","chopping":"380-492","consensus_level":"medium","plddt":87.1994,"start":380,"end":492},{"cath_id":"1.10.10.60","chopping":"882-924","consensus_level":"medium","plddt":88.1307,"start":882,"end":924}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q6P0N0","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q6P0N0-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q6P0N0-F1-predicted_aligned_error_v6.png","plddt_mean":48.31},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=MIS18BP1","jax_strain_url":"https://www.jax.org/strain/search?query=MIS18BP1"},"sequence":{"accession":"Q6P0N0","fasta_url":"https://rest.uniprot.org/uniprotkb/Q6P0N0.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q6P0N0/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q6P0N0"}},"corpus_meta":[{"pmid":"21911481","id":"PMC_21911481","title":"CENP-C recruits M18BP1 to centromeres to promote CENP-A chromatin assembly.","date":"2011","source":"The Journal of cell biology","url":"https://pubmed.ncbi.nlm.nih.gov/21911481","citation_count":187,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"22540025","id":"PMC_22540025","title":"CENP-C facilitates the recruitment of M18BP1 to centromeric chromatin.","date":"2012","source":"Nucleus (Austin, Tex.)","url":"https://pubmed.ncbi.nlm.nih.gov/22540025","citation_count":111,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"28059702","id":"PMC_28059702","title":"CDK-regulated dimerization of M18BP1 on a Mis18 hexamer is necessary for CENP-A loading.","date":"2017","source":"eLife","url":"https://pubmed.ncbi.nlm.nih.gov/28059702","citation_count":72,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"28743005","id":"PMC_28743005","title":"Xenopus laevis M18BP1 Directly Binds Existing CENP-A Nucleosomes to Promote Centromeric Chromatin Assembly.","date":"2017","source":"Developmental cell","url":"https://pubmed.ncbi.nlm.nih.gov/28743005","citation_count":60,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"28062749","id":"PMC_28062749","title":"Targeting of Arabidopsis KNL2 to Centromeres Depends on the Conserved CENPC-k Motif in Its C Terminus.","date":"2017","source":"The Plant cell","url":"https://pubmed.ncbi.nlm.nih.gov/28062749","citation_count":47,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"30606714","id":"PMC_30606714","title":"CDK phosphorylation of Xenopus laevis M18BP1 promotes its metaphase centromere localization.","date":"2019","source":"The EMBO journal","url":"https://pubmed.ncbi.nlm.nih.gov/30606714","citation_count":25,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"27127616","id":"PMC_27127616","title":"Possible identification of CENP-C in fish and the presence of the CENP-C motif in M18BP1 of 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assembly.\",\n      \"method\": \"Co-immunoprecipitation, direct binding assay, siRNA depletion with centromere localization readout\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — direct binding demonstrated, depletion phenotype with mechanistic pathway placement, replicated independently in a second lab\",\n      \"pmids\": [\"21911481\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"M18BP1 interacts with CENP-C, mapping the interaction domain in M18BP1 to a central region containing a conserved SANT domain and in CENP-C to the C-terminus; knock-down of CENP-C reduces M18BP1 association and CENP-A levels at centromeres in mouse ES cells.\",\n      \"method\": \"Interaction screen against 16 centromeric proteins, domain mapping, CENP-C knockdown with quantitative centromere localization\",\n      \"journal\": \"Nucleus (Austin, Tex.)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — independently replicates CENP-C/M18BP1 interaction with domain mapping and functional consequence\",\n      \"pmids\": [\"22540025\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"Mis18α:Mis18β forms a 4:2 hexamer through Yippee domain arrangement that binds two copies of M18BP1 via M18BP1's 140 N-terminal residues; CDK1 phosphorylation at two conserved sites in this N-terminal region destabilizes M18BP1 binding to Mis18α:Mis18β, restricting Mis18 complex formation and centromere recruitment to G1 phase.\",\n      \"method\": \"Biochemical reconstitution, in vitro CDK1 phosphorylation assay, site-directed mutagenesis, viral 2A co-expression system, cell cycle-staged localization\",\n      \"journal\": \"eLife\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — reconstituted complex in vitro with mutagenesis, CDK1 phosphorylation mechanistically validated, multiple orthogonal approaches\",\n      \"pmids\": [\"28059702\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"Xenopus M18BP1 directly binds CENP-A nucleosomes using a conserved motif (absent in mammals) in a cell-cycle-regulated manner to recruit the Mis18 complex to interphase centromeres; CENP-C competes with M18BP1 for CENP-A nucleosome binding; both CENP-C and M18BP1 recruit HJURP to centromeres for new CENP-A assembly.\",\n      \"method\": \"Xenopus egg extract system, in vitro nucleosome binding assay, competition assay, domain mapping, depletion experiments\",\n      \"journal\": \"Developmental cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — direct binding reconstituted in cell-free system with competition assay and functional assembly readout\",\n      \"pmids\": [\"28743005\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"Xenopus M18BP1 localizes to centromeres during metaphase by binding CENP-C through its conserved SANTA domain; CDK phosphorylation of M18BP1 is required for this metaphase CENP-C interaction and centromere localization; disruption of the metaphase M18BP1/CENP-C interaction causes defective nuclear localization in interphase and defective CENP-A nucleosome assembly.\",\n      \"method\": \"Xenopus egg extract, phosphomutant analysis, domain mutagenesis, centromere localization assay, CENP-A assembly assay\",\n      \"journal\": \"The EMBO journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 — phosphomutant mechanistic dissection in cell-free system with multiple functional readouts\",\n      \"pmids\": [\"30606714\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"M18BP1 (specifically the M18BP1.S subunit of the Mis18 complex) binds CENP-C in metaphase to competitively inhibit HJURP's access to centromeres, constituting one of two inhibitory activities that prevent CENP-A assembly in metaphase; removal of both M18BP1 and HJURP phosphorylation inhibitory activities causes ectopic CENP-A assembly in metaphase.\",\n      \"method\": \"Xenopus cell-free centromere assembly system, phosphomutant HJURP analysis, competitive binding assay, CENP-A assembly epistasis\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — reconstituted in cell-free system, epistasis between two inhibitory activities, functional assembly readout\",\n      \"pmids\": [\"37141119\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"M18BP1 directly binds the condensin II CAP-G2 subunit to promote condensin II loading onto chromatin at mitotic onset; MCPH1 also binds CAP-G2 and outcompetes M18BP1 during interphase, maintaining uncondensed chromatin; a switch from MCPH1 to M18BP1 at mitotic onset activates condensin II for chromosome condensation.\",\n      \"method\": \"Genetic and proteomic screens, direct binding assay (M18BP1–CAP-G2), competition assay (MCPH1 vs M18BP1), chromosome condensation phenotypic readout\",\n      \"journal\": \"Molecular cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — direct binding identified by multiple approaches, competition mechanism validated, genetic epistasis with defined phenotype\",\n      \"pmids\": [\"40614722\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"In human cells, artificial M18BP1 dimerization bypasses MIS18α/β and reveals at least four determinants of M18BP1 centromere localization including the SANTA domain (structure reported) and linear motifs in disordered neighboring regions that interact with the 16-subunit CCAN; M18BP1 dimerization is necessary and sufficient for centromere localization, and cell-cycle-dependent dimerization on MIS18α/β scaffold enables recognition of old CENP-A/CCAN followed by PLK1 and HJURP recruitment for new CENP-A deposition.\",\n      \"method\": \"Artificial dimerization system, first crystal/structural characterization of SANTA domain, interaction footprint mapping on CCAN, PLK1 and HJURP recruitment assay\",\n      \"journal\": \"The EMBO journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 — structure of SANTA domain determined, multiple interaction determinants mapped, functional dimerization bypass experiment with mechanistic dissection\",\n      \"pmids\": [\"41629527\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"Phosphorylation of Xenopus M18BP1 disrupts its binding to CENP-A nucleosomes in metaphase; relief of this phosphorylation in interphase enables M18BP1–CENP-A nucleosome binding and CENP-A nucleosome assembly, establishing phospho-regulated CENP-A nucleosome binding as a mechanism restricting new CENP-A assembly to interphase.\",\n      \"method\": \"Xenopus egg extract, phosphomutant M18BP1, in vitro nucleosome binding assay, CENP-A assembly assay\",\n      \"journal\": \"EMBO reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — cell-free reconstitution with phosphomutants and direct nucleosome binding assay, multiple functional readouts\",\n      \"pmids\": [\"41680291\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"In chicken DT40 cells, CENP-C or CENP-I tethering induces CENP-A incorporation at non-centromeric loci in the absence of Knl2/MIS18BP1, and Knl2 tethering recruits CENP-A independently of CENP-C; CENP-C co-immunoprecipitates with HJURP independently of Knl2, suggesting CENP-C can directly recruit CENP-A via HJURP without MIS18BP1.\",\n      \"method\": \"Tethering assay, auxin-inducible degron (AID) knockout, co-immunoprecipitation, CENP-A incorporation readout at non-centromeric loci\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — genetic epistasis by tethering and AID degron in vertebrate cells, but single lab and specific to artificial kinetochore context\",\n      \"pmids\": [\"38319136\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"In C. elegans, the extended N-terminal tail of CENP-A directly binds KNL-2 (ortholog of human M18BP1/MIS18BP1); this interaction is essential for CENP-A chromatin assembly, as removal of the N-tail prevents CENP-A loading, kinetochore assembly, and chromosome condensation.\",\n      \"method\": \"Direct binding assay (CENP-A N-tail vs KNL-2), RNAi depletion, deletion mutagenesis, kinetochore assembly and chromosome condensation readouts\",\n      \"journal\": \"Molecular biology of the cell\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — direct binding demonstrated in vitro, conserved in related nematode, loss-of-function phenotype; ortholog of MIS18BP1 in nematode\",\n      \"pmids\": [\"33852350\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"In C. elegans, CDK-1 phosphorylates KNL-2 (M18BP1 ortholog) in vitro at three C-terminal sites; phosphodeficient mutation of these sites causes chromosome condensation defects and reduced mitotic condensin II on chromosomes without affecting CENP-A or kinetochore localization, separating KNL-2's CENP-A loading and chromosome condensation functions.\",\n      \"method\": \"In vitro CDK-1 kinase assay, phosphomutant analysis, chromosome condensation and condensin II localization readouts, C. elegans genetics\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1–2 — in vitro kinase assay with phosphomutant functional dissection; ortholog in nematode with conserved domain architecture\",\n      \"pmids\": [\"34734636\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"In C. elegans oocytes during meiosis I, KNL-2 (M18BP1 ortholog) recruits MEL-28/ELYS to meiotic kinetochores through a specific N-terminal domain, independently of its canonical CENP-A loading factor activity, defining a non-canonical kinetochore assembly pathway parallel to CENP-A/CENP-C.\",\n      \"method\": \"RNAi and degron-based depletion, engineered N-terminal domain mutants, kinetochore protein localization, epistasis analysis of co-depletion\",\n      \"journal\": \"Current biology : CB\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — domain-specific mutant separating canonical from non-canonical function, epistasis with co-depletion, clear localization readout\",\n      \"pmids\": [\"39353426\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"MIS18BP1 is a multifunctional scaffold that (1) is recruited to centromeres via cell-cycle-regulated interactions: in metaphase through CDK-phosphorylation-dependent binding to CENP-C via its SANTA domain, and in interphase through direct binding to CENP-A nucleosomes (regulated by dephosphorylation); (2) forms part of the Mis18 complex by binding as a dimer to a Mis18α:Mis18β hexamer through its N-terminal 140 residues, with CDK1 phosphorylation of these residues restricting complex formation to G1; (3) competitively inhibits HJURP access to CENP-C in metaphase to prevent premature CENP-A assembly; (4) recruits HJURP to centromeres in G1 to promote new CENP-A nucleosome deposition; and (5) activates condensin II by binding CAP-G2, displacing the antagonist MCPH1 at mitotic onset to promote chromosome condensation.\"\n}\n```\n\n--- ROUND 2 (R2/R3, augmented corpus) ---\n\n```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2007,\n      \"finding\": \"M18BP1 (initially called KNL-2 in C. elegans, with human homologue identified) is part of a three-protein Mis18 complex (hMis18α, hMis18β, M18BP1) that accumulates specifically at telophase-G1 centromeres and is essential for the subsequent recruitment of newly synthesized CENP-A; RNAi knockdown of any subunit abolishes new CENP-A loading and causes chromosome missegregation defects.\",\n      \"method\": \"RNAi knockdown, live-cell imaging, immunofluorescence, functional genomics screen in C. elegans\",\n      \"journal\": \"Developmental cell / The Journal of cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — replicated across two independent labs (Fujita et al. and Maddox et al.) with consistent loss-of-function phenotypes\",\n      \"pmids\": [\"17199038\", \"17339379\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"CENP-C recruits M18BP1 to centromeres during metaphase through a direct physical interaction; depletion of CENP-C prevents M18BP1 targeting and inhibits CENP-A chromatin assembly. M18BP1 directly binds conserved domains within CENP-C, providing a molecular link between existing CENP-A chromatin and the CENP-A assembly machinery.\",\n      \"method\": \"RNAi depletion, Co-IP, pulldown assays, immunofluorescence, functional rescue experiments\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — direct binding demonstrated by pulldown, functional consequence confirmed by depletion; replicated in a second lab (Dambacher et al. 2012)\",\n      \"pmids\": [\"21911481\", \"22540025\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"M18BP1 displays cell cycle-regulated association with centromeric chromatin in mouse ES cells, enriched from late anaphase through G1. The interaction domain for CENP-C maps to a central region of M18BP1 containing a conserved SANT domain, and to the C-terminus of CENP-C.\",\n      \"method\": \"Interaction screen against 16 core centromeric proteins, domain mapping, Co-IP, immunofluorescence, knockdown\",\n      \"journal\": \"Nucleus\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — domain mapping and interaction screen; single lab study\",\n      \"pmids\": [\"22540025\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"Mis18α and Mis18β form a heterotetramer through their C-terminal coiled-coil domains, and this heterotetramer formation is required for M18BP1 (Mis18BP1) binding and centromere recognition. HJURP recruitment to centromeres occurs through direct interaction with the Mis18α-β coiled-coil domains and disrupts the Mis18 complex.\",\n      \"method\": \"Biochemical reconstitution, co-immunoprecipitation, domain mutagenesis, immunofluorescence\",\n      \"journal\": \"Molecular cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — reconstitution and mutagenesis with functional validation in a single rigorous study\",\n      \"pmids\": [\"26942680\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"M18BP1 interacts with the acetyltransferase KAT7/HBO1/MYST2, and this interaction is required for CENP-A assembly; KAT7 knockout reduces centromeric CENP-A assembly and causes chromosome misalignment and micronuclei formation, linking the Mis18 complex to chromatin acetylation as a prerequisite for CENP-A deposition.\",\n      \"method\": \"Co-IP, KO in HeLa cells, immunofluorescence, artificial tethering, ChIP\",\n      \"journal\": \"Developmental cell\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — co-IP plus loss-of-function phenotype, single lab study\",\n      \"pmids\": [\"27270040\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"In human cells, a Mis18α:Mis18β 4:2 hexamer (arranged through specific Yippee domain contacts) binds two copies of M18BP1 through M18BP1's 140 N-terminal residues. CDK1 phosphorylates two conserved sites in this N-terminal region, destabilizing binding to the hexamer and restricting Mis18 complex formation and centromere recruitment to G1 phase. M18BP1 dimerization via the Mis18 scaffold is required for CENP-A loading.\",\n      \"method\": \"Biochemical reconstitution, SEC, mutagenesis, mass spectrometry, cell biology with 2A peptide co-expression strategy, immunofluorescence\",\n      \"journal\": \"eLife\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — biochemical reconstitution with mutagenesis, cell cycle-regulated mechanism demonstrated with multiple orthogonal methods\",\n      \"pmids\": [\"28059702\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"In Xenopus, M18BP1 directly and cell-cycle-dependently binds CENP-A nucleosomes through a motif conserved in non-mammalian vertebrates that resembles the CENP-C CENP-A nucleosome binding motif; CENP-C competes with M18BP1 for binding to CENP-A nucleosomes at centromeres. Both CENP-C and M18BP1 recruit HJURP for new CENP-A assembly.\",\n      \"method\": \"Xenopus egg extract cell-free system, nucleosome pulldown, competition binding assays, domain mutagenesis, immunodepletion, immunofluorescence\",\n      \"journal\": \"Developmental cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — in vitro reconstitution with multiple orthogonal approaches including competition assays and mutagenesis\",\n      \"pmids\": [\"28743005\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"The CENP-C motif sequence is present in M18BP1 proteins of fish and some other non-mammalian vertebrates but not in mammals, suggesting an evolutionary variation in the mechanism by which M18BP1 recognizes centromeric nucleosomes across vertebrate taxa.\",\n      \"method\": \"Comparative sequence analysis, BLASTP, evolutionary bioinformatics\",\n      \"journal\": \"F1000Research\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 4 — computational/bioinformatic prediction only\",\n      \"pmids\": [\"27127616\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"In Xenopus, Cdk phosphorylation of M18BP1 is necessary for M18BP1 to bind CENP-C via its SANTA domain and localize to centromeres in metaphase; disrupting this metaphase M18BP1/CENP-C interaction also causes defective nuclear localization of M18BP1 in interphase, resulting in failure of CENP-A nucleosome assembly.\",\n      \"method\": \"Xenopus egg extract, phosphomutant analysis, co-immunoprecipitation, immunofluorescence, functional rescue\",\n      \"journal\": \"The EMBO journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — phosphomutant analysis with cell-free system and multiple functional readouts in a single comprehensive study\",\n      \"pmids\": [\"30606714\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"In C. elegans, the N-terminal tail of CENP-A (which contains an extended predicted structured region essential for CENP-A chromatin assembly) directly binds KNL-2 (the C. elegans ortholog of M18BP1); this interaction partially substitutes for the function of HJURP/Scm3 in organisms lacking a dedicated CENP-A chaperone.\",\n      \"method\": \"In vitro binding assays, RNAi depletion, CENP-A N-tail deletion mutants, immunofluorescence in C. elegans and C. briggsae\",\n      \"journal\": \"Molecular biology of the cell\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — direct binding demonstrated with functional validation, single lab but conserved in two nematode species\",\n      \"pmids\": [\"33852350\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"M18BP1 (specifically the M18BP1.S subunit in Xenopus) binds to CENP-C in metaphase to competitively inhibit HJURP's access to centromeres, representing one of two mechanisms that restrict CENP-A assembly to G1; the other mechanism is CDK-dependent phosphorylation of HJURP that blocks its interaction with CENP-C.\",\n      \"method\": \"Xenopus egg extract cell-free system, phosphomutant analysis, competitive binding assays, immunodepletion\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — reconstituted mechanistic competition in cell-free system with phosphomutants and rescue experiments\",\n      \"pmids\": [\"37141119\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"In C. elegans oocytes during meiosis I, KNL-2 (M18BP1 ortholog) promotes outer kinetochore assembly through a non-canonical pathway independent of its CENP-A loading activity; KNL-2 recruits the nucleoporin MEL-28/ELYS to meiotic kinetochores through a specific N-terminal domain, and co-depletion of CENP-A/CENP-C with KNL-2 fully prevents outer kinetochore assembly.\",\n      \"method\": \"RNAi and auxin-inducible degron depletion, engineered domain mutants, immunofluorescence, C. elegans genetics\",\n      \"journal\": \"Current biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — genetic epistasis with domain mutants demonstrating a distinct non-canonical function; single lab study\",\n      \"pmids\": [\"39353426\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"In chicken DT40 cells, Knl2 (MIS18BP1) tethering can recruit CENP-A to non-centromeric loci independently of CENP-C, and tethering of CENP-C or CENP-I can induce CENP-A incorporation even in the absence of Knl2, showing that multiple independent pathways exist for CENP-A recruitment to artificial kinetochore sites.\",\n      \"method\": \"Artificial tethering assay, auxin-inducible degron knockout, Co-IP, immunofluorescence in DT40 cells\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — systematic tethering with conditional knockouts revealing pathway relationships; single lab study\",\n      \"pmids\": [\"38319136\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"M18BP1 directly binds the CAP-G2 subunit of condensin II; during interphase, the condensin II antagonist MCPH1 also binds CAP-G2 and outcompetes M18BP1; at mitotic onset, a switch from MCPH1 to M18BP1 binding activates condensin II and promotes chromosome condensation. This identifies M18BP1 as the elusive activator of condensin II at mitotic entry.\",\n      \"method\": \"Genetic and proteomic approaches, Co-IP, competitive binding assays, loss-of-function studies, cell biology\",\n      \"journal\": \"Molecular cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — direct binding demonstrated with competition assays and functional genetic validation; strong mechanistic model supported by multiple orthogonal approaches\",\n      \"pmids\": [\"40614722\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"In human cells, artificial M18BP1 dimerization bypasses the need for MIS18α/β, enabling identification of at least four determinants of M18BP1 centromere localization including the SANTA domain (first structure reported) and linear motifs in disordered regions that interact with the 16-subunit CCAN. Cell-cycle-dependent dimerization of M18BP1 on MIS18α/β promotes multivalent recognition of old CENP-A and associated proteins, followed by PLK1 and HJURP recruitment for new CENP-A deposition.\",\n      \"method\": \"Artificial dimerization strategy, cryo-EM/structural determination of SANTA domain, mutagenesis, Co-IP, immunofluorescence, cell biology in human cells\",\n      \"journal\": \"The EMBO journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — first SANTA domain structure with functional validation and multiple orthogonal mechanistic approaches in one study\",\n      \"pmids\": [\"41629527\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"In Xenopus, cell-cycle-dependent phosphorylation of M18BP1 disrupts its binding to CENP-A nucleosomes in metaphase; when this phosphorylation is relieved in interphase, M18BP1 binds CENP-A nucleosomes to promote new CENP-A nucleosome assembly. This phospho-regulatory switch provides a mechanism for restricting CENP-A assembly to interphase.\",\n      \"method\": \"Xenopus egg extract, phosphomutant analysis, nucleosome binding assays, immunofluorescence\",\n      \"journal\": \"EMBO reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — direct nucleosome binding assays with phosphomutants in cell-free system; peer-reviewed publication of prior preprint data\",\n      \"pmids\": [\"41680291\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"Phosphorylation of Xenopus M18BP1 by CDK disrupts its binding to CENP-A nucleosomes in metaphase, and relief of this phosphorylation in interphase enables M18BP1 binding to CENP-A nucleosomes to drive new CENP-A assembly (preprint version of the EMBO reports 2026 study).\",\n      \"method\": \"Xenopus egg extract, phosphomutant analysis, nucleosome binding assays\",\n      \"journal\": \"bioRxiv\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — direct binding assays with functional validation; subsequently peer-reviewed\",\n      \"pmids\": [\"40791504\"],\n      \"is_preprint\": true\n    }\n  ],\n  \"current_model\": \"MIS18BP1/M18BP1 is a core subunit of the trimeric Mis18 complex (with Mis18α and Mis18β) that localizes to centromeres in a cell-cycle-regulated manner to prime centromeres for CENP-A nucleosome assembly by recruiting the CENP-A chaperone HJURP; its centromere recruitment is governed by CDK-regulated phosphorylation that controls its dimerization on a Mis18α:Mis18β hexameric scaffold, its direct binding to CENP-A nucleosomes (via a motif conserved in non-mammalian vertebrates), and its interaction with CENP-C (via the SANTA domain), while in metaphase M18BP1 competitively inhibits HJURP access to centromeres; additionally, M18BP1 activates condensin II at mitotic onset by binding CAP-G2 and displacing the antagonist MCPH1, revealing a dual role in both centromere identity maintenance and chromosome condensation.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"MIS18BP1 is a cell-cycle-regulated scaffold that coordinates centromeric CENP-A histone variant deposition and mitotic chromosome condensation. It forms a dimeric subunit of the Mis18 complex by binding its N-terminal 140 residues to a Mis18α:Mis18β hexamer, with CDK1 phosphorylation of these residues restricting complex assembly to G1; in G1, MIS18BP1 dimerization on the Mis18α/β scaffold enables recognition of existing CENP-A/CCAN through its SANTA domain and flanking linear motifs, followed by recruitment of PLK1 and HJURP for new CENP-A nucleosome deposition [PMID:28059702, PMID:41629527]. During metaphase, CDK-phosphorylated MIS18BP1 binds CENP-C via its SANTA domain to competitively block HJURP access, constituting a safeguard against premature CENP-A assembly; dephosphorylation in interphase switches MIS18BP1 to bind CENP-A nucleosomes directly, licensing new deposition [PMID:30606714, PMID:37141119, PMID:41680291]. Separately from its centromere function, MIS18BP1 directly binds condensin II subunit CAP-G2 at mitotic onset, displacing the antagonist MCPH1 to activate condensin II and promote chromosome condensation [PMID:40614722].\",\n  \"teleology\": [\n    {\n      \"year\": 2011,\n      \"claim\": \"Establishing that CENP-C is the centromere receptor for MIS18BP1 resolved how the Mis18 complex is targeted to centromeres and linked this targeting to CENP-A chromatin assembly.\",\n      \"evidence\": \"Co-immunoprecipitation, direct binding assay, and siRNA depletion with centromere localization readout in human cells, independently confirmed by domain mapping in mouse ES cells\",\n      \"pmids\": [\"21911481\", \"22540025\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Structural basis of the CENP-C–MIS18BP1 interface not resolved\",\n        \"Cell-cycle regulation of this interaction not yet addressed\"\n      ]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Reconstitution of the Mis18 complex revealed that MIS18BP1 binds as a dimer to a Mis18α:Mis18β hexamer via its N-terminus, and that CDK1 phosphorylation of MIS18BP1 restricts complex formation to G1, explaining the cell-cycle window for CENP-A loading.\",\n      \"evidence\": \"Biochemical reconstitution, in vitro CDK1 phosphorylation assay, site-directed mutagenesis, and cell-cycle-staged localization in human cells\",\n      \"pmids\": [\"28059702\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"How MIS18BP1 dimerization enables downstream HJURP recruitment was not established\",\n        \"Whether CDK phosphorylation is the sole mechanism restricting Mis18 complex assembly\"\n      ]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Discovery that Xenopus MIS18BP1 directly binds CENP-A nucleosomes via a conserved motif identified a second, CENP-C-independent centromere recognition mechanism used in interphase, with CENP-C and MIS18BP1 competing for CENP-A nucleosome binding.\",\n      \"evidence\": \"Xenopus egg extract system, in vitro nucleosome binding and competition assay, domain mapping\",\n      \"pmids\": [\"28743005\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Whether mammalian MIS18BP1 uses the same direct nucleosome-binding mechanism (the motif is absent in mammals)\",\n        \"How CENP-C vs MIS18BP1 competition is resolved at the transition from metaphase to interphase\"\n      ]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Demonstrating that CDK phosphorylation of the SANTA domain region promotes MIS18BP1–CENP-C binding in metaphase established that the same kinase provides opposing cell-cycle signals: promoting metaphase centromere localization via CENP-C while blocking Mis18 complex assembly.\",\n      \"evidence\": \"Xenopus egg extract, phosphomutant analysis, domain mutagenesis, CENP-A assembly readout\",\n      \"pmids\": [\"30606714\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Identity of the phosphatase(s) that reverse CDK phosphorylation in interphase\",\n        \"Structural basis of phospho-dependent SANTA–CENP-C recognition\"\n      ]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Work in C. elegans revealed that the MIS18BP1 ortholog KNL-2 directly binds the CENP-A N-terminal tail and that CDK-1 phosphorylation of KNL-2 separately regulates condensin II recruitment, genetically separating CENP-A loading from chromosome condensation functions.\",\n      \"evidence\": \"Direct binding assays, phosphomutant analysis, RNAi depletion with kinetochore assembly and condensin II localization readouts in C. elegans\",\n      \"pmids\": [\"33852350\", \"34734636\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Conservation of the CENP-A N-tail binding mode in vertebrates not confirmed\",\n        \"Whether KNL-2-dependent condensin II regulation proceeds through a CAP-G2 ortholog as in mammals\"\n      ]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Identification of MIS18BP1 as a competitive inhibitor of HJURP access to CENP-C in metaphase established that MIS18BP1 has a dual role — blocking premature CENP-A deposition in metaphase and promoting it in G1 — constituting a bistable switch with HJURP phosphorylation.\",\n      \"evidence\": \"Xenopus cell-free centromere assembly, phosphomutant HJURP, competitive binding assay, epistasis with CENP-A assembly readout\",\n      \"pmids\": [\"37141119\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Whether the competitive inhibition operates identically in mammalian cells\",\n        \"How the metaphase-to-G1 handoff from inhibition to promotion is coordinated at molecular resolution\"\n      ]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Tethering experiments in chicken DT40 cells showed that CENP-C can recruit CENP-A via HJURP independently of MIS18BP1, indicating that MIS18BP1 is not absolutely required for CENP-A loading when CENP-C is artificially concentrated, qualifying MIS18BP1 as a facilitator rather than an obligate factor.\",\n      \"evidence\": \"Tethering assay with auxin-inducible degron knockout of Knl2 in DT40 cells, co-immunoprecipitation\",\n      \"pmids\": [\"38319136\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Artificial tethering may not reflect physiological centromere conditions\",\n        \"Whether MIS18BP1-independent CENP-A loading occurs at endogenous centromeres in any natural context\"\n      ]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Discovery that MIS18BP1 directly binds condensin II subunit CAP-G2, outcompeting the antagonist MCPH1 at mitotic onset, established a centromere-independent function for MIS18BP1 in activating chromosome condensation.\",\n      \"evidence\": \"Genetic and proteomic screens, direct binding assay (MIS18BP1–CAP-G2), competition assay (MCPH1 vs MIS18BP1), chromosome condensation phenotype\",\n      \"pmids\": [\"40614722\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"What triggers the switch from MCPH1 to MIS18BP1 binding on CAP-G2 at mitotic onset\",\n        \"Whether MIS18BP1's condensin II activation is coordinated with its centromere functions or operates independently\"\n      ]\n    },\n    {\n      \"year\": 2026,\n      \"claim\": \"Structural characterization of the SANTA domain and mapping of multiple CCAN-interaction determinants in human MIS18BP1 defined how dimerization on the Mis18α/β scaffold enables multivalent centromere recognition and subsequent PLK1/HJURP recruitment for CENP-A deposition.\",\n      \"evidence\": \"Crystal structure of SANTA domain, artificial dimerization bypass, CCAN interaction footprint mapping, PLK1 and HJURP recruitment assay in human cells\",\n      \"pmids\": [\"41629527\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Full atomic structure of the complete Mis18 complex with MIS18BP1 dimer is not yet available\",\n        \"How PLK1 phosphorylation of MIS18BP1 is integrated with the dimerization-dependent recognition mechanism\"\n      ]\n    },\n    {\n      \"year\": 2026,\n      \"claim\": \"Demonstrating that phosphorylation of MIS18BP1 directly controls its binding to CENP-A nucleosomes in Xenopus completed the phospho-switch model: CDK phosphorylation blocks nucleosome binding in metaphase, and dephosphorylation restores it in interphase to license assembly.\",\n      \"evidence\": \"Xenopus egg extract, phosphomutant MIS18BP1, in vitro nucleosome binding assay, CENP-A assembly readout\",\n      \"pmids\": [\"41680291\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Whether an analogous phospho-regulated nucleosome-binding mechanism exists in mammalian MIS18BP1, which lacks the Xenopus-specific motif\",\n        \"Identity of the interphase phosphatase that dephosphorylates MIS18BP1 to enable nucleosome binding\"\n      ]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"A unified structural model of how MIS18BP1 simultaneously coordinates CENP-A deposition and condensin II activation across the cell cycle — and whether these functions are mechanistically coupled — remains to be established.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"No full-length structure of MIS18BP1 or complete Mis18 complex\",\n        \"Mechanistic coupling or independence of CENP-A loading and condensin II activation functions\",\n        \"Whether the Xenopus direct CENP-A nucleosome binding has a functional equivalent in mammals\"\n      ]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [0, 2, 5, 6, 7]},\n      {\"term_id\": \"GO:0042393\", \"supporting_discovery_ids\": [3, 8]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [5, 6]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005694\", \"supporting_discovery_ids\": [0, 1, 3, 4, 7]},\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [4, 7]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-1640170\", \"supporting_discovery_ids\": [2, 4, 5, 7, 8]},\n      {\"term_id\": \"R-HSA-4839726\", \"supporting_discovery_ids\": [3, 6, 8]}\n    ],\n    \"complexes\": [\n      \"Mis18 complex\"\n    ],\n    \"partners\": [\n      \"CENP-C\",\n      \"MIS18A\",\n      \"MIS18B\",\n      \"HJURP\",\n      \"CAPG2\",\n      \"CENP-A\",\n      \"MCPH1\",\n      \"PLK1\"\n    ],\n    \"other_free_text\": []\n  }\n}\n```\n\n--- ROUND 2 (R2/R3, augmented corpus) ---\n\n```json\n{\n  \"mechanistic_narrative\": \"MIS18BP1 is a central regulator of centromere identity that couples cell-cycle signaling to CENP-A nucleosome assembly and, independently, activates condensin II for mitotic chromosome condensation. It functions as a core subunit of the trimeric Mis18 complex (with Mis18α and Mis18β), where CDK1 phosphorylation of its N-terminal region restricts complex formation and centromere recruitment to G1 phase; upon dephosphorylation, M18BP1 dimerizes on a Mis18α:Mis18β hexameric scaffold and engages centromeric chromatin through multivalent contacts including direct binding to CENP-A nucleosomes (via a CENP-C-like motif in non-mammalian vertebrates), interaction with CENP-C through its SANTA domain, and recognition of the CCAN, thereby recruiting the CENP-A chaperone HJURP for new CENP-A deposition [PMID:17199038, PMID:28059702, PMID:28743005, PMID:41629527]. During metaphase, M18BP1 competitively inhibits HJURP access to centromeres via CENP-C binding, constituting one of two mechanisms that restrict CENP-A loading to the appropriate cell-cycle window [PMID:37141119]. At mitotic entry, M18BP1 directly binds the condensin II subunit CAP-G2, displacing the antagonist MCPH1 and activating condensin II to promote chromosome condensation, revealing a dual role in centromere maintenance and higher-order chromosome organization [PMID:40614722].\",\n  \"teleology\": [\n    {\n      \"year\": 2007,\n      \"claim\": \"Identification of M18BP1 as a component of a three-subunit Mis18 complex that localizes to centromeres in telophase–G1 and is essential for new CENP-A loading established the gene's foundational role in centromere propagation.\",\n      \"evidence\": \"RNAi knockdown in C. elegans and human cells with live-cell imaging and immunofluorescence, replicated across two independent labs\",\n      \"pmids\": [\"17199038\", \"17339379\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Mechanism by which M18BP1 is recruited to centromeres was unknown\",\n        \"How M18BP1 promotes CENP-A loading was not determined\",\n        \"Cell-cycle restriction mechanism was unresolved\"\n      ]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Discovery that CENP-C directly recruits M18BP1 to centromeres provided the first molecular link between existing CENP-A chromatin and the CENP-A assembly machinery, with the SANT/SANTA domain mediating this interaction.\",\n      \"evidence\": \"Co-IP, pulldown, RNAi depletion, immunofluorescence, and domain mapping in human cells and mouse ES cells\",\n      \"pmids\": [\"21911481\", \"22540025\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Whether M18BP1 directly recognizes CENP-A nucleosomes in addition to CENP-C was unknown\",\n        \"Structural basis of the SANTA domain–CENP-C interaction was not resolved\"\n      ]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Reconstitution of the Mis18α:Mis18β heterotetramer and demonstration that this scaffold is required for M18BP1 binding and HJURP recruitment defined the biochemical architecture through which M18BP1 operates, while the discovery that KAT7 interacts with M18BP1 linked the complex to chromatin acetylation.\",\n      \"evidence\": \"Biochemical reconstitution, domain mutagenesis, co-IP, and KAT7 knockout in HeLa cells\",\n      \"pmids\": [\"26942680\", \"27270040\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Stoichiometry and geometry of M18BP1 on the Mis18 scaffold were not yet resolved\",\n        \"How KAT7 acetylation facilitates CENP-A deposition mechanistically was unclear\"\n      ]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Determination that CDK1 phosphorylation of two conserved N-terminal sites on M18BP1 blocks its binding to the Mis18α:Mis18β 4:2 hexamer, restricting Mis18 complex assembly and centromere recruitment to G1, resolved the long-standing question of how CENP-A loading is cell-cycle-gated; separately, M18BP1 was shown to directly bind CENP-A nucleosomes in Xenopus through a CENP-C-like motif.\",\n      \"evidence\": \"Biochemical reconstitution with SEC and mass spectrometry in human cells; nucleosome pulldowns and competition binding assays in Xenopus egg extracts\",\n      \"pmids\": [\"28059702\", \"28743005\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Mammalian M18BP1 lacks the CENP-C-like motif, leaving the mammalian CENP-A nucleosome recognition mechanism unresolved\",\n        \"Phosphorylation of M18BP1's CENP-A-nucleosome-binding region was not yet characterized\"\n      ]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Demonstration that CDK phosphorylation of Xenopus M18BP1 is required for its SANTA-domain-mediated CENP-C binding in metaphase, and that this metaphase priming is necessary for subsequent interphase CENP-A assembly, revealed a two-step phospho-regulatory model linking metaphase centromere licensing to G1 CENP-A deposition.\",\n      \"evidence\": \"Phosphomutant analysis, co-IP, and functional rescue in Xenopus egg extracts\",\n      \"pmids\": [\"30606714\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Exact phospho-sites governing the CENP-A nucleosome binding switch were not yet mapped\",\n        \"Whether an analogous priming step exists in mammalian cells was unclear\"\n      ]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"In C. elegans, which lacks HJURP, direct binding of KNL-2 (M18BP1 ortholog) to the CENP-A N-terminal tail partially substitutes for a dedicated CENP-A chaperone, broadening the functional repertoire of M18BP1 across evolution.\",\n      \"evidence\": \"In vitro binding assays, RNAi, and CENP-A N-tail deletion mutants in C. elegans and C. briggsae\",\n      \"pmids\": [\"33852350\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Whether this chaperone-like activity exists in vertebrate M18BP1 is unknown\",\n        \"Structural basis of KNL-2–CENP-A tail interaction not determined\"\n      ]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Reconstitution of competitive binding showed that M18BP1 occupies CENP-C at metaphase centromeres to block HJURP access, establishing M18BP1 as an active inhibitor of premature CENP-A loading rather than merely a passive licensing factor.\",\n      \"evidence\": \"Competitive binding assays, immunodepletion, and phosphomutant analysis in Xenopus egg extracts\",\n      \"pmids\": [\"37141119\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Quantitative parameters of the competition (affinities, stoichiometry) not measured\",\n        \"Whether this inhibitory role is conserved in mammals was not tested\"\n      ]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Discovery that KNL-2 promotes outer kinetochore assembly in C. elegans meiosis I independently of CENP-A loading, by recruiting MEL-28/ELYS through its N-terminal domain, revealed a non-canonical function of the M18BP1 family beyond centromere maintenance; additionally, tethering experiments in chicken DT40 cells showed that M18BP1 can recruit CENP-A to ectopic sites independently of CENP-C.\",\n      \"evidence\": \"RNAi and auxin-inducible degron depletions with domain mutants in C. elegans; artificial tethering and conditional knockouts in DT40 cells\",\n      \"pmids\": [\"39353426\", \"38319136\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Whether the meiotic kinetochore assembly role exists in vertebrates is unknown\",\n        \"Mechanism by which tethered M18BP1 loads CENP-A without CENP-C is not defined\"\n      ]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Identification of M18BP1 as the direct binding partner and activator of condensin II (via CAP-G2), which displaces the interphase antagonist MCPH1 at mitotic entry, revealed a second major function of M18BP1 in chromosome condensation independent of its CENP-A loading role.\",\n      \"evidence\": \"Co-IP, competitive binding assays, loss-of-function studies, and proteomic approaches in human cells\",\n      \"pmids\": [\"40614722\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"How cell-cycle signals trigger the MCPH1-to-M18BP1 switch on CAP-G2 is not resolved\",\n        \"Whether condensin II activation and CENP-A loading are coordinated through shared M18BP1 pools is unknown\"\n      ]\n    },\n    {\n      \"year\": 2026,\n      \"claim\": \"First structural determination of the SANTA domain and identification of at least four centromere-localization determinants in M18BP1 — including SANTA, linear CCAN-binding motifs, and dimerization-dependent multivalent recognition of old CENP-A — provided an integrated structural framework for how M18BP1 bridges the Mis18 scaffold to centromeric chromatin; phospho-regulation of M18BP1–CENP-A nucleosome binding was also resolved in Xenopus.\",\n      \"evidence\": \"Cryo-EM/structural analysis, artificial dimerization, mutagenesis in human cells; phosphomutant nucleosome binding assays in Xenopus egg extracts\",\n      \"pmids\": [\"41629527\", \"41680291\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Full atomic-resolution structure of M18BP1 in complex with the Mis18 hexamer is lacking\",\n        \"How PLK1 recruitment by dimerized M18BP1 triggers HJURP loading is not structurally resolved\"\n      ]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"Outstanding questions include how mammalian M18BP1 recognizes CENP-A nucleosomes in the absence of the CENP-C-like motif found in non-mammalian vertebrates, how M18BP1's dual roles in CENP-A loading and condensin II activation are temporally and spatially coordinated within a single cell cycle, and whether the meiotic kinetochore assembly function of the M18BP1 family is conserved beyond nematodes.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\n        \"Mammalian CENP-A nucleosome recognition mechanism for M18BP1 is unresolved\",\n        \"Coordination between CENP-A loading and condensin II activation by shared M18BP1 is unexplored\",\n        \"Conservation of meiotic kinetochore assembly function outside C. elegans is untested\"\n      ]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0042393\", \"supporting_discovery_ids\": [6, 9, 15]},\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [0, 1, 3, 5, 13]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [10, 13]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005694\", \"supporting_discovery_ids\": [0, 1, 2, 5, 6, 8, 14]},\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [0, 8, 14]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-1640170\", \"supporting_discovery_ids\": [0, 5, 10, 13, 14]},\n      {\"term_id\": \"R-HSA-4839726\", \"supporting_discovery_ids\": [0, 4, 6, 14, 15]}\n    ],\n    \"complexes\": [\n      \"Mis18 complex (Mis18α:Mis18β:MIS18BP1)\",\n      \"Condensin II (via CAP-G2 binding)\"\n    ],\n    \"partners\": [\n      \"MIS18A\",\n      \"MIS18B\",\n      \"CENPC\",\n      \"HJURP\",\n      \"KAT7\",\n      \"CAPG2\",\n      \"MCPH1\",\n      \"ELYS\"\n    ],\n    \"other_free_text\": []\n  }\n}\n```"}