{"gene":"PEX26","run_date":"2026-04-29T11:37:58","timeline":{"discoveries":[{"year":2006,"finding":"PEX26 is a tail-anchored peroxisomal membrane protein whose C-terminal targeting signal contains two PEX19-binding sites: one overlapping with the transmembrane domain (TMD) and one within the luminal domain. The luminal PEX19-binding site is essential for correct peroxisomal targeting, preventing mislocalization to mitochondria, and PEX19 is required for PEX26 import into peroxisomes.","method":"Targeting signal analysis by deletion/chimeric constructs, heterologous TMD insertion assay, PEX19 knockdown/binding assays, fluorescence microscopy","journal":"Journal of cell science","confidence":"High","confidence_rationale":"Tier 2 — multiple orthogonal methods (mutagenesis, chimeric constructs, binding assays, knockdown) in a single study with strong mechanistic resolution","pmids":["16763195"],"is_preprint":false},{"year":2003,"finding":"PEX26 encodes an integral peroxisomal membrane protein (305 aa) that is deficient in peroxisome biogenesis disorder complementation group 8 (CG8); re-expression of PEX26 restores peroxisome assembly in CG8 patient fibroblasts, confirming its essential role in peroxisome biogenesis.","method":"Complementation assay in patient fibroblasts and pex26 CHO cells, catalase import assay, temperature-sensitivity rescue","journal":"American journal of human genetics","confidence":"High","confidence_rationale":"Tier 2 — direct loss-of-function complementation with defined cellular phenotype (peroxisome assembly), replicated across multiple patient cell lines","pmids":["12851857"],"is_preprint":false},{"year":2005,"finding":"PEX26 functions as the peroxisomal docking factor for the PEX1/PEX6 AAA ATPase heterodimer; the PEX6-binding domain maps to the N-terminal region (aa 29–174) of PEX26. A splice variant PEX26-Δex5 lacking the TMD retains full ability to rescue peroxisome biogenesis in PEX26-deficient cells, demonstrating that peroxisomal localization of PEX26 is not strictly required for its function.","method":"Co-immunoprecipitation, deletion mapping, chimeric protein (PEX26-Mito) redirected to mitochondria, rescue assay in PEX26-deficient cells, immunofluorescence","journal":"American journal of human genetics","confidence":"High","confidence_rationale":"Tier 2 — reciprocal binding domain mapping, chimeric misdirection experiment with functional rescue, multiple orthogonal methods","pmids":["15858711"],"is_preprint":false},{"year":2013,"finding":"PEX19 forms a cytosolic complex with PEX26 and translocates it directly to peroxisomes by interacting with the peroxisomal membrane protein PEX3. Basic amino acids within the luminal domain of PEX26 are essential for PEX19 binding and peroxisomal targeting. Unlike yeast, the TRC40 ATPase (which delivers TA proteins to the ER) is dispensable for peroxisomal PEX26 targeting.","method":"Co-immunoprecipitation, cytosol fractionation, dominant-negative TRC40 expression, site-directed mutagenesis of basic residues, fluorescence microscopy","journal":"The Journal of cell biology","confidence":"High","confidence_rationale":"Tier 2 — multiple orthogonal methods including mutagenesis, dominant-negative experiments, fractionation, and Co-IP; moderate-to-strong evidence","pmids":["23460677"],"is_preprint":false},{"year":2018,"finding":"PEX26 undergoes homooligomerization mediated by two heptad repeat domains adjacent to its transmembrane domain. PEX26 associates with the peroxisomal translocation pore via PEX14. The full-length PEX26 and the splice variant PEX26Δex5 show different interaction patterns with PEX2-PEX10 or PEX13-PEX14 complexes, and the splice variant uses a PEX14-dependent mechanism for peroxisomal membrane association.","method":"Co-immunoprecipitation, domain mapping, protein interaction assays, functional rescue (peroxisomal β-oxidation assay), fluorescence microscopy","journal":"Biochimica et biophysica acta. Molecular cell research","confidence":"Medium","confidence_rationale":"Tier 2-3 — Co-IP and functional assays from a single lab, multiple interactions mapped","pmids":["30366024"],"is_preprint":false},{"year":2019,"finding":"The PEX26-F51L missense mutation severely impairs binding to PEX1 and PEX6 AAA ATPases and reduces peroxisomal matrix protein import rate; Pex26-F51L protein is unstable in cells (~30% of control levels), establishing that the N-terminal region of PEX26 is required for PEX1/PEX6 docking and peroxisome assembly.","method":"Co-immunoprecipitation in patient fibroblasts, immunostaining for matrix proteins (PTS1, PTS2, catalase), biochemical quantitation of protein levels, temperature-sensitivity assay","journal":"Cold Spring Harbor molecular case studies","confidence":"Medium","confidence_rationale":"Tier 2 — binding and import assays in patient-derived cells with multiple orthogonal readouts, single study","pmids":["30446579"],"is_preprint":false},{"year":2021,"finding":"Systematic protein interaction screen identified 14 novel PEX26 protein-protein interactions, revealing PEX26 as a hub in the peroxisomal interactome. Variant-specific disruption of individual interactions (edgetic perturbations) correlates with severity of matrix protein import defects, and PEX26 participates in peroxisomal matrix protein import, division/proliferation, and membrane assembly.","method":"Organelle protein interaction screen (co-immunoprecipitation panel), network medicine analysis, correlation with matrix protein import phenotype","journal":"Frontiers in genetics","confidence":"Medium","confidence_rationale":"Tier 3 — Co-IP-based interaction screen with functional correlation; single lab, moderate scope","pmids":["34804114"],"is_preprint":false},{"year":2021,"finding":"Genetic silencing of PEX26 (component of the peroxisome exportomer complex with PEX1 and PEX6) via CRISPRi increases pexophagy and causes peroxisomal matrix protein import defects, linking the PEX1-PEX6-PEX26 complex to peroxisome homeostasis. ATM kinase mediates the pexophagy induced by PEX26 loss.","method":"CRISPRi knockdown, autophagosome enrichment by mass spectrometry, immunofluorescence for peroxisomal matrix proteins, ATM inhibitor rescue, in vivo xenograft model","journal":"Autophagy","confidence":"Medium","confidence_rationale":"Tier 2-3 — multiple methods (CRISPRi, MS, inhibitor rescue, in vivo) establishing pathway position, single lab","pmids":["34074205"],"is_preprint":false},{"year":2017,"finding":"In Arabidopsis (plant ortholog context), PEX26 functions together with PEX1 and PEX6 to remove ubiquitinated PEX5 from the peroxisomal membrane (retrotranslocation); loss of PEX26 leads to proteasomal degradation of ubiquitinated PEX5 and defective peroxisomal matrix protein import. Peroxisomes cluster around persisting oil bodies in pex26 seedlings, suggesting a role in oil body utilization.","method":"Arabidopsis pex26 mutant genetic analysis, proteasome inhibitor treatment, double-mutant epistasis with ubiquitination machinery mutants, 35S:PEX5 transgene, fluorescence microscopy","journal":"The Plant journal","confidence":"Medium","confidence_rationale":"Tier 2 — epistasis and genetic rescue in plant ortholog; mechanistically consistent with mammalian PEX26 function","pmids":["28742939"],"is_preprint":false}],"current_model":"PEX26 is a tail-anchored peroxisomal membrane protein that acts as the peroxisomal docking factor for the PEX1/PEX6 AAA ATPase heterodimer, facilitating retrotranslocation and recycling of ubiquitinated PEX5 cargo receptor; it is targeted to peroxisomes via two C-terminal PEX19-binding sites (one in the TMD, one in the luminal domain), with PEX19 forming a cytosolic complex with PEX26 and delivering it to peroxisomes through PEX3, and PEX26 further associates with the translocation pore via PEX14 and undergoes homooligomerization through heptad repeat domains flanking its TMD."},"narrative":{"teleology":[{"year":2003,"claim":"The gene responsible for peroxisome biogenesis disorder complementation group 8 was unknown; identification of PEX26 and rescue of peroxisome assembly in patient fibroblasts established it as essential for peroxisome biogenesis.","evidence":"Complementation cloning in CG8 patient fibroblasts and pex26 CHO cells with catalase import rescue","pmids":["12851857"],"confidence":"High","gaps":["Molecular mechanism by which PEX26 supports peroxisome assembly was not defined","No binding partners identified"]},{"year":2005,"claim":"The mechanism by which PEX26 supports peroxisome biogenesis was unclear; mapping of the PEX6-binding domain to the N-terminal region (aa 29–174) and demonstration that PEX26 serves as the peroxisomal docking factor for the PEX1/PEX6 AAA ATPase complex established its core molecular function.","evidence":"Co-immunoprecipitation, deletion mapping, chimeric PEX26-Mito redirection to mitochondria with functional rescue in PEX26-deficient cells","pmids":["15858711"],"confidence":"High","gaps":["How PEX26 itself is targeted to peroxisomes was not resolved","Whether peroxisomal membrane localization is strictly required remained paradoxical given the soluble splice variant rescue"]},{"year":2006,"claim":"The targeting mechanism of PEX26 as a tail-anchored protein was undefined; identification of two PEX19-binding sites in the C-terminal region and demonstration that the luminal PEX19-binding site prevents mitochondrial mislocalization revealed the dual-signal targeting logic.","evidence":"Deletion/chimeric constructs, heterologous TMD insertion, PEX19 knockdown and binding assays, fluorescence microscopy","pmids":["16763195"],"confidence":"High","gaps":["Whether PEX19 delivers PEX26 directly to peroxisomes or via the ER was not resolved","Role of TRC40/GET pathway in PEX26 targeting was not tested"]},{"year":2013,"claim":"The delivery pathway for PEX26 to peroxisomes was unresolved; demonstration that PEX19 forms a cytosolic complex with PEX26 and delivers it to peroxisomes via PEX3, independent of TRC40, defined a direct PEX19/PEX3-dependent insertion route.","evidence":"Co-immunoprecipitation, cytosol fractionation, dominant-negative TRC40 expression, site-directed mutagenesis of basic residues","pmids":["23460677"],"confidence":"High","gaps":["Structural basis of PEX19–PEX26 recognition not determined","Whether additional chaperones participate in cytosolic PEX26 stabilization is unknown"]},{"year":2017,"claim":"Conservation and the direct substrate of the PEX26-dependent export machinery were uncertain; Arabidopsis pex26 mutants showed accumulation of ubiquitinated PEX5 on peroxisomal membranes and its proteasomal degradation, confirming that PEX26 functions in retrotranslocation of ubiquitinated PEX5 across kingdoms.","evidence":"Arabidopsis pex26 mutant analysis, proteasome inhibitor treatment, double-mutant epistasis with ubiquitination machinery","pmids":["28742939"],"confidence":"Medium","gaps":["Plant ortholog evidence; direct demonstration of PEX5 retrotranslocation dependence on PEX26 in mammalian cells not shown in this study","Role of PEX26 in oil body utilization is correlative"]},{"year":2018,"claim":"How PEX26 integrates with the peroxisomal translocation machinery was unclear; identification of PEX26 homooligomerization via heptad repeat domains and its association with the translocation pore through PEX14 revealed its architectural role in connecting the exportomer to the importomer.","evidence":"Co-immunoprecipitation, domain mapping, functional rescue via peroxisomal β-oxidation assay","pmids":["30366024"],"confidence":"Medium","gaps":["Stoichiometry and structure of the PEX26 oligomer not determined","Functional significance of differential splice variant interactions with PEX2-PEX10 versus PEX13-PEX14 is unclear"]},{"year":2019,"claim":"The functional significance of specific PEX26 residues for PEX1/PEX6 docking was unresolved; the F51L missense mutation demonstrated that a single N-terminal residue is critical for PEX1/PEX6 binding, protein stability, and peroxisomal matrix protein import.","evidence":"Co-immunoprecipitation and matrix protein import assays in patient fibroblasts carrying the PEX26-F51L mutation","pmids":["30446579"],"confidence":"Medium","gaps":["Whether instability is the primary defect or loss of binding is causative was not disentangled","Structural basis of F51-dependent PEX6 interaction unknown"]},{"year":2021,"claim":"The broader interaction network of PEX26 and consequences of its loss for peroxisome homeostasis were incompletely defined; systematic interactomics revealed PEX26 as a hub connecting import, division, and membrane assembly pathways, while CRISPRi silencing showed that PEX26 loss triggers ATM-dependent pexophagy.","evidence":"Co-immunoprecipitation interaction screen with network analysis; CRISPRi knockdown with mass spectrometry, ATM inhibitor rescue, and in vivo xenograft model","pmids":["34804114","34074205"],"confidence":"Medium","gaps":["Many novel interactions lack reciprocal validation","Mechanism by which ATM senses PEX26 deficiency is unknown","Whether pexophagy is a direct consequence of PEX5 recycling failure or a secondary quality-control response is unresolved"]},{"year":null,"claim":"No high-resolution structural model of PEX26 or the PEX1–PEX6–PEX26 ternary complex exists, and the mechanism by which PEX26 couples PEX1/PEX6 ATPase activity to PEX5 retrotranslocation across the peroxisomal membrane remains undefined.","evidence":"","pmids":[],"confidence":"High","gaps":["No cryo-EM or crystal structure of PEX26 or the exportomer complex","Mechanochemical coupling between ATPase activity and receptor recycling not reconstituted","Functional role of the PEX26Δex5 splice variant in vivo is unclear"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[2,4,5]}],"localization":[{"term_id":"GO:0005777","term_label":"peroxisome","supporting_discovery_ids":[0,1,3,4]}],"pathway":[{"term_id":"R-HSA-1852241","term_label":"Organelle biogenesis and maintenance","supporting_discovery_ids":[1,2,8]},{"term_id":"R-HSA-9612973","term_label":"Autophagy","supporting_discovery_ids":[7]},{"term_id":"R-HSA-9609507","term_label":"Protein localization","supporting_discovery_ids":[0,3]}],"complexes":["PEX1-PEX6-PEX26 exportomer"],"partners":["PEX1","PEX6","PEX19","PEX3","PEX14","PEX5"],"other_free_text":[]},"mechanistic_narrative":"PEX26 is a tail-anchored peroxisomal membrane protein essential for peroxisome biogenesis that functions as the docking factor for the PEX1/PEX6 AAA ATPase complex, facilitating retrotranslocation and recycling of ubiquitinated PEX5 cargo receptor from the peroxisomal membrane [PMID:15858711, PMID:28742939]. PEX26 is targeted to peroxisomes via PEX19, which binds two sites in the C-terminal region (one overlapping the transmembrane domain and one in the luminal domain) and delivers PEX26 to the peroxisomal membrane through PEX3, with basic residues in the luminal domain essential for correct targeting and prevention of mitochondrial mislocalization [PMID:16763195, PMID:23460677]. PEX26 associates with the peroxisomal translocation pore via PEX14, undergoes homooligomerization through heptad repeat domains flanking its transmembrane domain, and its N-terminal region (aa 29–174) constitutes the PEX6-binding domain required for PEX1/PEX6 recruitment and peroxisomal matrix protein import [PMID:15858711, PMID:30366024, PMID:30446579]. Loss of PEX26 function causes peroxisome biogenesis disorder complementation group 8, and PEX26 deficiency triggers ATM-dependent pexophagy and proteasomal degradation of ubiquitinated PEX5 [PMID:12851857, PMID:34074205]."},"prefetch_data":{"uniprot":{"accession":"Q7Z412","full_name":"Peroxisome assembly protein 26","aliases":["Peroxin-26"],"length_aa":305,"mass_kda":33.9,"function":"Peroxisomal docking factor that anchors PEX1 and PEX6 to peroxisome membranes (PubMed:12717447, PubMed:12851857, PubMed:16257970, PubMed:16763195, PubMed:16854980, PubMed:21362118). PEX26 is therefore required for the formation of the PEX1-PEX6 AAA ATPase complex, a complex that mediates the extraction of the PEX5 receptor from peroxisomal membrane (PubMed:12717447, PubMed:12851857, PubMed:16257970, PubMed:16763195, PubMed:16854980, PubMed:21362118)","subcellular_location":"Peroxisome membrane","url":"https://www.uniprot.org/uniprotkb/Q7Z412/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/PEX26","classification":"Not Classified","n_dependent_lines":56,"n_total_lines":1208,"dependency_fraction":0.046357615894039736},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/PEX26","total_profiled":1310},"omim":[{"mim_id":"614873","title":"PEROXISOME BIOGENESIS DISORDER 7B; PBD7B","url":"https://www.omim.org/entry/614873"},{"mim_id":"614872","title":"PEROXISOME BIOGENESIS DISORDER 7A (ZELLWEGER); PBD7A","url":"https://www.omim.org/entry/614872"},{"mim_id":"608666","title":"PEROXISOME BIOGENESIS FACTOR 26; PEX26","url":"https://www.omim.org/entry/608666"},{"mim_id":"601539","title":"PEROXISOME BIOGENESIS DISORDER 1B; PBD1B","url":"https://www.omim.org/entry/601539"},{"mim_id":"214100","title":"PEROXISOME BIOGENESIS DISORDER 1A (ZELLWEGER); PBD1A","url":"https://www.omim.org/entry/214100"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"","locations":[],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/PEX26"},"hgnc":{"alias_symbol":["FLJ20695"],"prev_symbol":[]},"alphafold":{"accession":"Q7Z412","domains":[{"cath_id":"1.25.40","chopping":"32-171","consensus_level":"medium","plddt":93.4572,"start":32,"end":171}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q7Z412","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q7Z412-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q7Z412-F1-predicted_aligned_error_v6.png","plddt_mean":79.5},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=PEX26","jax_strain_url":"https://www.jax.org/strain/search?query=PEX26"},"sequence":{"accession":"Q7Z412","fasta_url":"https://rest.uniprot.org/uniprotkb/Q7Z412.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q7Z412/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q7Z412"}},"corpus_meta":[{"pmid":"16763195","id":"PMC_16763195","title":"Targeting of the tail-anchored peroxisomal membrane proteins PEX26 and PEX15 occurs through C-terminal PEX19-binding sites.","date":"2006","source":"Journal of cell science","url":"https://pubmed.ncbi.nlm.nih.gov/16763195","citation_count":104,"is_preprint":false},{"pmid":"23460677","id":"PMC_23460677","title":"Tail-anchored PEX26 targets peroxisomes via a PEX19-dependent and TRC40-independent class I pathway.","date":"2013","source":"The Journal of cell biology","url":"https://pubmed.ncbi.nlm.nih.gov/23460677","citation_count":80,"is_preprint":false},{"pmid":"12851857","id":"PMC_12851857","title":"Mutations in novel peroxin gene PEX26 that cause peroxisome-biogenesis disorders of complementation group 8 provide a genotype-phenotype correlation.","date":"2003","source":"American journal of human genetics","url":"https://pubmed.ncbi.nlm.nih.gov/12851857","citation_count":66,"is_preprint":false},{"pmid":"28944237","id":"PMC_28944237","title":"Next-generation sequencing reveals the mutational landscape of clinically diagnosed Usher syndrome: copy number variations, phenocopies, a predominant target for translational read-through, and PEX26 mutated in Heimler syndrome.","date":"2017","source":"Molecular genetics & genomic medicine","url":"https://pubmed.ncbi.nlm.nih.gov/28944237","citation_count":51,"is_preprint":false},{"pmid":"15858711","id":"PMC_15858711","title":"Alternative splicing suggests extended function of PEX26 in peroxisome biogenesis.","date":"2005","source":"American journal of human genetics","url":"https://pubmed.ncbi.nlm.nih.gov/15858711","citation_count":41,"is_preprint":false},{"pmid":"34074205","id":"PMC_34074205","title":"Silencing PEX26 as an unconventional mode to kill drug-resistant cancer cells and forestall drug resistance.","date":"2021","source":"Autophagy","url":"https://pubmed.ncbi.nlm.nih.gov/34074205","citation_count":17,"is_preprint":false},{"pmid":"28742939","id":"PMC_28742939","title":"Disparate peroxisome-related defects in Arabidopsis pex6 and pex26 mutants link peroxisomal retrotranslocation and oil body utilization.","date":"2017","source":"The Plant journal : for cell and molecular biology","url":"https://pubmed.ncbi.nlm.nih.gov/28742939","citation_count":16,"is_preprint":false},{"pmid":"30446579","id":"PMC_30446579","title":"A newly identified mutation in the PEX26 gene is associated with a milder form of Zellweger spectrum disorder.","date":"2019","source":"Cold Spring Harbor molecular case studies","url":"https://pubmed.ncbi.nlm.nih.gov/30446579","citation_count":14,"is_preprint":false},{"pmid":"30366024","id":"PMC_30366024","title":"Isoform-specific domain organization determines conformation and function of the peroxisomal biogenesis factor PEX26.","date":"2018","source":"Biochimica et biophysica acta. Molecular cell research","url":"https://pubmed.ncbi.nlm.nih.gov/30366024","citation_count":12,"is_preprint":false},{"pmid":"33926089","id":"PMC_33926089","title":"Identification of a Homozygous PEX26 Mutation in a Heimler Syndrome Patient.","date":"2021","source":"Genes","url":"https://pubmed.ncbi.nlm.nih.gov/33926089","citation_count":7,"is_preprint":false},{"pmid":"34430430","id":"PMC_34430430","title":"PEX26 gene genotype-phenotype correlation in neonates with Zellweger syndrome.","date":"2021","source":"Translational pediatrics","url":"https://pubmed.ncbi.nlm.nih.gov/34430430","citation_count":4,"is_preprint":false},{"pmid":"33912394","id":"PMC_33912394","title":"A novel mutation in the PEX26 gene in a family from Dagestan with members affected by Zellweger spectrum disorder.","date":"2021","source":"Molecular genetics and metabolism reports","url":"https://pubmed.ncbi.nlm.nih.gov/33912394","citation_count":3,"is_preprint":false},{"pmid":"37957408","id":"PMC_37957408","title":"PEX26 Functions as a Metastasis Suppressor in Colorectal Cancer.","date":"2023","source":"Digestive diseases and sciences","url":"https://pubmed.ncbi.nlm.nih.gov/37957408","citation_count":3,"is_preprint":false},{"pmid":"39757991","id":"PMC_39757991","title":"Zellweger syndrome; identification of mutations in PEX19 and PEX26 gene in Saudi families.","date":"2025","source":"Annals of medicine","url":"https://pubmed.ncbi.nlm.nih.gov/39757991","citation_count":2,"is_preprint":false},{"pmid":"34804114","id":"PMC_34804114","title":"Edgetic Perturbations Contribute to Phenotypic Variability in PEX26 Deficiency.","date":"2021","source":"Frontiers in genetics","url":"https://pubmed.ncbi.nlm.nih.gov/34804114","citation_count":2,"is_preprint":false},{"pmid":"38323187","id":"PMC_38323187","title":"Identification of a novel heterozygous variant in the PEX26 gene in an infant: a case report.","date":"2024","source":"Translational pediatrics","url":"https://pubmed.ncbi.nlm.nih.gov/38323187","citation_count":1,"is_preprint":false},{"pmid":"39359950","id":"PMC_39359950","title":"Biallelic Deletion of PEX26 Exon 4 in a Boy with Phenotypic Features of both Zellweger Syndrome and Infantile Refsum Disease.","date":"2024","source":"Molecular syndromology","url":"https://pubmed.ncbi.nlm.nih.gov/39359950","citation_count":0,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":10917,"output_tokens":2534,"usd":0.035381},"stage2":{"model":"claude-opus-4-6","input_tokens":5834,"output_tokens":2551,"usd":0.139417},"total_usd":0.174798,"stage1_batch_id":"msgbatch_012ZiiCUBfB62NCTQd4Bk1Jo","stage2_batch_id":"msgbatch_01Xuqq9aUHoQouS7UVGZNStZ","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2006,\n      \"finding\": \"PEX26 is a tail-anchored peroxisomal membrane protein whose C-terminal targeting signal contains two PEX19-binding sites: one overlapping with the transmembrane domain (TMD) and one within the luminal domain. The luminal PEX19-binding site is essential for correct peroxisomal targeting, preventing mislocalization to mitochondria, and PEX19 is required for PEX26 import into peroxisomes.\",\n      \"method\": \"Targeting signal analysis by deletion/chimeric constructs, heterologous TMD insertion assay, PEX19 knockdown/binding assays, fluorescence microscopy\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal methods (mutagenesis, chimeric constructs, binding assays, knockdown) in a single study with strong mechanistic resolution\",\n      \"pmids\": [\"16763195\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"PEX26 encodes an integral peroxisomal membrane protein (305 aa) that is deficient in peroxisome biogenesis disorder complementation group 8 (CG8); re-expression of PEX26 restores peroxisome assembly in CG8 patient fibroblasts, confirming its essential role in peroxisome biogenesis.\",\n      \"method\": \"Complementation assay in patient fibroblasts and pex26 CHO cells, catalase import assay, temperature-sensitivity rescue\",\n      \"journal\": \"American journal of human genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — direct loss-of-function complementation with defined cellular phenotype (peroxisome assembly), replicated across multiple patient cell lines\",\n      \"pmids\": [\"12851857\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"PEX26 functions as the peroxisomal docking factor for the PEX1/PEX6 AAA ATPase heterodimer; the PEX6-binding domain maps to the N-terminal region (aa 29–174) of PEX26. A splice variant PEX26-Δex5 lacking the TMD retains full ability to rescue peroxisome biogenesis in PEX26-deficient cells, demonstrating that peroxisomal localization of PEX26 is not strictly required for its function.\",\n      \"method\": \"Co-immunoprecipitation, deletion mapping, chimeric protein (PEX26-Mito) redirected to mitochondria, rescue assay in PEX26-deficient cells, immunofluorescence\",\n      \"journal\": \"American journal of human genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — reciprocal binding domain mapping, chimeric misdirection experiment with functional rescue, multiple orthogonal methods\",\n      \"pmids\": [\"15858711\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"PEX19 forms a cytosolic complex with PEX26 and translocates it directly to peroxisomes by interacting with the peroxisomal membrane protein PEX3. Basic amino acids within the luminal domain of PEX26 are essential for PEX19 binding and peroxisomal targeting. Unlike yeast, the TRC40 ATPase (which delivers TA proteins to the ER) is dispensable for peroxisomal PEX26 targeting.\",\n      \"method\": \"Co-immunoprecipitation, cytosol fractionation, dominant-negative TRC40 expression, site-directed mutagenesis of basic residues, fluorescence microscopy\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal methods including mutagenesis, dominant-negative experiments, fractionation, and Co-IP; moderate-to-strong evidence\",\n      \"pmids\": [\"23460677\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"PEX26 undergoes homooligomerization mediated by two heptad repeat domains adjacent to its transmembrane domain. PEX26 associates with the peroxisomal translocation pore via PEX14. The full-length PEX26 and the splice variant PEX26Δex5 show different interaction patterns with PEX2-PEX10 or PEX13-PEX14 complexes, and the splice variant uses a PEX14-dependent mechanism for peroxisomal membrane association.\",\n      \"method\": \"Co-immunoprecipitation, domain mapping, protein interaction assays, functional rescue (peroxisomal β-oxidation assay), fluorescence microscopy\",\n      \"journal\": \"Biochimica et biophysica acta. Molecular cell research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 — Co-IP and functional assays from a single lab, multiple interactions mapped\",\n      \"pmids\": [\"30366024\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"The PEX26-F51L missense mutation severely impairs binding to PEX1 and PEX6 AAA ATPases and reduces peroxisomal matrix protein import rate; Pex26-F51L protein is unstable in cells (~30% of control levels), establishing that the N-terminal region of PEX26 is required for PEX1/PEX6 docking and peroxisome assembly.\",\n      \"method\": \"Co-immunoprecipitation in patient fibroblasts, immunostaining for matrix proteins (PTS1, PTS2, catalase), biochemical quantitation of protein levels, temperature-sensitivity assay\",\n      \"journal\": \"Cold Spring Harbor molecular case studies\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — binding and import assays in patient-derived cells with multiple orthogonal readouts, single study\",\n      \"pmids\": [\"30446579\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"Systematic protein interaction screen identified 14 novel PEX26 protein-protein interactions, revealing PEX26 as a hub in the peroxisomal interactome. Variant-specific disruption of individual interactions (edgetic perturbations) correlates with severity of matrix protein import defects, and PEX26 participates in peroxisomal matrix protein import, division/proliferation, and membrane assembly.\",\n      \"method\": \"Organelle protein interaction screen (co-immunoprecipitation panel), network medicine analysis, correlation with matrix protein import phenotype\",\n      \"journal\": \"Frontiers in genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 — Co-IP-based interaction screen with functional correlation; single lab, moderate scope\",\n      \"pmids\": [\"34804114\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"Genetic silencing of PEX26 (component of the peroxisome exportomer complex with PEX1 and PEX6) via CRISPRi increases pexophagy and causes peroxisomal matrix protein import defects, linking the PEX1-PEX6-PEX26 complex to peroxisome homeostasis. ATM kinase mediates the pexophagy induced by PEX26 loss.\",\n      \"method\": \"CRISPRi knockdown, autophagosome enrichment by mass spectrometry, immunofluorescence for peroxisomal matrix proteins, ATM inhibitor rescue, in vivo xenograft model\",\n      \"journal\": \"Autophagy\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 — multiple methods (CRISPRi, MS, inhibitor rescue, in vivo) establishing pathway position, single lab\",\n      \"pmids\": [\"34074205\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"In Arabidopsis (plant ortholog context), PEX26 functions together with PEX1 and PEX6 to remove ubiquitinated PEX5 from the peroxisomal membrane (retrotranslocation); loss of PEX26 leads to proteasomal degradation of ubiquitinated PEX5 and defective peroxisomal matrix protein import. Peroxisomes cluster around persisting oil bodies in pex26 seedlings, suggesting a role in oil body utilization.\",\n      \"method\": \"Arabidopsis pex26 mutant genetic analysis, proteasome inhibitor treatment, double-mutant epistasis with ubiquitination machinery mutants, 35S:PEX5 transgene, fluorescence microscopy\",\n      \"journal\": \"The Plant journal\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — epistasis and genetic rescue in plant ortholog; mechanistically consistent with mammalian PEX26 function\",\n      \"pmids\": [\"28742939\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"PEX26 is a tail-anchored peroxisomal membrane protein that acts as the peroxisomal docking factor for the PEX1/PEX6 AAA ATPase heterodimer, facilitating retrotranslocation and recycling of ubiquitinated PEX5 cargo receptor; it is targeted to peroxisomes via two C-terminal PEX19-binding sites (one in the TMD, one in the luminal domain), with PEX19 forming a cytosolic complex with PEX26 and delivering it to peroxisomes through PEX3, and PEX26 further associates with the translocation pore via PEX14 and undergoes homooligomerization through heptad repeat domains flanking its TMD.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"PEX26 is a tail-anchored peroxisomal membrane protein essential for peroxisome biogenesis that functions as the docking factor for the PEX1/PEX6 AAA ATPase complex, facilitating retrotranslocation and recycling of ubiquitinated PEX5 cargo receptor from the peroxisomal membrane [PMID:15858711, PMID:28742939]. PEX26 is targeted to peroxisomes via PEX19, which binds two sites in the C-terminal region (one overlapping the transmembrane domain and one in the luminal domain) and delivers PEX26 to the peroxisomal membrane through PEX3, with basic residues in the luminal domain essential for correct targeting and prevention of mitochondrial mislocalization [PMID:16763195, PMID:23460677]. PEX26 associates with the peroxisomal translocation pore via PEX14, undergoes homooligomerization through heptad repeat domains flanking its transmembrane domain, and its N-terminal region (aa 29–174) constitutes the PEX6-binding domain required for PEX1/PEX6 recruitment and peroxisomal matrix protein import [PMID:15858711, PMID:30366024, PMID:30446579]. Loss of PEX26 function causes peroxisome biogenesis disorder complementation group 8, and PEX26 deficiency triggers ATM-dependent pexophagy and proteasomal degradation of ubiquitinated PEX5 [PMID:12851857, PMID:34074205].\",\n  \"teleology\": [\n    {\n      \"year\": 2003,\n      \"claim\": \"The gene responsible for peroxisome biogenesis disorder complementation group 8 was unknown; identification of PEX26 and rescue of peroxisome assembly in patient fibroblasts established it as essential for peroxisome biogenesis.\",\n      \"evidence\": \"Complementation cloning in CG8 patient fibroblasts and pex26 CHO cells with catalase import rescue\",\n      \"pmids\": [\"12851857\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular mechanism by which PEX26 supports peroxisome assembly was not defined\", \"No binding partners identified\"]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"The mechanism by which PEX26 supports peroxisome biogenesis was unclear; mapping of the PEX6-binding domain to the N-terminal region (aa 29–174) and demonstration that PEX26 serves as the peroxisomal docking factor for the PEX1/PEX6 AAA ATPase complex established its core molecular function.\",\n      \"evidence\": \"Co-immunoprecipitation, deletion mapping, chimeric PEX26-Mito redirection to mitochondria with functional rescue in PEX26-deficient cells\",\n      \"pmids\": [\"15858711\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How PEX26 itself is targeted to peroxisomes was not resolved\", \"Whether peroxisomal membrane localization is strictly required remained paradoxical given the soluble splice variant rescue\"]\n    },\n    {\n      \"year\": 2006,\n      \"claim\": \"The targeting mechanism of PEX26 as a tail-anchored protein was undefined; identification of two PEX19-binding sites in the C-terminal region and demonstration that the luminal PEX19-binding site prevents mitochondrial mislocalization revealed the dual-signal targeting logic.\",\n      \"evidence\": \"Deletion/chimeric constructs, heterologous TMD insertion, PEX19 knockdown and binding assays, fluorescence microscopy\",\n      \"pmids\": [\"16763195\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether PEX19 delivers PEX26 directly to peroxisomes or via the ER was not resolved\", \"Role of TRC40/GET pathway in PEX26 targeting was not tested\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"The delivery pathway for PEX26 to peroxisomes was unresolved; demonstration that PEX19 forms a cytosolic complex with PEX26 and delivers it to peroxisomes via PEX3, independent of TRC40, defined a direct PEX19/PEX3-dependent insertion route.\",\n      \"evidence\": \"Co-immunoprecipitation, cytosol fractionation, dominant-negative TRC40 expression, site-directed mutagenesis of basic residues\",\n      \"pmids\": [\"23460677\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural basis of PEX19–PEX26 recognition not determined\", \"Whether additional chaperones participate in cytosolic PEX26 stabilization is unknown\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Conservation and the direct substrate of the PEX26-dependent export machinery were uncertain; Arabidopsis pex26 mutants showed accumulation of ubiquitinated PEX5 on peroxisomal membranes and its proteasomal degradation, confirming that PEX26 functions in retrotranslocation of ubiquitinated PEX5 across kingdoms.\",\n      \"evidence\": \"Arabidopsis pex26 mutant analysis, proteasome inhibitor treatment, double-mutant epistasis with ubiquitination machinery\",\n      \"pmids\": [\"28742939\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Plant ortholog evidence; direct demonstration of PEX5 retrotranslocation dependence on PEX26 in mammalian cells not shown in this study\", \"Role of PEX26 in oil body utilization is correlative\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"How PEX26 integrates with the peroxisomal translocation machinery was unclear; identification of PEX26 homooligomerization via heptad repeat domains and its association with the translocation pore through PEX14 revealed its architectural role in connecting the exportomer to the importomer.\",\n      \"evidence\": \"Co-immunoprecipitation, domain mapping, functional rescue via peroxisomal β-oxidation assay\",\n      \"pmids\": [\"30366024\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Stoichiometry and structure of the PEX26 oligomer not determined\", \"Functional significance of differential splice variant interactions with PEX2-PEX10 versus PEX13-PEX14 is unclear\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"The functional significance of specific PEX26 residues for PEX1/PEX6 docking was unresolved; the F51L missense mutation demonstrated that a single N-terminal residue is critical for PEX1/PEX6 binding, protein stability, and peroxisomal matrix protein import.\",\n      \"evidence\": \"Co-immunoprecipitation and matrix protein import assays in patient fibroblasts carrying the PEX26-F51L mutation\",\n      \"pmids\": [\"30446579\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether instability is the primary defect or loss of binding is causative was not disentangled\", \"Structural basis of F51-dependent PEX6 interaction unknown\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"The broader interaction network of PEX26 and consequences of its loss for peroxisome homeostasis were incompletely defined; systematic interactomics revealed PEX26 as a hub connecting import, division, and membrane assembly pathways, while CRISPRi silencing showed that PEX26 loss triggers ATM-dependent pexophagy.\",\n      \"evidence\": \"Co-immunoprecipitation interaction screen with network analysis; CRISPRi knockdown with mass spectrometry, ATM inhibitor rescue, and in vivo xenograft model\",\n      \"pmids\": [\"34804114\", \"34074205\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Many novel interactions lack reciprocal validation\", \"Mechanism by which ATM senses PEX26 deficiency is unknown\", \"Whether pexophagy is a direct consequence of PEX5 recycling failure or a secondary quality-control response is unresolved\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"No high-resolution structural model of PEX26 or the PEX1–PEX6–PEX26 ternary complex exists, and the mechanism by which PEX26 couples PEX1/PEX6 ATPase activity to PEX5 retrotranslocation across the peroxisomal membrane remains undefined.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No cryo-EM or crystal structure of PEX26 or the exportomer complex\", \"Mechanochemical coupling between ATPase activity and receptor recycling not reconstituted\", \"Functional role of the PEX26Δex5 splice variant in vivo is unclear\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [2, 4, 5]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005777\", \"supporting_discovery_ids\": [0, 1, 3, 4]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-1852241\", \"supporting_discovery_ids\": [1, 2, 8]},\n      {\"term_id\": \"R-HSA-9612973\", \"supporting_discovery_ids\": [7]},\n      {\"term_id\": \"R-HSA-9609507\", \"supporting_discovery_ids\": [0, 3]}\n    ],\n    \"complexes\": [\n      \"PEX1-PEX6-PEX26 exportomer\"\n    ],\n    \"partners\": [\n      \"PEX1\",\n      \"PEX6\",\n      \"PEX19\",\n      \"PEX3\",\n      \"PEX14\",\n      \"PEX5\"\n    ],\n    \"other_free_text\": []\n  }\n}\n```"}