{"gene":"SNX6","run_date":"2026-06-10T07:46:37","timeline":{"discoveries":[{"year":2006,"finding":"SNX6 co-immunoprecipitates with SNX1 and colocalizes with SNX1 on early endosomes, forming a stable endosomally associated complex required for retromer-mediated retrieval of the cation-independent mannose-6-phosphate receptor (CI-MPR) from endosomes to the TGN. RNAi suppression of SNX6 also caused significant post-translational loss of SNX1 protein levels.","method":"RNAi loss-of-function screen, immunoprecipitation, immunofluorescence colocalization","journal":"Journal of cell science","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reciprocal Co-IP and RNAi phenotyping in single lab with two orthogonal methods","pmids":["17148574"],"is_preprint":false},{"year":2009,"finding":"SNX6 directly interacts with the p150(Glued) subunit of the dynein/dynactin motor complex; this interaction is required for recruitment of the dynein/dynactin complex to the membrane-associated retromer, and disruption of the SNX6–p150(Glued) interaction blocks formation and detachment of tubulovesicular sorting structures from endosomes and causes failure of CI-MPR retrieval from endosomes to the TGN.","method":"Co-immunoprecipitation, dominant-negative disruption of SNX6–p150(Glued) interaction, functional trafficking assays","journal":"Cell research","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reciprocal Co-IP plus functional perturbation, single lab, two orthogonal methods","pmids":["19935774"],"is_preprint":false},{"year":2017,"finding":"SNX6 interacts with the postsynaptic scaffold protein Homer1b/c and regulates its distribution in hippocampal CA1 dendritic shafts independently of retromer function; ablation of SNX6 in CNS-specific knockout mice reduces Homer1b/c in distal dendrites, decreases surface AMPAR levels, impairs AMPAR-mediated synaptic transmission, causes loss of dendritic spines, and results in deficits in spatial learning and memory.","method":"CNS-specific Snx6 conditional knockout mice, co-immunoprecipitation (SNX6–Homer1b/c), electrophysiology, surface biotinylation, immunofluorescence","journal":"eLife","confidence":"High","confidence_rationale":"Tier 2 / Strong — in vivo KO with multiple orthogonal readouts (electrophysiology, biochemistry, morphology), Co-IP interaction, single lab but comprehensive","pmids":["28134614"],"is_preprint":false},{"year":2019,"finding":"Rab32 directly interacts with SNX6, and both Rab32 and SNX6 affect the localization of CI-MPR, which is recycled to the TGN by the retromer, linking Rab32 to SNX6/retromer-mediated Golgi trafficking.","method":"Direct interaction assay (pulldown/co-immunoprecipitation), CI-MPR localization assay","journal":"PloS one","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single Co-IP/pulldown with functional localization assay, single lab, single method per claim","pmids":["30640902"],"is_preprint":false},{"year":2018,"finding":"SNX1 and SNX6 form a 1:1 heterodimer (the ESCPE-1 complex), established by co-expression and solution biochemistry; the heterodimer requires both proteins to be co-expressed for stable complex formation.","method":"Recombinant protein co-expression and purification, solution biochemistry (analytical size-exclusion chromatography)","journal":"Protein expression and purification","confidence":"Medium","confidence_rationale":"Tier 1 / Weak — in vitro reconstitution with solution-phase stoichiometry determination, single lab, single method","pmids":["29908913"],"is_preprint":false},{"year":2025,"finding":"SNX6 selectively mediates sorting of newly synthesized GluA2 AMPAR subunits into the post-Golgi secretory pathway before GluA2 assembles with GluA1; loss of SNX6 diverts GluA2 to lysosomal degradation, reducing constitutive and activity-dependent surface AMPAR expression, impairing AMPAR-mediated synaptic transmission, blocking NMDAR-dependent LTP, and causing learning and memory deficits.","method":"Conditional SNX6 knockout mice, hippocampal neurons, pulse-chase trafficking assays, immunofluorescence, electrophysiology, surface biotinylation","journal":"Communications biology","confidence":"High","confidence_rationale":"Tier 2 / Strong — in vivo conditional KO with multiple orthogonal methods (electrophysiology, biochemistry, trafficking assays, behavior), single lab but comprehensive","pmids":["41429886"],"is_preprint":false},{"year":2024,"finding":"ESCPE-1 (SNX2/SNX6) deforms membranes enriched with Folch I lipids and CI-MPR cargo motifs in a fully reconstituted biochemical system, but does not recruit Retromer to membranes on its own; VARP is required to reconstitute a supercomplex containing SNX27, ESCPE-1, and Retromer on PI(3)P-enriched membranes.","method":"In vitro membrane reconstitution with purified mammalian proteins, tubulation assays, AlphaFold2 Multimer modeling, biophysical binding assays","journal":"bioRxiv","confidence":"Medium","confidence_rationale":"Tier 1 / Weak — in vitro reconstitution with purified components and orthogonal biophysical methods, but preprint and single lab","pmids":[],"is_preprint":true},{"year":2016,"finding":"SNX6 is a target of miR-98-5p (which negatively regulates SNX6 via its 3'-UTR); SNX6-dependent signaling modulates levels of Aβ40, Aβ42, BACE1, sAPPβ, and βCTF — intermediates in amyloid precursor protein processing — in neuronal and HEK293 cell models.","method":"3'-UTR luciferase reporter assay, miRNA overexpression/inhibition, ELISA and Western blot for Aβ and APP processing intermediates","journal":"Journal of molecular neuroscience : MN","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single lab, indirect mechanistic link (miRNA target validation + downstream marker measurement, no direct SNX6 enzymatic or structural assay)","pmids":["27541017"],"is_preprint":false}],"current_model":"SNX6 is a PX-BAR sorting nexin that forms a 1:1 heterodimer with SNX1 (the ESCPE-1 coat complex) on early endosomes, where it recruits the dynein/dynactin motor via direct interaction with p150(Glued) to drive tubular retrograde transport of CI-MPR from endosomes to the TGN; in post-mitotic neurons, SNX6 additionally acts independently of retromer to regulate Homer1b/c distribution in dendritic shafts, and mediates subunit-specific (GluA2) post-Golgi secretory sorting of AMPA receptors, with loss of SNX6 diverting GluA2 to lysosomal degradation, impairing synaptic AMPAR delivery and LTP, and causing spatial memory deficits."},"narrative":{"mechanistic_narrative":"SNX6 is a sorting nexin that drives retrograde and secretory membrane trafficking by forming a stable, endosomally associated complex with SNX1 required for retromer-mediated retrieval of the cation-independent mannose-6-phosphate receptor (CI-MPR) from endosomes to the trans-Golgi network [PMID:17148574]. SNX6 and SNX1 assemble as a 1:1 heterodimer (the ESCPE-1 complex), with stable complex formation depending on co-expression of both subunits [PMID:29908913]. SNX6 couples this coat to the cytoskeletal transport machinery by directly binding the p150(Glued) subunit of the dynein/dynactin motor; this interaction recruits the motor to membrane-associated retromer and is required for formation and detachment of tubulovesicular sorting carriers from endosomes, such that disrupting it blocks CI-MPR retrieval [PMID:19935774]. Beyond its endosomal role, SNX6 has retromer-independent functions in neurons: it interacts with the postsynaptic scaffold Homer1b/c to regulate its distribution in CA1 dendritic shafts, and CNS-specific loss of SNX6 reduces distal-dendrite Homer1b/c, lowers surface AMPAR levels, impairs AMPAR-mediated transmission, eliminates dendritic spines, and produces spatial learning and memory deficits [PMID:28134614]. SNX6 also selectively sorts newly synthesized GluA2 AMPAR subunits into the post-Golgi secretory pathway before GluA2 assembles with GluA1, with loss of SNX6 diverting GluA2 to lysosomal degradation, reducing surface AMPAR, blocking NMDAR-dependent LTP, and causing memory deficits [PMID:41429886].","teleology":[{"year":2006,"claim":"Established that SNX6 is not an isolated protein but a functional partner of SNX1 in the retromer-associated retrieval of CI-MPR, defining its core endosome-to-TGN trafficking role.","evidence":"RNAi loss-of-function, reciprocal Co-IP, and immunofluorescence colocalization in cultured cells","pmids":["17148574"],"confidence":"Medium","gaps":["Stoichiometry of the SNX6-SNX1 complex not resolved","Mechanism by which SNX6 loss destabilizes SNX1 protein not defined","Did not address how the complex couples to motors or membrane deformation"]},{"year":2009,"claim":"Answered how the SNX6 coat physically drives carrier formation by showing it directly recruits the dynein/dynactin motor through p150(Glued), linking membrane sorting to cytoskeletal pulling forces.","evidence":"Co-IP, dominant-negative disruption of the SNX6-p150(Glued) interaction, and functional trafficking assays","pmids":["19935774"],"confidence":"Medium","gaps":["Binding interface on SNX6 not mapped structurally","Did not reconstitute motor recruitment with purified components","Single lab, two orthogonal methods"]},{"year":2016,"claim":"Linked SNX6 to amyloid precursor protein processing by placing it under miR-98-5p control with downstream effects on Aβ/BACE1 intermediates, raising a possible disease-relevant role.","evidence":"3'-UTR luciferase reporter, miRNA overexpression/inhibition, ELISA and Western blot in neuronal and HEK293 cells","pmids":["27541017"],"confidence":"Low","gaps":["Indirect link with no direct SNX6 enzymatic or structural assay","Mechanism connecting SNX6 trafficking to APP processing unestablished","Not validated in vivo"]},{"year":2017,"claim":"Revealed a retromer-independent neuronal function for SNX6 by showing it governs Homer1b/c distribution and synaptic AMPAR signaling, expanding SNX6 beyond endosome-to-TGN retrieval.","evidence":"CNS-specific conditional knockout mice with Co-IP, electrophysiology, surface biotinylation, and immunofluorescence","pmids":["28134614"],"confidence":"High","gaps":["Molecular basis of SNX6-Homer1b/c binding not mapped","How SNX6 distributes Homer1b/c along dendrites mechanistically unresolved","Relationship between Homer1b/c and AMPAR phenotypes not fully separated"]},{"year":2018,"claim":"Defined the molecular composition of the SNX6 coat by demonstrating that SNX1 and SNX6 form an obligate 1:1 heterodimer (ESCPE-1) requiring co-expression for stability.","evidence":"Recombinant co-expression, purification, and analytical size-exclusion chromatography","pmids":["29908913"],"confidence":"Medium","gaps":["No high-resolution structure of the heterodimer","Single in vitro method","Did not address cargo or membrane engagement"]},{"year":2019,"claim":"Added an upstream regulatory input by identifying Rab32 as a direct SNX6 interactor influencing CI-MPR localization, connecting a Rab GTPase to SNX6/retromer trafficking.","evidence":"Direct interaction assay (pulldown/Co-IP) and CI-MPR localization assay","pmids":["30640902"],"confidence":"Low","gaps":["Single Co-IP/pulldown without reciprocal validation","Functional role of Rab32 in carrier formation not dissected","Not independently confirmed"]},{"year":2024,"claim":"Reconstituted ESCPE-1 membrane activity, showing the heterodimer deforms cargo- and lipid-defined membranes but cannot recruit Retromer alone, identifying VARP as the factor needed to assemble a SNX27-ESCPE-1-Retromer supercomplex.","evidence":"In vitro reconstitution with purified mammalian proteins, tubulation assays, AlphaFold2-Multimer modeling, biophysical binding (preprint)","pmids":[],"confidence":"Medium","gaps":["Preprint, single lab","Used SNX2/SNX6 rather than SNX1/SNX6 in the reconstitution","In vivo relevance of the VARP-dependent supercomplex not established"]},{"year":2025,"claim":"Defined a subunit-selective secretory function by showing SNX6 sorts newly synthesized GluA2 into the post-Golgi pathway before GluA1 assembly, with loss rerouting GluA2 to lysosomes and abolishing LTP.","evidence":"Conditional knockout mice, pulse-chase trafficking, immunofluorescence, electrophysiology, surface biotinylation in hippocampal neurons","pmids":["41429886"],"confidence":"High","gaps":["Molecular recognition of GluA2 by SNX6 not mapped","Relationship between this secretory role and ESCPE-1/retromer endosomal role unresolved","Whether SNX1 participates in GluA2 sorting unknown"]},{"year":null,"claim":"How SNX6's endosomal ESCPE-1 retrieval activity, its retromer-independent Homer1b/c regulation, and its post-Golgi GluA2 secretory sorting are molecularly coordinated within the same protein remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No structure of SNX6 cargo- or partner-binding interfaces","Mechanistic basis for switching between endosomal and secretory roles unknown","Whether neuronal functions require the SNX1 heterodimer not established"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[0,1,4]},{"term_id":"GO:0008289","term_label":"lipid binding","supporting_discovery_ids":[6]}],"localization":[{"term_id":"GO:0005768","term_label":"endosome","supporting_discovery_ids":[0,1]},{"term_id":"GO:0005794","term_label":"Golgi apparatus","supporting_discovery_ids":[0,3]}],"pathway":[{"term_id":"R-HSA-5653656","term_label":"Vesicle-mediated transport","supporting_discovery_ids":[0,1]},{"term_id":"R-HSA-9609507","term_label":"Protein localization","supporting_discovery_ids":[0,5]},{"term_id":"R-HSA-112316","term_label":"Neuronal System","supporting_discovery_ids":[2,5]}],"complexes":["ESCPE-1 (SNX1-SNX6 heterodimer)"],"partners":["SNX1","DCTN1","HOMER1","RAB32","GRIA2"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q9UNH7","full_name":"Sorting nexin-6","aliases":["TRAF4-associated factor 2"],"length_aa":406,"mass_kda":46.6,"function":"Involved in several stages of intracellular trafficking. Interacts with membranes phosphatidylinositol 3,4-bisphosphate and/or phosphatidylinositol 4,5-bisphosphate (Probable). Acts in part as component of the retromer membrane-deforming SNX-BAR subcomplex (PubMed:19935774). 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 SNX-BAR subcomplex functions to deform the donor membrane into a tubular profile called endosome-to-TGN transport carrier (ETC) (Probable). Does not have in vitro vesicle-to-membrane remodeling activity (PubMed:23085988). Involved in retrograde endosome-to-TGN transport of lysosomal enzyme receptor IGF2R (PubMed:17148574). May function as link between transport vesicles and dynactin (Probable). Negatively regulates retrograde transport of BACE1 from the cell surface to the trans-Golgi network (PubMed:20354142). Involved in E-cadherin sorting and degradation; inhibits PIP5K1C isoform 3-mediated E-cadherin degradation (PubMed:24610942). In association with GIT1 involved in EGFR degradation. Promotes lysosomal degradation of CDKN1B (By similarity). May contribute to transcription regulation (Probable)","subcellular_location":"Early endosome; Early endosome membrane; Cytoplasmic vesicle; Cytoplasm; Nucleus","url":"https://www.uniprot.org/uniprotkb/Q9UNH7/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/SNX6","classification":"Not Classified","n_dependent_lines":21,"n_total_lines":1208,"dependency_fraction":0.0173841059602649},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[{"gene":"SNX1","stoichiometry":10.0},{"gene":"SNX2","stoichiometry":10.0}],"url":"https://opencell.sf.czbiohub.org/search/SNX6","total_profiled":1310},"omim":[{"mim_id":"621073","title":"SORTING NEXIN 32; SNX32","url":"https://www.omim.org/entry/621073"},{"mim_id":"606098","title":"SORTING NEXIN 6; SNX6","url":"https://www.omim.org/entry/606098"},{"mim_id":"605937","title":"SORTING NEXIN 5; SNX5","url":"https://www.omim.org/entry/605937"},{"mim_id":"605929","title":"SORTING NEXIN 2; SNX2","url":"https://www.omim.org/entry/605929"},{"mim_id":"601272","title":"SORTING NEXIN 1; SNX1","url":"https://www.omim.org/entry/601272"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Supported","locations":[{"location":"Endosomes","reliability":"Supported"},{"location":"Lysosomes","reliability":"Supported"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/SNX6"},"hgnc":{"alias_symbol":[],"prev_symbol":[]},"alphafold":{"accession":"Q9UNH7","domains":[{"cath_id":"3.30.1520.10","chopping":"24-171","consensus_level":"medium","plddt":91.2707,"start":24,"end":171},{"cath_id":"1.20.1270.60","chopping":"220-406","consensus_level":"medium","plddt":94.8791,"start":220,"end":406}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9UNH7","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q9UNH7-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q9UNH7-F1-predicted_aligned_error_v6.png","plddt_mean":88.81},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=SNX6","jax_strain_url":"https://www.jax.org/strain/search?query=SNX6"},"sequence":{"accession":"Q9UNH7","fasta_url":"https://rest.uniprot.org/uniprotkb/Q9UNH7.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q9UNH7/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9UNH7"}},"corpus_meta":[{"pmid":"17148574","id":"PMC_17148574","title":"A loss-of-function screen reveals SNX5 and SNX6 as potential components of the mammalian retromer.","date":"2006","source":"Journal of cell science","url":"https://pubmed.ncbi.nlm.nih.gov/17148574","citation_count":213,"is_preprint":false},{"pmid":"19935774","id":"PMC_19935774","title":"The retromer component SNX6 interacts with dynactin p150(Glued) and mediates endosome-to-TGN transport.","date":"2009","source":"Cell research","url":"https://pubmed.ncbi.nlm.nih.gov/19935774","citation_count":101,"is_preprint":false},{"pmid":"27541017","id":"PMC_27541017","title":"miR-98-5p Acts as a Target for Alzheimer's Disease by Regulating Aβ Production Through Modulating SNX6 Expression.","date":"2016","source":"Journal of molecular neuroscience : MN","url":"https://pubmed.ncbi.nlm.nih.gov/27541017","citation_count":47,"is_preprint":false},{"pmid":"28134614","id":"PMC_28134614","title":"Ablation of SNX6 leads to defects in synaptic function of CA1 pyramidal neurons and spatial memory.","date":"2017","source":"eLife","url":"https://pubmed.ncbi.nlm.nih.gov/28134614","citation_count":22,"is_preprint":false},{"pmid":"30640902","id":"PMC_30640902","title":"Rab32 interacts with SNX6 and affects retromer-dependent Golgi trafficking.","date":"2019","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/30640902","citation_count":20,"is_preprint":false},{"pmid":"21777593","id":"PMC_21777593","title":"The structure of BRMS1 nuclear export signal and SNX6 interacting region reveals a hexamer formed by antiparallel coiled coils.","date":"2011","source":"Journal of molecular biology","url":"https://pubmed.ncbi.nlm.nih.gov/21777593","citation_count":11,"is_preprint":false},{"pmid":"29908913","id":"PMC_29908913","title":"Expression and purification of the SNX1/SNX6 complex.","date":"2018","source":"Protein expression and purification","url":"https://pubmed.ncbi.nlm.nih.gov/29908913","citation_count":8,"is_preprint":false},{"pmid":"30738087","id":"PMC_30738087","title":"Pb exposure reduces the expression of SNX6 and Homer1 in offspring rats and PC12 cells.","date":"2019","source":"Toxicology","url":"https://pubmed.ncbi.nlm.nih.gov/30738087","citation_count":7,"is_preprint":false},{"pmid":"41429886","id":"PMC_41429886","title":"SNX6-mediated subunit-specific secretory trafficking of AMPA receptors regulates synaptic function and plasticity.","date":"2025","source":"Communications biology","url":"https://pubmed.ncbi.nlm.nih.gov/41429886","citation_count":1,"is_preprint":false},{"pmid":null,"id":"bio_10.1101_2025.07.24.666383","title":"Revealing the nervous system requirements of Alzheimer’s disease risk genes in  <i>Drosophila</i>","date":"2025-07-30","source":"bioRxiv","url":"https://doi.org/10.1101/2025.07.24.666383","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":7256,"output_tokens":2143,"usd":0.026957,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":9105,"output_tokens":3247,"usd":0.06335,"stage2_stop_reason":"end_turn"},"total_usd":0.090307,"stage1_batch_id":"msgbatch_013LWZZT6MWaqB9qyTSeQBmU","stage2_batch_id":"msgbatch_0194ZzQaTGNpruoNJBbEMbt3","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2006,\n      \"finding\": \"SNX6 co-immunoprecipitates with SNX1 and colocalizes with SNX1 on early endosomes, forming a stable endosomally associated complex required for retromer-mediated retrieval of the cation-independent mannose-6-phosphate receptor (CI-MPR) from endosomes to the TGN. RNAi suppression of SNX6 also caused significant post-translational loss of SNX1 protein levels.\",\n      \"method\": \"RNAi loss-of-function screen, immunoprecipitation, immunofluorescence colocalization\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal Co-IP and RNAi phenotyping in single lab with two orthogonal methods\",\n      \"pmids\": [\"17148574\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"SNX6 directly interacts with the p150(Glued) subunit of the dynein/dynactin motor complex; this interaction is required for recruitment of the dynein/dynactin complex to the membrane-associated retromer, and disruption of the SNX6–p150(Glued) interaction blocks formation and detachment of tubulovesicular sorting structures from endosomes and causes failure of CI-MPR retrieval from endosomes to the TGN.\",\n      \"method\": \"Co-immunoprecipitation, dominant-negative disruption of SNX6–p150(Glued) interaction, functional trafficking assays\",\n      \"journal\": \"Cell research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal Co-IP plus functional perturbation, single lab, two orthogonal methods\",\n      \"pmids\": [\"19935774\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"SNX6 interacts with the postsynaptic scaffold protein Homer1b/c and regulates its distribution in hippocampal CA1 dendritic shafts independently of retromer function; ablation of SNX6 in CNS-specific knockout mice reduces Homer1b/c in distal dendrites, decreases surface AMPAR levels, impairs AMPAR-mediated synaptic transmission, causes loss of dendritic spines, and results in deficits in spatial learning and memory.\",\n      \"method\": \"CNS-specific Snx6 conditional knockout mice, co-immunoprecipitation (SNX6–Homer1b/c), electrophysiology, surface biotinylation, immunofluorescence\",\n      \"journal\": \"eLife\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — in vivo KO with multiple orthogonal readouts (electrophysiology, biochemistry, morphology), Co-IP interaction, single lab but comprehensive\",\n      \"pmids\": [\"28134614\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"Rab32 directly interacts with SNX6, and both Rab32 and SNX6 affect the localization of CI-MPR, which is recycled to the TGN by the retromer, linking Rab32 to SNX6/retromer-mediated Golgi trafficking.\",\n      \"method\": \"Direct interaction assay (pulldown/co-immunoprecipitation), CI-MPR localization assay\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single Co-IP/pulldown with functional localization assay, single lab, single method per claim\",\n      \"pmids\": [\"30640902\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"SNX1 and SNX6 form a 1:1 heterodimer (the ESCPE-1 complex), established by co-expression and solution biochemistry; the heterodimer requires both proteins to be co-expressed for stable complex formation.\",\n      \"method\": \"Recombinant protein co-expression and purification, solution biochemistry (analytical size-exclusion chromatography)\",\n      \"journal\": \"Protein expression and purification\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Weak — in vitro reconstitution with solution-phase stoichiometry determination, single lab, single method\",\n      \"pmids\": [\"29908913\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"SNX6 selectively mediates sorting of newly synthesized GluA2 AMPAR subunits into the post-Golgi secretory pathway before GluA2 assembles with GluA1; loss of SNX6 diverts GluA2 to lysosomal degradation, reducing constitutive and activity-dependent surface AMPAR expression, impairing AMPAR-mediated synaptic transmission, blocking NMDAR-dependent LTP, and causing learning and memory deficits.\",\n      \"method\": \"Conditional SNX6 knockout mice, hippocampal neurons, pulse-chase trafficking assays, immunofluorescence, electrophysiology, surface biotinylation\",\n      \"journal\": \"Communications biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — in vivo conditional KO with multiple orthogonal methods (electrophysiology, biochemistry, trafficking assays, behavior), single lab but comprehensive\",\n      \"pmids\": [\"41429886\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"ESCPE-1 (SNX2/SNX6) deforms membranes enriched with Folch I lipids and CI-MPR cargo motifs in a fully reconstituted biochemical system, but does not recruit Retromer to membranes on its own; VARP is required to reconstitute a supercomplex containing SNX27, ESCPE-1, and Retromer on PI(3)P-enriched membranes.\",\n      \"method\": \"In vitro membrane reconstitution with purified mammalian proteins, tubulation assays, AlphaFold2 Multimer modeling, biophysical binding assays\",\n      \"journal\": \"bioRxiv\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Weak — in vitro reconstitution with purified components and orthogonal biophysical methods, but preprint and single lab\",\n      \"pmids\": [],\n      \"is_preprint\": true\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"SNX6 is a target of miR-98-5p (which negatively regulates SNX6 via its 3'-UTR); SNX6-dependent signaling modulates levels of Aβ40, Aβ42, BACE1, sAPPβ, and βCTF — intermediates in amyloid precursor protein processing — in neuronal and HEK293 cell models.\",\n      \"method\": \"3'-UTR luciferase reporter assay, miRNA overexpression/inhibition, ELISA and Western blot for Aβ and APP processing intermediates\",\n      \"journal\": \"Journal of molecular neuroscience : MN\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single lab, indirect mechanistic link (miRNA target validation + downstream marker measurement, no direct SNX6 enzymatic or structural assay)\",\n      \"pmids\": [\"27541017\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"SNX6 is a PX-BAR sorting nexin that forms a 1:1 heterodimer with SNX1 (the ESCPE-1 coat complex) on early endosomes, where it recruits the dynein/dynactin motor via direct interaction with p150(Glued) to drive tubular retrograde transport of CI-MPR from endosomes to the TGN; in post-mitotic neurons, SNX6 additionally acts independently of retromer to regulate Homer1b/c distribution in dendritic shafts, and mediates subunit-specific (GluA2) post-Golgi secretory sorting of AMPA receptors, with loss of SNX6 diverting GluA2 to lysosomal degradation, impairing synaptic AMPAR delivery and LTP, and causing spatial memory deficits.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"SNX6 is a sorting nexin that drives retrograde and secretory membrane trafficking by forming a stable, endosomally associated complex with SNX1 required for retromer-mediated retrieval of the cation-independent mannose-6-phosphate receptor (CI-MPR) from endosomes to the trans-Golgi network [#0]. SNX6 and SNX1 assemble as a 1:1 heterodimer (the ESCPE-1 complex), with stable complex formation depending on co-expression of both subunits [#4]. SNX6 couples this coat to the cytoskeletal transport machinery by directly binding the p150(Glued) subunit of the dynein/dynactin motor; this interaction recruits the motor to membrane-associated retromer and is required for formation and detachment of tubulovesicular sorting carriers from endosomes, such that disrupting it blocks CI-MPR retrieval [#1]. Beyond its endosomal role, SNX6 has retromer-independent functions in neurons: it interacts with the postsynaptic scaffold Homer1b/c to regulate its distribution in CA1 dendritic shafts, and CNS-specific loss of SNX6 reduces distal-dendrite Homer1b/c, lowers surface AMPAR levels, impairs AMPAR-mediated transmission, eliminates dendritic spines, and produces spatial learning and memory deficits [#2]. SNX6 also selectively sorts newly synthesized GluA2 AMPAR subunits into the post-Golgi secretory pathway before GluA2 assembles with GluA1, with loss of SNX6 diverting GluA2 to lysosomal degradation, reducing surface AMPAR, blocking NMDAR-dependent LTP, and causing memory deficits [#5].\",\n  \"teleology\": [\n    {\n      \"year\": 2006,\n      \"claim\": \"Established that SNX6 is not an isolated protein but a functional partner of SNX1 in the retromer-associated retrieval of CI-MPR, defining its core endosome-to-TGN trafficking role.\",\n      \"evidence\": \"RNAi loss-of-function, reciprocal Co-IP, and immunofluorescence colocalization in cultured cells\",\n      \"pmids\": [\"17148574\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Stoichiometry of the SNX6-SNX1 complex not resolved\", \"Mechanism by which SNX6 loss destabilizes SNX1 protein not defined\", \"Did not address how the complex couples to motors or membrane deformation\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Answered how the SNX6 coat physically drives carrier formation by showing it directly recruits the dynein/dynactin motor through p150(Glued), linking membrane sorting to cytoskeletal pulling forces.\",\n      \"evidence\": \"Co-IP, dominant-negative disruption of the SNX6-p150(Glued) interaction, and functional trafficking assays\",\n      \"pmids\": [\"19935774\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Binding interface on SNX6 not mapped structurally\", \"Did not reconstitute motor recruitment with purified components\", \"Single lab, two orthogonal methods\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Linked SNX6 to amyloid precursor protein processing by placing it under miR-98-5p control with downstream effects on Aβ/BACE1 intermediates, raising a possible disease-relevant role.\",\n      \"evidence\": \"3'-UTR luciferase reporter, miRNA overexpression/inhibition, ELISA and Western blot in neuronal and HEK293 cells\",\n      \"pmids\": [\"27541017\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"Indirect link with no direct SNX6 enzymatic or structural assay\", \"Mechanism connecting SNX6 trafficking to APP processing unestablished\", \"Not validated in vivo\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Revealed a retromer-independent neuronal function for SNX6 by showing it governs Homer1b/c distribution and synaptic AMPAR signaling, expanding SNX6 beyond endosome-to-TGN retrieval.\",\n      \"evidence\": \"CNS-specific conditional knockout mice with Co-IP, electrophysiology, surface biotinylation, and immunofluorescence\",\n      \"pmids\": [\"28134614\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular basis of SNX6-Homer1b/c binding not mapped\", \"How SNX6 distributes Homer1b/c along dendrites mechanistically unresolved\", \"Relationship between Homer1b/c and AMPAR phenotypes not fully separated\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Defined the molecular composition of the SNX6 coat by demonstrating that SNX1 and SNX6 form an obligate 1:1 heterodimer (ESCPE-1) requiring co-expression for stability.\",\n      \"evidence\": \"Recombinant co-expression, purification, and analytical size-exclusion chromatography\",\n      \"pmids\": [\"29908913\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No high-resolution structure of the heterodimer\", \"Single in vitro method\", \"Did not address cargo or membrane engagement\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Added an upstream regulatory input by identifying Rab32 as a direct SNX6 interactor influencing CI-MPR localization, connecting a Rab GTPase to SNX6/retromer trafficking.\",\n      \"evidence\": \"Direct interaction assay (pulldown/Co-IP) and CI-MPR localization assay\",\n      \"pmids\": [\"30640902\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"Single Co-IP/pulldown without reciprocal validation\", \"Functional role of Rab32 in carrier formation not dissected\", \"Not independently confirmed\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Reconstituted ESCPE-1 membrane activity, showing the heterodimer deforms cargo- and lipid-defined membranes but cannot recruit Retromer alone, identifying VARP as the factor needed to assemble a SNX27-ESCPE-1-Retromer supercomplex.\",\n      \"evidence\": \"In vitro reconstitution with purified mammalian proteins, tubulation assays, AlphaFold2-Multimer modeling, biophysical binding (preprint)\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Preprint, single lab\", \"Used SNX2/SNX6 rather than SNX1/SNX6 in the reconstitution\", \"In vivo relevance of the VARP-dependent supercomplex not established\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Defined a subunit-selective secretory function by showing SNX6 sorts newly synthesized GluA2 into the post-Golgi pathway before GluA1 assembly, with loss rerouting GluA2 to lysosomes and abolishing LTP.\",\n      \"evidence\": \"Conditional knockout mice, pulse-chase trafficking, immunofluorescence, electrophysiology, surface biotinylation in hippocampal neurons\",\n      \"pmids\": [\"41429886\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular recognition of GluA2 by SNX6 not mapped\", \"Relationship between this secretory role and ESCPE-1/retromer endosomal role unresolved\", \"Whether SNX1 participates in GluA2 sorting unknown\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How SNX6's endosomal ESCPE-1 retrieval activity, its retromer-independent Homer1b/c regulation, and its post-Golgi GluA2 secretory sorting are molecularly coordinated within the same protein remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No structure of SNX6 cargo- or partner-binding interfaces\", \"Mechanistic basis for switching between endosomal and secretory roles unknown\", \"Whether neuronal functions require the SNX1 heterodimer not established\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [0, 1, 4]},\n      {\"term_id\": \"GO:0008289\", \"supporting_discovery_ids\": [6]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005768\", \"supporting_discovery_ids\": [0, 1]},\n      {\"term_id\": \"GO:0005794\", \"supporting_discovery_ids\": [0, 3]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-5653656\", \"supporting_discovery_ids\": [0, 1]},\n      {\"term_id\": \"R-HSA-9609507\", \"supporting_discovery_ids\": [0, 5]},\n      {\"term_id\": \"R-HSA-112316\", \"supporting_discovery_ids\": [2, 5]}\n    ],\n    \"complexes\": [\"ESCPE-1 (SNX1-SNX6 heterodimer)\"],\n    \"partners\": [\"SNX1\", \"DCTN1\", \"HOMER1\", \"RAB32\", \"GRIA2\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":5,"faith_total":5,"faith_pct":100.0}}