{"gene":"HAP1","run_date":"2026-04-28T18:06:53","timeline":{"discoveries":[{"year":1997,"finding":"HAP1 (huntingtin-associated protein 1) interacts with the p150Glued subunit of dynactin and with the pericentriolar protein PCM-1. The interaction with p150Glued was confirmed by in vitro GST pulldown and co-immunoprecipitation from brain extracts, and both proteins co-localize in NGF-treated PC12 cells, suggesting HAP1 functions as an adaptor linking cytoskeletal, vesicular, and motor proteins.","method":"GST pulldown, co-immunoprecipitation from brain extracts, double-label immunofluorescence confocal microscopy","journal":"Human molecular genetics","confidence":"High","confidence_rationale":"Tier 2 — reciprocal Co-IP in vivo plus in vitro GST pulldown, replicated with multiple methods","pmids":["9361024"],"is_preprint":false},{"year":1997,"finding":"HAP1 interacts with a Trio-like polypeptide (Duo) containing a Rac1 guanine nucleotide exchange factor (GEF) domain, a pleckstrin homology domain, and spectrin-like repeats. The interaction was identified by yeast two-hybrid screen and confirmed by in vitro protein-binding assay, suggesting HAP1 may link huntingtin to a Ras-related signaling pathway.","method":"Yeast two-hybrid screen, in vitro protein-binding assay","journal":"Human molecular genetics","confidence":"Medium","confidence_rationale":"Tier 3 — yeast two-hybrid plus in vitro binding, single lab","pmids":["9285789"],"is_preprint":false},{"year":1996,"finding":"HAP1 is enriched in neurons and localizes to subcellular fractions containing synaptic vesicles. HAP1 and neuronal nitric oxide synthase (nNOS) co-localize in discrete neuronal populations and share similar brain regional distributions, with both enriched in the pedunculopontine nuclei, accessory olfactory bulb, and supraoptic nucleus.","method":"In situ hybridization, subcellular fractionation, immunocytochemistry","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"Medium","confidence_rationale":"Tier 2 — multiple localization methods with subcellular fractionation, single lab","pmids":["8643490"],"is_preprint":false},{"year":1998,"finding":"Human HAP1 (hHAP) is specifically expressed in brain tissues, encodes a 75-kDa protein, and binds to huntingtin in a polyglutamine repeat length-dependent manner (longer repeats bind more tightly). The interaction was confirmed by in vitro binding, co-immunoprecipitation, and coexpression studies.","method":"cDNA cloning, in vitro binding assay, co-immunoprecipitation, coexpression in mammalian cells","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 — multiple orthogonal methods confirming interaction, human gene characterized","pmids":["9668110"],"is_preprint":false},{"year":1998,"finding":"HAP1 isoforms (HAP1-A and HAP1-B) associate with a unique cytoplasmic structure in neurons resembling the stigmoid body/nematosome. HAP1-A, but not HAP1-B, is essential for forming this inclusion structure in transfected cell lines. Both isoforms self-associate, and the ratio of HAP1-A to HAP1-B regulates inclusion formation.","method":"Immunocytochemistry, electron microscopy, transfection of cell lines, yeast two-hybrid for self-association","journal":"Journal of neurochemistry","confidence":"Medium","confidence_rationale":"Tier 2 — direct localization by EM and light microscopy with functional isoform dissection, single lab","pmids":["9798945"],"is_preprint":false},{"year":2002,"finding":"Targeted disruption of HAP1 (Hap1-/-) in mice causes postnatal lethality due to severely depressed feeding behavior, malnutrition, and dehydration. 70% die by P2 and 100% by P9. HAP1 is particularly enriched in the hypothalamus, implicating it as essential for regulating postnatal feeding behavior.","method":"Homologous recombination knockout, behavioral observation, serum leptin measurement, brain weight analysis","journal":"Human molecular genetics","confidence":"High","confidence_rationale":"Tier 2 — clean KO with defined cellular/physiological phenotype, strong","pmids":["11971876"],"is_preprint":false},{"year":2003,"finding":"HAP1 interacts with NeuroD (a bHLH transcription factor) and serves as a scaffold facilitating NeuroD activation by MLK2 kinase. HAP1 and huntingtin facilitate MLK2-mediated phosphorylation and activation of NeuroD, identifying a neuron-specific transcriptional regulatory complex.","method":"Yeast two-hybrid, co-immunoprecipitation, transcriptional reporter assays, kinase assay","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"Medium","confidence_rationale":"Tier 2 — multiple methods including kinase assay and reporter, moderate evidence","pmids":["12881483"],"is_preprint":false},{"year":2004,"finding":"HAP1 null mutants rescued from early lethality (by litter size reduction) survive to adulthood with growth retardation but no overt brain or behavioral abnormalities, demonstrating HAP1 is required specifically for early postnatal feeding. Conditional gene repair restoring neuronal HAP1 expression before birth rescues early lethality. No synergism between Hap1 and huntingtin mutations was observed during development.","method":"Conditional gene rescue (neuronal-specific), Hap1 null mouse characterization, litter size manipulation","journal":"Human molecular genetics","confidence":"High","confidence_rationale":"Tier 2 — genetic epistasis via conditional rescue, strong functional evidence","pmids":["15496430"],"is_preprint":false},{"year":2010,"finding":"HAP1 acts as an adaptor linking GABA-A receptors (GABAARs) to the kinesin motor KIF5, mediating anterograde delivery of GABAARs to synapses. Disrupting the HAP1-KIF5 complex reduces synaptic GABAAR number and decreases inhibitory postsynaptic current amplitude. Mutant huntingtin (polyQ-expanded) impairs GABAAR transport via disruption of this complex.","method":"Co-immunoprecipitation, RNAi knockdown, electrophysiology (mIPSC recording), live imaging of receptor trafficking","journal":"Neuron","confidence":"High","confidence_rationale":"Tier 2 — multiple orthogonal methods including electrophysiology, imaging, and biochemistry; moderate-to-strong evidence","pmids":["20152113"],"is_preprint":false},{"year":2011,"finding":"HAP1 interacts with PCM1 (pericentriolar material 1 protein) and huntingtin (HTT) to regulate ciliogenesis. Loss of Htt in mouse cells impairs retrograde trafficking of PCM1 and reduces primary cilia formation. In HD mice, pathogenic polyQ-expanded HTT causes centrosomal accumulation of PCM1 and abnormally long primary cilia in striatal cells, altering CSF flow.","method":"Co-immunoprecipitation, immunofluorescence, conditional knockout (ependymal cell-specific Htt deletion), cilia length measurement in HD mouse models and patient tissue","journal":"The Journal of clinical investigation","confidence":"High","confidence_rationale":"Tier 2 — multiple orthogonal methods, in vivo genetic models, replicated in HD patients","pmids":["21985783"],"is_preprint":false},{"year":2011,"finding":"proBDNF forms a trimeric complex with HAP1 and sortilin that regulates proBDNF intracellular trafficking and stabilization. The HAP1-proBDNF interaction was confirmed by FRET and co-immunoprecipitation. GST pulldown mapping defined the HAP1 binding region (aa 371–445) for proBDNF. FRAP experiments in HAP1-/- neurons showed defective proBDNF vesicle movement, partially rescued by HAP1 re-expression. The complex also facilitates furin cleavage to release mature BDNF.","method":"Co-immunoprecipitation, FRET, GST pulldown domain mapping, FRAP in HAP1-/- neurons, Western blot","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1–2 — multiple orthogonal methods including FRET, FRAP in knockout neurons, and domain mapping","pmids":["21357693"],"is_preprint":false},{"year":2011,"finding":"Mecp2 deficiency reduces Htt and Hap1 levels in mouse brain, causing defective BDNF axonal transport in the cortico-striatal pathway. Velocity of BDNF-containing vesicles is reduced in Mecp2-deficient axons and rescued by Mecp2 re-expression. APP transport (also Htt/Hap1-dependent) is similarly impaired, placing HAP1 in the Mecp2-Htt-Hap1 axis controlling axonal transport.","method":"Live imaging of BDNF vesicle transport, in vitro neuronal culture, viral rescue, mouse behavioral and lifespan analysis","journal":"Neurobiology of disease","confidence":"Medium","confidence_rationale":"Tier 2 — live imaging of vesicle transport in KO neurons with rescue, single lab","pmids":["22127389"],"is_preprint":false},{"year":2014,"finding":"Huntingtin (HTT) and HAP1 copurify and colocalize with autophagosomes in neurons. Using RNAi in primary neurons from GFP-LC3 mice and live-cell imaging, HTT and HAP1 were shown to control autophagosome dynamics by regulating dynein and kinesin motors to promote processive retrograde transport. PolyQ-HTT expression disrupts autophagosomal transport and leads to inefficient cargo degradation, without affecting autophagosome formation or cargo loading.","method":"Autophagosome purification/co-purification, RNAi knockdown, live-cell imaging in primary neurons (GFP-LC3 mice), mitochondrial fragment degradation assay","journal":"The Journal of neuroscience","confidence":"High","confidence_rationale":"Tier 2 — copurification with organelle, RNAi knockdown with live imaging, multiple phenotypic readouts","pmids":["24453320"],"is_preprint":false},{"year":2006,"finding":"HAP1 interacts with androgen receptor (AR) through the AR ligand-binding domain in a polyglutamine length-dependent manner. HAP1 sequesters polyQ-expanded AR into inclusions (stigmoid bodies) and suppresses SBMA-mutant AR-induced apoptosis when cotransfected in HEp-2 cells. Dihydrotestosterone reduces HAP1-AR association more strongly for normal than expanded polyQ-AR.","method":"Co-transfection, co-immunoprecipitation, immunofluorescence, apoptosis assay","journal":"Human molecular genetics","confidence":"Medium","confidence_rationale":"Tier 3 — Co-IP plus functional apoptosis rescue, single lab","pmids":["16782802"],"is_preprint":false},{"year":2016,"finding":"HAP1 is required for GABAAR recycling to the neuronal surface. In hippocampal neurons subjected to oxygen/glucose deprivation (OGD), calpain cleaves HAP1, reducing GABAAR recycling. Overexpression of HAP1A or HAP1B isoforms restored GABAAR surface expression and reduced OGD-induced neuronal death, demonstrating HAP1's role in receptor recycling and neuroprotection during ischemia.","method":"Transfection with myc-tagged GABAAR β3, surface biotinylation, co-immunoprecipitation, calpain cleavage assay, cell death assay in OGD model","journal":"Molecular neurobiology","confidence":"Medium","confidence_rationale":"Tier 2 — multiple methods in primary neurons with defined phenotypic readout, single lab","pmids":["26732589"],"is_preprint":false},{"year":2017,"finding":"HAP1 regulates neuronal endocytosis and interacts with clathrin light chain B (validated by Co-IP and GST pulldown) and Sec23A (ER-to-Golgi vesicle coat; validated by endogenous Co-IP in rat brain). HAP1 co-localizes with clathrin light chain B. HAP1 knockout adrenal chromaffin cells show dramatically reduced vesicle retrieval and endocytosis, and HAP1-/- cortical neurons show impaired transferrin endocytosis.","method":"Affinity chromatography/mass spectrometry proteomics, Co-IP, GST pulldown, immunofluorescence co-localization, endocytosis assay in HAP1-/- neurons","journal":"Cellular signalling","confidence":"High","confidence_rationale":"Tier 2 — proteomics discovery validated by Co-IP/GST pulldown, functional endocytosis assay in KO neurons","pmids":["28259758"],"is_preprint":false},{"year":2019,"finding":"HAP1 forms a ternary complex with huntingtin and the IP3 receptor (inositol 1,4,5-trisphosphate receptor, an intracellular Ca2+ channel) on the ER membrane. Loss of HAP1 prevents this ternary complex formation, blocks ER Ca2+ release upon IP3 stimulation, inhibits external Ca2+ entry, and reduces activation of the Ca2+-dependent calpain-1-Bid-caspase-3/12 apoptotic pathway, causing l-asparaginase resistance in ALL cells.","method":"Genome-wide RNAi screen, Co-immunoprecipitation (ternary complex), Ca2+ imaging, calpain/caspase activity assays, HAP1 knockdown rescue experiments","journal":"Blood","confidence":"High","confidence_rationale":"Tier 2 — unbiased screen plus Co-IP of ternary complex, Ca2+ functional assays, multiple cell systems","pmids":["30819925"],"is_preprint":false},{"year":2020,"finding":"AAV-mediated depletion of Hap1 in adult HD knock-in mouse brains causes selective neuronal loss in the striatum, but only in the presence of mutant HTT. Rhes (a striatum-enriched GTPase) binds more N-terminal HTT when Hap1 is absent, and more soluble sumoylated N-terminal HTT accumulates in the striatum, suggesting Hap1 normally sequesters or protects against toxic HTT fragments and that Rhes-Hap1 cooperate to determine selective striatal vulnerability.","method":"AAV-mediated gene silencing in vivo, histological analysis of neuronal loss, Co-immunoprecipitation, Western blot for sumoylated HTT","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"Medium","confidence_rationale":"Tier 2 — in vivo AAV KD in HD KI mice with defined neuronal loss phenotype, biochemical pathway analysis, single lab","pmids":["32747555"],"is_preprint":false}],"current_model":"HAP1 (huntingtin-associated protein 1) is a neuronally enriched adaptor protein that scaffolds molecular motor complexes (dynein/dynactin via p150Glued, kinesin KIF5) to mediate anterograde and retrograde vesicular transport of cargoes including GABA-A receptors, BDNF/proBDNF, and autophagosomes; it forms a ternary complex with huntingtin and the IP3 receptor to regulate ER Ca2+ release and apoptotic signaling; it localizes to stigmoid bodies via HAP1-A isoform self-association; it regulates ciliogenesis through PCM1 trafficking; it controls neuronal endocytosis through clathrin light chain B interactions; and its loss selectively promotes striatal neurodegeneration in Huntington disease models, with polyQ-expanded huntingtin disrupting these trafficking functions."},"narrative":{"teleology":[],"mechanism_profile":{"molecular_activity":[],"localization":[],"pathway":[],"complexes":[],"partners":[],"other_free_text":[]},"mechanistic_narrative":"Insufficient on-target evidence to synthesize a narrative — discovery timeline does not match the canonical HAP1 protein."},"prefetch_data":{"uniprot":{"accession":"P54257","full_name":"Huntingtin-associated protein 1","aliases":["Neuroan 1"],"length_aa":671,"mass_kda":75.5,"function":"Originally identified as neuronal protein that specifically associates with HTT/huntingtin and the binding is enhanced by an expanded polyglutamine repeat within HTT possibly affecting HAP1 interaction properties. Both HTT and HAP1 are involved in intracellular trafficking and HAP1 is proposed to link HTT to motor proteins and/or transport cargos. Seems to play a role in vesicular transport within neurons and axons such as from early endosomes to late endocytic compartments and to promote neurite outgrowth. The vesicular transport function via association with microtubule-dependent transporters can be attenuated by association with mutant HTT. Involved in the axonal transport of BDNF and its activity-dependent secretion; the function seems to involve HTT, DCTN1 and a complex with SORT1. Involved in APP trafficking and seems to facilitate APP anterograde transport and membrane insertion thereby possibly reducing processing into amyloid beta. Involved in delivery of gamma-aminobutyric acid (GABA(A)) receptors to synapses; the function is dependent on kinesin motor protein KIF5 and is disrupted by HTT with expanded polyglutamine repeat. Involved in regulation of autophagosome motility by promoting efficient retrograde axonal transport. Seems to be involved in regulation of membrane receptor recycling and degradation, and respective signal transduction, including GABA(A) receptors, tyrosine kinase receptors, EGFR, IP3 receptor and androgen receptor. Among others suggested to be involved in control of feeding behavior (involving hypothalamic GABA(A) receptors), cerebellar and brainstem development (involving AHI1 and NTRK1/TrkA), postnatal neurogenesis (involving hypothalamic NTRK2/TrkB), and ITPR1/InsP3R1-mediated Ca(2+) release (involving HTT and possibly the effect of mutant HTT). Via association with DCTN1/dynactin p150-glued and HTT/huntingtin involved in cytoplasmic retention of REST in neurons. May be involved in ciliogenesis. Involved in regulation of exocytosis. Seems to be involved in formation of cytoplasmic inclusion bodies (STBs). In case of anomalous expression of TBP, can sequester a subset of TBP into STBs; sequestration is enhanced by an expanded polyglutamine repeat within TBP. HAP1-containing STBs have been proposed to play a protective role against neurodegeneration in Huntigton disease (HD) and spinocerebellar ataxia 17 (SCA17)","subcellular_location":"Cytoplasm; Cell projection, axon; Presynapse; Cytoplasm, cytoskeleton; Cell projection, dendritic spine; Cell projection, dendrite; Lysosome; Endoplasmic reticulum; Mitochondrion; Nucleus; Cytoplasmic vesicle, autophagosome; Early endosome; Cell projection, growth cone; Cell projection, neuron projection; Cytoplasmic vesicle, secretory vesicle, synaptic vesicle","url":"https://www.uniprot.org/uniprotkb/P54257/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/HAP1","classification":"Not Classified","n_dependent_lines":97,"n_total_lines":1208,"dependency_fraction":0.0802980132450331},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/HAP1","total_profiled":1310},"omim":[{"mim_id":"621430","title":"FIGNL1-INTERACTING REGULATOR OF RECOMBINATION AND MITOSIS; FIRRM","url":"https://www.omim.org/entry/621430"},{"mim_id":"621258","title":"FANCONI ANEMIA, COMPLEMENTATION GROUP X; FANCX","url":"https://www.omim.org/entry/621258"},{"mim_id":"621222","title":"LINE1-TYPE TRANSPOSASE DOMAIN-CONTAINING PROTEIN 1; L1TD1","url":"https://www.omim.org/entry/621222"},{"mim_id":"621024","title":"PROTEIN PRENYLTRANSFERASE ALPHA SUBUNIT REPEAT-CONTAINING PROTEIN 1; PTAR1","url":"https://www.omim.org/entry/621024"},{"mim_id":"620957","title":"tRNA METHYLTRANSFERASE 10B; TRMT10B","url":"https://www.omim.org/entry/620957"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Supported","locations":[{"location":"Cytosol","reliability":"Supported"},{"location":"Nucleoli","reliability":"Additional"}],"tissue_specificity":"Tissue enhanced","tissue_distribution":"Detected in many","driving_tissues":[{"tissue":"brain","ntpm":41.7}],"url":"https://www.proteinatlas.org/search/HAP1"},"hgnc":{"alias_symbol":["HLP","hHLP1","HIP5"],"prev_symbol":["HAP2"]},"alphafold":{"accession":"P27695","domains":[{"cath_id":"3.60.10.10","chopping":"61-315","consensus_level":"medium","plddt":97.5087,"start":61,"end":315}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/P27695","model_url":"https://alphafold.ebi.ac.uk/files/AF-P27695-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-P27695-F1-predicted_aligned_error_v6.png","plddt_mean":90.44},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=HAP1","jax_strain_url":"https://www.jax.org/strain/search?query=HAP1"},"sequence":{"accession":"P27695","fasta_url":"https://rest.uniprot.org/uniprotkb/P27695.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/P27695/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/P27695"}},"corpus_meta":[{"pmid":"2676721","id":"PMC_2676721","title":"Identification and characterization of HAP4: a third component of the CCAAT-bound HAP2/HAP3 heteromer.","date":"1989","source":"Genes & development","url":"https://pubmed.ncbi.nlm.nih.gov/2676721","citation_count":349,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"24453320","id":"PMC_24453320","title":"The regulation of autophagosome dynamics by huntingtin and HAP1 is disrupted by expression of mutant huntingtin, leading to defective cargo degradation.","date":"2014","source":"The Journal of neuroscience : the official journal of the Society for Neuroscience","url":"https://pubmed.ncbi.nlm.nih.gov/24453320","citation_count":300,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"9351835","id":"PMC_9351835","title":"The crystal structure of the human DNA repair endonuclease HAP1 suggests the recognition of extra-helical deoxyribose at DNA abasic sites.","date":"1997","source":"The EMBO journal","url":"https://pubmed.ncbi.nlm.nih.gov/9351835","citation_count":282,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"2643482","id":"PMC_2643482","title":"Functional dissection and sequence of yeast HAP1 activator.","date":"1989","source":"Cell","url":"https://pubmed.ncbi.nlm.nih.gov/2643482","citation_count":279,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"9361024","id":"PMC_9361024","title":"Huntingtin-associated protein 1 (HAP1) interacts with the p150Glued subunit of dynactin.","date":"1997","source":"Human molecular genetics","url":"https://pubmed.ncbi.nlm.nih.gov/9361024","citation_count":275,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"18367645","id":"PMC_18367645","title":"The conserved plant sterility gene HAP2 functions after attachment of fusogenic membranes in Chlamydomonas and Plasmodium gametes.","date":"2008","source":"Genes & development","url":"https://pubmed.ncbi.nlm.nih.gov/18367645","citation_count":252,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"17079265","id":"PMC_17079265","title":"Arabidopsis HAP2 (GCS1) is a sperm-specific gene required for pollen tube guidance and fertilization.","date":"2006","source":"Development (Cambridge, England)","url":"https://pubmed.ncbi.nlm.nih.gov/17079265","citation_count":232,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"20152113","id":"PMC_20152113","title":"Delivery of GABAARs to synapses is mediated by HAP1-KIF5 and disrupted by mutant huntingtin.","date":"2010","source":"Neuron","url":"https://pubmed.ncbi.nlm.nih.gov/20152113","citation_count":211,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"2826015","id":"PMC_2826015","title":"Yeast HAP2 and HAP3 activators both bind to the CYC1 upstream activation site, UAS2, in an interdependent manner.","date":"1987","source":"Cell","url":"https://pubmed.ncbi.nlm.nih.gov/2826015","citation_count":211,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"7800476","id":"PMC_7800476","title":"A role for the human DNA repair enzyme HAP1 in cellular protection against DNA damaging agents and hypoxic stress.","date":"1994","source":"Nucleic acids research","url":"https://pubmed.ncbi.nlm.nih.gov/7800476","citation_count":200,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"3030567","id":"PMC_3030567","title":"Yeast HAP1 activator competes with the factor RC2 for binding to the upstream activation site UAS1 of the CYC1 gene.","date":"1987","source":"Cell","url":"https://pubmed.ncbi.nlm.nih.gov/3030567","citation_count":196,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"9765213","id":"PMC_9765213","title":"Identification of APN2, the Saccharomyces cerevisiae homolog of the major human AP endonuclease HAP1, and its role in the repair of abasic sites.","date":"1998","source":"Genes & development","url":"https://pubmed.ncbi.nlm.nih.gov/9765213","citation_count":180,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"11212295","id":"PMC_11212295","title":"Molecular mechanism of heme signaling in yeast: the transcriptional activator Hap1 serves as the key mediator.","date":"1999","source":"Cellular and molecular life sciences : CMLS","url":"https://pubmed.ncbi.nlm.nih.gov/11212295","citation_count":166,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"2123465","id":"PMC_2123465","title":"The HAP2 subunit of yeast CCAAT transcriptional activator contains adjacent domains for subunit association and DNA recognition: model for the HAP2/3/4 complex.","date":"1990","source":"Genes & development","url":"https://pubmed.ncbi.nlm.nih.gov/2123465","citation_count":154,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"16943288","id":"PMC_16943288","title":"Global structural changes in hepatitis B virus capsids induced by the assembly effector HAP1.","date":"2006","source":"Journal of virology","url":"https://pubmed.ncbi.nlm.nih.gov/16943288","citation_count":150,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"8223474","id":"PMC_8223474","title":"Mutations in yeast HAP2/HAP3 define a hybrid CCAAT box binding domain.","date":"1993","source":"The EMBO journal","url":"https://pubmed.ncbi.nlm.nih.gov/8223474","citation_count":136,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"28235200","id":"PMC_28235200","title":"The Ancient Gamete Fusogen HAP2 Is a Eukaryotic Class II Fusion Protein.","date":"2017","source":"Cell","url":"https://pubmed.ncbi.nlm.nih.gov/28235200","citation_count":136,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"21985783","id":"PMC_21985783","title":"Ciliogenesis is regulated by a huntingtin-HAP1-PCM1 pathway and is altered in Huntington disease.","date":"2011","source":"The Journal of clinical investigation","url":"https://pubmed.ncbi.nlm.nih.gov/21985783","citation_count":130,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"3547076","id":"PMC_3547076","title":"Sequence and nuclear localization of the Saccharomyces cerevisiae HAP2 protein, a transcriptional activator.","date":"1987","source":"Molecular and cellular biology","url":"https://pubmed.ncbi.nlm.nih.gov/3547076","citation_count":123,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"3915775","id":"PMC_3915775","title":"Cloning and molecular analysis of the HAP2 locus: a global regulator of respiratory genes in Saccharomyces cerevisiae.","date":"1985","source":"Molecular and cellular biology","url":"https://pubmed.ncbi.nlm.nih.gov/3915775","citation_count":122,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"8643490","id":"PMC_8643490","title":"Huntingtin-associated protein (HAP1): discrete neuronal localizations in the brain resemble those of neuronal nitric oxide synthase.","date":"1996","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/8643490","citation_count":121,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"7664124","id":"PMC_7664124","title":"Identification of critical active-site residues in the multifunctional human DNA repair enzyme HAP1.","date":"1995","source":"Nature structural biology","url":"https://pubmed.ncbi.nlm.nih.gov/7664124","citation_count":120,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"10541856","id":"PMC_10541856","title":"A 'natural' mutation in Saccharomyces cerevisiae strains derived from S288c affects the complex regulatory gene HAP1 (CYP1).","date":"1999","source":"Current genetics","url":"https://pubmed.ncbi.nlm.nih.gov/10541856","citation_count":119,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"2832731","id":"PMC_2832731","title":"Mutational analysis of upstream activation sequence 2 of the CYC1 gene of Saccharomyces cerevisiae: a HAP2-HAP3-responsive site.","date":"1988","source":"Molecular and cellular biology","url":"https://pubmed.ncbi.nlm.nih.gov/2832731","citation_count":119,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"9285789","id":"PMC_9285789","title":"Huntingtin-associated protein 1 (HAP1) binds to a Trio-like polypeptide, with a rac1 guanine nucleotide exchange factor domain.","date":"1997","source":"Human molecular genetics","url":"https://pubmed.ncbi.nlm.nih.gov/9285789","citation_count":116,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"2832951","id":"PMC_2832951","title":"Yeast HAP2 and HAP3: transcriptional activators in a heteromeric complex.","date":"1988","source":"Science (New York, N.Y.)","url":"https://pubmed.ncbi.nlm.nih.gov/2832951","citation_count":115,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"2196566","id":"PMC_2196566","title":"The B subunit of a rat heteromeric CCAAT-binding transcription factor shows a striking sequence identity with the yeast Hap2 transcription factor.","date":"1990","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/2196566","citation_count":109,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"17785431","id":"PMC_17785431","title":"Heme levels switch the function of Hap1 of Saccharomyces cerevisiae between transcriptional activator and transcriptional repressor.","date":"2007","source":"Molecular and cellular biology","url":"https://pubmed.ncbi.nlm.nih.gov/17785431","citation_count":108,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"1588959","id":"PMC_1588959","title":"HAP1 and ROX1 form a regulatory pathway in the repression of HEM13 transcription in Saccharomyces cerevisiae.","date":"1992","source":"Molecular and cellular biology","url":"https://pubmed.ncbi.nlm.nih.gov/1588959","citation_count":105,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"12112237","id":"PMC_12112237","title":"A microarray-assisted screen for potential Hap1 and Rox1 target genes in Saccharomyces cerevisiae.","date":"2002","source":"Yeast (Chichester, England)","url":"https://pubmed.ncbi.nlm.nih.gov/12112237","citation_count":103,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"19596419","id":"PMC_19596419","title":"Plasmodium berghei HAP2 induces strong malaria transmission-blocking immunity in vivo and in vitro.","date":"2009","source":"Vaccine","url":"https://pubmed.ncbi.nlm.nih.gov/19596419","citation_count":92,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"7958882","id":"PMC_7958882","title":"The yeast activator HAP1--a GAL4 family member--binds DNA in a directly repeated orientation.","date":"1994","source":"Genes & development","url":"https://pubmed.ncbi.nlm.nih.gov/7958882","citation_count":91,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"2847035","id":"PMC_2847035","title":"Differential regulation of the two genes encoding Saccharomyces cerevisiae cytochrome c oxidase subunit V by heme and the HAP2 and REO1 genes.","date":"1988","source":"Molecular and cellular biology","url":"https://pubmed.ncbi.nlm.nih.gov/2847035","citation_count":90,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"9886294","id":"PMC_9886294","title":"Structure of a HAP1-DNA complex reveals dramatically asymmetric DNA binding by a homodimeric protein.","date":"1999","source":"Nature structural biology","url":"https://pubmed.ncbi.nlm.nih.gov/9886294","citation_count":85,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"15548548","id":"PMC_15548548","title":"Transcriptional dysregulation in striatal projection- and interneurons in a mouse model of Huntington's disease: neuronal selectivity and potential neuroprotective role of HAP1.","date":"2004","source":"Human molecular genetics","url":"https://pubmed.ncbi.nlm.nih.gov/15548548","citation_count":84,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"28137780","id":"PMC_28137780","title":"Arabidopsis HAP2/GCS1 is a gamete fusion protein homologous to somatic and viral fusogens.","date":"2017","source":"The Journal of cell biology","url":"https://pubmed.ncbi.nlm.nih.gov/28137780","citation_count":81,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"28238660","id":"PMC_28238660","title":"Structure-Function Studies Link Class II Viral Fusogens with the Ancestral Gamete Fusion Protein HAP2.","date":"2017","source":"Current biology : CB","url":"https://pubmed.ncbi.nlm.nih.gov/28238660","citation_count":76,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"11971876","id":"PMC_11971876","title":"Targeted disruption of Huntingtin-associated protein-1 (Hap1) results in postnatal death due to depressed feeding behavior.","date":"2002","source":"Human molecular genetics","url":"https://pubmed.ncbi.nlm.nih.gov/11971876","citation_count":73,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"1656218","id":"PMC_1656218","title":"Regulation of the yeast CYT1 gene encoding cytochrome c1 by HAP1 and HAP2/3/4.","date":"1991","source":"Molecular and cellular biology","url":"https://pubmed.ncbi.nlm.nih.gov/1656218","citation_count":73,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"11929514","id":"PMC_11929514","title":"The yeast transcriptome in aerobic and hypoxic conditions: effects of hap1, rox1, rox3 and srb10 deletions.","date":"2002","source":"Molecular microbiology","url":"https://pubmed.ncbi.nlm.nih.gov/11929514","citation_count":71,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"29212032","id":"PMC_29212032","title":"Targeting the Conserved Fusion Loop of HAP2 Inhibits the Transmission of Plasmodium berghei and falciparum.","date":"2017","source":"Cell reports","url":"https://pubmed.ncbi.nlm.nih.gov/29212032","citation_count":69,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"1899284","id":"PMC_1899284","title":"The Schizosaccharomyces pombe homolog of Saccharomyces cerevisiae HAP2 reveals selective and stringent conservation of the small essential core protein domain.","date":"1991","source":"Molecular and cellular biology","url":"https://pubmed.ncbi.nlm.nih.gov/1899284","citation_count":67,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"14512429","id":"PMC_14512429","title":"A mechanism of oxygen sensing in yeast. Multiple oxygen-responsive steps in the heme biosynthetic pathway affect Hap1 activity.","date":"2003","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/14512429","citation_count":67,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"9668110","id":"PMC_9668110","title":"A human HAP1 homologue. Cloning, expression, and interaction with huntingtin.","date":"1998","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/9668110","citation_count":62,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"10749126","id":"PMC_10749126","title":"Ultraviolet B radiation-induced skin cancer in mice defective in the Xpc, Trp53, and Apex (HAP1) genes: genotype-specific effects on cancer predisposition and pathology of tumors.","date":"2000","source":"Cancer research","url":"https://pubmed.ncbi.nlm.nih.gov/10749126","citation_count":62,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"8159696","id":"PMC_8159696","title":"Subunit interaction in the CCAAT-binding heteromeric complex is mediated by a very short alpha-helix in HAP2.","date":"1994","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/8159696","citation_count":62,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"15629196","id":"PMC_15629196","title":"HAP1 and intracellular trafficking.","date":"2005","source":"Trends in pharmacological sciences","url":"https://pubmed.ncbi.nlm.nih.gov/15629196","citation_count":61,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"2046677","id":"PMC_2046677","title":"Complex transcriptional regulation of the Saccharomyces cerevisiae CYB2 gene encoding cytochrome b2: CYP1(HAP1) activator binds to the CYB2 upstream activation site UAS1-B2.","date":"1991","source":"Molecular and cellular biology","url":"https://pubmed.ncbi.nlm.nih.gov/2046677","citation_count":61,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"8458333","id":"PMC_8458333","title":"Evidence for an interaction between the CYP1(HAP1) activator and a cellular factor during heme-dependent transcriptional regulation in the yeast Saccharomyces cerevisiae.","date":"1993","source":"The EMBO journal","url":"https://pubmed.ncbi.nlm.nih.gov/8458333","citation_count":61,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"12881483","id":"PMC_12881483","title":"Stimulation of NeuroD activity by huntingtin and huntingtin-associated proteins HAP1 and MLK2.","date":"2003","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/12881483","citation_count":60,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"21357693","id":"PMC_21357693","title":"Precursor of brain-derived neurotrophic factor (proBDNF) forms a complex with Huntingtin-associated protein-1 (HAP1) and sortilin that modulates proBDNF trafficking, degradation, and processing.","date":"2011","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/21357693","citation_count":60,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"22127389","id":"PMC_22127389","title":"Modification of Mecp2 dosage alters axonal transport through the Huntingtin/Hap1 pathway.","date":"2011","source":"Neurobiology of disease","url":"https://pubmed.ncbi.nlm.nih.gov/22127389","citation_count":55,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"1383925","id":"PMC_1383925","title":"Structure of the human DNA repair gene HAP1 and its localisation to chromosome 14q 11.2-12.","date":"1992","source":"Nucleic acids research","url":"https://pubmed.ncbi.nlm.nih.gov/1383925","citation_count":55,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"10871340","id":"PMC_10871340","title":"Substitution of Asp-210 in HAP1 (APE/Ref-1) eliminates endonuclease activity but stabilises substrate binding.","date":"2000","source":"Nucleic acids research","url":"https://pubmed.ncbi.nlm.nih.gov/10871340","citation_count":54,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"25155508","id":"PMC_25155508","title":"Function of the male-gamete-specific fusion protein HAP2 in a seven-sexed ciliate.","date":"2014","source":"Current biology : CB","url":"https://pubmed.ncbi.nlm.nih.gov/25155508","citation_count":52,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"9044264","id":"PMC_9044264","title":"Stationary-phase regulation of the Saccharomyces cerevisiae SOD2 gene is dependent on additive effects of HAP2/3/4/5- and STRE-binding elements.","date":"1997","source":"Molecular microbiology","url":"https://pubmed.ncbi.nlm.nih.gov/9044264","citation_count":51,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"15686847","id":"PMC_15686847","title":"Polymerase chain reaction assay specific for pathogenic Leptospira based on the gene hap1 encoding the hemolysis-associated protein-1.","date":"2005","source":"FEMS microbiology letters","url":"https://pubmed.ncbi.nlm.nih.gov/15686847","citation_count":50,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"30102690","id":"PMC_30102690","title":"Evolutionary diversification of the HAP2 membrane insertion motifs to drive gamete fusion across eukaryotes.","date":"2018","source":"PLoS biology","url":"https://pubmed.ncbi.nlm.nih.gov/30102690","citation_count":50,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"9798945","id":"PMC_9798945","title":"Association of HAP1 isoforms with a unique cytoplasmic structure.","date":"1998","source":"Journal of neurochemistry","url":"https://pubmed.ncbi.nlm.nih.gov/9798945","citation_count":48,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"8464899","id":"PMC_8464899","title":"Antibody-promoted dimerization bypasses the regulation of DNA binding by the heme domain of the yeast transcriptional activator HAP1.","date":"1993","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/8464899","citation_count":48,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"16782802","id":"PMC_16782802","title":"Huntingtin-associated protein 1 (HAP1) interacts with androgen receptor (AR) and suppresses SBMA-mutant-AR-induced apoptosis.","date":"2006","source":"Human molecular genetics","url":"https://pubmed.ncbi.nlm.nih.gov/16782802","citation_count":46,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"8628677","id":"PMC_8628677","title":"Mutations in target DNA elements of yeast HAP1 modulate its transcriptional activity without affecting DNA binding.","date":"1996","source":"Nucleic acids research","url":"https://pubmed.ncbi.nlm.nih.gov/8628677","citation_count":45,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"11689685","id":"PMC_11689685","title":"The Hsp70-Ydj1 molecular chaperone represses the activity of the heme activator protein Hap1 in the absence of heme.","date":"2001","source":"Molecular and cellular biology","url":"https://pubmed.ncbi.nlm.nih.gov/11689685","citation_count":44,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"8932375","id":"PMC_8932375","title":"Asparagine 212 is essential for abasic site recognition by the human DNA repair endonuclease HAP1.","date":"1996","source":"Nucleic acids research","url":"https://pubmed.ncbi.nlm.nih.gov/8932375","citation_count":44,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"9751154","id":"PMC_9751154","title":"The expression of Huntingtin-associated protein (HAP1) mRNA in developing, adult and ageing rat CNS: implications for Huntington's disease neuropathology.","date":"1998","source":"The European journal of neuroscience","url":"https://pubmed.ncbi.nlm.nih.gov/9751154","citation_count":44,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"1314953","id":"PMC_1314953","title":"Regulation of yeast COX6 by the general transcription factor ABF1 and separate HAP2- and heme-responsive elements.","date":"1992","source":"Molecular and cellular biology","url":"https://pubmed.ncbi.nlm.nih.gov/1314953","citation_count":42,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"1715975","id":"PMC_1715975","title":"CYP1 (HAP1) is a determinant effector of alternative expression of heme-dependent transcribed genes in yeast [corrected].","date":"1991","source":"Molecular & general genetics : MGG","url":"https://pubmed.ncbi.nlm.nih.gov/1715975","citation_count":42,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"19888453","id":"PMC_19888453","title":"Evolutionary history of the HAP2/GCS1 gene and sexual reproduction in metazoans.","date":"2009","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/19888453","citation_count":41,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"15496430","id":"PMC_15496430","title":"Huntingtin-associated protein 1 (Hap1) mutant mice bypassing the early postnatal lethality are neuroanatomically normal and fertile but display growth retardation.","date":"2004","source":"Human molecular genetics","url":"https://pubmed.ncbi.nlm.nih.gov/15496430","citation_count":41,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"10873649","id":"PMC_10873649","title":"Functional analysis of heme regulatory elements of the transcriptional activator Hap1.","date":"2000","source":"Biochemical and biophysical research communications","url":"https://pubmed.ncbi.nlm.nih.gov/10873649","citation_count":41,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"11506820","id":"PMC_11506820","title":"The HAP1 protein stimulates the turnover of human mismatch-specific thymine-DNA-glycosylase to process 3,N(4)-ethenocytosine residues.","date":"2001","source":"Mutation research","url":"https://pubmed.ncbi.nlm.nih.gov/11506820","citation_count":40,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"28985216","id":"PMC_28985216","title":"The Babesia bovis hap2 gene is not required for blood stage replication, but expressed upon in vitro sexual stage induction.","date":"2017","source":"PLoS neglected tropical diseases","url":"https://pubmed.ncbi.nlm.nih.gov/28985216","citation_count":40,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"15919224","id":"PMC_15919224","title":"Mapping the laminin-binding and adhesive domain of the cell surface-associated Hlp/LBP protein from Mycobacterium leprae.","date":"2005","source":"Microbes and infection","url":"https://pubmed.ncbi.nlm.nih.gov/15919224","citation_count":40,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"7984086","id":"PMC_7984086","title":"The HAP2,3,4 transcriptional activator is required for derepression of the yeast citrate synthase gene, CIT1.","date":"1994","source":"Molecular microbiology","url":"https://pubmed.ncbi.nlm.nih.gov/7984086","citation_count":39,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"8005436","id":"PMC_8005436","title":"Evidence that TUP1/SSN6 has a positive effect on the activity of the yeast activator HAP1.","date":"1994","source":"Genetics","url":"https://pubmed.ncbi.nlm.nih.gov/8005436","citation_count":39,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"8887558","id":"PMC_8887558","title":"The C6 zinc cluster dictates asymmetric binding by HAP1.","date":"1996","source":"The EMBO journal","url":"https://pubmed.ncbi.nlm.nih.gov/8887558","citation_count":39,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"1310523","id":"PMC_1310523","title":"Positive regulation of the LPD1 gene of Saccharomyces cerevisiae by the HAP2/HAP3/HAP4 activation system.","date":"1992","source":"Molecular & general genetics : MGG","url":"https://pubmed.ncbi.nlm.nih.gov/1310523","citation_count":38,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"30819925","id":"PMC_30819925","title":"HAP1 loss confers l-asparaginase resistance in ALL by downregulating the calpain-1-Bid-caspase-3/12 pathway.","date":"2019","source":"Blood","url":"https://pubmed.ncbi.nlm.nih.gov/30819925","citation_count":37,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"20512606","id":"PMC_20512606","title":"Age at onset in Huntington's disease: replication study on the associations of ADORA2A, HAP1 and OGG1.","date":"2010","source":"Neurogenetics","url":"https://pubmed.ncbi.nlm.nih.gov/20512606","citation_count":37,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"10330173","id":"PMC_10330173","title":"A new class of repression modules is critical for heme regulation of the yeast transcriptional activator Hap1.","date":"1999","source":"Molecular and cellular biology","url":"https://pubmed.ncbi.nlm.nih.gov/10330173","citation_count":36,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"9406232","id":"PMC_9406232","title":"The structure and functions of the HAP1/Ref-1 protein.","date":"1997","source":"Oncology research","url":"https://pubmed.ncbi.nlm.nih.gov/9406232","citation_count":34,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"15654089","id":"PMC_15654089","title":"The heme activator protein Hap1 represses transcription by a heme-independent mechanism in Saccharomyces cerevisiae.","date":"2005","source":"Genetics","url":"https://pubmed.ncbi.nlm.nih.gov/15654089","citation_count":34,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"9744526","id":"PMC_9744526","title":"Differential cleavage of oligonucleotides containing the benzene-derived adduct, 1,N6-benzetheno-dA, by the major human AP endonuclease HAP1 and Escherichia coli exonuclease III and endonuclease IV.","date":"1998","source":"Carcinogenesis","url":"https://pubmed.ncbi.nlm.nih.gov/9744526","citation_count":34,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"33184093","id":"PMC_33184093","title":"Efficient and crucial quality control of HAP1 cell ploidy status.","date":"2020","source":"Biology open","url":"https://pubmed.ncbi.nlm.nih.gov/33184093","citation_count":33,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"32747555","id":"PMC_32747555","title":"Loss of Hap1 selectively promotes striatal degeneration in Huntington disease mice.","date":"2020","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/32747555","citation_count":33,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"19995727","id":"PMC_19995727","title":"The Chlamydomonas chloroplast HLP protein is required for nucleoid organization and genome maintenance.","date":"2009","source":"Molecular plant","url":"https://pubmed.ncbi.nlm.nih.gov/19995727","citation_count":32,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"30281023","id":"PMC_30281023","title":"Fusion surface structure, function, and dynamics of gamete fusogen HAP2.","date":"2018","source":"eLife","url":"https://pubmed.ncbi.nlm.nih.gov/30281023","citation_count":32,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"10190555","id":"PMC_10190555","title":"Overexpression of the human HAP1 protein sensitizes cells to the lethal effect of bioreductive drugs.","date":"1999","source":"Carcinogenesis","url":"https://pubmed.ncbi.nlm.nih.gov/10190555","citation_count":32,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"7828916","id":"PMC_7828916","title":"The respiratory system of Kluyveromyces lactis escapes from HAP2 control.","date":"1995","source":"Gene","url":"https://pubmed.ncbi.nlm.nih.gov/7828916","citation_count":32,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"26732589","id":"PMC_26732589","title":"Downregulation of GABAA Receptor Recycling Mediated by HAP1 Contributes to Neuronal Death in In Vitro Brain Ischemia.","date":"2016","source":"Molecular neurobiology","url":"https://pubmed.ncbi.nlm.nih.gov/26732589","citation_count":31,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"17474105","id":"PMC_17474105","title":"Regulation of intracellular HAP1 trafficking.","date":"2007","source":"Journal of neuroscience research","url":"https://pubmed.ncbi.nlm.nih.gov/17474105","citation_count":30,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"35794124","id":"PMC_35794124","title":"Discovery of archaeal fusexins homologous to eukaryotic HAP2/GCS1 gamete fusion proteins.","date":"2022","source":"Nature communications","url":"https://pubmed.ncbi.nlm.nih.gov/35794124","citation_count":30,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"36322734","id":"PMC_36322734","title":"DMP8 and 9 regulate HAP2/GCS1 trafficking for the timely acquisition of sperm fusion competence.","date":"2022","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/36322734","citation_count":30,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"18656956","id":"PMC_18656956","title":"The C-terminal domain of HU-related histone-like protein Hlp from Mycobacterium smegmatis mediates DNA end-joining.","date":"2008","source":"Biochemistry","url":"https://pubmed.ncbi.nlm.nih.gov/18656956","citation_count":30,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"10428861","id":"PMC_10428861","title":"The yeast heme-responsive transcriptional activator Hap1 is a preexisting dimer in the absence of heme.","date":"1999","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/10428861","citation_count":30,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"12897155","id":"PMC_12897155","title":"Structural environment dictates the biological significance of heme-responsive motifs and the role of Hsp90 in the activation of the heme activator protein Hap1.","date":"2003","source":"Molecular and cellular biology","url":"https://pubmed.ncbi.nlm.nih.gov/12897155","citation_count":30,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"28259758","id":"PMC_28259758","title":"Huntingtin-associated protein-1 (HAP1) regulates endocytosis and interacts with multiple trafficking-related proteins.","date":"2017","source":"Cellular signalling","url":"https://pubmed.ncbi.nlm.nih.gov/28259758","citation_count":29,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"9545379","id":"PMC_9545379","title":"Assembly characteristics of flagellar cap protein HAP2 of Salmonella: decamer and pentamer in the pH-sensitive equilibrium.","date":"1998","source":"Journal of molecular biology","url":"https://pubmed.ncbi.nlm.nih.gov/9545379","citation_count":29,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"2318304","id":"PMC_2318304","title":"Bacterial 'histone-like protein I' (HLP-I) is an outer membrane constituent?","date":"1990","source":"FEBS letters","url":"https://pubmed.ncbi.nlm.nih.gov/2318304","citation_count":28,"is_preprint":false,"source_track":"pubmed_title"},{"pmid":"11751848","id":"PMC_11751848","title":"The molecular chaperone Hsp90 mediates heme activation of the yeast transcriptional activator Hap1.","date":"2002","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/11751848","citation_count":28,"is_preprint":false,"source_track":"pubmed_title"},{"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":"26777405","id":"PMC_26777405","title":"ATPase-Modulated Stress Granules Contain a Diverse Proteome and Substructure.","date":"2016","source":"Cell","url":"https://pubmed.ncbi.nlm.nih.gov/26777405","citation_count":1233,"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":"21496894","id":"PMC_21496894","title":"Hydroxylation of 5-methylcytosine by TET1 promotes active DNA demethylation in the adult brain.","date":"2011","source":"Cell","url":"https://pubmed.ncbi.nlm.nih.gov/21496894","citation_count":1055,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"22681889","id":"PMC_22681889","title":"The mRNA-bound proteome and its global occupancy profile on protein-coding transcripts.","date":"2012","source":"Molecular cell","url":"https://pubmed.ncbi.nlm.nih.gov/22681889","citation_count":973,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"15635413","id":"PMC_15635413","title":"Nucleolar proteome dynamics.","date":"2005","source":"Nature","url":"https://pubmed.ncbi.nlm.nih.gov/15635413","citation_count":934,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"15592455","id":"PMC_15592455","title":"Immunoaffinity profiling of tyrosine phosphorylation in cancer cells.","date":"2004","source":"Nature biotechnology","url":"https://pubmed.ncbi.nlm.nih.gov/15592455","citation_count":916,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"1380454","id":"PMC_1380454","title":"Redox activation of Fos-Jun DNA binding activity is mediated by a DNA repair enzyme.","date":"1992","source":"The EMBO journal","url":"https://pubmed.ncbi.nlm.nih.gov/1380454","citation_count":849,"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":"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":"9108029","id":"PMC_9108029","title":"AP-1 transcriptional activity is regulated by a direct association between thioredoxin and Ref-1.","date":"1997","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/9108029","citation_count":698,"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":"10667800","id":"PMC_10667800","title":"DNA-bound structures and mutants reveal abasic DNA binding by APE1 and DNA repair coordination [corrected].","date":"2000","source":"Nature","url":"https://pubmed.ncbi.nlm.nih.gov/10667800","citation_count":640,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"20211142","id":"PMC_20211142","title":"An atlas of combinatorial transcriptional regulation in mouse and man.","date":"2010","source":"Cell","url":"https://pubmed.ncbi.nlm.nih.gov/20211142","citation_count":573,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"1722334","id":"PMC_1722334","title":"Cloning and expression of APE, the cDNA encoding the major human apurinic endonuclease: definition of a family of DNA repair enzymes.","date":"1991","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/1722334","citation_count":479,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"12628186","id":"PMC_12628186","title":"Tumor suppressor NM23-H1 is a granzyme A-activated DNase during CTL-mediated apoptosis, and the nucleosome assembly protein SET is its inhibitor.","date":"2003","source":"Cell","url":"https://pubmed.ncbi.nlm.nih.gov/12628186","citation_count":439,"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":"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":"16221808","id":"PMC_16221808","title":"Genetic polymorphisms in the base excision repair pathway and cancer risk: a HuGE review.","date":"2005","source":"American journal of epidemiology","url":"https://pubmed.ncbi.nlm.nih.gov/16221808","citation_count":431,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"9119221","id":"PMC_9119221","title":"Identification of redox/repair protein Ref-1 as a potent activator of p53.","date":"1997","source":"Genes & development","url":"https://pubmed.ncbi.nlm.nih.gov/9119221","citation_count":423,"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":"11707423","id":"PMC_11707423","title":"XRCC1 coordinates the initial and late stages of DNA abasic site repair through protein-protein interactions.","date":"2001","source":"The EMBO journal","url":"https://pubmed.ncbi.nlm.nih.gov/11707423","citation_count":392,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"28319085","id":"PMC_28319085","title":"Synergistic drug combinations for cancer identified in a CRISPR screen for pairwise genetic interactions.","date":"2017","source":"Nature biotechnology","url":"https://pubmed.ncbi.nlm.nih.gov/28319085","citation_count":378,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"9560228","id":"PMC_9560228","title":"Activation of apurinic/apyrimidinic endonuclease in human cells by reactive oxygen species and its correlation with their adaptive response to genotoxicity of free radicals.","date":"1998","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/9560228","citation_count":359,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"10585464","id":"PMC_10585464","title":"Thioredoxin-dependent redox regulation of p53-mediated p21 activation.","date":"1999","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/10585464","citation_count":356,"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":"16195237","id":"PMC_16195237","title":"Polymorphisms of DNA repair genes and risk of non-small cell lung cancer.","date":"2005","source":"Carcinogenesis","url":"https://pubmed.ncbi.nlm.nih.gov/16195237","citation_count":333,"is_preprint":false,"source_track":"gene2pubmed"},{"pmid":"15735682","id":"PMC_15735682","title":"HIF-1alpha, STAT3, CBP/p300 and Ref-1/APE are components of a transcriptional complex that regulates Src-dependent hypoxia-induced expression of VEGF in pancreatic and prostate carcinomas.","date":"2005","source":"Oncogene","url":"https://pubmed.ncbi.nlm.nih.gov/15735682","citation_count":329,"is_preprint":false,"source_track":"gene2pubmed"}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":41808,"output_tokens":5508,"usd":0.104022},"stage2":{"model":"claude-opus-4-6","input_tokens":9091,"output_tokens":3336,"usd":0.193282},"total_usd":0.484264,"stage1_batch_id":"msgbatch_01DzrsgVgYngY1hvM3DU1yF2","stage2_batch_id":"msgbatch_01KA9b7iRzKFdhoBUT7vCvSe","note":"batch pricing = 50% of standard","round2_stage1":{"model":"claude-sonnet-4-6","input_tokens":54400,"output_tokens":5195,"usd":0.120563},"round2_rules_fired":"R3","round2_stage2":{"model":"claude-opus-4-6","input_tokens":8323,"output_tokens":106,"usd":0.066397}},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 1997,\n      \"finding\": \"Crystal structure of human HAP1 (APE1/Ref-1) solved at 2.2 Å resolution, revealing two symmetrically related domains with structural similarity to bovine DNase I and E. coli exonuclease III; three loop regions specific to HAP1 and EXOIII are implicated in AP site recognition and cleavage, and the structure suggests a mechanism involving recognition of the deoxyribose moiety in an extrahelical conformation.\",\n      \"method\": \"X-ray crystallography at 2.2 Å resolution with structural comparison\",\n      \"journal\": \"The EMBO journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — crystal structure with mechanistic interpretation and structural comparisons\",\n      \"pmids\": [\"9351835\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1995,\n      \"finding\": \"Active-site mutagenesis of human HAP1 identified an aspartate/histidine pair and a metal ion-coordinating glutamate residue as critical for catalyzing multiple repair activities (AP endonuclease); this mechanism is distinct from the two-metal-ion mechanism of other hydrolytic nucleases.\",\n      \"method\": \"Site-directed mutagenesis combined with predicted 3D structure modeling\",\n      \"journal\": \"Nature structural biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — active-site mutagenesis with structural modeling, foundational mechanistic paper\",\n      \"pmids\": [\"7664124\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1996,\n      \"finding\": \"Asparagine 212 of human HAP1 is essential for AP site recognition (substrate binding), not catalysis per se; chelation of the active-site metal ion stabilizes HAP1 binding to AP-site-containing oligonucleotides, and Asn212 substitutions abolished both endonuclease activity and AP site binding.\",\n      \"method\": \"Site-directed mutagenesis and gel retardation (EMSA) with metal-chelated HAP1\",\n      \"journal\": \"Nucleic acids research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — mutagenesis plus binding assay, orthogonal methods distinguishing recognition from catalysis\",\n      \"pmids\": [\"8932375\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2000,\n      \"finding\": \"Asp-210 of human HAP1 is required for catalysis but not substrate recognition; substitution by Asn or Ala eliminates AP endonuclease activity while mutant proteins still bind AP site-containing and pBQ-adduct oligonucleotides efficiently, consistent with a stable HAP1-substrate complex that exists transiently during the wild-type catalytic cycle.\",\n      \"method\": \"Active-site mutagenesis, enzyme kinetics (Kcat/Km), and gel retardation substrate binding assays\",\n      \"journal\": \"Nucleic acids research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — mutagenesis plus kinetics plus binding assays, multiple orthogonal methods\",\n      \"pmids\": [\"10871340\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1994,\n      \"finding\": \"Antisense-mediated reduction of HAP1 protein in HeLa cells causes hypersensitivity to MMS, H2O2, menadione, paraquat, and to hypoxic/hyperoxic stress, but not to UV irradiation, establishing HAP1 as a key cellular protective factor against oxidative DNA damage and redox stress.\",\n      \"method\": \"Stable antisense RNA transfection with cytotoxicity assays across multiple agents\",\n      \"journal\": \"Nucleic acids research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — clean loss-of-function with multiple defined phenotypic readouts replicated across different stresses\",\n      \"pmids\": [\"7800476\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1997,\n      \"finding\": \"HAP1 (huntingtin-associated protein 1) interacts with the p150Glued subunit of dynactin (amino acids 879–1150) and with pericentriolar protein PCM-1; interaction with p150Glued was confirmed by GST pulldown in vitro and co-immunoprecipitation from brain extracts, and HAP1 co-localizes with p150Glued in NGF-treated PC12 cells, suggesting HAP1 functions as an adaptor between cytoskeletal, vesicular, and motor proteins.\",\n      \"method\": \"GST pulldown, co-immunoprecipitation from brain extracts, confocal immunofluorescence\",\n      \"journal\": \"Human molecular genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — reciprocal Co-IP from brain extracts plus in vitro GST pulldown plus colocalization, multiple orthogonal methods\",\n      \"pmids\": [\"9361024\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"HAP1 serves as the adaptor linking GABAA receptors to the kinesin motor KIF5 for anterograde trafficking to synapses; disrupting the HAP1-KIF5 complex decreases synaptic GABAAR number and reduces inhibitory postsynaptic current amplitude; mutant huntingtin impairs this transport and reduces inhibitory synaptic currents.\",\n      \"method\": \"Protein interaction studies, RNAi knockdown, electrophysiology (IPSC recordings), live imaging of receptor trafficking\",\n      \"journal\": \"Neuron\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal methods (interaction, KD, electrophysiology), strong mechanistic dissection\",\n      \"pmids\": [\"20152113\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"HAP1 and huntingtin copurify and colocalize with autophagosomes in neurons; RNAi depletion of HAP1 in primary neurons disrupts processive retrograde autophagosome transport by misregulating dynein and kinesin motors, and this transport defect correlates with inefficient degradation of engulfed mitochondrial fragments.\",\n      \"method\": \"Live-cell imaging, RNAi in GFP-LC3 transgenic primary neurons, subcellular fractionation/copurification\",\n      \"journal\": \"The Journal of neuroscience\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — live imaging plus RNAi with defined cargo-degradation phenotype, multiple orthogonal methods\",\n      \"pmids\": [\"24453320\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"HAP1 interacts with pericentriolar material 1 protein (PCM1) to regulate retrograde trafficking of PCM1 to the centrosome; loss of Hap1 in mouse cells impairs PCM1 retrograde trafficking and reduces primary cilia formation, and conditional deletion of Htt in ependymal cells leads to PCM1 mislocalization, cilia alteration, and hydrocephalus.\",\n      \"method\": \"Mouse knockout (conditional), immunofluorescence, protein interaction (co-IP), primary cilia quantification\",\n      \"journal\": \"The Journal of clinical investigation\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — conditional KO with defined cellular phenotype plus protein interaction, replicated across cell types\",\n      \"pmids\": [\"21985783\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"Targeted disruption of Hap1 in mice results in postnatal death due to depressed feeding behavior; Hap1-/- pups show markedly decreased milk ingestion, consistent with HAP1's enrichment in the hypothalamus and its essential role in regulating postnatal feeding.\",\n      \"method\": \"Targeted gene knockout in mice, behavioral (feeding) assays, serum leptin measurements\",\n      \"journal\": \"Human molecular genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — clean KO with well-defined behavioral and physiological phenotype\",\n      \"pmids\": [\"11971876\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"Conditional neuronal rescue of Hap1 expression before birth rescues the early postnatal lethality of Hap1 null mice; surviving Hap1 null adults display growth retardation but no overt brain or behavioral abnormalities, demonstrating Hap1 function is neuronal and essential specifically for early postnatal feeding.\",\n      \"method\": \"Conditional gene repair strategy (neuronal Cre-mediated rescue), mouse behavioral and neuroanatomical analysis\",\n      \"journal\": \"Human molecular genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — conditional rescue experiment with defined cellular and phenotypic specificity\",\n      \"pmids\": [\"15496430\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"HAP1 forms a complex with proBDNF and sortilin; the interaction is confirmed by FRET and co-IP in HEK293 cells; GST pulldown mapping defined the proBDNF-binding region of HAP1 (amino acids 371–445); HAP1 deficiency impairs proBDNF vesicle movement in neurites (confirmed by FRAP), and sortilin stabilizes the proBDNF-HAP1 complex and facilitates furin cleavage to release mature BDNF.\",\n      \"method\": \"Co-IP, FRET, GST pulldown, FRAP in HAP1-/- neurons, Western blot\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 — multiple orthogonal methods including FRAP in null neurons and domain mapping\",\n      \"pmids\": [\"21357693\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1997,\n      \"finding\": \"HAP1 interacts with a Trio-like polypeptide (Duo) containing a rac1 guanine nucleotide exchange factor domain; interaction was identified by yeast two-hybrid and confirmed by in vitro protein-binding assay, suggesting HAP1 may link huntingtin to a Ras-related signaling pathway.\",\n      \"method\": \"Yeast two-hybrid screen, in vitro protein-binding assay\",\n      \"journal\": \"Human molecular genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 — yeast two-hybrid confirmed by single in vitro binding assay, no functional follow-up\",\n      \"pmids\": [\"9285789\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1998,\n      \"finding\": \"The human HAP1 homologue (hHAP) encodes a 75-kDa brain-specific protein; in vitro binding, immunoprecipitation, and coexpression studies confirm hHAP interaction with huntingtin, with binding enhanced by polyglutamine repeat length.\",\n      \"method\": \"In vitro binding, co-immunoprecipitation, coexpression in cell lines\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — reciprocal Co-IP and in vitro binding for human protein, but limited mechanistic follow-up\",\n      \"pmids\": [\"9668110\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1998,\n      \"finding\": \"Both HAP1-A and HAP1-B isoforms associate with a unique cytoplasmic structure (stigmoid body/nematosome) in neurons; HAP1-A but not HAP1-B is essential for forming this structure when transfected into cell lines; both isoforms can self-associate, and the HAP1-A to HAP1-B ratio regulates inclusion formation.\",\n      \"method\": \"Immunoelectron microscopy, transfection of cell lines, yeast two-hybrid for self-association\",\n      \"journal\": \"Journal of neurochemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2–3 — direct localization with functional consequence (inclusion formation), supported by transfection experiments\",\n      \"pmids\": [\"9798945\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"HAP1 interacts with NeuroD (bHLH transcription factor) via a yeast two-hybrid screen; HAP1 and huntingtin facilitate the activation of NeuroD by MLK2 (which phosphorylates NeuroD), forming a scaffold complex; co-IP confirmed HAP1-NeuroD interaction.\",\n      \"method\": \"Yeast two-hybrid, co-immunoprecipitation, transcriptional reporter assays\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 — interaction confirmed by Co-IP with functional reporter evidence, single lab\",\n      \"pmids\": [\"12881483\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"HAP1 interacts with androgen receptor (AR) through the AR ligand-binding domain in a polyglutamine-length-dependent manner; co-expression with SBMA-mutant ARQ65 results in HAP1 sequestering polyQ-AR into inclusions; HAP1 co-transfection suppresses SBMA-mutant-AR-induced apoptosis.\",\n      \"method\": \"Co-transfection and immunofluorescence in HEp-2 cells, apoptosis assay\",\n      \"journal\": \"Human molecular genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 — single lab, cell-based interaction and apoptosis readout, no biochemical pulldown validation reported\",\n      \"pmids\": [\"16782802\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"HAP1 forms a ternary complex with huntingtin and the IP3 receptor (IP3R) that mediates ER Ca2+ release upon IP3 stimulation; loss of HAP1 prevents ternary complex formation and l-asparaginase-mediated ER Ca2+ release, blocking Ca2+-dependent calpain-1/Bid/caspase-3/caspase-12 apoptotic signaling, leading to l-asparaginase resistance in ALL cells.\",\n      \"method\": \"Co-immunoprecipitation, Ca2+ imaging, caspase activity assays, RNAi/gene knockout\",\n      \"journal\": \"Blood\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — Co-IP plus functional Ca2+ and apoptosis assays, single lab but multiple orthogonal methods\",\n      \"pmids\": [\"30819925\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"HAP1 is required for GABAAR recycling in neurons; OGD (ischemia model) induces calpain-mediated cleavage of HAP1 and reduces its interaction with GABAAR β3 subunits, decreasing receptor surface expression; reintroduction of HAP1A or HAP1B rescues receptor recycling rates and reduces OGD-induced neuronal death.\",\n      \"method\": \"Transfection of myc-tagged GABAAR β3, surface receptor assays, co-immunoprecipitation, cell death quantification\",\n      \"journal\": \"Molecular neurobiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2–3 — rescue experiment with defined trafficking and cell death readout, single lab\",\n      \"pmids\": [\"26732589\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"HAP1 interacts with clathrin light chain B and Sec23A (ER-to-Golgi COPII coat component); HAP1-clathrin light chain B interaction validated by Co-IP and GST-binding assay; HAP1 co-localizes with clathrin light chain B; HAP1 loss dramatically reduces vesicle retrieval/endocytosis in chromaffin cells and impairs transferrin endocytosis in cortical neurons.\",\n      \"method\": \"Affinity chromatography/mass spectrometry, co-IP, GST-binding, endocytosis assay in HAP1-/- neurons\",\n      \"journal\": \"Cellular signalling\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — proteomics-identified interactions validated by Co-IP/GST plus null-neuron functional assay\",\n      \"pmids\": [\"28259758\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2001,\n      \"finding\": \"HAP1 (APE1) stimulates the turnover of human thymine-DNA glycosylase (hTDG) for repair of 3,N(4)-ethenocytosine residues in vitro by displacing hTDG from the AP site product, increasing hTDG enzymatic turnover; this effect is specific to HAP1 among tested AP endonucleases.\",\n      \"method\": \"In vitro biochemical assay, dose-response stimulation, specificity controls with other AP endonucleases\",\n      \"journal\": \"Mutation research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 — in vitro reconstitution with specificity controls, but limited mechanistic follow-up on direct interaction\",\n      \"pmids\": [\"11506820\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1999,\n      \"finding\": \"HAP1 (APE1) redox function, separate from its AP endonuclease activity, sensitizes cells to bioreductive drugs (mitomycin C, daunorubicin, etc.); a HAP1 deletion mutant lacking redox function but retaining AP endonuclease activity abolished the sensitization, demonstrating that the redox domain specifically activates bioreduction of these drugs.\",\n      \"method\": \"Stable transfection with wild-type and redox-deletion mutant HAP1 in CHO cells, cytotoxicity assays\",\n      \"journal\": \"Carcinogenesis\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — domain-deletion mutant distinguishes two functions with cytotoxicity readout\",\n      \"pmids\": [\"10190555\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"AAV-mediated depletion of Hap1 in adult HD knock-in mice leads to selective neuronal loss in the striatum only in the presence of mutant huntingtin; Hap1 deficiency causes increased binding of Rhes (a striatum-enriched GTPase) to N-terminal HTT and increased soluble, sumoylated N-terminal mutant HTT, linking Hap1 to the Rhes-HTT sumoylation pathway mediating striatal neurotoxicity.\",\n      \"method\": \"AAV-mediated in vivo gene knockdown in KI mice, Co-IP, Western blot for sumoylated HTT\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — in vivo loss-of-function with defined neurodegeneration phenotype and biochemical pathway placement\",\n      \"pmids\": [\"32747555\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1996,\n      \"finding\": \"HAP1 (huntingtin-associated protein 1) is enriched in subcellular fractions containing synaptic vesicles and shows discrete neuronal localizations in brain that resemble those of neuronal nitric oxide synthase (nNOS), with immunocytochemical co-localization of HAP1 and nNOS in some neurons.\",\n      \"method\": \"In situ hybridization, subcellular fractionation, immunocytochemistry\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 — localization without direct functional link, expression pattern data\",\n      \"pmids\": [\"8643490\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"Human HAP1 (APE1/Ref-1) functions as a bifunctional nuclear enzyme: its AP endonuclease activity (requiring Asp-210 for catalysis and Asn-212 for substrate recognition, with an Asp/His/Glu catalytic triad) initiates base excision repair of abasic sites by cleaving the phosphodiester backbone 5' to extrahelical deoxyribose, and its separate redox domain activates transcription factors and can sensitize cells to bioreductive drugs; additionally, the neuronal HAP1 protein (huntingtin-associated protein 1, an unrelated protein sharing the gene symbol in some contexts) acts as an intracellular trafficking adaptor linking huntingtin to dynactin (p150Glued), KIF5, and other motors to regulate anterograde GABAAR delivery, retrograde autophagosome transport, and PCM1/cilia trafficking in neurons, with these functions disrupted by polyglutamine-expanded mutant huntingtin in Huntington's disease.\"\n}\n```\n\n--- ROUND 2 (R2/R3, augmented corpus) ---\n\nLooking at the corpus, I need to classify papers carefully. The query is for human/mammalian **HAP1** (Huntingtin-Associated Protein 1, also known as APE1/Ref-1 in some contexts).\n\nKey observations:\n- Many papers describe **yeast HAP1/HAP2/HAP3/HAP4** (transcription factors) → SYMBOL COLLISION (different proteins in yeast, not orthologs of mammalian HAP1)\n- Papers about **HAP2/GCS1** (gamete fusogen in plants/protists) → SYMBOL COLLISION\n- Papers about **human APE1/Ref-1** (also called HAP1 = Human AP endonuclease 1) → KEEP\n- Papers about **huntingtin-associated protein 1 (HAP1)** → KEEP\n- Papers about bacterial **HAP2** (flagellar cap, Salmonella) → SYMBOL COLLISION\n- Papers about **Leptospira hap1** → SYMBOL COLLISION\n\nThe human HAP1 gene actually refers to two different proteins in this corpus:\n1. **APE1/Ref-1** (AP endonuclease, encoded by APEX1) - papers [3], [10], [12 curated], [22], [54], [64], etc.\n2. **Huntingtin-Associated Protein 1** (HAP1) - papers [2], [5], [8], [18], [21], [25], [35], [38], [44], [47], [51], [52], [59], [61], [69], [78], [85], [90], [91], [97]\n\nThe gene being queried is **HAP1** (Huntingtin-Associated Protein 1, gene symbol HAP1). The APE1/Ref-1 papers use \"HAP1\" as an alias for APEX1 - this is a genuine alias collision situation. However, reviewing the HGNC record, HAP1 as a gene symbol refers to Huntingtin Associated Protein 1. APE1/Ref-1/APEX1 papers using \"HAP1\" represent an alias collision (APEX1 was sometimes called HAP1 = Human AP endonuclease 1).\n\nI will KEEP papers about huntingtin-associated protein 1 (HAP1) and EXCLUDE APE1/APEX1 papers.\n\n```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 1997,\n      \"finding\": \"HAP1 (huntingtin-associated protein 1) interacts with the p150Glued subunit of dynactin and with the pericentriolar protein PCM-1. The interaction with p150Glued was confirmed by in vitro GST pulldown and co-immunoprecipitation from brain extracts, and both proteins co-localize in NGF-treated PC12 cells, suggesting HAP1 functions as an adaptor linking cytoskeletal, vesicular, and motor proteins.\",\n      \"method\": \"GST pulldown, co-immunoprecipitation from brain extracts, double-label immunofluorescence confocal microscopy\",\n      \"journal\": \"Human molecular genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — reciprocal Co-IP in vivo plus in vitro GST pulldown, replicated with multiple methods\",\n      \"pmids\": [\"9361024\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1997,\n      \"finding\": \"HAP1 interacts with a Trio-like polypeptide (Duo) containing a Rac1 guanine nucleotide exchange factor (GEF) domain, a pleckstrin homology domain, and spectrin-like repeats. The interaction was identified by yeast two-hybrid screen and confirmed by in vitro protein-binding assay, suggesting HAP1 may link huntingtin to a Ras-related signaling pathway.\",\n      \"method\": \"Yeast two-hybrid screen, in vitro protein-binding assay\",\n      \"journal\": \"Human molecular genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 — yeast two-hybrid plus in vitro binding, single lab\",\n      \"pmids\": [\"9285789\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1996,\n      \"finding\": \"HAP1 is enriched in neurons and localizes to subcellular fractions containing synaptic vesicles. HAP1 and neuronal nitric oxide synthase (nNOS) co-localize in discrete neuronal populations and share similar brain regional distributions, with both enriched in the pedunculopontine nuclei, accessory olfactory bulb, and supraoptic nucleus.\",\n      \"method\": \"In situ hybridization, subcellular fractionation, immunocytochemistry\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — multiple localization methods with subcellular fractionation, single lab\",\n      \"pmids\": [\"8643490\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1998,\n      \"finding\": \"Human HAP1 (hHAP) is specifically expressed in brain tissues, encodes a 75-kDa protein, and binds to huntingtin in a polyglutamine repeat length-dependent manner (longer repeats bind more tightly). The interaction was confirmed by in vitro binding, co-immunoprecipitation, and coexpression studies.\",\n      \"method\": \"cDNA cloning, in vitro binding assay, co-immunoprecipitation, coexpression in mammalian cells\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal methods confirming interaction, human gene characterized\",\n      \"pmids\": [\"9668110\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1998,\n      \"finding\": \"HAP1 isoforms (HAP1-A and HAP1-B) associate with a unique cytoplasmic structure in neurons resembling the stigmoid body/nematosome. HAP1-A, but not HAP1-B, is essential for forming this inclusion structure in transfected cell lines. Both isoforms self-associate, and the ratio of HAP1-A to HAP1-B regulates inclusion formation.\",\n      \"method\": \"Immunocytochemistry, electron microscopy, transfection of cell lines, yeast two-hybrid for self-association\",\n      \"journal\": \"Journal of neurochemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — direct localization by EM and light microscopy with functional isoform dissection, single lab\",\n      \"pmids\": [\"9798945\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"Targeted disruption of HAP1 (Hap1-/-) in mice causes postnatal lethality due to severely depressed feeding behavior, malnutrition, and dehydration. 70% die by P2 and 100% by P9. HAP1 is particularly enriched in the hypothalamus, implicating it as essential for regulating postnatal feeding behavior.\",\n      \"method\": \"Homologous recombination knockout, behavioral observation, serum leptin measurement, brain weight analysis\",\n      \"journal\": \"Human molecular genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — clean KO with defined cellular/physiological phenotype, strong\",\n      \"pmids\": [\"11971876\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"HAP1 interacts with NeuroD (a bHLH transcription factor) and serves as a scaffold facilitating NeuroD activation by MLK2 kinase. HAP1 and huntingtin facilitate MLK2-mediated phosphorylation and activation of NeuroD, identifying a neuron-specific transcriptional regulatory complex.\",\n      \"method\": \"Yeast two-hybrid, co-immunoprecipitation, transcriptional reporter assays, kinase assay\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — multiple methods including kinase assay and reporter, moderate evidence\",\n      \"pmids\": [\"12881483\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"HAP1 null mutants rescued from early lethality (by litter size reduction) survive to adulthood with growth retardation but no overt brain or behavioral abnormalities, demonstrating HAP1 is required specifically for early postnatal feeding. Conditional gene repair restoring neuronal HAP1 expression before birth rescues early lethality. No synergism between Hap1 and huntingtin mutations was observed during development.\",\n      \"method\": \"Conditional gene rescue (neuronal-specific), Hap1 null mouse characterization, litter size manipulation\",\n      \"journal\": \"Human molecular genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — genetic epistasis via conditional rescue, strong functional evidence\",\n      \"pmids\": [\"15496430\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"HAP1 acts as an adaptor linking GABA-A receptors (GABAARs) to the kinesin motor KIF5, mediating anterograde delivery of GABAARs to synapses. Disrupting the HAP1-KIF5 complex reduces synaptic GABAAR number and decreases inhibitory postsynaptic current amplitude. Mutant huntingtin (polyQ-expanded) impairs GABAAR transport via disruption of this complex.\",\n      \"method\": \"Co-immunoprecipitation, RNAi knockdown, electrophysiology (mIPSC recording), live imaging of receptor trafficking\",\n      \"journal\": \"Neuron\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal methods including electrophysiology, imaging, and biochemistry; moderate-to-strong evidence\",\n      \"pmids\": [\"20152113\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"HAP1 interacts with PCM1 (pericentriolar material 1 protein) and huntingtin (HTT) to regulate ciliogenesis. Loss of Htt in mouse cells impairs retrograde trafficking of PCM1 and reduces primary cilia formation. In HD mice, pathogenic polyQ-expanded HTT causes centrosomal accumulation of PCM1 and abnormally long primary cilia in striatal cells, altering CSF flow.\",\n      \"method\": \"Co-immunoprecipitation, immunofluorescence, conditional knockout (ependymal cell-specific Htt deletion), cilia length measurement in HD mouse models and patient tissue\",\n      \"journal\": \"The Journal of clinical investigation\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal methods, in vivo genetic models, replicated in HD patients\",\n      \"pmids\": [\"21985783\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"proBDNF forms a trimeric complex with HAP1 and sortilin that regulates proBDNF intracellular trafficking and stabilization. The HAP1-proBDNF interaction was confirmed by FRET and co-immunoprecipitation. GST pulldown mapping defined the HAP1 binding region (aa 371–445) for proBDNF. FRAP experiments in HAP1-/- neurons showed defective proBDNF vesicle movement, partially rescued by HAP1 re-expression. The complex also facilitates furin cleavage to release mature BDNF.\",\n      \"method\": \"Co-immunoprecipitation, FRET, GST pulldown domain mapping, FRAP in HAP1-/- neurons, Western blot\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 — multiple orthogonal methods including FRET, FRAP in knockout neurons, and domain mapping\",\n      \"pmids\": [\"21357693\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"Mecp2 deficiency reduces Htt and Hap1 levels in mouse brain, causing defective BDNF axonal transport in the cortico-striatal pathway. Velocity of BDNF-containing vesicles is reduced in Mecp2-deficient axons and rescued by Mecp2 re-expression. APP transport (also Htt/Hap1-dependent) is similarly impaired, placing HAP1 in the Mecp2-Htt-Hap1 axis controlling axonal transport.\",\n      \"method\": \"Live imaging of BDNF vesicle transport, in vitro neuronal culture, viral rescue, mouse behavioral and lifespan analysis\",\n      \"journal\": \"Neurobiology of disease\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — live imaging of vesicle transport in KO neurons with rescue, single lab\",\n      \"pmids\": [\"22127389\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"Huntingtin (HTT) and HAP1 copurify and colocalize with autophagosomes in neurons. Using RNAi in primary neurons from GFP-LC3 mice and live-cell imaging, HTT and HAP1 were shown to control autophagosome dynamics by regulating dynein and kinesin motors to promote processive retrograde transport. PolyQ-HTT expression disrupts autophagosomal transport and leads to inefficient cargo degradation, without affecting autophagosome formation or cargo loading.\",\n      \"method\": \"Autophagosome purification/co-purification, RNAi knockdown, live-cell imaging in primary neurons (GFP-LC3 mice), mitochondrial fragment degradation assay\",\n      \"journal\": \"The Journal of neuroscience\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — copurification with organelle, RNAi knockdown with live imaging, multiple phenotypic readouts\",\n      \"pmids\": [\"24453320\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"HAP1 interacts with androgen receptor (AR) through the AR ligand-binding domain in a polyglutamine length-dependent manner. HAP1 sequesters polyQ-expanded AR into inclusions (stigmoid bodies) and suppresses SBMA-mutant AR-induced apoptosis when cotransfected in HEp-2 cells. Dihydrotestosterone reduces HAP1-AR association more strongly for normal than expanded polyQ-AR.\",\n      \"method\": \"Co-transfection, co-immunoprecipitation, immunofluorescence, apoptosis assay\",\n      \"journal\": \"Human molecular genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 — Co-IP plus functional apoptosis rescue, single lab\",\n      \"pmids\": [\"16782802\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"HAP1 is required for GABAAR recycling to the neuronal surface. In hippocampal neurons subjected to oxygen/glucose deprivation (OGD), calpain cleaves HAP1, reducing GABAAR recycling. Overexpression of HAP1A or HAP1B isoforms restored GABAAR surface expression and reduced OGD-induced neuronal death, demonstrating HAP1's role in receptor recycling and neuroprotection during ischemia.\",\n      \"method\": \"Transfection with myc-tagged GABAAR β3, surface biotinylation, co-immunoprecipitation, calpain cleavage assay, cell death assay in OGD model\",\n      \"journal\": \"Molecular neurobiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — multiple methods in primary neurons with defined phenotypic readout, single lab\",\n      \"pmids\": [\"26732589\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"HAP1 regulates neuronal endocytosis and interacts with clathrin light chain B (validated by Co-IP and GST pulldown) and Sec23A (ER-to-Golgi vesicle coat; validated by endogenous Co-IP in rat brain). HAP1 co-localizes with clathrin light chain B. HAP1 knockout adrenal chromaffin cells show dramatically reduced vesicle retrieval and endocytosis, and HAP1-/- cortical neurons show impaired transferrin endocytosis.\",\n      \"method\": \"Affinity chromatography/mass spectrometry proteomics, Co-IP, GST pulldown, immunofluorescence co-localization, endocytosis assay in HAP1-/- neurons\",\n      \"journal\": \"Cellular signalling\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — proteomics discovery validated by Co-IP/GST pulldown, functional endocytosis assay in KO neurons\",\n      \"pmids\": [\"28259758\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"HAP1 forms a ternary complex with huntingtin and the IP3 receptor (inositol 1,4,5-trisphosphate receptor, an intracellular Ca2+ channel) on the ER membrane. Loss of HAP1 prevents this ternary complex formation, blocks ER Ca2+ release upon IP3 stimulation, inhibits external Ca2+ entry, and reduces activation of the Ca2+-dependent calpain-1-Bid-caspase-3/12 apoptotic pathway, causing l-asparaginase resistance in ALL cells.\",\n      \"method\": \"Genome-wide RNAi screen, Co-immunoprecipitation (ternary complex), Ca2+ imaging, calpain/caspase activity assays, HAP1 knockdown rescue experiments\",\n      \"journal\": \"Blood\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — unbiased screen plus Co-IP of ternary complex, Ca2+ functional assays, multiple cell systems\",\n      \"pmids\": [\"30819925\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"AAV-mediated depletion of Hap1 in adult HD knock-in mouse brains causes selective neuronal loss in the striatum, but only in the presence of mutant HTT. Rhes (a striatum-enriched GTPase) binds more N-terminal HTT when Hap1 is absent, and more soluble sumoylated N-terminal HTT accumulates in the striatum, suggesting Hap1 normally sequesters or protects against toxic HTT fragments and that Rhes-Hap1 cooperate to determine selective striatal vulnerability.\",\n      \"method\": \"AAV-mediated gene silencing in vivo, histological analysis of neuronal loss, Co-immunoprecipitation, Western blot for sumoylated HTT\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — in vivo AAV KD in HD KI mice with defined neuronal loss phenotype, biochemical pathway analysis, single lab\",\n      \"pmids\": [\"32747555\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"HAP1 (huntingtin-associated protein 1) is a neuronally enriched adaptor protein that scaffolds molecular motor complexes (dynein/dynactin via p150Glued, kinesin KIF5) to mediate anterograde and retrograde vesicular transport of cargoes including GABA-A receptors, BDNF/proBDNF, and autophagosomes; it forms a ternary complex with huntingtin and the IP3 receptor to regulate ER Ca2+ release and apoptotic signaling; it localizes to stigmoid bodies via HAP1-A isoform self-association; it regulates ciliogenesis through PCM1 trafficking; it controls neuronal endocytosis through clathrin light chain B interactions; and its loss selectively promotes striatal neurodegeneration in Huntington disease models, with polyQ-expanded huntingtin disrupting these trafficking functions.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"HAP1 (huntingtin-associated protein 1) is a neuron-enriched intracellular trafficking adaptor that bridges cargo proteins to molecular motor complexes, thereby regulating vesicular transport along microtubules. HAP1 links GABAA receptors to the kinesin motor KIF5 for anterograde synaptic delivery and facilitates receptor recycling, while also associating with dynactin (p150Glued) and huntingtin to drive retrograde transport of autophagosomes and PCM1 to the centrosome, the latter being required for primary cilia formation [PMID:20152113, PMID:9361024, PMID:24453320, PMID:21985783]. HAP1 additionally forms complexes with proBDNF/sortilin to regulate neurotrophin trafficking, interacts with clathrin light chain B to support endocytosis, and scaffolds a huntingtin–IP3 receptor ternary complex that controls ER calcium release [PMID:21357693, PMID:28259758, PMID:30819925]. Targeted disruption of Hap1 in mice causes postnatal lethality due to depressed feeding behavior attributable to its essential neuronal function in the hypothalamus, and polyglutamine-expanded mutant huntingtin disrupts HAP1-dependent transport, contributing to Huntington's disease pathogenesis [PMID:11971876, PMID:15496430, PMID:32747555].\",\n  \"teleology\": [\n    {\n      \"year\": 1996,\n      \"claim\": \"Establishing HAP1 as a neuronally enriched protein associated with synaptic vesicle-containing fractions addressed whether HAP1 had a specific subcellular context, placing it at vesicular compartments in discrete neuronal populations.\",\n      \"evidence\": \"Subcellular fractionation and immunocytochemistry in rat brain\",\n      \"pmids\": [\"8643490\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"No direct functional assay linking HAP1 to vesicle function; localization-only evidence\", \"nNOS co-localization not functionally validated\", \"No motor protein connections established\"]\n    },\n    {\n      \"year\": 1997,\n      \"claim\": \"Identification of dynactin p150Glued and PCM1 as HAP1-binding partners established HAP1 as a candidate adaptor linking cargo to the cytoplasmic dynein motor complex, answering how HAP1 might connect huntingtin to intracellular transport machinery.\",\n      \"evidence\": \"GST pulldown, co-immunoprecipitation from brain extracts, confocal colocalization in PC12 cells\",\n      \"pmids\": [\"9361024\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No direct demonstration that HAP1 bridges huntingtin to dynactin in a single complex\", \"Functional consequence of disrupting the interaction not tested in neurons\"]\n    },\n    {\n      \"year\": 1998,\n      \"claim\": \"Characterization of the human HAP1 orthologue and demonstration that huntingtin binding is enhanced by polyglutamine expansion provided the molecular basis for how mutant huntingtin might aberrantly engage HAP1 in Huntington's disease.\",\n      \"evidence\": \"In vitro binding and co-immunoprecipitation with human HAP1 and huntingtin variants\",\n      \"pmids\": [\"9668110\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Enhanced binding not linked to a specific trafficking defect\", \"Stoichiometry and affinity measurements not reported\"]\n    },\n    {\n      \"year\": 1998,\n      \"claim\": \"Discovery that HAP1-A, but not HAP1-B, drives formation of a cytoplasmic stigmoid body structure revealed isoform-specific self-assembly properties, raising the question of whether these structures serve a trafficking or sequestration function.\",\n      \"evidence\": \"Immunoelectron microscopy and transfection of isoforms into cell lines, yeast two-hybrid self-association\",\n      \"pmids\": [\"9798945\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Biological function of stigmoid bodies remains unclear\", \"No link to motor-dependent trafficking established\"]\n    },\n    {\n      \"year\": 2002,\n      \"claim\": \"Hap1 knockout mice die postnatally from depressed feeding, demonstrating that HAP1 is essential for a specific physiological behavior and resolving whether the gene is required for viability.\",\n      \"evidence\": \"Targeted gene disruption in mice with behavioral and serum analysis\",\n      \"pmids\": [\"11971876\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular mechanism connecting HAP1 loss to hypothalamic feeding circuits not identified\", \"Whether trafficking defects underlie the feeding phenotype unclear\"]\n    },\n    {\n      \"year\": 2004,\n      \"claim\": \"Neuronal-specific rescue of Hap1 expression before birth fully rescued postnatal lethality, establishing that the critical function is neuronal and temporally restricted to early postnatal life.\",\n      \"evidence\": \"Conditional Cre-mediated gene repair in neurons of Hap1 null mice\",\n      \"pmids\": [\"15496430\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Identity of the specific neuronal population and downstream signaling pathway driving the feeding phenotype unknown\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Demonstration that HAP1 directly links GABAA receptors to KIF5 for anterograde synaptic transport answered how inhibitory neurotransmitter receptors reach synapses and showed that mutant huntingtin impairs this process, providing a concrete Huntington's disease-relevant trafficking defect.\",\n      \"evidence\": \"Protein interaction studies, RNAi, electrophysiology (miniature IPSCs), and live receptor trafficking imaging in neurons\",\n      \"pmids\": [\"20152113\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether HAP1 also regulates other ionotropic receptor transport not addressed\", \"Structural basis of the HAP1-KIF5 interface unknown\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Two contemporaneous studies showed that HAP1 mediates retrograde PCM1 trafficking to the centrosome (required for ciliogenesis) and forms a complex with proBDNF/sortilin to regulate neurotrophin vesicle movement, broadening HAP1's role from a single-cargo adaptor to a general neuronal trafficking hub.\",\n      \"evidence\": \"Conditional Htt KO mice with PCM1 mislocalization and cilia defects; co-IP/FRET/FRAP in HAP1-null neurons for proBDNF transport\",\n      \"pmids\": [\"21985783\", \"21357693\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether HAP1 recognizes a common motif across its diverse cargoes is unknown\", \"Cilia phenotype not directly tested in HAP1 conditional KO (Htt KO used as proxy)\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Live imaging revealed that HAP1 and huntingtin co-purify with autophagosomes and that HAP1 loss disrupts processive retrograde autophagosome transport, establishing a role in autophagy-related cargo clearance in neurons.\",\n      \"evidence\": \"Live-cell imaging of GFP-LC3 autophagosomes in RNAi-treated primary neurons, subcellular fractionation\",\n      \"pmids\": [\"24453320\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether HAP1 directly activates dynein on autophagosomes or acts indirectly through huntingtin not resolved\", \"Relevance to non-neuronal autophagy unknown\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Showing that ischemia-induced calpain cleavage of HAP1 disrupts GABAAR recycling linked HAP1 degradation to pathological loss of inhibitory synaptic transmission, answering whether HAP1 function is regulated by proteolytic processing under stress.\",\n      \"evidence\": \"OGD model in neurons, surface receptor assays, co-IP with GABAAR β3, rescue with HAP1A/B reintroduction\",\n      \"pmids\": [\"26732589\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Calpain cleavage site on HAP1 not mapped\", \"In vivo relevance of calpain-mediated regulation not confirmed\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Identification of clathrin light chain B and Sec23A as HAP1 interactors, and demonstration that HAP1 loss impairs endocytosis in chromaffin cells and neurons, extended HAP1's role to clathrin-mediated vesicle retrieval and ER-to-Golgi trafficking.\",\n      \"evidence\": \"Affinity chromatography/mass spectrometry, co-IP/GST pulldown, endocytosis assays in HAP1-null neurons\",\n      \"pmids\": [\"28259758\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether HAP1 acts as a cargo-selective endocytic adaptor or a general endocytosis factor not distinguished\", \"Sec23A interaction not functionally validated\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Discovery that HAP1 scaffolds a huntingtin–IP3R ternary complex mediating ER calcium release revealed a non-trafficking function for HAP1 in calcium signaling, with loss of HAP1 conferring l-asparaginase resistance in leukemia cells.\",\n      \"evidence\": \"Co-IP, calcium imaging, caspase activity assays, RNAi/gene knockout in ALL cell lines\",\n      \"pmids\": [\"30819925\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether HAP1-IP3R interaction occurs in neurons or is restricted to leukemia cells unclear\", \"Structural basis of ternary complex formation unknown\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"In vivo depletion of Hap1 in adult HD knock-in mice caused striatal neuronal loss only with mutant huntingtin and increased Rhes-mediated HTT sumoylation, mechanistically linking HAP1 to striatal vulnerability in Huntington's disease through the Rhes-sumoylation axis.\",\n      \"evidence\": \"AAV-mediated Hap1 knockdown in Hdh KI mice, co-IP, Western blot for sumoylated HTT\",\n      \"pmids\": [\"32747555\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether HAP1 normally prevents Rhes–HTT interaction by competitive binding not directly tested\", \"Contribution of trafficking defects versus sumoylation to neuronal death not separated\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"A unifying structural and mechanistic model explaining how HAP1 recognizes its diverse array of cargo (GABAAR, proBDNF, PCM1, autophagosomes, IP3R, clathrin) and coordinates their engagement with distinct motor complexes (kinesin versus dynein/dynactin) remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"No high-resolution structure of HAP1 or any HAP1-cargo/motor complex\", \"Cargo-selectivity determinants not mapped beyond single domain-mapping experiments\", \"Regulation of HAP1 adaptor function (post-translational modifications, isoform switching) poorly understood\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [5, 6, 7, 8, 11, 19]},\n      {\"term_id\": \"GO:0008092\", \"supporting_discovery_ids\": [5, 6, 19]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0031410\", \"supporting_discovery_ids\": [6, 7, 11, 19, 23]},\n      {\"term_id\": \"GO:0005856\", \"supporting_discovery_ids\": [5, 8]},\n      {\"term_id\": \"GO:0005829\", \"supporting_discovery_ids\": [14, 23]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-5653656\", \"supporting_discovery_ids\": [6, 7, 8, 11, 19]},\n      {\"term_id\": \"R-HSA-9612973\", \"supporting_discovery_ids\": [7]},\n      {\"term_id\": \"R-HSA-112316\", \"supporting_discovery_ids\": [6, 18]},\n      {\"term_id\": \"R-HSA-9609507\", \"supporting_discovery_ids\": [6, 8, 11]}\n    ],\n    \"complexes\": [\n      \"HAP1-huntingtin-dynactin complex\",\n      \"HAP1-KIF5-GABAAR transport complex\",\n      \"HAP1-huntingtin-IP3R ternary complex\"\n    ],\n    \"partners\": [\n      \"HTT\",\n      \"DCTN1\",\n      \"KIF5B\",\n      \"PCM1\",\n      \"SORT1\",\n      \"CLTB\",\n      \"ITPR1\",\n      \"GABRB3\"\n    ],\n    \"other_free_text\": []\n  }\n}\n```\n\n--- ROUND 2 (R2/R3, augmented corpus) ---\n\n```json\n{\n  \"mechanistic_narrative\": \"Insufficient on-target evidence to synthesize a narrative — discovery timeline does not match the canonical HAP1 protein.\",\n  \"teleology\": [],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [],\n    \"localization\": [],\n    \"pathway\": [],\n    \"complexes\": [],\n    \"partners\": [],\n    \"other_free_text\": []\n  }\n}\n```"}