{"gene":"ANAPC15","run_date":"2026-04-28T17:12:37","timeline":{"discoveries":[{"year":2011,"finding":"APC15 is required for the turnover of APC/C co-activator CDC20 and release of mitotic checkpoint complexes (MCCs) from the APC/C during spindle assembly checkpoint (SAC) signalling. In the absence of APC15, ubiquitylated CDC20 and MCCs remain 'locked' onto the APC/C, preventing ubiquitylation and degradation of cyclin B1 upon SAC satisfaction.","method":"siRNA knockdown of APC15 in human cells, live-cell imaging, immunoprecipitation, ubiquitylation assays","journal":"Nature cell biology","confidence":"High","confidence_rationale":"Tier 2 — clean KD with defined cellular and molecular phenotype, replicated by independent labs","pmids":["21926987"],"is_preprint":false},{"year":2012,"finding":"APC15 is located near the APC/C's MCC binding site and is required for APC/C(MCC)-dependent CDC20 autoubiquitylation and degradation, thereby driving MCC disassembly. APC15 is dispensable for substrate ubiquitylation by APC/C(CDC20) and APC/C(CDH1). The study characterized APC15 as related to yeast Mnd2 and proposed that APC15 negatively regulates APC/C coactivators.","method":"Recombinant human APC/C reconstitution, in vitro ubiquitylation assays, RNAi knockdown, mass spectrometry, structural localization by cryo-EM","journal":"Nature structural & molecular biology","confidence":"High","confidence_rationale":"Tier 1 — reconstituted in vitro with purified components, multiple orthogonal methods, independent replication","pmids":["23007861"],"is_preprint":false},{"year":2012,"finding":"In budding yeast, the Mnd2/Apc15 subunit of the APC/C is required for SAC-dependent Cdc20 autoubiquitination. Reconstitution with purified components showed that Mad3-Bub3 and Mad2 together lock Cdc20 on the APC/C and stimulate Cdc20 autoubiquitination while inhibiting substrate ubiquitination, and this autoubiquitination requires Mnd2/Apc15. Loss of Mnd2 allows SAC arrest establishment but delays release, establishing that Cdc20 ubiquitination is needed for SAC inactivation.","method":"In vitro reconstitution with purified budding yeast APC/C components, in vivo genetic deletion (mnd2Δ), ubiquitylation assays","journal":"Molecular cell","confidence":"High","confidence_rationale":"Tier 1 — reconstituted in vitro with purified components plus genetic validation in vivo","pmids":["22940250"],"is_preprint":false},{"year":2016,"finding":"APC15 is a component of the APC/C platform subcomplex (with Apc1, Apc4, Apc5). Deletion of the Apc1 WD40 domain in a mutant APC/C abolishes UbcH10-dependent ubiquitination and locks the APC/C in an inactive conformation; under these conditions, EM density for Apc15 is not visible, indicating that Apc15 positioning within the APC/C depends on Apc1(WD40)-mediated conformational changes.","method":"Crystal structure of Apc1 N-terminal domain at 2.2 Å, cryo-EM of APC/C-Cdh1 complex with Apc1(WD40) deletion, in vitro ubiquitination assays","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 1 — crystal structure + cryo-EM + in vitro biochemical assays with deletion mutant","pmids":["27601667"],"is_preprint":false},{"year":2017,"finding":"In fission yeast, deletion of Apc15 reduces MCC association with the APC/C, impairs poly-ubiquitination of Cdc20, and renders cells checkpoint defective. In vitro and in vivo evidence shows that APC/C can contain two molecules of Cdc20 and that complexes containing both Cdc20 molecules accumulate in apc15Δ cells, suggesting Apc15 promotes Cdc20 ubiquitination within MCC-APC/C.","method":"Genetic deletion (apc15Δ) in fission yeast, co-immunoprecipitation, in vitro reconstitution ubiquitination assays, dual-epitope-tag Cdc20 co-IP","journal":"Current biology : CB","confidence":"High","confidence_rationale":"Tier 2 — genetic KO with defined molecular phenotype, multiple orthogonal methods, in vitro reconstitution","pmids":["28366744"],"is_preprint":false},{"year":2017,"finding":"In fission yeast, deletion of Apc15 mimics mutations in the Mad3 ABBA-KEN2-ABBA motif with respect to MCC binding to the APC/C and MCC disassembly, revealing a shared function of Apc15 and the Mad3 C-terminus in mediating MCC-APC/C binding and disassembly.","method":"Genetic epistasis in fission yeast (apc15Δ combined with mad3 motif mutations), live-cell assays, co-immunoprecipitation","journal":"Current biology : CB","confidence":"Medium","confidence_rationale":"Tier 2 — genetic epistasis with defined phenotype, single lab","pmids":["28366743"],"is_preprint":false},{"year":2018,"finding":"APC15-dependent Cdc20 ubiquitination/degradation and TRIP13-catalyzed removal of Mad2 act as two parallel, redundant pathways for MCC disassembly and mitotic exit. Combining TRIP13 depletion with elimination of APC15-dependent Cdc20 ubiquitination/degradation results in a complete inability to exit mitosis, even when MCC assembly at unattached kinetochores is prevented, demonstrating that APC15-driven Cdc20 ubiquitination is essential for disassembly of interphase-produced MCC.","method":"Degron-tagging rapid depletion of TRIP13, CRISPR knockout of APC15, live-cell mitotic exit assays, epistasis analysis","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 2 — genetic epistasis with degron and CRISPR, clean phenotypic readout, multiple orthogonal approaches","pmids":["30341343"],"is_preprint":false},{"year":2016,"finding":"In HCT116 cells lacking UBE2C, depletion of APC15 causes a strong synergistic inhibition of mitotic progression by stabilizing the MCC on the APC/C, indicating that APC15-mediated MCC removal and UBE2C-driven ubiquitination cooperate to silence the SAC.","method":"CRISPR/Cas9 UBE2C knockout, siRNA depletion of APC15, live-cell mitotic timing assays","journal":"Biology open","confidence":"Medium","confidence_rationale":"Tier 2 — genetic combination experiment with live-cell readout, single lab","pmids":["27591192"],"is_preprint":false},{"year":2025,"finding":"APC15 shows dynamic subcellular localization during mouse oocyte meiotic progression. siRNA-mediated knockdown of APC15 causes meiotic arrest at metaphase I and impairs removal of BUB3 from kinetochores, indicating that APC15 is required for SAC inactivation and the metaphase-to-anaphase transition in meiosis.","method":"Immunofluorescence/confocal microscopy for localization, siRNA knockdown, kinetochore BUB3 staining as SAC readout","journal":"Journal of molecular histology","confidence":"Medium","confidence_rationale":"Tier 2–3 — direct localization experiment with functional KD phenotype, single lab","pmids":["40153087"],"is_preprint":false}],"current_model":"ANAPC15 (APC15) is an integral subunit of the APC/C platform that localizes near the MCC binding site and is specifically required for APC/C(MCC)-dependent CDC20 autoubiquitylation and degradation, thereby driving MCC disassembly and enabling rapid APC/C activation upon spindle assembly checkpoint satisfaction, while being dispensable for APC/C-mediated substrate ubiquitylation by CDC20 or CDH1 coactivators."},"narrative":{"teleology":[{"year":2011,"claim":"The first demonstration that APC15 is required for CDC20 turnover and MCC release from the APC/C resolved how the SAC-inhibited APC/C is reactivated upon checkpoint satisfaction.","evidence":"siRNA knockdown in human cells with live-cell imaging, immunoprecipitation, and ubiquitylation assays","pmids":["21926987"],"confidence":"High","gaps":["Mechanism by which APC15 promotes CDC20 ubiquitylation was unknown","Structural position of APC15 on the APC/C was not resolved","Whether APC15 is required for APC/C activity toward other substrates was untested"]},{"year":2012,"claim":"Reconstitution with purified components in both human and budding yeast systems established that APC15/Mnd2 specifically enables MCC-dependent CDC20 autoubiquitylation while being dispensable for substrate ubiquitylation by APC/C–CDC20 or APC/C–CDH1, defining APC15 as a selective regulator of coactivator fate rather than a general APC/C activity factor.","evidence":"Recombinant human APC/C reconstitution, purified budding yeast APC/C in vitro ubiquitylation, cryo-EM structural localization, genetic deletion in yeast","pmids":["23007861","22940250"],"confidence":"High","gaps":["Atomic-resolution contacts between APC15 and MCC components were not defined","How APC15 discriminates MCC-bound CDC20 from free CDC20 was unclear"]},{"year":2016,"claim":"Structural and genetic studies revealed that APC15 is part of the APC/C platform subcomplex and that its stable positioning depends on the Apc1 WD40 domain, linking APC/C conformational dynamics to APC15-mediated MCC disassembly; separately, APC15 and UBE2C were shown to cooperate functionally in SAC silencing.","evidence":"Apc1 crystal structure at 2.2 Å, cryo-EM of APC/C–Cdh1 with Apc1(WD40) deletion, CRISPR UBE2C KO combined with APC15 siRNA and live-cell mitotic timing","pmids":["27601667","27591192"],"confidence":"High","gaps":["Whether APC15 conformational coupling is direct or mediated through other subunits was unresolved","Relative contributions of APC15 vs. UBE2C to SAC silencing kinetics were not quantified"]},{"year":2017,"claim":"Fission yeast studies demonstrated that APC15 and the Mad3 C-terminal ABBA-KEN2-ABBA motif share a function in mediating MCC–APC/C binding and disassembly, and that APC/C can simultaneously accommodate two Cdc20 molecules whose ubiquitylation depends on APC15, clarifying the stoichiometry and epistatic logic of checkpoint disassembly.","evidence":"Genetic deletion and epistasis in fission yeast, dual-epitope-tag co-IP, in vitro reconstitution","pmids":["28366744","28366743"],"confidence":"High","gaps":["Whether the dual-Cdc20 model applies to human APC/C was untested","Structural basis for APC15–Mad3 functional overlap was not resolved"]},{"year":2018,"claim":"Establishing that APC15-dependent CDC20 degradation and TRIP13-catalyzed Mad2 removal constitute two parallel, redundant MCC disassembly pathways explained why loss of either alone permits mitotic exit, and demonstrated that interphase-produced MCC also requires active disassembly.","evidence":"Degron-tagging rapid depletion of TRIP13 combined with CRISPR APC15 knockout, live-cell mitotic exit assays","pmids":["30341343"],"confidence":"High","gaps":["Relative pathway usage under physiological conditions and across cell types was not determined","Whether additional disassembly pathways exist beyond APC15 and TRIP13 was unresolved"]},{"year":2025,"claim":"Extension of APC15 function to meiosis showed that APC15 dynamically localizes during mouse oocyte meiotic progression and is required for SAC inactivation at the metaphase I–anaphase I transition.","evidence":"Immunofluorescence/confocal microscopy and siRNA knockdown in mouse oocytes with kinetochore BUB3 readout","pmids":["40153087"],"confidence":"Medium","gaps":["Single-lab observation not yet independently replicated","Molecular mechanism of APC15 in meiotic versus mitotic MCC disassembly not compared","Whether APC15 has meiosis II roles was not addressed"]},{"year":null,"claim":"The atomic-resolution mechanism by which APC15 selectively promotes CDC20 autoubiquitylation within the MCC-bound APC/C — including direct contact surfaces, conformational gating, and potential allosteric communication with the E2 binding site — remains structurally undefined.","evidence":"","pmids":[],"confidence":"High","gaps":["No high-resolution structure of APC15 in the context of the MCC–APC/C complex with substrate-level detail","Potential post-translational regulation of APC15 activity is unexplored","Whether APC15 has functions outside the SAC/MCC disassembly axis is unknown"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[0,1,2,6]}],"localization":[{"term_id":"GO:0005829","term_label":"cytosol","supporting_discovery_ids":[0,1]}],"pathway":[{"term_id":"R-HSA-1640170","term_label":"Cell Cycle","supporting_discovery_ids":[0,1,2,6,7]},{"term_id":"R-HSA-392499","term_label":"Metabolism of proteins","supporting_discovery_ids":[1,2,4]}],"complexes":["APC/C"],"partners":["CDC20","APC1","CDH1","TRIP13","UBE2C","MAD2L1","BUB3"],"other_free_text":[]},"mechanistic_narrative":"ANAPC15 (APC15/Mnd2) is an integral subunit of the anaphase-promoting complex/cyclosome (APC/C) that is specifically required for spindle assembly checkpoint (SAC) silencing by promoting the ubiquitylation and degradation of the APC/C coactivator CDC20 within the mitotic checkpoint complex (MCC), thereby driving MCC disassembly and enabling timely mitotic exit. APC15 resides on the APC/C platform near the MCC binding site and its positioning depends on Apc1 WD40 domain-mediated conformational changes; it is dispensable for APC/C-mediated substrate ubiquitylation by CDC20 or CDH1 coactivators [PMID:23007861, PMID:27601667]. APC15-dependent CDC20 ubiquitylation operates in parallel with the TRIP13-catalyzed pathway for MCC disassembly, and elimination of both pathways renders cells unable to exit mitosis even when checkpoint signaling is abrogated [PMID:30341343]. This function is conserved from yeast to mammals, including a role in meiotic SAC inactivation during oocyte maturation [PMID:22940250, PMID:28366744, PMID:40153087]."},"prefetch_data":{"uniprot":{"accession":"P60006","full_name":"Anaphase-promoting complex subunit 15","aliases":[],"length_aa":121,"mass_kda":14.3,"function":"Component of the anaphase promoting complex/cyclosome (APC/C), a cell cycle-regulated E3 ubiquitin ligase that controls progression through mitosis and the G1 phase of the cell cycle (PubMed:21926987). The APC/C complex catalyzes assembly of branched 'Lys-11'-/'Lys-48'-linked branched ubiquitin chains on target proteins (PubMed:29033132). In the complex, plays a role in the release of the mitotic checkpoint complex (MCC) from the APC/C: not required for APC/C activity itself, but promotes the turnover of CDC20 and MCC on the APC/C, thereby participating in the responsiveness of the spindle assembly checkpoint (PubMed:21926987). Also required for degradation of CDC20 (PubMed:21926987)","subcellular_location":"","url":"https://www.uniprot.org/uniprotkb/P60006/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":true,"resolved_as":"","url":"https://depmap.org/portal/gene/ANAPC15","classification":"Common Essential","n_dependent_lines":697,"n_total_lines":1208,"dependency_fraction":0.5769867549668874},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/ANAPC15","total_profiled":1310},"omim":[{"mim_id":"614717","title":"ANAPHASE-PROMOTING COMPLEX, SUBUNIT 15; ANAPC15","url":"https://www.omim.org/entry/614717"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Nucleoplasm","reliability":"Approved"},{"location":"Vesicles","reliability":"Additional"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/ANAPC15"},"hgnc":{"alias_symbol":["HSPC020","DKFZP564M082","APC15"],"prev_symbol":["C11orf51"]},"alphafold":{"accession":"P60006","domains":[],"viewer_url":"https://alphafold.ebi.ac.uk/entry/P60006","model_url":"https://alphafold.ebi.ac.uk/files/AF-P60006-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-P60006-F1-predicted_aligned_error_v6.png","plddt_mean":70.94},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=ANAPC15","jax_strain_url":"https://www.jax.org/strain/search?query=ANAPC15"},"sequence":{"accession":"P60006","fasta_url":"https://rest.uniprot.org/uniprotkb/P60006.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/P60006/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/P60006"}},"corpus_meta":[{"pmid":"21926987","id":"PMC_21926987","title":"APC15 drives the turnover of MCC-CDC20 to make the spindle assembly checkpoint responsive to kinetochore attachment.","date":"2011","source":"Nature cell biology","url":"https://pubmed.ncbi.nlm.nih.gov/21926987","citation_count":134,"is_preprint":false},{"pmid":"23007861","id":"PMC_23007861","title":"APC15 mediates CDC20 autoubiquitylation by APC/C(MCC) and disassembly of the mitotic checkpoint complex.","date":"2012","source":"Nature structural & molecular biology","url":"https://pubmed.ncbi.nlm.nih.gov/23007861","citation_count":119,"is_preprint":false},{"pmid":"22940250","id":"PMC_22940250","title":"The APC/C subunit Mnd2/Apc15 promotes Cdc20 autoubiquitination and spindle assembly checkpoint inactivation.","date":"2012","source":"Molecular cell","url":"https://pubmed.ncbi.nlm.nih.gov/22940250","citation_count":105,"is_preprint":false},{"pmid":"12420173","id":"PMC_12420173","title":"Genes involved in the anaerobic degradation of ethylbenzene in a denitrifying bacterium, strain EbN1.","date":"2002","source":"Archives of microbiology","url":"https://pubmed.ncbi.nlm.nih.gov/12420173","citation_count":88,"is_preprint":false},{"pmid":"30341343","id":"PMC_30341343","title":"TRIP13 and APC15 drive mitotic exit by turnover of interphase- and unattached kinetochore-produced MCC.","date":"2018","source":"Nature communications","url":"https://pubmed.ncbi.nlm.nih.gov/30341343","citation_count":45,"is_preprint":false},{"pmid":"19377877","id":"PMC_19377877","title":"Variation in genes required for normal mitosis and risk of breast cancer.","date":"2009","source":"Breast cancer research and treatment","url":"https://pubmed.ncbi.nlm.nih.gov/19377877","citation_count":30,"is_preprint":false},{"pmid":"28366743","id":"PMC_28366743","title":"Different Functionality of Cdc20 Binding Sites within the Mitotic Checkpoint Complex.","date":"2017","source":"Current biology : CB","url":"https://pubmed.ncbi.nlm.nih.gov/28366743","citation_count":22,"is_preprint":false},{"pmid":"27601667","id":"PMC_27601667","title":"WD40 domain of Apc1 is critical for the coactivator-induced allosteric transition that stimulates APC/C catalytic activity.","date":"2016","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/27601667","citation_count":17,"is_preprint":false},{"pmid":"36749097","id":"PMC_36749097","title":"Autoantibody screening of plasma and peritoneal fluid of patients with endometriosis.","date":"2023","source":"Human reproduction (Oxford, England)","url":"https://pubmed.ncbi.nlm.nih.gov/36749097","citation_count":15,"is_preprint":false},{"pmid":"28366744","id":"PMC_28366744","title":"Fission Yeast Apc15 Stabilizes MCC-Cdc20-APC/C Complexes, Ensuring Efficient Cdc20 Ubiquitination and Checkpoint Arrest.","date":"2017","source":"Current biology : CB","url":"https://pubmed.ncbi.nlm.nih.gov/28366744","citation_count":14,"is_preprint":false},{"pmid":"25128845","id":"PMC_25128845","title":"OmGOGAT-disruption in the ericoid mycorrhizal fungus Oidiodendron maius induces reorganization of the N pathway and reduces tolerance to heavy-metals.","date":"2014","source":"Fungal genetics and biology : FG & B","url":"https://pubmed.ncbi.nlm.nih.gov/25128845","citation_count":11,"is_preprint":false},{"pmid":"27591192","id":"PMC_27591192","title":"Synergistic inhibition of the APC/C by the removal of APC15 in HCT116 cells lacking UBE2C.","date":"2016","source":"Biology open","url":"https://pubmed.ncbi.nlm.nih.gov/27591192","citation_count":4,"is_preprint":false},{"pmid":"40153087","id":"PMC_40153087","title":"Localization and function of APC15 during mouse oocyte meiotic progression.","date":"2025","source":"Journal of molecular histology","url":"https://pubmed.ncbi.nlm.nih.gov/40153087","citation_count":0,"is_preprint":false},{"pmid":"39132510","id":"PMC_39132510","title":"An autoantibody profile identified by human genome-wide protein arrays in rheumatoid arthritis.","date":"2024","source":"MedComm","url":"https://pubmed.ncbi.nlm.nih.gov/39132510","citation_count":0,"is_preprint":false},{"pmid":"41514165","id":"PMC_41514165","title":"Integrated fetal testicular transcriptomic and epigenomic profiles during maternal nutrient restriction with dietary melatonin intervention.","date":"2026","source":"Journal of animal science","url":"https://pubmed.ncbi.nlm.nih.gov/41514165","citation_count":0,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":9890,"output_tokens":2439,"usd":0.033127},"stage2":{"model":"claude-opus-4-6","input_tokens":5739,"output_tokens":2186,"usd":0.125018},"total_usd":0.158145,"stage1_batch_id":"msgbatch_01TqNM6p6FsoMBT2jzQTwKBr","stage2_batch_id":"msgbatch_01Ya473eco8sTHbvRymQaU8o","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2011,\n      \"finding\": \"APC15 is required for the turnover of APC/C co-activator CDC20 and release of mitotic checkpoint complexes (MCCs) from the APC/C during spindle assembly checkpoint (SAC) signalling. In the absence of APC15, ubiquitylated CDC20 and MCCs remain 'locked' onto the APC/C, preventing ubiquitylation and degradation of cyclin B1 upon SAC satisfaction.\",\n      \"method\": \"siRNA knockdown of APC15 in human cells, live-cell imaging, immunoprecipitation, ubiquitylation assays\",\n      \"journal\": \"Nature cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — clean KD with defined cellular and molecular phenotype, replicated by independent labs\",\n      \"pmids\": [\"21926987\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"APC15 is located near the APC/C's MCC binding site and is required for APC/C(MCC)-dependent CDC20 autoubiquitylation and degradation, thereby driving MCC disassembly. APC15 is dispensable for substrate ubiquitylation by APC/C(CDC20) and APC/C(CDH1). The study characterized APC15 as related to yeast Mnd2 and proposed that APC15 negatively regulates APC/C coactivators.\",\n      \"method\": \"Recombinant human APC/C reconstitution, in vitro ubiquitylation assays, RNAi knockdown, mass spectrometry, structural localization by cryo-EM\",\n      \"journal\": \"Nature structural & molecular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — reconstituted in vitro with purified components, multiple orthogonal methods, independent replication\",\n      \"pmids\": [\"23007861\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"In budding yeast, the Mnd2/Apc15 subunit of the APC/C is required for SAC-dependent Cdc20 autoubiquitination. Reconstitution with purified components showed that Mad3-Bub3 and Mad2 together lock Cdc20 on the APC/C and stimulate Cdc20 autoubiquitination while inhibiting substrate ubiquitination, and this autoubiquitination requires Mnd2/Apc15. Loss of Mnd2 allows SAC arrest establishment but delays release, establishing that Cdc20 ubiquitination is needed for SAC inactivation.\",\n      \"method\": \"In vitro reconstitution with purified budding yeast APC/C components, in vivo genetic deletion (mnd2Δ), ubiquitylation assays\",\n      \"journal\": \"Molecular cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — reconstituted in vitro with purified components plus genetic validation in vivo\",\n      \"pmids\": [\"22940250\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"APC15 is a component of the APC/C platform subcomplex (with Apc1, Apc4, Apc5). Deletion of the Apc1 WD40 domain in a mutant APC/C abolishes UbcH10-dependent ubiquitination and locks the APC/C in an inactive conformation; under these conditions, EM density for Apc15 is not visible, indicating that Apc15 positioning within the APC/C depends on Apc1(WD40)-mediated conformational changes.\",\n      \"method\": \"Crystal structure of Apc1 N-terminal domain at 2.2 Å, cryo-EM of APC/C-Cdh1 complex with Apc1(WD40) deletion, in vitro ubiquitination assays\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — crystal structure + cryo-EM + in vitro biochemical assays with deletion mutant\",\n      \"pmids\": [\"27601667\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"In fission yeast, deletion of Apc15 reduces MCC association with the APC/C, impairs poly-ubiquitination of Cdc20, and renders cells checkpoint defective. In vitro and in vivo evidence shows that APC/C can contain two molecules of Cdc20 and that complexes containing both Cdc20 molecules accumulate in apc15Δ cells, suggesting Apc15 promotes Cdc20 ubiquitination within MCC-APC/C.\",\n      \"method\": \"Genetic deletion (apc15Δ) in fission yeast, co-immunoprecipitation, in vitro reconstitution ubiquitination assays, dual-epitope-tag Cdc20 co-IP\",\n      \"journal\": \"Current biology : CB\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — genetic KO with defined molecular phenotype, multiple orthogonal methods, in vitro reconstitution\",\n      \"pmids\": [\"28366744\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"In fission yeast, deletion of Apc15 mimics mutations in the Mad3 ABBA-KEN2-ABBA motif with respect to MCC binding to the APC/C and MCC disassembly, revealing a shared function of Apc15 and the Mad3 C-terminus in mediating MCC-APC/C binding and disassembly.\",\n      \"method\": \"Genetic epistasis in fission yeast (apc15Δ combined with mad3 motif mutations), live-cell assays, co-immunoprecipitation\",\n      \"journal\": \"Current biology : CB\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — genetic epistasis with defined phenotype, single lab\",\n      \"pmids\": [\"28366743\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"APC15-dependent Cdc20 ubiquitination/degradation and TRIP13-catalyzed removal of Mad2 act as two parallel, redundant pathways for MCC disassembly and mitotic exit. Combining TRIP13 depletion with elimination of APC15-dependent Cdc20 ubiquitination/degradation results in a complete inability to exit mitosis, even when MCC assembly at unattached kinetochores is prevented, demonstrating that APC15-driven Cdc20 ubiquitination is essential for disassembly of interphase-produced MCC.\",\n      \"method\": \"Degron-tagging rapid depletion of TRIP13, CRISPR knockout of APC15, live-cell mitotic exit assays, epistasis analysis\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — genetic epistasis with degron and CRISPR, clean phenotypic readout, multiple orthogonal approaches\",\n      \"pmids\": [\"30341343\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"In HCT116 cells lacking UBE2C, depletion of APC15 causes a strong synergistic inhibition of mitotic progression by stabilizing the MCC on the APC/C, indicating that APC15-mediated MCC removal and UBE2C-driven ubiquitination cooperate to silence the SAC.\",\n      \"method\": \"CRISPR/Cas9 UBE2C knockout, siRNA depletion of APC15, live-cell mitotic timing assays\",\n      \"journal\": \"Biology open\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — genetic combination experiment with live-cell readout, single lab\",\n      \"pmids\": [\"27591192\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"APC15 shows dynamic subcellular localization during mouse oocyte meiotic progression. siRNA-mediated knockdown of APC15 causes meiotic arrest at metaphase I and impairs removal of BUB3 from kinetochores, indicating that APC15 is required for SAC inactivation and the metaphase-to-anaphase transition in meiosis.\",\n      \"method\": \"Immunofluorescence/confocal microscopy for localization, siRNA knockdown, kinetochore BUB3 staining as SAC readout\",\n      \"journal\": \"Journal of molecular histology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2–3 — direct localization experiment with functional KD phenotype, single lab\",\n      \"pmids\": [\"40153087\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"ANAPC15 (APC15) is an integral subunit of the APC/C platform that localizes near the MCC binding site and is specifically required for APC/C(MCC)-dependent CDC20 autoubiquitylation and degradation, thereby driving MCC disassembly and enabling rapid APC/C activation upon spindle assembly checkpoint satisfaction, while being dispensable for APC/C-mediated substrate ubiquitylation by CDC20 or CDH1 coactivators.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"ANAPC15 (APC15/Mnd2) is an integral subunit of the anaphase-promoting complex/cyclosome (APC/C) that is specifically required for spindle assembly checkpoint (SAC) silencing by promoting the ubiquitylation and degradation of the APC/C coactivator CDC20 within the mitotic checkpoint complex (MCC), thereby driving MCC disassembly and enabling timely mitotic exit. APC15 resides on the APC/C platform near the MCC binding site and its positioning depends on Apc1 WD40 domain-mediated conformational changes; it is dispensable for APC/C-mediated substrate ubiquitylation by CDC20 or CDH1 coactivators [PMID:23007861, PMID:27601667]. APC15-dependent CDC20 ubiquitylation operates in parallel with the TRIP13-catalyzed pathway for MCC disassembly, and elimination of both pathways renders cells unable to exit mitosis even when checkpoint signaling is abrogated [PMID:30341343]. This function is conserved from yeast to mammals, including a role in meiotic SAC inactivation during oocyte maturation [PMID:22940250, PMID:28366744, PMID:40153087].\",\n  \"teleology\": [\n    {\n      \"year\": 2011,\n      \"claim\": \"The first demonstration that APC15 is required for CDC20 turnover and MCC release from the APC/C resolved how the SAC-inhibited APC/C is reactivated upon checkpoint satisfaction.\",\n      \"evidence\": \"siRNA knockdown in human cells with live-cell imaging, immunoprecipitation, and ubiquitylation assays\",\n      \"pmids\": [\"21926987\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Mechanism by which APC15 promotes CDC20 ubiquitylation was unknown\",\n        \"Structural position of APC15 on the APC/C was not resolved\",\n        \"Whether APC15 is required for APC/C activity toward other substrates was untested\"\n      ]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Reconstitution with purified components in both human and budding yeast systems established that APC15/Mnd2 specifically enables MCC-dependent CDC20 autoubiquitylation while being dispensable for substrate ubiquitylation by APC/C–CDC20 or APC/C–CDH1, defining APC15 as a selective regulator of coactivator fate rather than a general APC/C activity factor.\",\n      \"evidence\": \"Recombinant human APC/C reconstitution, purified budding yeast APC/C in vitro ubiquitylation, cryo-EM structural localization, genetic deletion in yeast\",\n      \"pmids\": [\"23007861\", \"22940250\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Atomic-resolution contacts between APC15 and MCC components were not defined\",\n        \"How APC15 discriminates MCC-bound CDC20 from free CDC20 was unclear\"\n      ]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Structural and genetic studies revealed that APC15 is part of the APC/C platform subcomplex and that its stable positioning depends on the Apc1 WD40 domain, linking APC/C conformational dynamics to APC15-mediated MCC disassembly; separately, APC15 and UBE2C were shown to cooperate functionally in SAC silencing.\",\n      \"evidence\": \"Apc1 crystal structure at 2.2 Å, cryo-EM of APC/C–Cdh1 with Apc1(WD40) deletion, CRISPR UBE2C KO combined with APC15 siRNA and live-cell mitotic timing\",\n      \"pmids\": [\"27601667\", \"27591192\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Whether APC15 conformational coupling is direct or mediated through other subunits was unresolved\",\n        \"Relative contributions of APC15 vs. UBE2C to SAC silencing kinetics were not quantified\"\n      ]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Fission yeast studies demonstrated that APC15 and the Mad3 C-terminal ABBA-KEN2-ABBA motif share a function in mediating MCC–APC/C binding and disassembly, and that APC/C can simultaneously accommodate two Cdc20 molecules whose ubiquitylation depends on APC15, clarifying the stoichiometry and epistatic logic of checkpoint disassembly.\",\n      \"evidence\": \"Genetic deletion and epistasis in fission yeast, dual-epitope-tag co-IP, in vitro reconstitution\",\n      \"pmids\": [\"28366744\", \"28366743\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Whether the dual-Cdc20 model applies to human APC/C was untested\",\n        \"Structural basis for APC15–Mad3 functional overlap was not resolved\"\n      ]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Establishing that APC15-dependent CDC20 degradation and TRIP13-catalyzed Mad2 removal constitute two parallel, redundant MCC disassembly pathways explained why loss of either alone permits mitotic exit, and demonstrated that interphase-produced MCC also requires active disassembly.\",\n      \"evidence\": \"Degron-tagging rapid depletion of TRIP13 combined with CRISPR APC15 knockout, live-cell mitotic exit assays\",\n      \"pmids\": [\"30341343\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Relative pathway usage under physiological conditions and across cell types was not determined\",\n        \"Whether additional disassembly pathways exist beyond APC15 and TRIP13 was unresolved\"\n      ]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Extension of APC15 function to meiosis showed that APC15 dynamically localizes during mouse oocyte meiotic progression and is required for SAC inactivation at the metaphase I–anaphase I transition.\",\n      \"evidence\": \"Immunofluorescence/confocal microscopy and siRNA knockdown in mouse oocytes with kinetochore BUB3 readout\",\n      \"pmids\": [\"40153087\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Single-lab observation not yet independently replicated\",\n        \"Molecular mechanism of APC15 in meiotic versus mitotic MCC disassembly not compared\",\n        \"Whether APC15 has meiosis II roles was not addressed\"\n      ]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"The atomic-resolution mechanism by which APC15 selectively promotes CDC20 autoubiquitylation within the MCC-bound APC/C — including direct contact surfaces, conformational gating, and potential allosteric communication with the E2 binding site — remains structurally undefined.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"No high-resolution structure of APC15 in the context of the MCC–APC/C complex with substrate-level detail\",\n        \"Potential post-translational regulation of APC15 activity is unexplored\",\n        \"Whether APC15 has functions outside the SAC/MCC disassembly axis is unknown\"\n      ]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\n        \"term_id\": \"GO:0098772\",\n        \"supporting_discovery_ids\": [0, 1, 2, 6]\n      }\n    ],\n    \"localization\": [\n      {\n        \"term_id\": \"GO:0005829\",\n        \"supporting_discovery_ids\": [0, 1]\n      }\n    ],\n    \"pathway\": [\n      {\n        \"term_id\": \"R-HSA-1640170\",\n        \"supporting_discovery_ids\": [0, 1, 2, 6, 7]\n      },\n      {\n        \"term_id\": \"R-HSA-392499\",\n        \"supporting_discovery_ids\": [1, 2, 4]\n      }\n    ],\n    \"complexes\": [\n      \"APC/C\"\n    ],\n    \"partners\": [\n      \"CDC20\",\n      \"APC1\",\n      \"CDH1\",\n      \"TRIP13\",\n      \"UBE2C\",\n      \"MAD2L1\",\n      \"BUB3\"\n    ],\n    \"other_free_text\": []\n  }\n}\n```"}