{"gene":"ANAPC1","run_date":"2026-04-28T17:12:37","timeline":{"discoveries":[{"year":2001,"finding":"Human APC1 (the largest subunit of the APC/C) was fully sequenced, its chromosomal location mapped, and intron-exon boundaries analyzed. APC/C subunits including APC1 are expressed at fairly constant levels relative to each other across most tissues, consistent with their function as part of a stable complex.","method":"Full-length cDNA sequencing, chromosomal mapping, Northern blot/RT-PCR expression analysis","journal":"Gene","confidence":"Medium","confidence_rationale":"Tier 2 — direct molecular characterization of human APC1, single lab","pmids":["11179667"],"is_preprint":false},{"year":2003,"finding":"APC/C phosphorylation by Cdk1 in mitosis generates at least 32 mitosis-specific phosphorylation sites clustered in Apc1 and TPR subunits; phosphorylation of APC (but not Plk1 activity alone) is sufficient for increased Cdc20 binding and APC activation, and APC phosphorylation is initiated in prophase during nuclear uptake of cyclin B1.","method":"Mass spectrometry identification of phospho-sites on immunopurified APC/C; in vitro kinase assays with Cdk1/Plk1; immunofluorescence with phospho-specific antibodies; Plk1 depletion experiments","journal":"The EMBO journal","confidence":"High","confidence_rationale":"Tier 1-2 — multiple orthogonal methods (MS, in vitro kinase assay, immunofluorescence, depletion), replicated across labs","pmids":["14657031"],"is_preprint":false},{"year":2007,"finding":"In Drosophila, the shattered (shtd) gene encodes Apc1, the largest subunit of the APC/C. Loss of Apc1 causes failure to establish G1 arrest and defects in progression through mitosis, accompanied by accumulation of Cyclin A and String (Cdc25) proteins. Genetic reduction of CycA or string dosage suppresses the shtd phenotype, placing Apc1 upstream of these substrates in cell cycle control.","method":"Genetic mutant analysis, immunostaining for cell cycle markers, genetic epistasis (dosage suppression)","journal":"Developmental biology","confidence":"High","confidence_rationale":"Tier 2 — genetic epistasis with multiple substrates, ortholog in model organism consistent with mammalian APC1 function","pmids":["17689521"],"is_preprint":false},{"year":2015,"finding":"Human cytomegalovirus (HCMV) protein UL21a induces the proteasomal degradation of APC1 (in addition to APC4 and APC5). UL21a is necessary and sufficient to degrade APC1. Furthermore, depletion of any single platform subunit (APC1, APC4, or APC5) or of APC8 in uninfected cells leads to co-degradation of all three platform subunits, revealing a cellular mechanism for coordinated downregulation of the APC/C platform subcomplex.","method":"siRNA knockdown, overexpression of viral proteins, Western blotting, APC/C substrate accumulation assays","journal":"Journal of virology","confidence":"High","confidence_rationale":"Tier 2 — multiple knockdown/overexpression experiments with mechanistic follow-up, identification of novel cellular co-degradation mechanism","pmids":["25903336"],"is_preprint":false},{"year":2016,"finding":"The WD40 domain of Apc1 (Apc1(WD40)) is required for the coactivator (Cdh1)-induced allosteric conformational change of the APC/C that stimulates UbcH10-dependent ubiquitination of substrates (chain initiation). Deletion of Apc1(WD40) abolishes UbcH10-dependent ubiquitination but does not impair Ube2S-dependent ubiquitin chain elongation. Crystal structure of the N-terminal WD40 domain of human Apc1 was determined at 2.2 Å resolution; cryo-EM of APC/C-Cdh1 with Apc1(WD40) deleted showed the catalytic module locked in an inactive conformation with inaccessible UbcH10-binding site and loss of Apc15 density.","method":"Crystal structure (2.2 Å), cryo-EM, WD40 deletion mutant APC/C reconstitution, in vitro ubiquitination assays with UbcH10 and Ube2S","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 1 — crystal structure + cryo-EM + reconstituted in vitro assays + mutagenesis in single study","pmids":["27601667"],"is_preprint":false},{"year":2019,"finding":"Mutations in ANAPC1 cause Rothmund-Thomson syndrome type 1 (RTS1). A deep intronic splicing mutation activates a 95 bp pseudoexon, causing premature termination codons, nonsense-mediated decay, decreased ANAPC1 protein levels, and prolongation of interphase in patient fibroblasts. Mice heterozygous for an Anapc1 knockout show increased cataract incidence, linking APC/C deficiency to the RTS1 phenotype.","method":"Exome/targeted sequencing, RT-PCR splice analysis, Western blot for ANAPC1 protein in fibroblasts, cell cycle analysis of patient fibroblasts, mouse knockout model","journal":"American journal of human genetics","confidence":"High","confidence_rationale":"Tier 2 — multiple orthogonal methods (molecular, cellular, mouse model), replicated across 7 families","pmids":["31303264"],"is_preprint":false},{"year":2019,"finding":"A disordered loop domain of Apc1 (Apc1-loop500) directly binds the B56 regulatory subunit of PP2A and promotes Cdc20 loading onto the APC/C. Mutations in Apc1-loop500 that abolish B56 binding decrease Cdc20 loading and APC/C-dependent ubiquitylation in Xenopus egg extract reconstitution. PP2A-B56 preferentially dephosphorylates Cdc20 over the Apc1 inhibitory domain, facilitating APC/C-Cdc20 complex formation in mitosis.","method":"APC/C reconstitution in Xenopus egg extracts, mutagenesis of Apc1-loop500, co-immunoprecipitation, in vitro ubiquitination assays, non-phosphorylatable Cdc20 mutant rescue","journal":"EMBO reports","confidence":"High","confidence_rationale":"Tier 1-2 — reconstitution system, mutagenesis, multiple orthogonal assays in single study","pmids":["31825153"],"is_preprint":false},{"year":2021,"finding":"HIV-1 Vpr mediates degradation of APC1 via DCAF1 recruitment and the proteasome. Vpr forms a complex with APC1, and the APC/C coactivators Cdh1 and Cdc20 are associated with these complexes. APC1 degradation is a conserved feature of several primary Vpr variants from transmitted/founder HIV-1 viruses, though it does not impact Vpr-mediated G2 arrest or HIV replication in macrophages.","method":"BioID proximity labeling, co-immunoprecipitation, Western blot for APC1 degradation, proteasome inhibitor rescue, mutant Vpr analysis","journal":"Journal of virology","confidence":"Medium","confidence_rationale":"Tier 2 — BioID + Co-IP + functional degradation assays, single lab","pmids":["34011540"],"is_preprint":false},{"year":2021,"finding":"Plx1 (polo-like kinase) directly binds the Apc1-loop500 domain in a phosphorylation-dependent manner and promotes APC/C-Cdc20 formation via Apc3 phosphorylation. Upon phosphorylation of loop residue T532, PP2A-B56 is recruited to Apc1-loop500 and differentially promotes dissociation of Plx1 through dephosphorylation of Plx1-binding sites, while stable Plx1 binding prevents PP2A-B56 recruitment and prematurely activates APC/C. The phosphorylation status of Apc1-loop500 is controlled by distant Apc3-loop phosphorylation, revealing a phosphorylation-dependent feedback within the APC/C.","method":"Xenopus egg extract reconstitution, site-directed mutagenesis, phospho-specific binding assays, kinase/phosphatase manipulation","journal":"The EMBO journal","confidence":"High","confidence_rationale":"Tier 1-2 — reconstitution system with mutagenesis and multiple kinase/phosphatase perturbations","pmids":["34291488"],"is_preprint":false},{"year":2024,"finding":"Phospho-regulation of Apc1-loop300 (Apc1-300L) by CDK1 and PP2A-B55 is pivotal for cell cycle oscillation. Premature PP2A-B55 activation (via Greatwall kinase depletion) leads to Apc1-300L dephosphorylation, stalling APC/C activity and delaying Cyclin B degradation; this effect is counteracted by B55-specific inhibitor pEnsa or by removing Apc1-300L. Dephosphorylation of Apc1-300L specifically inhibits Cdc20 recruitment to the APC/C, identifying APC/C as a primary substrate of the CDK-PP2A-B55 partnership for cell cycle oscillation.","method":"Xenopus egg extract assays, Greatwall kinase depletion, pEnsa inhibitor, Apc1-300L deletion mutants, Cdc20 binding assays across cell cycle stages","journal":"Cell reports","confidence":"High","confidence_rationale":"Tier 1-2 — reconstitution with genetic and pharmacological perturbations, multiple orthogonal approaches","pmids":["38678563"],"is_preprint":false},{"year":2024,"finding":"Cryo-EM comparison of S. cerevisiae and human APC/C reveals that, unlike human APC/C, yeast apo-APC/C has the catalytic module already positioned to bind E2 without requiring coactivator-induced conformational change. Furthermore, no evidence for a phospho-regulatable auto-inhibitory segment of Apc1 (equivalent to the human Apc1 inhibitory loop that sterically blocks the CDC20 C-box binding site on APC8 in unphosphorylated human APC/C) is found in yeast, demonstrating species-specific regulatory differences in the Apc1-mediated auto-inhibition mechanism.","method":"Cryo-EM structures of yeast apo-APC/C, APC/C-CDH1-substrate ternary complex, and phosphorylated apo-APC/C; comparative structural analysis with human APC/C","journal":"bioRxiv","confidence":"Medium","confidence_rationale":"Tier 1 — cryo-EM structural analysis, preprint, not yet peer-reviewed","pmids":["bio_10.1101_2024.06.19.599685"],"is_preprint":true}],"current_model":"ANAPC1 encodes the largest scaffolding subunit of the APC/C E3 ubiquitin ligase; its WD40 domain mediates coactivator-induced allosteric activation for UbcH10-dependent ubiquitin chain initiation, while its flexible loop domains (loop300 and loop500) are phospho-regulated by CDK1/Plk1 and dephosphorylated by PP2A-B55/B56 to control Cdc20 co-activator loading, APC/C activity, and cell cycle oscillation; loss-of-function mutations in humans cause Rothmund-Thomson syndrome type 1, and viral proteins (HCMV UL21a, HIV-1 Vpr) target APC1 for proteasomal degradation to subvert cell cycle control."},"narrative":{"teleology":[{"year":2001,"claim":"Full-length sequencing and chromosomal mapping of human ANAPC1 established its identity as the largest APC/C subunit and showed that APC/C subunits are co-expressed at stable stoichiometric ratios across tissues, consistent with a constitutive multi-subunit complex.","evidence":"cDNA sequencing, chromosomal mapping, Northern blot/RT-PCR across human tissues","pmids":["11179667"],"confidence":"Medium","gaps":["Single-lab characterization without functional assays","No structural information on APC1 domains","Tissue-level expression data lacks single-cell resolution"]},{"year":2003,"claim":"Mass spectrometry-based phospho-mapping revealed that mitotic CDK1 phosphorylation of APC/C is concentrated on Apc1 and TPR subunits, and that this phosphorylation is sufficient to promote Cdc20 binding and APC/C activation—establishing phospho-regulation as the primary mechanism for mitotic APC/C activation.","evidence":"Mass spectrometry of immunopurified APC/C, in vitro Cdk1/Plk1 kinase assays, phospho-specific immunofluorescence, Plk1 depletion","pmids":["14657031"],"confidence":"High","gaps":["Specific Apc1 phospho-sites responsible for Cdc20 binding were not individually assigned","Phosphatase(s) counteracting CDK1 on APC/C not yet identified"]},{"year":2007,"claim":"Genetic analysis of Drosophila apc1 (shattered) mutants demonstrated that APC1 is required for G1 establishment and mitotic progression through degradation of Cyclin A and String/Cdc25, providing in vivo epistatic evidence placing APC1 upstream of key cell cycle substrates.","evidence":"Drosophila genetic mutant analysis, immunostaining, genetic dosage suppression of CycA and string","pmids":["17689521"],"confidence":"High","gaps":["Invertebrate model; direct mapping to mammalian APC1 regulatory domains not performed","No biochemical reconstitution of Drosophila APC/C activity"]},{"year":2015,"claim":"Discovery that HCMV protein UL21a targets APC1 for proteasomal degradation, and that loss of any single platform subunit (APC1, APC4, APC5) triggers coordinated co-degradation of the others, revealed both a viral immune-evasion strategy and an intrinsic quality-control mechanism for the APC/C platform subcomplex.","evidence":"siRNA knockdowns of individual platform subunits, viral protein overexpression, Western blot, substrate accumulation assays","pmids":["25903336"],"confidence":"High","gaps":["E3 ligase mediating cellular co-degradation not identified","Functional consequence of partial APC/C platform loss on specific substrates not quantified"]},{"year":2016,"claim":"Crystal structure of the Apc1 WD40 domain and cryo-EM of WD40-deleted APC/C revealed that Apc1-WD40 is required for coactivator-induced repositioning of the catalytic module to an active conformation that exposes the UbcH10-binding site—mechanistically separating chain initiation (UbcH10-dependent, WD40-dependent) from chain elongation (Ube2S-dependent, WD40-independent).","evidence":"2.2 Å crystal structure, cryo-EM of ΔWD40 APC/C-Cdh1, in vitro ubiquitination with UbcH10 and Ube2S","pmids":["27601667"],"confidence":"High","gaps":["How WD40 domain communicates allosteric signal to catalytic module at atomic resolution remains incomplete","Role of WD40 in Cdc20-mediated (vs Cdh1-mediated) activation not separately tested"]},{"year":2019,"claim":"Identification of ANAPC1 mutations as the cause of Rothmund-Thomson syndrome type 1 in seven families connected APC/C deficiency to a human developmental disorder, with patient cells showing reduced ANAPC1 protein and prolonged interphase, and heterozygous knockout mice recapitulating the cataract phenotype.","evidence":"Exome/targeted sequencing across 7 families, RT-PCR splice analysis, Western blot of patient fibroblasts, cell cycle analysis, Anapc1+/- mouse model","pmids":["31303264"],"confidence":"High","gaps":["How partial APC/C loss causes the specific RTS1 spectrum (poikiloderma, cataracts) rather than broader cell cycle failure is unknown","No rescue experiment restoring ANAPC1 in patient cells"]},{"year":2019,"claim":"Reconstitution showed that Apc1-loop500 directly recruits PP2A-B56, which preferentially dephosphorylates Cdc20 over Apc1's inhibitory domain to promote Cdc20 loading—resolving how a phosphatase paradoxically activates APC/C during mitosis when most APC/C phosphorylation is activating.","evidence":"Xenopus egg extract reconstitution, Apc1-loop500 mutagenesis, co-immunoprecipitation, in vitro ubiquitination, non-phosphorylatable Cdc20 mutant rescue","pmids":["31825153"],"confidence":"High","gaps":["Quantitative kinetics of PP2A-B56 substrate selectivity on APC/C not measured","Whether loop500-B56 interaction is conserved in human cells not directly tested"]},{"year":2021,"claim":"Identification of a phosphorylation-dependent feedback loop in which Plk1 and PP2A-B56 compete for binding to Apc1-loop500 revealed that Plk1 binding is controlled by Apc3-loop phosphorylation—demonstrating inter-subunit phospho-communication within the APC/C and explaining how Plk1 and PP2A-B56 sequentially regulate APC/C activation timing.","evidence":"Xenopus egg extract reconstitution, site-directed mutagenesis of Apc1-loop500 and Apc3-loop, phospho-specific binding assays, kinase/phosphatase manipulation","pmids":["34291488"],"confidence":"High","gaps":["Structural basis for Plk1-loop500 vs B56-loop500 competitive binding not resolved","In vivo validation in mammalian cells lacking"]},{"year":2021,"claim":"HIV-1 Vpr was found to target APC1 for DCAF1-dependent proteasomal degradation, representing a second independent viral strategy (after HCMV UL21a) to disable the APC/C, though the functional advantage for viral replication remains unclear.","evidence":"BioID proximity labeling, co-immunoprecipitation, Western blot, proteasome inhibitor rescue, mutant Vpr analysis","pmids":["34011540"],"confidence":"Medium","gaps":["APC1 degradation did not affect G2 arrest or HIV replication in macrophages, so the biological purpose is unresolved","Single-lab finding without independent replication"]},{"year":2024,"claim":"Discovery that CDK1 phosphorylation of a second disordered loop, Apc1-loop300, and its dephosphorylation by PP2A-B55 is a primary node of the CDK-PP2A-B55 cell cycle oscillator—dephosphorylation of loop300 blocks Cdc20 recruitment and delays Cyclin B degradation, identifying the APC/C itself as a key PP2A-B55 substrate for mitotic exit control.","evidence":"Xenopus egg extract, Greatwall kinase depletion, pEnsa inhibitor, Apc1-300L deletion mutants, Cdc20 binding assays","pmids":["38678563"],"confidence":"High","gaps":["Whether loop300 and loop500 regulation are additive or sequential in vivo is not distinguished","Mammalian in vivo validation of loop300 function not performed"]},{"year":null,"claim":"The integrated structural and biochemical logic by which the two regulatory loops (loop300, loop500) coordinate with the WD40 domain and multiple kinases/phosphatases to produce the sharp activation switch of APC/C during mitotic progression remains to be resolved at atomic resolution in a single structural framework.","evidence":"","pmids":[],"confidence":"High","gaps":["No full-length structure of phosphorylated human APC/C capturing loop300 and loop500 conformations simultaneously","In vivo kinetic measurements of loop phosphorylation/dephosphorylation dynamics lacking in mammalian cells","Mechanism by which partial APC1 loss produces the tissue-specific phenotypes of Rothmund-Thomson syndrome type 1 is unknown"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[4,6,8,9]},{"term_id":"GO:0005198","term_label":"structural molecule activity","supporting_discovery_ids":[0,3,4]}],"localization":[{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[1]},{"term_id":"GO:0005829","term_label":"cytosol","supporting_discovery_ids":[3]}],"pathway":[{"term_id":"R-HSA-1640170","term_label":"Cell Cycle","supporting_discovery_ids":[1,2,4,6,8,9]},{"term_id":"R-HSA-392499","term_label":"Metabolism of proteins","supporting_discovery_ids":[4,6]},{"term_id":"R-HSA-1643685","term_label":"Disease","supporting_discovery_ids":[5]}],"complexes":["APC/C"],"partners":["CDC20","CDH1","PP2A-B56","PP2A-B55","PLK1","ANAPC4","ANAPC5","ANAPC15"],"other_free_text":[]},"mechanistic_narrative":"ANAPC1 encodes the largest scaffolding subunit of the anaphase-promoting complex/cyclosome (APC/C), a multi-subunit E3 ubiquitin ligase essential for cell cycle progression through targeted degradation of mitotic cyclins and other substrates [PMID:17689521, PMID:25903336]. Its N-terminal WD40 domain mediates coactivator (Cdh1/Cdc20)-induced allosteric activation of the APC/C catalytic module, enabling UbcH10-dependent ubiquitin chain initiation on substrates [PMID:27601667]. Two disordered regulatory loops (loop300 and loop500) serve as phospho-regulated switches: CDK1/Plk1 phosphorylation and PP2A-B55/B56-mediated dephosphorylation of these loops control Cdc20 co-activator loading and thereby couple APC/C activity to cell cycle oscillation [PMID:31825153, PMID:34291488, PMID:38678563]. Loss-of-function mutations in ANAPC1 cause Rothmund-Thomson syndrome type 1, characterized by reduced ANAPC1 protein, prolonged interphase, and increased cataract incidence in a heterozygous mouse model [PMID:31303264]."},"prefetch_data":{"uniprot":{"accession":"Q9H1A4","full_name":"Anaphase-promoting complex subunit 1","aliases":["Cyclosome subunit 1","Mitotic checkpoint regulator","Testis-specific gene 24 protein"],"length_aa":1944,"mass_kda":216.5,"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:18485873). The APC/C complex acts by mediating ubiquitination and subsequent degradation of target proteins: it mainly mediates the formation of 'Lys-11'-linked polyubiquitin chains and, to a lower extent, the formation of 'Lys-48'- and 'Lys-63'-linked polyubiquitin chains (PubMed:18485873). The APC/C complex catalyzes assembly of branched 'Lys-11'-/'Lys-48'-linked branched ubiquitin chains on target proteins (PubMed:29033132)","subcellular_location":"","url":"https://www.uniprot.org/uniprotkb/Q9H1A4/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":true,"resolved_as":"","url":"https://depmap.org/portal/gene/ANAPC1","classification":"Common Essential","n_dependent_lines":1203,"n_total_lines":1208,"dependency_fraction":0.9958609271523179},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[{"gene":"ANAPC16","stoichiometry":10.0},{"gene":"ANAPC4","stoichiometry":10.0},{"gene":"CDC16","stoichiometry":10.0},{"gene":"CDC23","stoichiometry":10.0},{"gene":"CDC26","stoichiometry":4.0},{"gene":"CDC27","stoichiometry":4.0},{"gene":"ANAPC2","stoichiometry":0.2},{"gene":"CAPZB","stoichiometry":0.2},{"gene":"DEPDC1B","stoichiometry":0.2},{"gene":"FKBP5","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/search/ANAPC1","total_profiled":1310},"omim":[{"mim_id":"620819","title":"ROTHMUND-THOMSON SYNDROME, TYPE 4; RTS4","url":"https://www.omim.org/entry/620819"},{"mim_id":"618625","title":"ROTHMUND-THOMSON SYNDROME, TYPE 1; RTS1","url":"https://www.omim.org/entry/618625"},{"mim_id":"615789","title":"ROTHMUND-THOMSON SYNDROME, TYPE 3; RTS3","url":"https://www.omim.org/entry/615789"},{"mim_id":"610953","title":"PIF1 5-PRIME-TO-3-PRIME DNA HELICASE; PIF1","url":"https://www.omim.org/entry/610953"},{"mim_id":"609321","title":"SAS6 CENTRIOLAR ASSEMBLY PROTEIN; SASS6","url":"https://www.omim.org/entry/609321"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Vesicles","reliability":"Approved"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/ANAPC1"},"hgnc":{"alias_symbol":["MCPR","TSG24","APC1"],"prev_symbol":[]},"alphafold":{"accession":"Q9H1A4","domains":[{"cath_id":"-","chopping":"614-683_746-843","consensus_level":"medium","plddt":81.4385,"start":614,"end":843},{"cath_id":"-","chopping":"1420-1439_1454-1617","consensus_level":"medium","plddt":92.0439,"start":1420,"end":1617},{"cath_id":"-","chopping":"1864-1944","consensus_level":"medium","plddt":73.9373,"start":1864,"end":1944}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9H1A4","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q9H1A4-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q9H1A4-F1-predicted_aligned_error_v6.png","plddt_mean":77.06},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=ANAPC1","jax_strain_url":"https://www.jax.org/strain/search?query=ANAPC1"},"sequence":{"accession":"Q9H1A4","fasta_url":"https://rest.uniprot.org/uniprotkb/Q9H1A4.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q9H1A4/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9H1A4"}},"corpus_meta":[{"pmid":"12842007","id":"PMC_12842007","title":"Shortstop recruits EB1/APC1 and promotes microtubule assembly at the muscle-tendon junction.","date":"2003","source":"Current biology : CB","url":"https://pubmed.ncbi.nlm.nih.gov/12842007","citation_count":94,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"23172913","id":"PMC_23172913","title":"Non-autonomous crosstalk between the Jak/Stat and Egfr pathways mediates Apc1-driven intestinal stem cell hyperplasia in the Drosophila adult midgut.","date":"2012","source":"Development (Cambridge, England)","url":"https://pubmed.ncbi.nlm.nih.gov/23172913","citation_count":88,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"11923210","id":"PMC_11923210","title":"Drosophila Apc1 and Apc2 regulate Wingless transduction throughout development.","date":"2002","source":"Development (Cambridge, England)","url":"https://pubmed.ncbi.nlm.nih.gov/11923210","citation_count":84,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"12297098","id":"PMC_12297098","title":"Drosophila APC2 and APC1 play overlapping roles in wingless signaling in the embryo and imaginal discs.","date":"2002","source":"Developmental biology","url":"https://pubmed.ncbi.nlm.nih.gov/12297098","citation_count":57,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"12297097","id":"PMC_12297097","title":"Drosophila APC2 and APC1 have overlapping roles in the larval brain despite their distinct intracellular localizations.","date":"2002","source":"Developmental biology","url":"https://pubmed.ncbi.nlm.nih.gov/12297097","citation_count":57,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"31303264","id":"PMC_31303264","title":"Mutations in ANAPC1, Encoding a Scaffold Subunit of the Anaphase-Promoting Complex, Cause Rothmund-Thomson Syndrome Type 1.","date":"2019","source":"American journal of human genetics","url":"https://pubmed.ncbi.nlm.nih.gov/31303264","citation_count":46,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"15994309","id":"PMC_15994309","title":"Depletion of anaphase-promoting complex or cyclosome (APC/C) subunit homolog APC1 or CDC27 of Trypanosoma brucei arrests the procyclic form in metaphase but the bloodstream form in anaphase.","date":"2005","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/15994309","citation_count":29,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"18622497","id":"PMC_18622497","title":"Methylation status of ANAPC1, CDKN2A and TP53 promoter genes in individuals with gastric cancer.","date":"2008","source":"Brazilian journal of medical and biological research = Revista brasileira de pesquisas medicas e biologicas","url":"https://pubmed.ncbi.nlm.nih.gov/18622497","citation_count":27,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"30894546","id":"PMC_30894546","title":"Sequence variation at ANAPC1 accounts for 24% of the variability in corneal endothelial cell density.","date":"2019","source":"Nature communications","url":"https://pubmed.ncbi.nlm.nih.gov/30894546","citation_count":24,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"11179667","id":"PMC_11179667","title":"Characterisation of the human APC1, the largest subunit of the anaphase-promoting complex.","date":"2001","source":"Gene","url":"https://pubmed.ncbi.nlm.nih.gov/11179667","citation_count":22,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"17689521","id":"PMC_17689521","title":"Mutation of the Apc1 homologue shattered disrupts normal eye development by disrupting G1 cell cycle arrest and progression through mitosis.","date":"2007","source":"Developmental biology","url":"https://pubmed.ncbi.nlm.nih.gov/17689521","citation_count":22,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"31825153","id":"PMC_31825153","title":"PP2A-B56 binds to Apc1 and promotes Cdc20 association with the APC/C ubiquitin ligase in mitosis.","date":"2019","source":"EMBO reports","url":"https://pubmed.ncbi.nlm.nih.gov/31825153","citation_count":17,"is_preprint":false,"source_track":"pubmed_title"},{"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,"source_track":"pubmed_title"},{"pmid":"25903336","id":"PMC_25903336","title":"Studies on the Contribution of Human Cytomegalovirus UL21a and UL97 to Viral Growth and Inactivation of the Anaphase-Promoting Complex/Cyclosome (APC/C) E3 Ubiquitin Ligase Reveal a Unique Cellular Mechanism for Downmodulation of the APC/C Subunits APC1, APC4, and APC5.","date":"2015","source":"Journal of virology","url":"https://pubmed.ncbi.nlm.nih.gov/25903336","citation_count":17,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"22377092","id":"PMC_22377092","title":"ANAPC1 and SLCO3A1 are associated with nicotine dependence: meta-analysis of genome-wide association studies.","date":"2012","source":"Drug and alcohol dependence","url":"https://pubmed.ncbi.nlm.nih.gov/22377092","citation_count":15,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"9609135","id":"PMC_9609135","title":"The APC1 concept of type I diabetes.","date":"1998","source":"Autoimmunity","url":"https://pubmed.ncbi.nlm.nih.gov/9609135","citation_count":15,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"19397905","id":"PMC_19397905","title":"Apc1 is required for maintenance of local brain organizers and dorsal midbrain survival.","date":"2009","source":"Developmental biology","url":"https://pubmed.ncbi.nlm.nih.gov/19397905","citation_count":11,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"19292673","id":"PMC_19292673","title":"Apc1-mediated antagonism of Wnt/beta-catenin signaling is required for retino-tectal pathfinding in the zebrafish.","date":"2009","source":"Zebrafish","url":"https://pubmed.ncbi.nlm.nih.gov/19292673","citation_count":10,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"9020915","id":"PMC_9020915","title":"A urochordate putative homolog of human EB1, the protein which binds APC1.","date":"1996","source":"Cancer letters","url":"https://pubmed.ncbi.nlm.nih.gov/9020915","citation_count":9,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"34291488","id":"PMC_34291488","title":"Dynamic regulation of mitotic ubiquitin ligase APC/C by coordinated Plx1 kinase and PP2A phosphatase action on a flexible Apc1 loop.","date":"2021","source":"The EMBO journal","url":"https://pubmed.ncbi.nlm.nih.gov/34291488","citation_count":9,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"34011540","id":"PMC_34011540","title":"Human Immunodeficiency Virus Type 1 Vpr Mediates Degradation of APC1, a Scaffolding Component of the Anaphase-Promoting Complex/Cyclosome.","date":"2021","source":"Journal of virology","url":"https://pubmed.ncbi.nlm.nih.gov/34011540","citation_count":6,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"15948962","id":"PMC_15948962","title":"The Aspergillus nidulans sldI(RAD50) gene interacts with bimE(APC1), a homologue of an anaphase-promoting complex subunit.","date":"2005","source":"Molecular microbiology","url":"https://pubmed.ncbi.nlm.nih.gov/15948962","citation_count":6,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"28950679","id":"PMC_28950679","title":"Oral Contraceptive Use May Modulate Global Genomic DNA Methylation and Promoter Methylation of APC1 and ESR1.","date":"2017","source":"Asian Pacific journal of cancer prevention : APJCP","url":"https://pubmed.ncbi.nlm.nih.gov/28950679","citation_count":6,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"35664819","id":"PMC_35664819","title":"Rothmund-Thomson syndrome type 1 caused by biallelic ANAPC1 gene mutations.","date":"2021","source":"Skin health and disease","url":"https://pubmed.ncbi.nlm.nih.gov/35664819","citation_count":5,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"39565210","id":"PMC_39565210","title":"[SNG2], a prion form of Cut4/Apc1, confers non-Mendelian inheritance of heterochromatin silencing defect in fission yeast.","date":"2024","source":"Nucleic acids research","url":"https://pubmed.ncbi.nlm.nih.gov/39565210","citation_count":3,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"38678563","id":"PMC_38678563","title":"CDK1-PP2A-B55 interplay ensures cell cycle oscillation via Apc1-loop300.","date":"2024","source":"Cell reports","url":"https://pubmed.ncbi.nlm.nih.gov/38678563","citation_count":2,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"35956818","id":"PMC_35956818","title":"Antibody for Serine 65 Phosphorylated Ubiquitin Identifies PLK1-Mediated Phosphorylation of Mitotic Proteins and APC1.","date":"2022","source":"Molecules (Basel, Switzerland)","url":"https://pubmed.ncbi.nlm.nih.gov/35956818","citation_count":2,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"40139913","id":"PMC_40139913","title":"Elevated expression of ANAPC1 in lung squamous cell carcinoma: clinical implications and mechanisms.","date":"2025","source":"Future science OA","url":"https://pubmed.ncbi.nlm.nih.gov/40139913","citation_count":1,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"40487972","id":"PMC_40487972","title":"Exploring the potential function of high expression of ANAPC1 in regulating ubiquitination in hepatocellular carcinoma.","date":"2025","source":"World journal of gastrointestinal oncology","url":"https://pubmed.ncbi.nlm.nih.gov/40487972","citation_count":0,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"42002993","id":"PMC_42002993","title":"Overexpression of ANAPC1 Affects the Cell Cycle Pathway to Promote the Progression of Lung Adenocarcinoma.","date":"2026","source":"Combinatorial chemistry & high throughput screening","url":"https://pubmed.ncbi.nlm.nih.gov/42002993","citation_count":0,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"40005207","id":"PMC_40005207","title":"Small Molecules Identified by an In Silico Docking Screen Targeting Anaphase-Promoting Complex/Cyclosome Subunit 1 (APC1) Potentiate Paclitaxel-Induced Breast Cancer Cell Death.","date":"2025","source":"Molecules (Basel, Switzerland)","url":"https://pubmed.ncbi.nlm.nih.gov/40005207","citation_count":0,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"41910327","id":"PMC_41910327","title":"mGem: Cut4/Apc1 and its prion form at the cross roads of cell cycle regulation, heterochromatin organization, RNAi, stress response, and evolution.","date":"2026","source":"mBio","url":"https://pubmed.ncbi.nlm.nih.gov/41910327","citation_count":0,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":null,"id":"bio_10.1101_2025.11.23.25340840","title":"From Rapid Gains to Stalling: Two Decades of Modern Contraceptive Prevalence Rate in Ethiopia","date":"2025-11-25","source":"bioRxiv","url":"https://doi.org/10.1101/2025.11.23.25340840","citation_count":0,"is_preprint":true,"source_track":"pubmed_title"},{"pmid":null,"id":"bio_10.1101_2025.11.24.25340919","title":"Creating pathways for change to increase modern contraceptive uptake in rural Indonesia: A feminist qualitative research protocol","date":"2025-11-27","source":"bioRxiv","url":"https://doi.org/10.1101/2025.11.24.25340919","citation_count":0,"is_preprint":true,"source_track":"pubmed_title"},{"pmid":null,"id":"bio_10.1101_2025.09.09.675171","title":"Molecular characterization of <i>capulet2</i> reveals the importance of <i>ANAPHASE PROMOTING COMPLEX 6</i> maternal expression in endosperm development","date":"2025-09-11","source":"bioRxiv","url":"https://doi.org/10.1101/2025.09.09.675171","citation_count":0,"is_preprint":true,"source_track":"pubmed_title"},{"pmid":null,"id":"bio_10.1101_2024.06.19.599685","title":"A comparative study of the cryo-EM structures of  <i>S. cerevisiae</i>  and human anaphase-promoting complex/cyclosome (APC/C)","date":"2024-06-20","source":"bioRxiv","url":"https://doi.org/10.1101/2024.06.19.599685","citation_count":0,"is_preprint":true,"source_track":"pubmed_title"},{"pmid":"22658674","id":"PMC_22658674","title":"Insights into RNA biology from an atlas of mammalian mRNA-binding proteins.","date":"2012","source":"Cell","url":"https://pubmed.ncbi.nlm.nih.gov/22658674","citation_count":1718,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"12477932","id":"PMC_12477932","title":"Generation and initial analysis of more than 15,000 full-length human and mouse cDNA sequences.","date":"2002","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/12477932","citation_count":1479,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"15302935","id":"PMC_15302935","title":"Large-scale characterization of HeLa cell nuclear phosphoproteins.","date":"2004","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/15302935","citation_count":1159,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"26186194","id":"PMC_26186194","title":"The BioPlex Network: A Systematic Exploration of the Human Interactome.","date":"2015","source":"Cell","url":"https://pubmed.ncbi.nlm.nih.gov/26186194","citation_count":1118,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"28514442","id":"PMC_28514442","title":"Architecture of the human interactome defines protein communities and disease networks.","date":"2017","source":"Nature","url":"https://pubmed.ncbi.nlm.nih.gov/28514442","citation_count":1085,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"26496610","id":"PMC_26496610","title":"A human interactome in three quantitative dimensions organized by stoichiometries and abundances.","date":"2015","source":"Cell","url":"https://pubmed.ncbi.nlm.nih.gov/26496610","citation_count":1015,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"22504420","id":"PMC_22504420","title":"Genome-wide meta-analysis identifies 56 bone mineral density loci and reveals 14 loci associated with risk of fracture.","date":"2012","source":"Nature genetics","url":"https://pubmed.ncbi.nlm.nih.gov/22504420","citation_count":958,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"19490893","id":"PMC_19490893","title":"A genome-wide RNAi screen identifies multiple synthetic lethal interactions with the Ras oncogene.","date":"2009","source":"Cell","url":"https://pubmed.ncbi.nlm.nih.gov/19490893","citation_count":843,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"29507755","id":"PMC_29507755","title":"VIRMA mediates preferential m6A mRNA methylation in 3'UTR and near stop codon and associates with alternative polyadenylation.","date":"2018","source":"Cell discovery","url":"https://pubmed.ncbi.nlm.nih.gov/29507755","citation_count":829,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"14702039","id":"PMC_14702039","title":"Complete sequencing and characterization of 21,243 full-length human cDNAs.","date":"2003","source":"Nature genetics","url":"https://pubmed.ncbi.nlm.nih.gov/14702039","citation_count":754,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"11535616","id":"PMC_11535616","title":"Checkpoint inhibition of the APC/C in HeLa cells is mediated by a complex of BUBR1, BUB3, CDC20, and MAD2.","date":"2001","source":"The Journal of cell biology","url":"https://pubmed.ncbi.nlm.nih.gov/11535616","citation_count":726,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"33961781","id":"PMC_33961781","title":"Dual proteome-scale networks reveal cell-specific remodeling of the human interactome.","date":"2021","source":"Cell","url":"https://pubmed.ncbi.nlm.nih.gov/33961781","citation_count":705,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"22939629","id":"PMC_22939629","title":"A census of human soluble protein complexes.","date":"2012","source":"Cell","url":"https://pubmed.ncbi.nlm.nih.gov/22939629","citation_count":689,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"21873635","id":"PMC_21873635","title":"Phylogenetic-based propagation of functional annotations within the Gene Ontology consortium.","date":"2011","source":"Briefings in bioinformatics","url":"https://pubmed.ncbi.nlm.nih.gov/21873635","citation_count":656,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"22190034","id":"PMC_22190034","title":"Global landscape of HIV-human protein complexes.","date":"2011","source":"Nature","url":"https://pubmed.ncbi.nlm.nih.gov/22190034","citation_count":593,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"18485873","id":"PMC_18485873","title":"Mechanism of ubiquitin-chain formation by the human anaphase-promoting complex.","date":"2008","source":"Cell","url":"https://pubmed.ncbi.nlm.nih.gov/18485873","citation_count":442,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"22014574","id":"PMC_22014574","title":"SIRT2 maintains genome integrity and suppresses tumorigenesis through regulating APC/C activity.","date":"2011","source":"Cancer cell","url":"https://pubmed.ncbi.nlm.nih.gov/22014574","citation_count":441,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"15489334","id":"PMC_15489334","title":"The status, quality, and expansion of the NIH full-length cDNA project: the Mammalian Gene Collection (MGC).","date":"2004","source":"Genome research","url":"https://pubmed.ncbi.nlm.nih.gov/15489334","citation_count":438,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"26638075","id":"PMC_26638075","title":"A Dynamic Protein Interaction Landscape of the Human Centrosome-Cilium Interface.","date":"2015","source":"Cell","url":"https://pubmed.ncbi.nlm.nih.gov/26638075","citation_count":433,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"35271311","id":"PMC_35271311","title":"OpenCell: Endogenous tagging for the cartography of human cellular organization.","date":"2022","source":"Science (New York, N.Y.)","url":"https://pubmed.ncbi.nlm.nih.gov/35271311","citation_count":432,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"20360068","id":"PMC_20360068","title":"Systematic analysis of human protein complexes identifies chromosome segregation proteins.","date":"2010","source":"Science (New York, N.Y.)","url":"https://pubmed.ncbi.nlm.nih.gov/20360068","citation_count":421,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"26344197","id":"PMC_26344197","title":"Panorama of ancient metazoan macromolecular complexes.","date":"2015","source":"Nature","url":"https://pubmed.ncbi.nlm.nih.gov/26344197","citation_count":407,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"24255178","id":"PMC_24255178","title":"Protein interaction network of the mammalian Hippo pathway reveals mechanisms of kinase-phosphatase interactions.","date":"2013","source":"Science signaling","url":"https://pubmed.ncbi.nlm.nih.gov/24255178","citation_count":383,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"11285280","id":"PMC_11285280","title":"Anaphase-promoting complex/cyclosome-dependent proteolysis of human cyclin A starts at the beginning of mitosis and is not subject to the spindle assembly checkpoint.","date":"2001","source":"The Journal of cell biology","url":"https://pubmed.ncbi.nlm.nih.gov/11285280","citation_count":372,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"17643375","id":"PMC_17643375","title":"Systematic analysis of the protein interaction network for the human transcription machinery reveals the identity of the 7SK capping enzyme.","date":"2007","source":"Molecular cell","url":"https://pubmed.ncbi.nlm.nih.gov/17643375","citation_count":367,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"10793135","id":"PMC_10793135","title":"Mitotic regulation of the APC activator proteins CDC20 and CDH1.","date":"2000","source":"Molecular biology of the cell","url":"https://pubmed.ncbi.nlm.nih.gov/10793135","citation_count":363,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"11076961","id":"PMC_11076961","title":"Characterization of vertebrate cohesin complexes and their regulation in prophase.","date":"2000","source":"The Journal of cell biology","url":"https://pubmed.ncbi.nlm.nih.gov/11076961","citation_count":358,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"14657031","id":"PMC_14657031","title":"Mitotic regulation of the human anaphase-promoting complex by phosphorylation.","date":"2003","source":"The EMBO journal","url":"https://pubmed.ncbi.nlm.nih.gov/14657031","citation_count":341,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"34079125","id":"PMC_34079125","title":"A proximity-dependent biotinylation map of a human cell.","date":"2021","source":"Nature","url":"https://pubmed.ncbi.nlm.nih.gov/34079125","citation_count":339,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"21633387","id":"PMC_21633387","title":"Cubism and the cell cycle: the many faces of the APC/C.","date":"2011","source":"Nature reviews. Molecular cell biology","url":"https://pubmed.ncbi.nlm.nih.gov/21633387","citation_count":323,"is_preprint":false,"source_track":"gene2pubmed"}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":18987,"output_tokens":3116,"usd":0.051851},"stage2":{"model":"claude-opus-4-6","input_tokens":6447,"output_tokens":2933,"usd":0.15834},"total_usd":0.449875,"stage1_batch_id":"msgbatch_01TqNM6p6FsoMBT2jzQTwKBr","stage2_batch_id":"msgbatch_01Ya473eco8sTHbvRymQaU8o","note":"batch pricing = 50% of standard","round2_stage1":{"model":"claude-sonnet-4-6","input_tokens":30875,"output_tokens":3394,"usd":0.071767},"round2_rules_fired":"R3","round2_stage2":{"model":"claude-opus-4-6","input_tokens":6969,"output_tokens":3084,"usd":0.167917}},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2016,\n      \"finding\": \"The WD40 domain of Apc1 (Apc1(WD40)) is required for the coactivator (Cdh1)-induced allosteric conformational change of the APC/C that allows UbcH10 binding to the catalytic module, thereby stimulating APC/C-dependent ubiquitination of substrates. Deletion of Apc1(WD40) abolishes UbcH10-dependent ubiquitination without impairing Ube2S-dependent chain elongation, and locks the APC/C in an inactive conformation with an inaccessible UbcH10-binding site.\",\n      \"method\": \"Crystal structure of human Apc1 N-terminal domain (2.2 Å), cryo-EM of APC/C-Cdh1 with Apc1(WD40) deletion, in vitro ubiquitination assays with mutant APC/C\",\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 plus cryo-EM plus in vitro reconstitution with deletion mutant, multiple orthogonal methods in single study\",\n      \"pmids\": [\"27601667\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"A disordered loop domain of Apc1 (Apc1-loop500) directly binds the B56 regulatory subunit of PP2A. PP2A-B56 binding to Apc1-loop500 promotes dephosphorylation of Cdc20, thereby stimulating Cdc20 loading onto the APC/C and APC/C-dependent ubiquitylation. Mutations in Apc1-loop500 abolishing B56 binding decrease Cdc20 loading; a non-phosphorylatable Cdc20 mutant bypasses the requirement for PP2A-B56.\",\n      \"method\": \"APC/C reconstitution in Xenopus egg extracts, mutagenesis of Apc1-loop500, in vitro ubiquitylation assays, co-immunoprecipitation\",\n      \"journal\": \"EMBO reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — reconstitution in Xenopus extracts with mutagenesis and functional ubiquitylation assays\",\n      \"pmids\": [\"31825153\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"Polo-like kinase (Plx1) directly binds the Apc1-loop500 in a phosphorylation-dependent manner and promotes APC/C-Cdc20 formation via Apc3 phosphorylation. PP2A-B56 is recruited to Apc1-loop500 upon phosphorylation of loop residue T532 and differentially promotes dissociation of Plx1 and PP2A-B56 through dephosphorylation of Plx1-binding sites. The phosphorylation status of Apc1-loop500 is additionally controlled by distant Apc3-loop phosphorylation, establishing a phosphorylation-dependent feedback loop.\",\n      \"method\": \"Xenopus egg extract APC/C reconstitution, mutagenesis of Apc1-loop500 and Apc3-loop, kinase assays, phosphoproteomics\",\n      \"journal\": \"The EMBO journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — reconstitution plus mutagenesis plus mechanistic dissection of Plx1/PP2A-B56 interplay\",\n      \"pmids\": [\"34291488\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"Apc1-loop300 (Apc1-300L) is a primary substrate of the CDK1–PP2A-B55 phosphorylation axis that controls APC/C activity and cell cycle oscillation. Premature PP2A-B55 activation (via Greatwall kinase depletion) leads to Apc1-300L dephosphorylation, stalling APC/C activity and delaying Cyclin B degradation. Dephosphorylation of Apc1-300L specifically inhibits Cdc20 recruitment to the APC/C, and removal of Apc1-300L counteracts this inhibition.\",\n      \"method\": \"Xenopus egg extract APC/C reconstitution, Greatwall kinase depletion, pEnsa (B55-specific inhibitor), Apc1-300L deletion mutant, phosphoproteomics\",\n      \"journal\": \"Cell reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — reconstitution with genetic and chemical perturbations, multiple orthogonal approaches\",\n      \"pmids\": [\"38678563\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2001,\n      \"finding\": \"Human APC1 is the largest subunit of the APC/C ubiquitin ligase complex; it is expressed at relatively constant levels alongside other APC/C subunits across tissues, consistent with it functioning as a core scaffold component of the complex.\",\n      \"method\": \"Full-length human APC1 cDNA sequencing, chromosomal mapping, intron-exon boundary analysis, RNA/protein expression analysis across tissues and cell lines, EST analysis\",\n      \"journal\": \"Gene\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — characterization of human cDNA and protein expression, single lab, no direct functional reconstitution\",\n      \"pmids\": [\"11179667\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"ANAPC1 encodes a scaffold subunit of the APC/C; biallelic loss-of-function mutations (deep intronic splicing mutation activating a 95 bp pseudoexon causing NMD) decrease ANAPC1 protein levels, prolong interphase, and cause Rothmund-Thomson syndrome type 1. Mice heterozygous for a knockout mutation have increased incidence of cataracts.\",\n      \"method\": \"Patient fibroblast studies, mRNA splicing analysis, protein level quantification, cell cycle duration measurement, mouse heterozygous knockout model\",\n      \"journal\": \"American journal of human genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — defined cellular phenotype (prolonged interphase) from loss-of-function with molecular mechanism identified in patient cells\",\n      \"pmids\": [\"31303264\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"Drosophila Apc1 (encoded by shattered/shtd) is required for G1 arrest in the morphogenetic furrow and for proper progression through mitosis; loss of Apc1 causes accumulation of Cyclin A and String (Cdc25) proteins. Genetic reduction of Cyclin A dosage suppresses premature S-phase entry, while reduction of String dosage suppresses the mitotic progression defect.\",\n      \"method\": \"Drosophila genetics — shtd1 mutant analysis, genetic epistasis (CycA and stg dosage reduction), immunostaining for cell cycle markers\",\n      \"journal\": \"Developmental biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — genetic epistasis in Drosophila ortholog with defined cellular phenotype and suppressor analysis\",\n      \"pmids\": [\"17689521\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"HCMV protein UL21a induces proteasome-dependent degradation of APC1 (in addition to APC4 and APC5), disrupting APC/C function and causing accumulation of APC/C substrates. Additionally, depletion of any single APC/C platform subunit (APC1, APC4, or APC5) or of APC8 triggers a coordinated decrease in levels of all three platform subunits via a cellular mechanism.\",\n      \"method\": \"UL21a expression in uninfected cells, siRNA knockdown of APC subunits, proteasome inhibitor experiments, APC/C substrate accumulation assays\",\n      \"journal\": \"Journal of virology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — loss-of-function with defined substrate accumulation phenotype, multiple perturbations\",\n      \"pmids\": [\"25903336\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"HIV-1 Vpr forms a complex with APC1 and induces DCAF1-dependent, proteasome-mediated degradation of APC1. APC/C coactivators Cdh1 and Cdc20 are associated with Vpr-APC1 complexes. APC1 degradation is a conserved feature of primary Vpr variants from transmitted/founder viruses but does not impact Vpr-induced G2 arrest or enhancement of HIV-1 replication in macrophages.\",\n      \"method\": \"BioID proximity labeling, co-immunoprecipitation, DCAF1 knockdown, proteasome inhibitor treatment, mutant Vpr analysis\",\n      \"journal\": \"Journal of virology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 — reciprocal co-IP and proximity labeling with functional validation using knockdown of required factors\",\n      \"pmids\": [\"34011540\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"Cryo-EM comparative structures of S. cerevisiae and human APC/C reveal that the phospho-regulatable auto-inhibitory segment of Apc1, which in unphosphorylated human APC/C sterically blocks the CDC20 C-box binding site of APC8, is absent in S. cerevisiae APC/C, explaining mechanistic differences in APC/C-CDC20 activation between species.\",\n      \"method\": \"Cryo-EM structures of yeast apo-APC/C, APC/C-CDH1-substrate, and phosphorylated apo-APC/C compared with human APC/C\",\n      \"journal\": \"bioRxiv (preprint)\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 method (cryo-EM), but preprint and single study without mutagenesis validation\",\n      \"pmids\": [\"bio_10.1101_2024.06.19.599685\"],\n      \"is_preprint\": true\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"In fission yeast (S. pombe), the Cut4/Apc1 subunit of APC/C interacts with Swi6/HP1 and Clr4/Suv39 to regulate heterochromatin assembly; a mutant form (sng2-1) shows defective Swi6 binding and recruitment, abrogating heterochromatin structure.\",\n      \"method\": \"Fission yeast genetics, binding assays, heterochromatin silencing assays (referenced in 2024 papers citing earlier work)\",\n      \"journal\": \"Nucleic acids research (2024 prion paper referencing earlier finding)\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 — fungal ortholog, single lab, mechanistic details inferred from 2024 paper description of prior work\",\n      \"pmids\": [\"39565210\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"ANAPC1 encodes the largest scaffold subunit of the APC/C E3 ubiquitin ligase; its WD40 domain mediates the coactivator-induced allosteric conformational change required for UbcH10-dependent ubiquitination, while two flexible loop domains (Apc1-loop500 and Apc1-loop300) serve as phosphorylation-regulated hubs that integrate CDK1, Plx1/PLK1, PP2A-B56, and PP2A-B55 signaling to control Cdc20 co-activator loading and APC/C activity during mitotic entry and exit.\"\n}\n```\n\n--- ROUND 2 (R2/R3, augmented corpus) ---\n\n```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2001,\n      \"finding\": \"Human APC1 (the largest subunit of the APC/C) was fully sequenced, its chromosomal location mapped, and intron-exon boundaries analyzed. APC/C subunits including APC1 are expressed at fairly constant levels relative to each other across most tissues, consistent with their function as part of a stable complex.\",\n      \"method\": \"Full-length cDNA sequencing, chromosomal mapping, Northern blot/RT-PCR expression analysis\",\n      \"journal\": \"Gene\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — direct molecular characterization of human APC1, single lab\",\n      \"pmids\": [\"11179667\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"APC/C phosphorylation by Cdk1 in mitosis generates at least 32 mitosis-specific phosphorylation sites clustered in Apc1 and TPR subunits; phosphorylation of APC (but not Plk1 activity alone) is sufficient for increased Cdc20 binding and APC activation, and APC phosphorylation is initiated in prophase during nuclear uptake of cyclin B1.\",\n      \"method\": \"Mass spectrometry identification of phospho-sites on immunopurified APC/C; in vitro kinase assays with Cdk1/Plk1; immunofluorescence with phospho-specific antibodies; Plk1 depletion experiments\",\n      \"journal\": \"The EMBO journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — multiple orthogonal methods (MS, in vitro kinase assay, immunofluorescence, depletion), replicated across labs\",\n      \"pmids\": [\"14657031\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"In Drosophila, the shattered (shtd) gene encodes Apc1, the largest subunit of the APC/C. Loss of Apc1 causes failure to establish G1 arrest and defects in progression through mitosis, accompanied by accumulation of Cyclin A and String (Cdc25) proteins. Genetic reduction of CycA or string dosage suppresses the shtd phenotype, placing Apc1 upstream of these substrates in cell cycle control.\",\n      \"method\": \"Genetic mutant analysis, immunostaining for cell cycle markers, genetic epistasis (dosage suppression)\",\n      \"journal\": \"Developmental biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — genetic epistasis with multiple substrates, ortholog in model organism consistent with mammalian APC1 function\",\n      \"pmids\": [\"17689521\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"Human cytomegalovirus (HCMV) protein UL21a induces the proteasomal degradation of APC1 (in addition to APC4 and APC5). UL21a is necessary and sufficient to degrade APC1. Furthermore, depletion of any single platform subunit (APC1, APC4, or APC5) or of APC8 in uninfected cells leads to co-degradation of all three platform subunits, revealing a cellular mechanism for coordinated downregulation of the APC/C platform subcomplex.\",\n      \"method\": \"siRNA knockdown, overexpression of viral proteins, Western blotting, APC/C substrate accumulation assays\",\n      \"journal\": \"Journal of virology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple knockdown/overexpression experiments with mechanistic follow-up, identification of novel cellular co-degradation mechanism\",\n      \"pmids\": [\"25903336\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"The WD40 domain of Apc1 (Apc1(WD40)) is required for the coactivator (Cdh1)-induced allosteric conformational change of the APC/C that stimulates UbcH10-dependent ubiquitination of substrates (chain initiation). Deletion of Apc1(WD40) abolishes UbcH10-dependent ubiquitination but does not impair Ube2S-dependent ubiquitin chain elongation. Crystal structure of the N-terminal WD40 domain of human Apc1 was determined at 2.2 Å resolution; cryo-EM of APC/C-Cdh1 with Apc1(WD40) deleted showed the catalytic module locked in an inactive conformation with inaccessible UbcH10-binding site and loss of Apc15 density.\",\n      \"method\": \"Crystal structure (2.2 Å), cryo-EM, WD40 deletion mutant APC/C reconstitution, in vitro ubiquitination assays with UbcH10 and Ube2S\",\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 + reconstituted in vitro assays + mutagenesis in single study\",\n      \"pmids\": [\"27601667\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"Mutations in ANAPC1 cause Rothmund-Thomson syndrome type 1 (RTS1). A deep intronic splicing mutation activates a 95 bp pseudoexon, causing premature termination codons, nonsense-mediated decay, decreased ANAPC1 protein levels, and prolongation of interphase in patient fibroblasts. Mice heterozygous for an Anapc1 knockout show increased cataract incidence, linking APC/C deficiency to the RTS1 phenotype.\",\n      \"method\": \"Exome/targeted sequencing, RT-PCR splice analysis, Western blot for ANAPC1 protein in fibroblasts, cell cycle analysis of patient fibroblasts, mouse knockout model\",\n      \"journal\": \"American journal of human genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal methods (molecular, cellular, mouse model), replicated across 7 families\",\n      \"pmids\": [\"31303264\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"A disordered loop domain of Apc1 (Apc1-loop500) directly binds the B56 regulatory subunit of PP2A and promotes Cdc20 loading onto the APC/C. Mutations in Apc1-loop500 that abolish B56 binding decrease Cdc20 loading and APC/C-dependent ubiquitylation in Xenopus egg extract reconstitution. PP2A-B56 preferentially dephosphorylates Cdc20 over the Apc1 inhibitory domain, facilitating APC/C-Cdc20 complex formation in mitosis.\",\n      \"method\": \"APC/C reconstitution in Xenopus egg extracts, mutagenesis of Apc1-loop500, co-immunoprecipitation, in vitro ubiquitination assays, non-phosphorylatable Cdc20 mutant rescue\",\n      \"journal\": \"EMBO reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — reconstitution system, mutagenesis, multiple orthogonal assays in single study\",\n      \"pmids\": [\"31825153\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"HIV-1 Vpr mediates degradation of APC1 via DCAF1 recruitment and the proteasome. Vpr forms a complex with APC1, and the APC/C coactivators Cdh1 and Cdc20 are associated with these complexes. APC1 degradation is a conserved feature of several primary Vpr variants from transmitted/founder HIV-1 viruses, though it does not impact Vpr-mediated G2 arrest or HIV replication in macrophages.\",\n      \"method\": \"BioID proximity labeling, co-immunoprecipitation, Western blot for APC1 degradation, proteasome inhibitor rescue, mutant Vpr analysis\",\n      \"journal\": \"Journal of virology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — BioID + Co-IP + functional degradation assays, single lab\",\n      \"pmids\": [\"34011540\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"Plx1 (polo-like kinase) directly binds the Apc1-loop500 domain in a phosphorylation-dependent manner and promotes APC/C-Cdc20 formation via Apc3 phosphorylation. Upon phosphorylation of loop residue T532, PP2A-B56 is recruited to Apc1-loop500 and differentially promotes dissociation of Plx1 through dephosphorylation of Plx1-binding sites, while stable Plx1 binding prevents PP2A-B56 recruitment and prematurely activates APC/C. The phosphorylation status of Apc1-loop500 is controlled by distant Apc3-loop phosphorylation, revealing a phosphorylation-dependent feedback within the APC/C.\",\n      \"method\": \"Xenopus egg extract reconstitution, site-directed mutagenesis, phospho-specific binding assays, kinase/phosphatase manipulation\",\n      \"journal\": \"The EMBO journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — reconstitution system with mutagenesis and multiple kinase/phosphatase perturbations\",\n      \"pmids\": [\"34291488\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"Phospho-regulation of Apc1-loop300 (Apc1-300L) by CDK1 and PP2A-B55 is pivotal for cell cycle oscillation. Premature PP2A-B55 activation (via Greatwall kinase depletion) leads to Apc1-300L dephosphorylation, stalling APC/C activity and delaying Cyclin B degradation; this effect is counteracted by B55-specific inhibitor pEnsa or by removing Apc1-300L. Dephosphorylation of Apc1-300L specifically inhibits Cdc20 recruitment to the APC/C, identifying APC/C as a primary substrate of the CDK-PP2A-B55 partnership for cell cycle oscillation.\",\n      \"method\": \"Xenopus egg extract assays, Greatwall kinase depletion, pEnsa inhibitor, Apc1-300L deletion mutants, Cdc20 binding assays across cell cycle stages\",\n      \"journal\": \"Cell reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — reconstitution with genetic and pharmacological perturbations, multiple orthogonal approaches\",\n      \"pmids\": [\"38678563\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"Cryo-EM comparison of S. cerevisiae and human APC/C reveals that, unlike human APC/C, yeast apo-APC/C has the catalytic module already positioned to bind E2 without requiring coactivator-induced conformational change. Furthermore, no evidence for a phospho-regulatable auto-inhibitory segment of Apc1 (equivalent to the human Apc1 inhibitory loop that sterically blocks the CDC20 C-box binding site on APC8 in unphosphorylated human APC/C) is found in yeast, demonstrating species-specific regulatory differences in the Apc1-mediated auto-inhibition mechanism.\",\n      \"method\": \"Cryo-EM structures of yeast apo-APC/C, APC/C-CDH1-substrate ternary complex, and phosphorylated apo-APC/C; comparative structural analysis with human APC/C\",\n      \"journal\": \"bioRxiv\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 — cryo-EM structural analysis, preprint, not yet peer-reviewed\",\n      \"pmids\": [\"bio_10.1101_2024.06.19.599685\"],\n      \"is_preprint\": true\n    }\n  ],\n  \"current_model\": \"ANAPC1 encodes the largest scaffolding subunit of the APC/C E3 ubiquitin ligase; its WD40 domain mediates coactivator-induced allosteric activation for UbcH10-dependent ubiquitin chain initiation, while its flexible loop domains (loop300 and loop500) are phospho-regulated by CDK1/Plk1 and dephosphorylated by PP2A-B55/B56 to control Cdc20 co-activator loading, APC/C activity, and cell cycle oscillation; loss-of-function mutations in humans cause Rothmund-Thomson syndrome type 1, and viral proteins (HCMV UL21a, HIV-1 Vpr) target APC1 for proteasomal degradation to subvert cell cycle control.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"ANAPC1 encodes the largest scaffold subunit of the anaphase-promoting complex/cyclosome (APC/C), an essential E3 ubiquitin ligase that drives cell cycle progression by targeting mitotic cyclins and other substrates for proteasomal degradation. Its N-terminal WD40 domain mediates a coactivator-induced allosteric conformational change that exposes the UbcH10-binding site on the catalytic module, a step required for E2-dependent substrate ubiquitination [PMID:27601667]. Two intrinsically disordered loops—Apc1-loop500 and Apc1-loop300—serve as phosphorylation-regulated signaling hubs: Apc1-loop500 recruits both Plx1/PLK1 and PP2A-B56 in a phosphorylation-dependent manner to control Cdc20 loading, while Apc1-loop300 is a primary target of the CDK1–PP2A-B55 axis whose dephosphorylation inhibits Cdc20 recruitment and delays cyclin B degradation, thereby coupling APC/C activation to mitotic entry and exit [PMID:31825153, PMID:34291488, PMID:38678563]. Biallelic loss-of-function mutations in ANAPC1 that reduce protein levels cause Rothmund-Thomson syndrome type 1, characterized by prolonged interphase in patient fibroblasts [PMID:31303264].\",\n  \"teleology\": [\n    {\n      \"year\": 2001,\n      \"claim\": \"Cloning of full-length human APC1 established it as the largest APC/C subunit with constitutive expression across tissues, consistent with a core scaffold role rather than a regulatory one.\",\n      \"evidence\": \"cDNA sequencing, chromosomal mapping, and RNA/protein expression profiling across human tissues and cell lines\",\n      \"pmids\": [\"11179667\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"No direct functional assay demonstrating scaffold activity\",\n        \"Protein–protein interactions within the APC/C not mapped\"\n      ]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"Study of the S. pombe ortholog Cut4/Apc1 suggested a non-canonical role in heterochromatin assembly through interaction with Swi6/HP1 and Clr4/Suv39, raising the question of whether APC1 functions extend beyond ubiquitin-dependent proteolysis.\",\n      \"evidence\": \"Fission yeast genetics and binding assays with heterochromatin silencing readouts\",\n      \"pmids\": [\"39565210\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\n        \"Finding described only through a later paper's reference to earlier work; primary data not independently assessed\",\n        \"No evidence this heterochromatin function is conserved in vertebrates\",\n        \"Mechanism linking APC/C scaffold to heterochromatin unclear\"\n      ]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Genetic analysis of Drosophila Apc1 (shattered) demonstrated that APC1 is required for both G1 arrest and mitotic progression through its role in degrading Cyclin A and String/Cdc25, providing the first in vivo epistasis-based evidence for APC1's function in cell cycle substrate turnover.\",\n      \"evidence\": \"Drosophila shtd1 mutant analysis with genetic epistasis (CycA and stg dosage reduction) and immunostaining\",\n      \"pmids\": [\"17689521\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Drosophila ortholog; direct biochemical mechanism not addressed\",\n        \"Contribution of APC1 versus other APC/C subunits not distinguished\"\n      ]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Discovery that HCMV UL21a targets APC1 (along with APC4 and APC5) for proteasomal degradation revealed that APC1 is a platform subunit whose loss triggers coordinated destabilization of other platform subunits, establishing interdependence among APC/C structural components.\",\n      \"evidence\": \"UL21a expression in uninfected cells, siRNA knockdown of individual APC subunits, proteasome inhibitor rescue, substrate accumulation assays\",\n      \"pmids\": [\"25903336\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Mechanism of coordinated platform subunit degradation unknown\",\n        \"Structural basis for platform subunit interdependence not resolved\"\n      ]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Structural and biochemical dissection of the Apc1 WD40 domain revealed the first defined catalytic-regulation mechanism within APC1: this domain is required for coactivator-induced allosteric opening of the UbcH10-binding site, directly coupling APC1 conformation to E2 engagement.\",\n      \"evidence\": \"2.2 Å crystal structure of Apc1 N-terminal domain, cryo-EM of APC/C–Cdh1 with Apc1(WD40) deletion, in vitro ubiquitination assays\",\n      \"pmids\": [\"27601667\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"How phosphorylation of other APC1 regions influences WD40-mediated conformational change was unknown\",\n        \"In vivo validation of WD40-deletion phenotype not performed\"\n      ]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Identification of Apc1-loop500 as a PP2A-B56 docking site that promotes Cdc20 dephosphorylation and loading onto APC/C established the first phosphatase-recruitment mechanism on a specific APC/C subunit, explaining how phospho-regulation controls coactivator binding.\",\n      \"evidence\": \"Xenopus egg extract APC/C reconstitution, Apc1-loop500 mutagenesis, in vitro ubiquitylation, co-immunoprecipitation\",\n      \"pmids\": [\"31825153\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Whether Apc1-loop500 recruits additional signaling factors was unknown\",\n        \"Structural basis of loop500–B56 interaction not resolved\"\n      ]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Biallelic loss-of-function mutations in ANAPC1 were identified as the genetic cause of Rothmund-Thomson syndrome type 1, demonstrating that partial APC/C insufficiency due to reduced APC1 protein prolongs interphase and leads to a recognizable human developmental disorder.\",\n      \"evidence\": \"Patient fibroblast studies, mRNA splicing analysis, protein quantification, cell cycle duration measurement, heterozygous mouse knockout model\",\n      \"pmids\": [\"31303264\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Precise APC/C substrates responsible for the developmental phenotype not identified\",\n        \"Whether residual APC/C activity or alternative E3 ligases partially compensate is unknown\"\n      ]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Polo-like kinase Plx1 was shown to bind Apc1-loop500 in a phosphorylation-dependent manner alongside PP2A-B56, with a feedback loop involving Apc3-loop phosphorylation; this revealed that Apc1-loop500 is a multi-kinase/phosphatase signaling hub integrating PLK1 and PP2A inputs to tune APC/C–Cdc20 formation.\",\n      \"evidence\": \"Xenopus egg extract reconstitution, Apc1-loop500 and Apc3-loop mutagenesis, kinase assays, phosphoproteomics\",\n      \"pmids\": [\"34291488\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Structural basis of Plx1–loop500 interaction not resolved at atomic level\",\n        \"Whether this feedback operates identically in human cells was untested\"\n      ]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"HIV-1 Vpr was found to hijack APC1 for DCAF1-dependent proteasomal degradation, establishing APC1 as a conserved viral target across unrelated viruses (HCMV and HIV-1), though the biological advantage of APC1 destruction for HIV-1 replication remained unclear.\",\n      \"evidence\": \"BioID proximity labeling, co-immunoprecipitation, DCAF1 knockdown, proteasome inhibitor treatment, mutant Vpr analysis in macrophages\",\n      \"pmids\": [\"34011540\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Functional consequence of APC1 degradation for HIV-1 biology not established\",\n        \"Whether APC1 degradation affects the cell cycle in infected macrophages not resolved\"\n      ]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Apc1-loop300 was identified as a primary CDK1–PP2A-B55 substrate whose phosphorylation state directly controls Cdc20 recruitment and cyclin B degradation timing, establishing a second phospho-regulatory loop on APC1 distinct from loop500.\",\n      \"evidence\": \"Xenopus egg extract reconstitution, Greatwall kinase depletion, pEnsa inhibitor, Apc1-loop300 deletion mutant, phosphoproteomics\",\n      \"pmids\": [\"38678563\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Structural mechanism by which loop300 phosphorylation promotes or blocks Cdc20 binding not resolved\",\n        \"Cross-talk between loop300 and loop500 phospho-regulation not fully dissected\"\n      ]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"The interplay between Apc1-loop300 (CDK1/PP2A-B55 axis) and Apc1-loop500 (PLK1/PP2A-B56 axis) in coordinating mitotic APC/C activation has been individually characterized, but how these two regulatory loops are integrated quantitatively in human cells and how they relate to the WD40-mediated conformational switch remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"No reconstitution integrating both loop regulatory axes with the WD40 conformational switch simultaneously\",\n        \"In vivo validation in human cells for most phospho-regulatory mechanisms (primarily characterized in Xenopus extracts)\",\n        \"Structural basis of loop300 and loop500 auto-inhibitory conformations at atomic resolution not determined\"\n      ]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [0, 1, 2, 3]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [0, 1, 3]}\n    ],\n    \"localization\": [],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-1640170\", \"supporting_discovery_ids\": [0, 1, 2, 3, 5, 6]},\n      {\"term_id\": \"R-HSA-392499\", \"supporting_discovery_ids\": [0, 1, 7]}\n    ],\n    \"complexes\": [\n      \"APC/C\"\n    ],\n    \"partners\": [\n      \"CDC20\",\n      \"CDH1\",\n      \"PPP2R5A\",\n      \"PLK1\",\n      \"ANAPC3\",\n      \"DCAF1\"\n    ],\n    \"other_free_text\": []\n  }\n}\n```\n\n--- ROUND 2 (R2/R3, augmented corpus) ---\n\n```json\n{\n  \"mechanistic_narrative\": \"ANAPC1 encodes the largest scaffolding subunit of the anaphase-promoting complex/cyclosome (APC/C), a multi-subunit E3 ubiquitin ligase essential for cell cycle progression through targeted degradation of mitotic cyclins and other substrates [PMID:17689521, PMID:25903336]. Its N-terminal WD40 domain mediates coactivator (Cdh1/Cdc20)-induced allosteric activation of the APC/C catalytic module, enabling UbcH10-dependent ubiquitin chain initiation on substrates [PMID:27601667]. Two disordered regulatory loops (loop300 and loop500) serve as phospho-regulated switches: CDK1/Plk1 phosphorylation and PP2A-B55/B56-mediated dephosphorylation of these loops control Cdc20 co-activator loading and thereby couple APC/C activity to cell cycle oscillation [PMID:31825153, PMID:34291488, PMID:38678563]. Loss-of-function mutations in ANAPC1 cause Rothmund-Thomson syndrome type 1, characterized by reduced ANAPC1 protein, prolonged interphase, and increased cataract incidence in a heterozygous mouse model [PMID:31303264].\",\n  \"teleology\": [\n    {\n      \"year\": 2001,\n      \"claim\": \"Full-length sequencing and chromosomal mapping of human ANAPC1 established its identity as the largest APC/C subunit and showed that APC/C subunits are co-expressed at stable stoichiometric ratios across tissues, consistent with a constitutive multi-subunit complex.\",\n      \"evidence\": \"cDNA sequencing, chromosomal mapping, Northern blot/RT-PCR across human tissues\",\n      \"pmids\": [\"11179667\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single-lab characterization without functional assays\", \"No structural information on APC1 domains\", \"Tissue-level expression data lacks single-cell resolution\"]\n    },\n    {\n      \"year\": 2003,\n      \"claim\": \"Mass spectrometry-based phospho-mapping revealed that mitotic CDK1 phosphorylation of APC/C is concentrated on Apc1 and TPR subunits, and that this phosphorylation is sufficient to promote Cdc20 binding and APC/C activation—establishing phospho-regulation as the primary mechanism for mitotic APC/C activation.\",\n      \"evidence\": \"Mass spectrometry of immunopurified APC/C, in vitro Cdk1/Plk1 kinase assays, phospho-specific immunofluorescence, Plk1 depletion\",\n      \"pmids\": [\"14657031\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Specific Apc1 phospho-sites responsible for Cdc20 binding were not individually assigned\", \"Phosphatase(s) counteracting CDK1 on APC/C not yet identified\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Genetic analysis of Drosophila apc1 (shattered) mutants demonstrated that APC1 is required for G1 establishment and mitotic progression through degradation of Cyclin A and String/Cdc25, providing in vivo epistatic evidence placing APC1 upstream of key cell cycle substrates.\",\n      \"evidence\": \"Drosophila genetic mutant analysis, immunostaining, genetic dosage suppression of CycA and string\",\n      \"pmids\": [\"17689521\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Invertebrate model; direct mapping to mammalian APC1 regulatory domains not performed\", \"No biochemical reconstitution of Drosophila APC/C activity\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Discovery that HCMV protein UL21a targets APC1 for proteasomal degradation, and that loss of any single platform subunit (APC1, APC4, APC5) triggers coordinated co-degradation of the others, revealed both a viral immune-evasion strategy and an intrinsic quality-control mechanism for the APC/C platform subcomplex.\",\n      \"evidence\": \"siRNA knockdowns of individual platform subunits, viral protein overexpression, Western blot, substrate accumulation assays\",\n      \"pmids\": [\"25903336\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"E3 ligase mediating cellular co-degradation not identified\", \"Functional consequence of partial APC/C platform loss on specific substrates not quantified\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Crystal structure of the Apc1 WD40 domain and cryo-EM of WD40-deleted APC/C revealed that Apc1-WD40 is required for coactivator-induced repositioning of the catalytic module to an active conformation that exposes the UbcH10-binding site—mechanistically separating chain initiation (UbcH10-dependent, WD40-dependent) from chain elongation (Ube2S-dependent, WD40-independent).\",\n      \"evidence\": \"2.2 Å crystal structure, cryo-EM of ΔWD40 APC/C-Cdh1, in vitro ubiquitination with UbcH10 and Ube2S\",\n      \"pmids\": [\"27601667\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How WD40 domain communicates allosteric signal to catalytic module at atomic resolution remains incomplete\", \"Role of WD40 in Cdc20-mediated (vs Cdh1-mediated) activation not separately tested\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Identification of ANAPC1 mutations as the cause of Rothmund-Thomson syndrome type 1 in seven families connected APC/C deficiency to a human developmental disorder, with patient cells showing reduced ANAPC1 protein and prolonged interphase, and heterozygous knockout mice recapitulating the cataract phenotype.\",\n      \"evidence\": \"Exome/targeted sequencing across 7 families, RT-PCR splice analysis, Western blot of patient fibroblasts, cell cycle analysis, Anapc1+/- mouse model\",\n      \"pmids\": [\"31303264\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How partial APC/C loss causes the specific RTS1 spectrum (poikiloderma, cataracts) rather than broader cell cycle failure is unknown\", \"No rescue experiment restoring ANAPC1 in patient cells\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Reconstitution showed that Apc1-loop500 directly recruits PP2A-B56, which preferentially dephosphorylates Cdc20 over Apc1's inhibitory domain to promote Cdc20 loading—resolving how a phosphatase paradoxically activates APC/C during mitosis when most APC/C phosphorylation is activating.\",\n      \"evidence\": \"Xenopus egg extract reconstitution, Apc1-loop500 mutagenesis, co-immunoprecipitation, in vitro ubiquitination, non-phosphorylatable Cdc20 mutant rescue\",\n      \"pmids\": [\"31825153\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Quantitative kinetics of PP2A-B56 substrate selectivity on APC/C not measured\", \"Whether loop500-B56 interaction is conserved in human cells not directly tested\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Identification of a phosphorylation-dependent feedback loop in which Plk1 and PP2A-B56 compete for binding to Apc1-loop500 revealed that Plk1 binding is controlled by Apc3-loop phosphorylation—demonstrating inter-subunit phospho-communication within the APC/C and explaining how Plk1 and PP2A-B56 sequentially regulate APC/C activation timing.\",\n      \"evidence\": \"Xenopus egg extract reconstitution, site-directed mutagenesis of Apc1-loop500 and Apc3-loop, phospho-specific binding assays, kinase/phosphatase manipulation\",\n      \"pmids\": [\"34291488\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural basis for Plk1-loop500 vs B56-loop500 competitive binding not resolved\", \"In vivo validation in mammalian cells lacking\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"HIV-1 Vpr was found to target APC1 for DCAF1-dependent proteasomal degradation, representing a second independent viral strategy (after HCMV UL21a) to disable the APC/C, though the functional advantage for viral replication remains unclear.\",\n      \"evidence\": \"BioID proximity labeling, co-immunoprecipitation, Western blot, proteasome inhibitor rescue, mutant Vpr analysis\",\n      \"pmids\": [\"34011540\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"APC1 degradation did not affect G2 arrest or HIV replication in macrophages, so the biological purpose is unresolved\", \"Single-lab finding without independent replication\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Discovery that CDK1 phosphorylation of a second disordered loop, Apc1-loop300, and its dephosphorylation by PP2A-B55 is a primary node of the CDK-PP2A-B55 cell cycle oscillator—dephosphorylation of loop300 blocks Cdc20 recruitment and delays Cyclin B degradation, identifying the APC/C itself as a key PP2A-B55 substrate for mitotic exit control.\",\n      \"evidence\": \"Xenopus egg extract, Greatwall kinase depletion, pEnsa inhibitor, Apc1-300L deletion mutants, Cdc20 binding assays\",\n      \"pmids\": [\"38678563\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether loop300 and loop500 regulation are additive or sequential in vivo is not distinguished\", \"Mammalian in vivo validation of loop300 function not performed\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"The integrated structural and biochemical logic by which the two regulatory loops (loop300, loop500) coordinate with the WD40 domain and multiple kinases/phosphatases to produce the sharp activation switch of APC/C during mitotic progression remains to be resolved at atomic resolution in a single structural framework.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No full-length structure of phosphorylated human APC/C capturing loop300 and loop500 conformations simultaneously\", \"In vivo kinetic measurements of loop phosphorylation/dephosphorylation dynamics lacking in mammalian cells\", \"Mechanism by which partial APC1 loss produces the tissue-specific phenotypes of Rothmund-Thomson syndrome type 1 is unknown\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [4, 6, 8, 9]},\n      {\"term_id\": \"GO:0005198\", \"supporting_discovery_ids\": [0, 3, 4]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [1]},\n      {\"term_id\": \"GO:0005829\", \"supporting_discovery_ids\": [3]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-1640170\", \"supporting_discovery_ids\": [1, 2, 4, 6, 8, 9]},\n      {\"term_id\": \"R-HSA-392499\", \"supporting_discovery_ids\": [4, 6]},\n      {\"term_id\": \"R-HSA-1643685\", \"supporting_discovery_ids\": [5]}\n    ],\n    \"complexes\": [\"APC/C\"],\n    \"partners\": [\"CDC20\", \"CDH1\", \"PP2A-B56\", \"PP2A-B55\", \"PLK1\", \"ANAPC4\", \"ANAPC5\", \"ANAPC15\"],\n    \"other_free_text\": []\n  }\n}\n```"}