{"gene":"VPS26A","run_date":"2026-06-11T09:02:06","timeline":{"discoveries":[{"year":2000,"finding":"Human VPS26 (hVps26) assembles into a ~220-440 kDa retromer complex by binding directly to the N-terminal region (residues 1-172) of hVps35, which serves as the scaffold; in the absence of hVps35, hVps26 is not found in the large complex. Both recombinant and endogenous hVps26 are found in membrane-associated and cytosolic compartments.","method":"Yeast two-hybrid, co-immunoprecipitation, gel filtration chromatography, deletion mapping in COS7 cells","journal":"Molecular biology of the cell","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal Co-IP, deletion mapping, gel filtration, multiple orthogonal methods in a single foundational study","pmids":["11102511"],"is_preprint":false},{"year":2006,"finding":"Crystal structure of human VPS26A at 2.1-Å resolution reveals two curved β-sandwich domains connected by a polar core and flexible linker, with an arrestin-like fold. The Vps35-binding site maps to a mobile loop (residues 235-246) at the tip of the C-terminal domain; hydrophobic residues and a glycine in this loop are required for retromer complex integration and endosomal localization of VPS26A, and for yeast Vps26 function in carboxypeptidase Y sorting.","method":"X-ray crystallography (2.1-Å), site-directed mutagenesis, endosomal localization assay, yeast carboxypeptidase Y sorting assay","journal":"Nature structural & molecular biology","confidence":"High","confidence_rationale":"Tier 1 / Strong — crystal structure combined with mutagenesis and functional validation in two systems (mammalian localization and yeast sorting)","pmids":["16732284"],"is_preprint":false},{"year":2011,"finding":"Vps26A and Vps26B define distinct retromer complexes with different functional properties: Vps26A-retromer interacts with CI-M6PR and recycles it, whereas Vps26B-retromer does not interact with CI-M6PR, leading to receptor degradation and increased cathepsin D secretion. The Vps26B C-terminal variable region is directly responsible for this differential cargo selection, as its deletion restores CI-M6PR cycling. Both paralogues associate with TBC1D5 and GOLPH3.","method":"Stable expression of Vps26A-myc or Vps26B-myc in HEK293 cells, co-immunoprecipitation, colocalization with Rab markers, deletion analysis","journal":"Traffic (Copenhagen, Denmark)","confidence":"High","confidence_rationale":"Tier 2 / Moderate — reciprocal Co-IP with deletion mapping, functional readouts (receptor degradation, cathepsin D secretion), multiple orthogonal approaches in a single study","pmids":["21920005"],"is_preprint":false},{"year":2012,"finding":"Rabankyrin-5 (Rank-5) colocalizes and interacts with VPS26 as a component of retromer-based transport. Depletion of Rank-5 causes mislocalization of Vps26 and impairs retrieval of mannose 6-phosphate receptor to the Golgi.","method":"Co-immunoprecipitation, colocalization, siRNA knockdown with functional rescue","journal":"Traffic (Copenhagen, Denmark)","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — Co-IP and colocalization with functional knockdown readout, single lab","pmids":["22284051"],"is_preprint":false},{"year":2014,"finding":"VPS26 plays an allosteric role in Rab7-mediated endosomal recruitment of the retromer core complex: Rab7 directly interacts with VPS35 to recruit retromer, but disruption of the Vps35-Vps26 interaction perturbs this recruitment. Association of Vps26 with Vps35 results in high-affinity binding between the Vps sub-complex and activated Rab7, indicating a positive allosteric contribution of Vps26.","method":"FRET-based interaction assay in HeLa cells, biophysical binding measurements, site-directed mutagenesis disrupting Vps35-Vps26 interaction","journal":"Traffic (Copenhagen, Denmark)","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — FRET in cells plus biophysical measurements, single lab with two orthogonal approaches","pmids":["25367362"],"is_preprint":false},{"year":2015,"finding":"VPS26A interacts with SNX27 in spinal dorsal horn neurons to mediate mGluR5 recycling to the plasma membrane. Spinal nerve ligation increases VPS26A-SNX27 coprecipitation and VPS26A-bound mGluR5; knockdown of VPS26A reduces membrane-bound mGluR5 and attenuates neuropathic allodynia.","method":"Co-immunoprecipitation, immunofluorescence, siRNA knockdown in rat dorsal horn neurons, behavioral allodynia assay","journal":"The Journal of neuroscience","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — Co-IP with in vivo knockdown phenotype, multiple readouts, single lab","pmids":["26538661"],"is_preprint":false},{"year":2017,"finding":"In yeast, the CDC25 family phosphatase Mih1 directly modulates the phosphorylation state of the Vps26 retromer subunit. Phosphomimetic and phospho-null mutations in Vps26 alter its binding affinity for a retromer cargo, causing corresponding changes in cargo sorting at the endosome, indicating phosphorylation-based gating of cargo selection by retromer.","method":"Spontaneous activating mutation screen, in vitro phosphatase assay, phosphomimetic mutagenesis, cargo sorting assay in yeast","journal":"eLife","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct phosphatase activity assay plus engineered phospho-state mutations with functional cargo-sorting readout, single lab","pmids":["28362258"],"is_preprint":false},{"year":2017,"finding":"In Drosophila oogenesis, loss-of-function of Vps26 in germline clones impairs Notch signaling in follicle cells, as evidenced by misexpression of multiple Notch pathway proteins and increased LysoTracker staining, placing Vps26-dependent retromer function upstream of Notch ligand/receptor trafficking.","method":"Drosophila germline clonal analysis, immunofluorescence, LysoTracker staining","journal":"Mechanisms of development","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — genetic loss-of-function with defined pathway phenotype (Notch signaling markers), single lab, single model organism","pmids":["29031909"],"is_preprint":false},{"year":2018,"finding":"Vps26a physically interacts with the NADPH oxidase Nox4; in mouse embryonic stem cells, Vps26a deficiency suppresses neurogenesis and reduces ROS levels. Vps26a-Nox4 interaction linked to ERK1/2 activation constitutes a redox-signaling cascade required for neural differentiation.","method":"Vps26a knockout ESCs, co-immunoprecipitation, ROS measurement, inhibitor treatments, neurogenesis markers","journal":"Cell death and differentiation","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — Co-IP demonstrating Vps26a-Nox4 interaction with knockout phenotype and rescue by antioxidants, single lab","pmids":["30464227"],"is_preprint":false},{"year":2018,"finding":"In Drosophila, the PLA2G6 ortholog iPLA2-VIA binds retromer subunits Vps35 and Vps26 and enhances retromer function; loss of iPLA2-VIA impairs retromer function similarly to loss of vps26 or vps35, causing ceramide accumulation and neurodegeneration.","method":"Protein-protein interaction assay (fly system), genetic epistasis (vps26/vps35 loss-of-function), lipid profiling, neurodegeneration phenotype","journal":"Cell metabolism","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — Co-IP/interaction assay plus genetic epistasis with multiple phenotypic readouts, single lab","pmids":["29909971"],"is_preprint":false},{"year":2022,"finding":"VPS26a down-regulation in high-glucose-treated neurons causes retention of APP and CI-M6PR in endosomes and impairs their transport to the trans-Golgi network; VPS26a recovery restores this transport, decreases Aβ levels, and restores cathepsin D activity to reduce p-tau. High glucose reduces VPS26a expression via ROS/NF-κB/DNMT1-mediated promoter hypermethylation.","method":"VPS26a overexpression/knockdown in iPSC-derived neurons and SH-SY5Y cells, endosomal/TGN trafficking assay, streptozotocin diabetic mouse model","journal":"British journal of pharmacology","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — loss-of-function and gain-of-function with defined trafficking readouts, multiple cell models and in vivo confirmation, single lab","pmids":["35297035"],"is_preprint":false},{"year":2023,"finding":"VPS26 co-localizes and co-immunoprecipitates with β-catenin in osteogenic cells; VPS26 overexpression activates Wnt/β-catenin signaling (43% increase in TOP/FOP ratio) and promotes osteogenesis while inhibiting adipogenesis of rat BMSCs under high-fat conditions.","method":"Immunofluorescence co-localization, co-immunoprecipitation, dual luciferase TOP/FOP reporter assay, ALP/oil-red-O staining, lentiviral overexpression in vivo","journal":"Zhonghua kou qiang yi xue za zhi","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single lab, single Co-IP plus reporter assay, no mechanistic detail on how VPS26 activates β-catenin","pmids":["37005781"],"is_preprint":false},{"year":2024,"finding":"ATG5 associates with retromer core components VPS26, VPS29, and VPS35; ATG5 knockout blocks trafficking of the retromer cargo GLUT1 to the plasma membrane. Knockouts of other genes required for membrane atg8ylation also affect GLUT1 sorting, indicating that membrane atg8ylation modulates retromer function independently of canonical autophagy.","method":"Co-immunoprecipitation (ATG5 with VPS26/VPS29/VPS35), ATG5 and atg8ylation pathway knockouts with GLUT1 trafficking readout","journal":"bioRxiv","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — Co-IP plus multiple gene knockouts with defined trafficking readout, preprint","pmids":[],"is_preprint":true},{"year":2024,"finding":"Biochemical reconstitution with purified mammalian proteins shows that SNX27 alone and SNX27 together with Retromer (VPS26/VPS35/VPS29) induces membrane tubule formation in the presence of PI(3)P and PDZ cargo motifs. VARP bridges SNX27 and the ESCPE-1 complex to form an endosomal supercomplex on membranes; without VARP, the full supercomplex containing SNX27, ESCPE-1, and Retromer cannot be reconstituted.","method":"In vitro membrane reconstitution with purified proteins, biochemical binding assays, AlphaFold2 Multimer modeling, point mutagenesis confirming VARP-SNX27 interaction","journal":"bioRxiv","confidence":"Medium","confidence_rationale":"Tier 1 / Weak — reconstitution in vitro with defined lipid/cargo composition plus mutagenesis, preprint not yet peer-reviewed","pmids":[],"is_preprint":true},{"year":2026,"finding":"The VPS26A-containing retromer complex, together with SNX27, mediates unconventional (Golgi-bypass) protein secretion (UPS) of transmembrane proteins under cellular stress. SNX27 recruits the trafficking-deficient ΔF508-CFTR to the VPS26A-VPS35-VPS29 retromer complex for transport to the cell surface. VPS26A and SNX27 are also required for UPS of the SARS-CoV-2 spike protein and formation of intact virions. VPS26A was identified as a key contributor via a targeted CRISPR knockout screen.","method":"CRISPR knockout screen, co-immunoprecipitation (SNX27 with ΔF508-CFTR and VPS26A-retromer), cell surface trafficking assay, VPS26A/SNX27 knockouts","journal":"Nature communications","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — CRISPR screen plus Co-IP and functional trafficking assay, single lab, peer-reviewed","pmids":["41942457"],"is_preprint":false}],"current_model":"VPS26A is a structural subunit of the retromer heterotrimer (VPS26A-VPS35-VPS29) with an arrestin-like fold; it binds VPS35 via a conserved mobile loop (residues 235-246), allosterically enhances Rab7-mediated endosomal recruitment of the complex, and its phosphorylation state gates cargo recognition; together with SNX27, the VPS26A retromer mediates canonical endosome-to-TGN/plasma-membrane recycling of receptors (CI-M6PR, GLUT1, mGluR5) and, under cellular stress, an unconventional Golgi-bypass secretion pathway for transmembrane proteins such as ΔF508-CFTR and the SARS-CoV-2 spike protein."},"narrative":{"mechanistic_narrative":"VPS26A is a structural subunit of the retromer complex, a heterotrimeric assembly that governs endosomal cargo retrieval and recycling [PMID:11102511]. It binds directly to the N-terminal scaffold region of VPS35, and in the absence of VPS35 it fails to incorporate into the large retromer complex [PMID:11102511]; structurally, VPS26A adopts an arrestin-like fold of two curved β-sandwich domains, and its VPS35-binding determinant maps to a mobile loop (residues 235-246) whose hydrophobic residues and conserved glycine are required for complex integration, endosomal localization, and cargo sorting [PMID:16732284]. Within the assembled complex VPS26A contributes allosterically to Rab7-mediated endosomal recruitment of retromer, enhancing the affinity of the VPS35-containing subcomplex for activated Rab7 [PMID:25367362], and its phosphorylation state gates cargo selection, as engineered phospho-mimetic and phospho-null mutations alter cargo binding affinity and sorting [PMID:28362258]. Acting together with the cargo adaptor SNX27, VPS26A-retromer recycles transmembrane receptors including CI-M6PR, GLUT1, and mGluR5 from endosomes to the trans-Golgi network and plasma membrane [PMID:21920005, PMID:26538661], and the paralogue-specific C-terminal region of VPS26 dictates which cargoes a given retromer engages [PMID:21920005]. Beyond canonical recycling, the VPS26A-SNX27 retromer also mediates an unconventional Golgi-bypass secretion pathway, delivering trafficking-deficient ΔF508-CFTR and the SARS-CoV-2 spike protein to the cell surface under cellular stress [PMID:41942457]. Through these trafficking functions VPS26A is required for diverse downstream processes, including Notch signaling in Drosophila oogenesis [PMID:29031909], neural differentiation via a Nox4/ROS/ERK redox cascade [PMID:30464227], and endosome-to-TGN delivery of APP and CI-M6PR in neurons, where its loss elevates Aβ and p-tau [PMID:35297035].","teleology":[{"year":2000,"claim":"Established that human VPS26 is not an autonomous factor but a subunit that requires VPS35 to assemble into the large retromer complex, defining the architectural dependency of the complex.","evidence":"Yeast two-hybrid, reciprocal co-IP, gel filtration, and deletion mapping in COS7 cells","pmids":["11102511"],"confidence":"High","gaps":["Did not resolve the atomic interface or fold of VPS26","Cargo specificity of the complex not addressed","Membrane recruitment mechanism not defined"]},{"year":2006,"claim":"Resolved the arrestin-like fold of VPS26A and pinpointed the VPS35-binding mobile loop (residues 235-246), explaining at residue resolution how the subunit integrates into retromer and supports cargo sorting.","evidence":"2.1-Å X-ray crystallography with site-directed mutagenesis, mammalian endosomal localization assay, and yeast carboxypeptidase Y sorting assay","pmids":["16732284"],"confidence":"High","gaps":["Structure of the full assembled trimer on membranes not determined","How the arrestin fold contributes to cargo binding not defined"]},{"year":2011,"claim":"Showed that the two VPS26 paralogues define functionally distinct retromers, with VPS26A-retromer (not VPS26B) recycling CI-M6PR, and localized cargo discrimination to the VPS26B C-terminal variable region.","evidence":"Stable myc-tagged paralogue expression in HEK293, co-IP, Rab colocalization, and deletion analysis with receptor degradation and cathepsin D secretion readouts","pmids":["21920005"],"confidence":"High","gaps":["Molecular basis of how the C-terminal region selects cargo not resolved","Whether paralogue choice is regulated in vivo unknown"]},{"year":2012,"claim":"Identified Rabankyrin-5 as a partner needed to maintain VPS26 localization and M6PR retrieval, extending the set of factors organizing retromer-based transport.","evidence":"Co-IP, colocalization, and siRNA knockdown with functional rescue","pmids":["22284051"],"confidence":"Medium","gaps":["Direct vs indirect interaction with VPS26 not distinguished","Single lab, no structural detail of the contact"]},{"year":2014,"claim":"Defined a mechanistic role for VPS26 in membrane recruitment, showing it allosterically enhances binding of the VPS35 subcomplex to activated Rab7.","evidence":"FRET interaction assay in HeLa cells, biophysical binding measurements, and mutagenesis disrupting the VPS35-VPS26 interaction","pmids":["25367362"],"confidence":"Medium","gaps":["Structural basis of the allosteric effect not resolved","Single lab; in vitro reconstitution of the allostery not performed"]},{"year":2015,"claim":"Connected VPS26A to SNX27-dependent recycling of a specific GPCR cargo (mGluR5) in neurons and linked this trafficking to a behavioral phenotype.","evidence":"Co-IP, immunofluorescence, and siRNA knockdown in rat dorsal horn neurons with an allodynia behavioral assay","pmids":["26538661"],"confidence":"Medium","gaps":["Whether VPS26A-SNX27-mGluR5 contact is direct not established","Single lab, single cargo in one neuronal context"]},{"year":2017,"claim":"Demonstrated phosphorylation-based gating of cargo selection, showing that the phosphatase Mih1 sets the VPS26 phospho-state and that phospho-state mutations change cargo binding and sorting.","evidence":"Activating mutation screen, in vitro phosphatase assay, and phospho-mimetic/null mutagenesis with cargo sorting readout in yeast","pmids":["28362258"],"confidence":"Medium","gaps":["Mammalian kinase/phosphatase regulating VPS26A not identified","Phosphosites and structural consequences in human VPS26A unmapped"]},{"year":2017,"claim":"Placed VPS26-dependent retromer upstream of Notch signaling, establishing a developmental signaling output of the complex.","evidence":"Drosophila germline clonal loss-of-function with Notch pathway marker immunofluorescence and LysoTracker staining","pmids":["29031909"],"confidence":"Medium","gaps":["Specific Notch-pathway cargo trafficked by retromer not identified","Single model organism"]},{"year":2018,"claim":"Linked Vps26a to redox signaling and differentiation through a physical interaction with the NADPH oxidase Nox4 driving ERK1/2-dependent neurogenesis.","evidence":"Vps26a knockout ESCs, co-IP, ROS measurement, inhibitor treatments, and neurogenesis markers","pmids":["30464227"],"confidence":"Medium","gaps":["Whether the Nox4 interaction is retromer-dependent unclear","Single lab; direct vs scaffolded contact not resolved"]},{"year":2018,"claim":"Showed that the PLA2G6 ortholog iPLA2-VIA binds VPS35/VPS26 and enhances retromer function, tying retromer activity to lipid homeostasis and neurodegeneration.","evidence":"Fly protein-interaction assay, genetic epistasis with vps26/vps35 loss, lipid profiling, and neurodegeneration phenotype","pmids":["29909971"],"confidence":"Medium","gaps":["Direct VPS26 contact vs VPS35-mediated association not separated","Mechanism by which iPLA2-VIA enhances retromer unknown"]},{"year":2022,"claim":"Connected VPS26a loss to Alzheimer-relevant pathology, showing its down-regulation traps APP and CI-M6PR in endosomes to raise Aβ and p-tau, with recovery reversing the defect.","evidence":"Gain/loss-of-function in iPSC-derived neurons and SH-SY5Y cells, endosome/TGN trafficking assays, and a streptozotocin diabetic mouse model","pmids":["35297035"],"confidence":"Medium","gaps":["Whether APP is a direct retromer cargo not established here","Single lab"]},{"year":2023,"claim":"Reported a link between VPS26 and Wnt/β-catenin signaling promoting osteogenesis, extending putative functions beyond endosomal trafficking.","evidence":"Co-localization, co-IP with β-catenin, TOP/FOP luciferase reporter, and lentiviral overexpression with osteogenic/adipogenic staining","pmids":["37005781"],"confidence":"Low","gaps":["Single Co-IP plus reporter assay with no mechanism for how VPS26 activates β-catenin","Direct vs indirect β-catenin interaction not tested","Not independently confirmed"]},{"year":2024,"claim":"Implicated membrane atg8ylation, via ATG5, as a modulator of retromer-dependent GLUT1 sorting independent of canonical autophagy.","evidence":"Co-IP of ATG5 with VPS26/VPS29/VPS35 and atg8ylation-pathway knockouts with GLUT1 trafficking readout (preprint)","pmids":[],"confidence":"Medium","gaps":["Preprint, not peer-reviewed","Whether ATG5 contacts VPS26 directly not established","Generality across other retromer cargoes unknown"]},{"year":2024,"claim":"Provided in vitro reconstitution showing SNX27 plus Retromer tubulates membranes and that VARP is required to assemble a SNX27-ESCPE-1-Retromer supercomplex, clarifying the higher-order organization of the recycling machinery.","evidence":"Membrane reconstitution with purified proteins, binding assays, AlphaFold2-Multimer modeling, and point mutagenesis (preprint)","pmids":[],"confidence":"Medium","gaps":["Preprint, not peer-reviewed","Specific role of VPS26A within the supercomplex not isolated","Cargo selectivity of the reconstituted supercomplex not fully defined"]},{"year":2026,"claim":"Established a non-canonical role for VPS26A-retromer with SNX27 in unconventional Golgi-bypass secretion of ΔF508-CFTR and SARS-CoV-2 spike, expanding retromer function from recycling to stress-induced surface delivery.","evidence":"CRISPR knockout screen, co-IP of SNX27 with ΔF508-CFTR and VPS26A-retromer, and surface trafficking assays with VPS26A/SNX27 knockouts","pmids":["41942457"],"confidence":"Medium","gaps":["Molecular trigger linking cellular stress to UPS routing not defined","Whether VPS26A directly contacts the secreted cargoes unknown"]},{"year":null,"claim":"How VPS26A phosphorylation, paralogue choice, and partner inputs (Rab7, SNX27, VARP, atg8ylation) are integrated to switch retromer between canonical recycling and unconventional secretion in human cells remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No structure of the full assembled, membrane-bound supercomplex with cargo","Human kinases/phosphatases controlling VPS26A phospho-gating unidentified","Mechanism selecting canonical vs Golgi-bypass routing uncharacterized"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0005198","term_label":"structural molecule activity","supporting_discovery_ids":[0,1]},{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[2,5,14]},{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[4]}],"localization":[{"term_id":"GO:0005768","term_label":"endosome","supporting_discovery_ids":[0,1,4]},{"term_id":"GO:0005829","term_label":"cytosol","supporting_discovery_ids":[0]},{"term_id":"GO:0005794","term_label":"Golgi apparatus","supporting_discovery_ids":[2,10]}],"pathway":[{"term_id":"R-HSA-9609507","term_label":"Protein localization","supporting_discovery_ids":[0,2,5,14]},{"term_id":"R-HSA-5653656","term_label":"Vesicle-mediated transport","supporting_discovery_ids":[2,10,14]},{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[7,8,11]}],"complexes":["retromer (VPS26A-VPS35-VPS29)"],"partners":["VPS35","VPS29","SNX27","RAB7","TBC1D5","GOLPH3","NOX4","ATG5"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"O75436","full_name":"Vacuolar protein sorting-associated protein 26A","aliases":["Vesicle protein sorting 26A","hVPS26"],"length_aa":327,"mass_kda":38.2,"function":"Acts as a component of the retromer cargo-selective complex (CSC). The CSC is believed to be the core functional component of retromer or respective retromer complex variants acting to prevent missorting of selected transmembrane cargo proteins into the lysosomal degradation pathway. The recruitment of the CSC to the endosomal membrane involves RAB7A and SNX3. The SNX-BAR retromer mediates retrograde transport of cargo proteins from endosomes to the trans-Golgi network (TGN) and is involved in endosome-to-plasma membrane transport for cargo protein recycling. The SNX3-retromer mediates the retrograde endosome-to-TGN transport of WLS distinct from the SNX-BAR retromer pathway. The SNX27-retromer is believed to be involved in endosome-to-plasma membrane trafficking and recycling of a broad spectrum of cargo proteins (Probable). The CSC seems to act as recruitment hub for other proteins, such as the WASH complex and TBC1D5 (Probable). Required for retrograde transport of lysosomal enzyme receptor IGF2R (PubMed:15078902, PubMed:15078903). Required to regulate transcytosis of the polymeric immunoglobulin receptor (pIgR-pIgA) (PubMed:15247922). Required for the endosomal localization of WASHC2A (indicative for the WASH complex) (PubMed:22070227). Required for the endosomal localization of TBC1D5 (PubMed:20923837). Mediates retromer cargo recognition of SORL1 and is involved in trafficking of SORL1 implicated in sorting and processing of APP (PubMed:22279231). Involved in retromer-independent lysosomal sorting of F2R (PubMed:16407403). Involved in recycling of ADRB2 (PubMed:21602791). Enhances the affinity of SNX27 for PDZ-binding motifs in cargo proteins (By similarity)","subcellular_location":"Cytoplasm; Endosome membrane; Early endosome","url":"https://www.uniprot.org/uniprotkb/O75436/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/VPS26A","classification":"Not Classified","n_dependent_lines":148,"n_total_lines":1208,"dependency_fraction":0.12251655629139073},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[{"gene":"VPS35","stoichiometry":10.0},{"gene":"CAPZB","stoichiometry":0.2},{"gene":"RAB7A","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/search/VPS26A","total_profiled":1310},"omim":[{"mim_id":"614905","title":"SORTING NEXIN 8; SNX8","url":"https://www.omim.org/entry/614905"},{"mim_id":"614824","title":"ADAPTOR-RELATED PROTEIN COMPLEX 5, SIGMA-1 SUBUNIT; AP5S1","url":"https://www.omim.org/entry/614824"},{"mim_id":"610027","title":"VPS26 RETROMER COMPLEX COMPONENT B; VPS26B","url":"https://www.omim.org/entry/610027"},{"mim_id":"605506","title":"VPS26 RETROMER COMPLEX COMPONENT A; VPS26A","url":"https://www.omim.org/entry/605506"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Enhanced","locations":[{"location":"Endosomes","reliability":"Enhanced"},{"location":"Lysosomes","reliability":"Enhanced"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/VPS26A"},"hgnc":{"alias_symbol":["Hbeta58","PEP8A"],"prev_symbol":["VPS26"]},"alphafold":{"accession":"O75436","domains":[{"cath_id":"2.60.40.640","chopping":"11-150","consensus_level":"high","plddt":94.0844,"start":11,"end":150},{"cath_id":"2.60.40.640","chopping":"163-298","consensus_level":"high","plddt":92.7621,"start":163,"end":298}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/O75436","model_url":"https://alphafold.ebi.ac.uk/files/AF-O75436-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-O75436-F1-predicted_aligned_error_v6.png","plddt_mean":87.69},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=VPS26A","jax_strain_url":"https://www.jax.org/strain/search?query=VPS26A"},"sequence":{"accession":"O75436","fasta_url":"https://rest.uniprot.org/uniprotkb/O75436.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/O75436/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/O75436"}},"corpus_meta":[{"pmid":"11102511","id":"PMC_11102511","title":"Human orthologs of yeast vacuolar protein sorting proteins Vps26, 29, and 35: assembly into multimeric complexes.","date":"2000","source":"Molecular biology of the cell","url":"https://pubmed.ncbi.nlm.nih.gov/11102511","citation_count":254,"is_preprint":false},{"pmid":"29909971","id":"PMC_29909971","title":"Phospholipase PLA2G6, a Parkinsonism-Associated Gene, Affects Vps26 and Vps35, Retromer Function, and Ceramide Levels, Similar to α-Synuclein Gain.","date":"2018","source":"Cell metabolism","url":"https://pubmed.ncbi.nlm.nih.gov/29909971","citation_count":146,"is_preprint":false},{"pmid":"16732284","id":"PMC_16732284","title":"The retromer subunit Vps26 has an arrestin fold and binds Vps35 through its C-terminal domain.","date":"2006","source":"Nature structural & molecular biology","url":"https://pubmed.ncbi.nlm.nih.gov/16732284","citation_count":143,"is_preprint":false},{"pmid":"21920005","id":"PMC_21920005","title":"Vps26A and Vps26B subunits define distinct retromer complexes.","date":"2011","source":"Traffic (Copenhagen, Denmark)","url":"https://pubmed.ncbi.nlm.nih.gov/21920005","citation_count":87,"is_preprint":false},{"pmid":"25367362","id":"PMC_25367362","title":"Molecular insights into Rab7-mediated endosomal recruitment of core retromer: deciphering the role of Vps26 and Vps35.","date":"2014","source":"Traffic (Copenhagen, Denmark)","url":"https://pubmed.ncbi.nlm.nih.gov/25367362","citation_count":68,"is_preprint":false},{"pmid":"22284051","id":"PMC_22284051","title":"Rabankyrin-5 interacts with EHD1 and Vps26 to regulate endocytic trafficking and retromer function.","date":"2012","source":"Traffic (Copenhagen, Denmark)","url":"https://pubmed.ncbi.nlm.nih.gov/22284051","citation_count":50,"is_preprint":false},{"pmid":"26538661","id":"PMC_26538661","title":"VPS26A-SNX27 Interaction-Dependent mGluR5 Recycling in Dorsal Horn Neurons Mediates Neuropathic Pain in Rats.","date":"2015","source":"The Journal of neuroscience : the official journal of the Society for Neuroscience","url":"https://pubmed.ncbi.nlm.nih.gov/26538661","citation_count":31,"is_preprint":false},{"pmid":"24684791","id":"PMC_24684791","title":"Genetic variation of the retromer subunits VPS26A/B-VPS29 in Parkinson's disease.","date":"2014","source":"Neurobiology of aging","url":"https://pubmed.ncbi.nlm.nih.gov/24684791","citation_count":21,"is_preprint":false},{"pmid":"35297035","id":"PMC_35297035","title":"High glucose-mediated VPS26a down-regulation dysregulates neuronal amyloid precursor protein processing and tau phosphorylation.","date":"2022","source":"British journal of pharmacology","url":"https://pubmed.ncbi.nlm.nih.gov/35297035","citation_count":16,"is_preprint":false},{"pmid":"28362258","id":"PMC_28362258","title":"A CDC25 family protein phosphatase gates cargo recognition by the Vps26 retromer subunit.","date":"2017","source":"eLife","url":"https://pubmed.ncbi.nlm.nih.gov/28362258","citation_count":12,"is_preprint":false},{"pmid":"30464227","id":"PMC_30464227","title":"Novel crosstalk between Vps26a and Nox4 signaling during neurogenesis.","date":"2018","source":"Cell death and differentiation","url":"https://pubmed.ncbi.nlm.nih.gov/30464227","citation_count":10,"is_preprint":false},{"pmid":"29031909","id":"PMC_29031909","title":"The retromer subunit Vps26 mediates Notch signaling during Drosophila oogenesis.","date":"2017","source":"Mechanisms of development","url":"https://pubmed.ncbi.nlm.nih.gov/29031909","citation_count":9,"is_preprint":false},{"pmid":"39116045","id":"PMC_39116045","title":"The Entamoeba histolytica Vps26 (EhVps26) retromeric protein is involved in phagocytosis: Bioinformatic and experimental approaches.","date":"2024","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/39116045","citation_count":2,"is_preprint":false},{"pmid":"41942457","id":"PMC_41942457","title":"VPS26A retromer complex and SNX27 mediate stress-induced Golgi bypass of membrane proteins.","date":"2026","source":"Nature communications","url":"https://pubmed.ncbi.nlm.nih.gov/41942457","citation_count":0,"is_preprint":false},{"pmid":"37005781","id":"PMC_37005781","title":"[Mechanism of VPS26 gene promoting implant osseointegration through Wnt/β-catenin pathway in hyperlipidemia rats].","date":"2023","source":"Zhonghua kou qiang yi xue za zhi = Zhonghua kouqiang yixue zazhi = Chinese journal of stomatology","url":"https://pubmed.ncbi.nlm.nih.gov/37005781","citation_count":0,"is_preprint":false},{"pmid":null,"id":"bio_10.1101_2024.07.10.602886","title":"Noncanonical roles of ATG5 and membrane atg8ylation in retromer assembly and function","date":"2024-07-12","source":"bioRxiv","url":"https://doi.org/10.1101/2024.07.10.602886","citation_count":0,"is_preprint":true},{"pmid":null,"id":"bio_10.1101_2024.07.11.603126","title":"VARP binds SNX27 to promote endosomal supercomplex formation on membranes","date":"2024-07-11","source":"bioRxiv","url":"https://doi.org/10.1101/2024.07.11.603126","citation_count":0,"is_preprint":true}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":10693,"output_tokens":3996,"usd":0.04601,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":11766,"output_tokens":5292,"usd":0.095565,"stage2_stop_reason":"end_turn"},"total_usd":0.141575,"stage1_batch_id":"msgbatch_01UT1AahFPCAyn2uVweS7A9z","stage2_batch_id":"msgbatch_01HuKWtKNT4Pqj1bc8eEP5RV","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2000,\n      \"finding\": \"Human VPS26 (hVps26) assembles into a ~220-440 kDa retromer complex by binding directly to the N-terminal region (residues 1-172) of hVps35, which serves as the scaffold; in the absence of hVps35, hVps26 is not found in the large complex. Both recombinant and endogenous hVps26 are found in membrane-associated and cytosolic compartments.\",\n      \"method\": \"Yeast two-hybrid, co-immunoprecipitation, gel filtration chromatography, deletion mapping in COS7 cells\",\n      \"journal\": \"Molecular biology of the cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal Co-IP, deletion mapping, gel filtration, multiple orthogonal methods in a single foundational study\",\n      \"pmids\": [\"11102511\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"Crystal structure of human VPS26A at 2.1-Å resolution reveals two curved β-sandwich domains connected by a polar core and flexible linker, with an arrestin-like fold. The Vps35-binding site maps to a mobile loop (residues 235-246) at the tip of the C-terminal domain; hydrophobic residues and a glycine in this loop are required for retromer complex integration and endosomal localization of VPS26A, and for yeast Vps26 function in carboxypeptidase Y sorting.\",\n      \"method\": \"X-ray crystallography (2.1-Å), site-directed mutagenesis, endosomal localization assay, yeast carboxypeptidase Y sorting assay\",\n      \"journal\": \"Nature structural & molecular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — crystal structure combined with mutagenesis and functional validation in two systems (mammalian localization and yeast sorting)\",\n      \"pmids\": [\"16732284\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"Vps26A and Vps26B define distinct retromer complexes with different functional properties: Vps26A-retromer interacts with CI-M6PR and recycles it, whereas Vps26B-retromer does not interact with CI-M6PR, leading to receptor degradation and increased cathepsin D secretion. The Vps26B C-terminal variable region is directly responsible for this differential cargo selection, as its deletion restores CI-M6PR cycling. Both paralogues associate with TBC1D5 and GOLPH3.\",\n      \"method\": \"Stable expression of Vps26A-myc or Vps26B-myc in HEK293 cells, co-immunoprecipitation, colocalization with Rab markers, deletion analysis\",\n      \"journal\": \"Traffic (Copenhagen, Denmark)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal Co-IP with deletion mapping, functional readouts (receptor degradation, cathepsin D secretion), multiple orthogonal approaches in a single study\",\n      \"pmids\": [\"21920005\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"Rabankyrin-5 (Rank-5) colocalizes and interacts with VPS26 as a component of retromer-based transport. Depletion of Rank-5 causes mislocalization of Vps26 and impairs retrieval of mannose 6-phosphate receptor to the Golgi.\",\n      \"method\": \"Co-immunoprecipitation, colocalization, siRNA knockdown with functional rescue\",\n      \"journal\": \"Traffic (Copenhagen, Denmark)\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — Co-IP and colocalization with functional knockdown readout, single lab\",\n      \"pmids\": [\"22284051\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"VPS26 plays an allosteric role in Rab7-mediated endosomal recruitment of the retromer core complex: Rab7 directly interacts with VPS35 to recruit retromer, but disruption of the Vps35-Vps26 interaction perturbs this recruitment. Association of Vps26 with Vps35 results in high-affinity binding between the Vps sub-complex and activated Rab7, indicating a positive allosteric contribution of Vps26.\",\n      \"method\": \"FRET-based interaction assay in HeLa cells, biophysical binding measurements, site-directed mutagenesis disrupting Vps35-Vps26 interaction\",\n      \"journal\": \"Traffic (Copenhagen, Denmark)\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — FRET in cells plus biophysical measurements, single lab with two orthogonal approaches\",\n      \"pmids\": [\"25367362\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"VPS26A interacts with SNX27 in spinal dorsal horn neurons to mediate mGluR5 recycling to the plasma membrane. Spinal nerve ligation increases VPS26A-SNX27 coprecipitation and VPS26A-bound mGluR5; knockdown of VPS26A reduces membrane-bound mGluR5 and attenuates neuropathic allodynia.\",\n      \"method\": \"Co-immunoprecipitation, immunofluorescence, siRNA knockdown in rat dorsal horn neurons, behavioral allodynia assay\",\n      \"journal\": \"The Journal of neuroscience\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — Co-IP with in vivo knockdown phenotype, multiple readouts, single lab\",\n      \"pmids\": [\"26538661\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"In yeast, the CDC25 family phosphatase Mih1 directly modulates the phosphorylation state of the Vps26 retromer subunit. Phosphomimetic and phospho-null mutations in Vps26 alter its binding affinity for a retromer cargo, causing corresponding changes in cargo sorting at the endosome, indicating phosphorylation-based gating of cargo selection by retromer.\",\n      \"method\": \"Spontaneous activating mutation screen, in vitro phosphatase assay, phosphomimetic mutagenesis, cargo sorting assay in yeast\",\n      \"journal\": \"eLife\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct phosphatase activity assay plus engineered phospho-state mutations with functional cargo-sorting readout, single lab\",\n      \"pmids\": [\"28362258\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"In Drosophila oogenesis, loss-of-function of Vps26 in germline clones impairs Notch signaling in follicle cells, as evidenced by misexpression of multiple Notch pathway proteins and increased LysoTracker staining, placing Vps26-dependent retromer function upstream of Notch ligand/receptor trafficking.\",\n      \"method\": \"Drosophila germline clonal analysis, immunofluorescence, LysoTracker staining\",\n      \"journal\": \"Mechanisms of development\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — genetic loss-of-function with defined pathway phenotype (Notch signaling markers), single lab, single model organism\",\n      \"pmids\": [\"29031909\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"Vps26a physically interacts with the NADPH oxidase Nox4; in mouse embryonic stem cells, Vps26a deficiency suppresses neurogenesis and reduces ROS levels. Vps26a-Nox4 interaction linked to ERK1/2 activation constitutes a redox-signaling cascade required for neural differentiation.\",\n      \"method\": \"Vps26a knockout ESCs, co-immunoprecipitation, ROS measurement, inhibitor treatments, neurogenesis markers\",\n      \"journal\": \"Cell death and differentiation\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — Co-IP demonstrating Vps26a-Nox4 interaction with knockout phenotype and rescue by antioxidants, single lab\",\n      \"pmids\": [\"30464227\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"In Drosophila, the PLA2G6 ortholog iPLA2-VIA binds retromer subunits Vps35 and Vps26 and enhances retromer function; loss of iPLA2-VIA impairs retromer function similarly to loss of vps26 or vps35, causing ceramide accumulation and neurodegeneration.\",\n      \"method\": \"Protein-protein interaction assay (fly system), genetic epistasis (vps26/vps35 loss-of-function), lipid profiling, neurodegeneration phenotype\",\n      \"journal\": \"Cell metabolism\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — Co-IP/interaction assay plus genetic epistasis with multiple phenotypic readouts, single lab\",\n      \"pmids\": [\"29909971\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"VPS26a down-regulation in high-glucose-treated neurons causes retention of APP and CI-M6PR in endosomes and impairs their transport to the trans-Golgi network; VPS26a recovery restores this transport, decreases Aβ levels, and restores cathepsin D activity to reduce p-tau. High glucose reduces VPS26a expression via ROS/NF-κB/DNMT1-mediated promoter hypermethylation.\",\n      \"method\": \"VPS26a overexpression/knockdown in iPSC-derived neurons and SH-SY5Y cells, endosomal/TGN trafficking assay, streptozotocin diabetic mouse model\",\n      \"journal\": \"British journal of pharmacology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — loss-of-function and gain-of-function with defined trafficking readouts, multiple cell models and in vivo confirmation, single lab\",\n      \"pmids\": [\"35297035\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"VPS26 co-localizes and co-immunoprecipitates with β-catenin in osteogenic cells; VPS26 overexpression activates Wnt/β-catenin signaling (43% increase in TOP/FOP ratio) and promotes osteogenesis while inhibiting adipogenesis of rat BMSCs under high-fat conditions.\",\n      \"method\": \"Immunofluorescence co-localization, co-immunoprecipitation, dual luciferase TOP/FOP reporter assay, ALP/oil-red-O staining, lentiviral overexpression in vivo\",\n      \"journal\": \"Zhonghua kou qiang yi xue za zhi\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single lab, single Co-IP plus reporter assay, no mechanistic detail on how VPS26 activates β-catenin\",\n      \"pmids\": [\"37005781\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"ATG5 associates with retromer core components VPS26, VPS29, and VPS35; ATG5 knockout blocks trafficking of the retromer cargo GLUT1 to the plasma membrane. Knockouts of other genes required for membrane atg8ylation also affect GLUT1 sorting, indicating that membrane atg8ylation modulates retromer function independently of canonical autophagy.\",\n      \"method\": \"Co-immunoprecipitation (ATG5 with VPS26/VPS29/VPS35), ATG5 and atg8ylation pathway knockouts with GLUT1 trafficking readout\",\n      \"journal\": \"bioRxiv\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — Co-IP plus multiple gene knockouts with defined trafficking readout, preprint\",\n      \"pmids\": [],\n      \"is_preprint\": true\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"Biochemical reconstitution with purified mammalian proteins shows that SNX27 alone and SNX27 together with Retromer (VPS26/VPS35/VPS29) induces membrane tubule formation in the presence of PI(3)P and PDZ cargo motifs. VARP bridges SNX27 and the ESCPE-1 complex to form an endosomal supercomplex on membranes; without VARP, the full supercomplex containing SNX27, ESCPE-1, and Retromer cannot be reconstituted.\",\n      \"method\": \"In vitro membrane reconstitution with purified proteins, biochemical binding assays, AlphaFold2 Multimer modeling, point mutagenesis confirming VARP-SNX27 interaction\",\n      \"journal\": \"bioRxiv\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Weak — reconstitution in vitro with defined lipid/cargo composition plus mutagenesis, preprint not yet peer-reviewed\",\n      \"pmids\": [],\n      \"is_preprint\": true\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"The VPS26A-containing retromer complex, together with SNX27, mediates unconventional (Golgi-bypass) protein secretion (UPS) of transmembrane proteins under cellular stress. SNX27 recruits the trafficking-deficient ΔF508-CFTR to the VPS26A-VPS35-VPS29 retromer complex for transport to the cell surface. VPS26A and SNX27 are also required for UPS of the SARS-CoV-2 spike protein and formation of intact virions. VPS26A was identified as a key contributor via a targeted CRISPR knockout screen.\",\n      \"method\": \"CRISPR knockout screen, co-immunoprecipitation (SNX27 with ΔF508-CFTR and VPS26A-retromer), cell surface trafficking assay, VPS26A/SNX27 knockouts\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — CRISPR screen plus Co-IP and functional trafficking assay, single lab, peer-reviewed\",\n      \"pmids\": [\"41942457\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"VPS26A is a structural subunit of the retromer heterotrimer (VPS26A-VPS35-VPS29) with an arrestin-like fold; it binds VPS35 via a conserved mobile loop (residues 235-246), allosterically enhances Rab7-mediated endosomal recruitment of the complex, and its phosphorylation state gates cargo recognition; together with SNX27, the VPS26A retromer mediates canonical endosome-to-TGN/plasma-membrane recycling of receptors (CI-M6PR, GLUT1, mGluR5) and, under cellular stress, an unconventional Golgi-bypass secretion pathway for transmembrane proteins such as ΔF508-CFTR and the SARS-CoV-2 spike protein.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"VPS26A is a structural subunit of the retromer complex, a heterotrimeric assembly that governs endosomal cargo retrieval and recycling [#0]. It binds directly to the N-terminal scaffold region of VPS35, and in the absence of VPS35 it fails to incorporate into the large retromer complex [#0]; structurally, VPS26A adopts an arrestin-like fold of two curved \\u03b2-sandwich domains, and its VPS35-binding determinant maps to a mobile loop (residues 235-246) whose hydrophobic residues and conserved glycine are required for complex integration, endosomal localization, and cargo sorting [#1]. Within the assembled complex VPS26A contributes allosterically to Rab7-mediated endosomal recruitment of retromer, enhancing the affinity of the VPS35-containing subcomplex for activated Rab7 [#4], and its phosphorylation state gates cargo selection, as engineered phospho-mimetic and phospho-null mutations alter cargo binding affinity and sorting [#6]. Acting together with the cargo adaptor SNX27, VPS26A-retromer recycles transmembrane receptors including CI-M6PR, GLUT1, and mGluR5 from endosomes to the trans-Golgi network and plasma membrane [#2, #5, #12], and the paralogue-specific C-terminal region of VPS26 dictates which cargoes a given retromer engages [#2]. Beyond canonical recycling, the VPS26A-SNX27 retromer also mediates an unconventional Golgi-bypass secretion pathway, delivering trafficking-deficient \\u0394F508-CFTR and the SARS-CoV-2 spike protein to the cell surface under cellular stress [#14]. Through these trafficking functions VPS26A is required for diverse downstream processes, including Notch signaling in Drosophila oogenesis [#7], neural differentiation via a Nox4/ROS/ERK redox cascade [#8], and endosome-to-TGN delivery of APP and CI-M6PR in neurons, where its loss elevates A\\u03b2 and p-tau [#10].\",\n  \"teleology\": [\n    {\n      \"year\": 2000,\n      \"claim\": \"Established that human VPS26 is not an autonomous factor but a subunit that requires VPS35 to assemble into the large retromer complex, defining the architectural dependency of the complex.\",\n      \"evidence\": \"Yeast two-hybrid, reciprocal co-IP, gel filtration, and deletion mapping in COS7 cells\",\n      \"pmids\": [\n        \"11102511\"\n      ],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Did not resolve the atomic interface or fold of VPS26\",\n        \"Cargo specificity of the complex not addressed\",\n        \"Membrane recruitment mechanism not defined\"\n      ]\n    },\n    {\n      \"year\": 2006,\n      \"claim\": \"Resolved the arrestin-like fold of VPS26A and pinpointed the VPS35-binding mobile loop (residues 235-246), explaining at residue resolution how the subunit integrates into retromer and supports cargo sorting.\",\n      \"evidence\": \"2.1-\\u00c5 X-ray crystallography with site-directed mutagenesis, mammalian endosomal localization assay, and yeast carboxypeptidase Y sorting assay\",\n      \"pmids\": [\n        \"16732284\"\n      ],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Structure of the full assembled trimer on membranes not determined\",\n        \"How the arrestin fold contributes to cargo binding not defined\"\n      ]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Showed that the two VPS26 paralogues define functionally distinct retromers, with VPS26A-retromer (not VPS26B) recycling CI-M6PR, and localized cargo discrimination to the VPS26B C-terminal variable region.\",\n      \"evidence\": \"Stable myc-tagged paralogue expression in HEK293, co-IP, Rab colocalization, and deletion analysis with receptor degradation and cathepsin D secretion readouts\",\n      \"pmids\": [\n        \"21920005\"\n      ],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Molecular basis of how the C-terminal region selects cargo not resolved\",\n        \"Whether paralogue choice is regulated in vivo unknown\"\n      ]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Identified Rabankyrin-5 as a partner needed to maintain VPS26 localization and M6PR retrieval, extending the set of factors organizing retromer-based transport.\",\n      \"evidence\": \"Co-IP, colocalization, and siRNA knockdown with functional rescue\",\n      \"pmids\": [\n        \"22284051\"\n      ],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Direct vs indirect interaction with VPS26 not distinguished\",\n        \"Single lab, no structural detail of the contact\"\n      ]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Defined a mechanistic role for VPS26 in membrane recruitment, showing it allosterically enhances binding of the VPS35 subcomplex to activated Rab7.\",\n      \"evidence\": \"FRET interaction assay in HeLa cells, biophysical binding measurements, and mutagenesis disrupting the VPS35-VPS26 interaction\",\n      \"pmids\": [\n        \"25367362\"\n      ],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Structural basis of the allosteric effect not resolved\",\n        \"Single lab; in vitro reconstitution of the allostery not performed\"\n      ]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Connected VPS26A to SNX27-dependent recycling of a specific GPCR cargo (mGluR5) in neurons and linked this trafficking to a behavioral phenotype.\",\n      \"evidence\": \"Co-IP, immunofluorescence, and siRNA knockdown in rat dorsal horn neurons with an allodynia behavioral assay\",\n      \"pmids\": [\n        \"26538661\"\n      ],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Whether VPS26A-SNX27-mGluR5 contact is direct not established\",\n        \"Single lab, single cargo in one neuronal context\"\n      ]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Demonstrated phosphorylation-based gating of cargo selection, showing that the phosphatase Mih1 sets the VPS26 phospho-state and that phospho-state mutations change cargo binding and sorting.\",\n      \"evidence\": \"Activating mutation screen, in vitro phosphatase assay, and phospho-mimetic/null mutagenesis with cargo sorting readout in yeast\",\n      \"pmids\": [\n        \"28362258\"\n      ],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Mammalian kinase/phosphatase regulating VPS26A not identified\",\n        \"Phosphosites and structural consequences in human VPS26A unmapped\"\n      ]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Placed VPS26-dependent retromer upstream of Notch signaling, establishing a developmental signaling output of the complex.\",\n      \"evidence\": \"Drosophila germline clonal loss-of-function with Notch pathway marker immunofluorescence and LysoTracker staining\",\n      \"pmids\": [\n        \"29031909\"\n      ],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Specific Notch-pathway cargo trafficked by retromer not identified\",\n        \"Single model organism\"\n      ]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Linked Vps26a to redox signaling and differentiation through a physical interaction with the NADPH oxidase Nox4 driving ERK1/2-dependent neurogenesis.\",\n      \"evidence\": \"Vps26a knockout ESCs, co-IP, ROS measurement, inhibitor treatments, and neurogenesis markers\",\n      \"pmids\": [\n        \"30464227\"\n      ],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Whether the Nox4 interaction is retromer-dependent unclear\",\n        \"Single lab; direct vs scaffolded contact not resolved\"\n      ]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Showed that the PLA2G6 ortholog iPLA2-VIA binds VPS35/VPS26 and enhances retromer function, tying retromer activity to lipid homeostasis and neurodegeneration.\",\n      \"evidence\": \"Fly protein-interaction assay, genetic epistasis with vps26/vps35 loss, lipid profiling, and neurodegeneration phenotype\",\n      \"pmids\": [\n        \"29909971\"\n      ],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Direct VPS26 contact vs VPS35-mediated association not separated\",\n        \"Mechanism by which iPLA2-VIA enhances retromer unknown\"\n      ]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Connected VPS26a loss to Alzheimer-relevant pathology, showing its down-regulation traps APP and CI-M6PR in endosomes to raise A\\u03b2 and p-tau, with recovery reversing the defect.\",\n      \"evidence\": \"Gain/loss-of-function in iPSC-derived neurons and SH-SY5Y cells, endosome/TGN trafficking assays, and a streptozotocin diabetic mouse model\",\n      \"pmids\": [\n        \"35297035\"\n      ],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Whether APP is a direct retromer cargo not established here\",\n        \"Single lab\"\n      ]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Reported a link between VPS26 and Wnt/\\u03b2-catenin signaling promoting osteogenesis, extending putative functions beyond endosomal trafficking.\",\n      \"evidence\": \"Co-localization, co-IP with \\u03b2-catenin, TOP/FOP luciferase reporter, and lentiviral overexpression with osteogenic/adipogenic staining\",\n      \"pmids\": [\n        \"37005781\"\n      ],\n      \"confidence\": \"Low\",\n      \"gaps\": [\n        \"Single Co-IP plus reporter assay with no mechanism for how VPS26 activates \\u03b2-catenin\",\n        \"Direct vs indirect \\u03b2-catenin interaction not tested\",\n        \"Not independently confirmed\"\n      ]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Implicated membrane atg8ylation, via ATG5, as a modulator of retromer-dependent GLUT1 sorting independent of canonical autophagy.\",\n      \"evidence\": \"Co-IP of ATG5 with VPS26/VPS29/VPS35 and atg8ylation-pathway knockouts with GLUT1 trafficking readout (preprint)\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Preprint, not peer-reviewed\",\n        \"Whether ATG5 contacts VPS26 directly not established\",\n        \"Generality across other retromer cargoes unknown\"\n      ]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Provided in vitro reconstitution showing SNX27 plus Retromer tubulates membranes and that VARP is required to assemble a SNX27-ESCPE-1-Retromer supercomplex, clarifying the higher-order organization of the recycling machinery.\",\n      \"evidence\": \"Membrane reconstitution with purified proteins, binding assays, AlphaFold2-Multimer modeling, and point mutagenesis (preprint)\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Preprint, not peer-reviewed\",\n        \"Specific role of VPS26A within the supercomplex not isolated\",\n        \"Cargo selectivity of the reconstituted supercomplex not fully defined\"\n      ]\n    },\n    {\n      \"year\": 2026,\n      \"claim\": \"Established a non-canonical role for VPS26A-retromer with SNX27 in unconventional Golgi-bypass secretion of \\u0394F508-CFTR and SARS-CoV-2 spike, expanding retromer function from recycling to stress-induced surface delivery.\",\n      \"evidence\": \"CRISPR knockout screen, co-IP of SNX27 with \\u0394F508-CFTR and VPS26A-retromer, and surface trafficking assays with VPS26A/SNX27 knockouts\",\n      \"pmids\": [\n        \"41942457\"\n      ],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Molecular trigger linking cellular stress to UPS routing not defined\",\n        \"Whether VPS26A directly contacts the secreted cargoes unknown\"\n      ]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How VPS26A phosphorylation, paralogue choice, and partner inputs (Rab7, SNX27, VARP, atg8ylation) are integrated to switch retromer between canonical recycling and unconventional secretion in human cells remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"No structure of the full assembled, membrane-bound supercomplex with cargo\",\n        \"Human kinases/phosphatases controlling VPS26A phospho-gating unidentified\",\n        \"Mechanism selecting canonical vs Golgi-bypass routing uncharacterized\"\n      ]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\n        \"term_id\": \"GO:0005198\",\n        \"supporting_discovery_ids\": [\n          0,\n          1\n        ]\n      },\n      {\n        \"term_id\": \"GO:0060090\",\n        \"supporting_discovery_ids\": [\n          2,\n          5,\n          14\n        ]\n      },\n      {\n        \"term_id\": \"GO:0098772\",\n        \"supporting_discovery_ids\": [\n          4\n        ]\n      }\n    ],\n    \"localization\": [\n      {\n        \"term_id\": \"GO:0005768\",\n        \"supporting_discovery_ids\": [\n          0,\n          1,\n          4\n        ]\n      },\n      {\n        \"term_id\": \"GO:0005829\",\n        \"supporting_discovery_ids\": [\n          0\n        ]\n      },\n      {\n        \"term_id\": \"GO:0005794\",\n        \"supporting_discovery_ids\": [\n          2,\n          10\n        ]\n      }\n    ],\n    \"pathway\": [\n      {\n        \"term_id\": \"R-HSA-9609507\",\n        \"supporting_discovery_ids\": [\n          0,\n          2,\n          5,\n          14\n        ]\n      },\n      {\n        \"term_id\": \"R-HSA-5653656\",\n        \"supporting_discovery_ids\": [\n          2,\n          10,\n          14\n        ]\n      },\n      {\n        \"term_id\": \"R-HSA-162582\",\n        \"supporting_discovery_ids\": [\n          7,\n          8,\n          11\n        ]\n      }\n    ],\n    \"complexes\": [\n      \"retromer (VPS26A-VPS35-VPS29)\"\n    ],\n    \"partners\": [\n      \"VPS35\",\n      \"VPS29\",\n      \"SNX27\",\n      \"Rab7\",\n      \"TBC1D5\",\n      \"GOLPH3\",\n      \"Nox4\",\n      \"ATG5\"\n    ],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":6,"faith_total":6,"faith_pct":100.0}}