{"gene":"EXOC3","run_date":"2026-04-28T17:46:03","timeline":{"discoveries":[{"year":1995,"finding":"Sec6 (EXOC3 ortholog in yeast) is a stable component of the Sec6/8/15 multisubunit complex (~1-2 MDa) that localizes to small bud tips in S. cerevisiae, identifying its position in the exocytic machinery at sites of polarized secretion.","method":"Immobilized metal affinity chromatography, gel filtration, sucrose velocity centrifugation, coimmunoprecipitation, immunofluorescence","journal":"The Journal of cell biology","confidence":"High","confidence_rationale":"Tier 1-2 — multiple orthogonal biochemical fractionation methods plus localization, foundational study","pmids":["7615633"],"is_preprint":false},{"year":1992,"finding":"SEC6 encodes an 85 kDa soluble protein required for fusion of post-Golgi vesicles with the plasma membrane in yeast; SEC6 is essential for growth and its product sediments at 14S in the soluble fraction.","method":"Gene cloning by complementation, nucleotide sequencing, gene disruption, subcellular fractionation","journal":"Yeast (Chichester, England)","confidence":"High","confidence_rationale":"Tier 1-2 — genetic loss-of-function with defined secretory phenotype, essential gene confirmed by disruption","pmids":["1523887"],"is_preprint":false},{"year":1998,"finding":"In MDCK epithelial cells, the Sec6/8 (exocyst) complex is cytosolic in non-polarized cells and is rapidly recruited (~70%) to sites of cell-cell contact upon calcium-dependent adhesion; Sec8 antibodies in permeabilized cells inhibit LDL receptor delivery to the basolateral membrane but not apical delivery of p75NTR, demonstrating that the complex specifically directs vesicle delivery to the basolateral membrane.","method":"Immunofluorescence, streptolysin-O permeabilization assay with function-blocking antibodies, subcellular fractionation","journal":"Cell","confidence":"High","confidence_rationale":"Tier 2 — direct functional antibody-blocking experiment with specific membrane-domain readout, highly cited foundational study","pmids":["9630218"],"is_preprint":false},{"year":1998,"finding":"The rat brain Sec6/8 complex coimmunoprecipitates with septin filaments (including CDC10) and adopts a 'T' or 'Y' shaped conformation by electron microscopy, establishing a physical interaction between the exocyst and septin complexes at the plasma membrane of neurons.","method":"Coimmunoprecipitation, electron microscopy of purified complexes","journal":"Neuron","confidence":"High","confidence_rationale":"Tier 2 — reciprocal co-IP plus structural visualization; highly cited","pmids":["9655500"],"is_preprint":false},{"year":2001,"finding":"The Sec6/8 complex localizes to both the trans-Golgi network (TGN) and plasma membrane in mammalian cells and is required for multiple steps of exocytic transport; antibodies against TGN-bound or plasma membrane-bound Sec6/8 each cause cargo accumulation at distinct intracellular sites, and Brefeldin A treatment blocks plasma membrane recruitment while blocking exocytosis causes TGN accumulation.","method":"Immunofluorescence colocalization with VSVG-tsO45 cargo, Brefeldin A treatment, antibody inhibition in semiintact cells","journal":"The Journal of cell biology","confidence":"High","confidence_rationale":"Tier 2 — function-blocking antibodies in semiintact cells with specific cargo-accumulation readout, multiple orthogonal approaches","pmids":["11696560"],"is_preprint":false},{"year":2001,"finding":"Human Sec3 (hSec3), the last mammalian exocyst subunit to be identified, interacts with Sec5 and Sec8 in yeast two-hybrid assays but lacks the Rho1-binding site present in yeast Sec3p; GFP-Exo70 (but not other subunits) localizes to lateral membrane cell-cell contacts in MDCK cells and its overexpression disrupts tight monolayer formation.","method":"Sequence cloning, yeast two-hybrid, GFP-fusion imaging in MDCK cells","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"Medium","confidence_rationale":"Tier 2-3 — characterization of subunit interactions and localization but limited functional validation for Sec6 specifically","pmids":["11493706"],"is_preprint":false},{"year":2004,"finding":"The Sec6/8 complex is recruited to the apical junctional complex in epithelial cells via direct interaction with E-cadherin and nectin-2α; co-expression of both adhesion proteins in fibroblasts is sufficient to recruit the complex to cell-cell contacts, placing E-cadherin/nectin complexes upstream of exocyst localization.","method":"Coimmunoprecipitation with surface-labeled E-cadherin and nectin-2α, high-molecular-mass fractionation, fibroblast reconstitution","journal":"Journal of cell science","confidence":"High","confidence_rationale":"Tier 2 — reciprocal co-IP plus reconstitution in fibroblasts with defined localization readout","pmids":["14709721"],"is_preprint":false},{"year":2000,"finding":"In pancreatic acinar and brain cells, Sec8 coimmunoprecipitates Sec6, IP3R3, Gβγ, plasma membrane Ca2+ pump, Gαq, PLCβ1, and IP3R1; interaction between Sec6/8 and Ca2+ signaling proteins is mediated by actin filaments; anti-Sec6/Sec8 antibodies inhibit Ca2+ signaling upstream of Ca2+ release, and actin disruption causes Sec6/8 translocation to cytosol and impairs polarized Ca2+ waves.","method":"Immunoprecipitation, confocal immunolocalization, actin depolymerization (latrunculin B), antibody inhibition experiments","journal":"The Journal of cell biology","confidence":"High","confidence_rationale":"Tier 2 — multiple co-IP partners confirmed, actin-mediated interaction mechanism established, function-blocking antibodies with Ca2+ signaling readout","pmids":["10973998"],"is_preprint":false},{"year":2003,"finding":"Crystal structure of the Sec5 Ral-binding domain (immunoglobulin-like β-sandwich) in complex with RalA-GppNHp at 2.1 Å reveals a nucleotide-dependent switch mechanism; key residues Sec5 Thr11, Arg27, and RalA Glu38 are required for complex formation, establishing the structural basis of GTP-dependent exocyst regulation by Ral GTPases.","method":"X-ray crystallography, isothermal titration calorimetry, mutagenesis","journal":"The EMBO journal","confidence":"High","confidence_rationale":"Tier 1 — crystal structure plus mutagenesis and ITC binding validation","pmids":["12839989"],"is_preprint":false},{"year":2005,"finding":"Crystal structure of the Exo84 Ral-binding domain (pleckstrin homology fold) in complex with active RalA shows that Exo84 and Sec5 competitively and mutually exclusively bind RalA via overlapping switch-region interfaces; key residues determining specificity were confirmed by mutagenesis.","method":"X-ray crystallography, mutagenesis, biochemical binding assays","journal":"The EMBO journal","confidence":"High","confidence_rationale":"Tier 1 — crystal structure, mutagenesis, and competitive binding assays","pmids":["15920473"],"is_preprint":false},{"year":2005,"finding":"In Drosophila epithelial cells, loss of sec6 (but not sec5 or sec8) causes accumulation at adherens junctions; in photoreceptors, reduced Sec6 leads to accumulation of secretory vesicles and failure to transport proteins to the apical rhabdomere; Rab11 forms a complex with Sec5, and Sec5 interacts with Sec6, positioning the exocyst as a Rab11 effector for apical membrane protein transport.","method":"Drosophila genetics (loss-of-function mutations), immunolocalization, coimmunoprecipitation (Rab11-Sec5-Sec6)","journal":"The Journal of cell biology","confidence":"High","confidence_rationale":"Tier 2 — genetic loss-of-function with defined vesicle-accumulation phenotype, co-IP establishing Rab11-exocyst interaction","pmids":["15897260"],"is_preprint":false},{"year":2005,"finding":"In Drosophila epithelial cells, sec5, sec6, and sec15 loss-of-function results in accumulation of DE-Cadherin in an enlarged Rab11-positive recycling endosomal compartment and blocks DE-Cad delivery to the plasma membrane; Rab11 interacts with Sec15 and Armadillo interacts with Sec10, placing the exocyst in a Rab11-dependent recycling endosome-to-membrane trafficking pathway.","method":"Drosophila genetics, immunofluorescence, coimmunoprecipitation","journal":"Developmental cell","confidence":"High","confidence_rationale":"Tier 2 — genetic loss-of-function with defined trafficking phenotype plus co-IP interaction data, highly cited","pmids":["16224820"],"is_preprint":false},{"year":2011,"finding":"Yeast Sec6 directly binds the SM protein Sec1 (Munc18 family); the Sec6-Sec1 interaction is mutually exclusive with Sec6-Sec9 (SNARE) interaction but compatible with Sec6-exocyst assembly; the Sec6-exocyst interaction is incompatible with Sec6-Sec9 binding. Upon vesicle arrival, Sec6 is proposed to release Sec9 and recruit Sec1 for coordinated SNARE complex formation.","method":"In vitro binding assays, pull-down, yeast genetics","journal":"Molecular biology of the cell","confidence":"High","confidence_rationale":"Tier 1-2 — in vitro binding assays defining mutually exclusive interactions, mechanistic model supported by multiple interaction experiments","pmids":["22114349"],"is_preprint":false},{"year":2015,"finding":"Yeast Sec6 directly binds assembled binary (Sec9-Sso1) and ternary (Sec9-Sso1-Snc2) SNARE complexes but does not inhibit SNARE assembly rate; cross-linking/mass spectrometry identified Sec6 residues at the interface, and mutation of these residues causes a growth defect, suggesting Sec6 promotes rather than inhibits SNARE complex assembly.","method":"In vitro SNARE assembly assays, cross-linking mass spectrometry, yeast mutagenesis growth assays","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 — in vitro reconstitution with cross-linking/MS and mutagenesis; revises prior model","pmids":["26446795"],"is_preprint":false},{"year":2003,"finding":"In neurons, Sec6 concentrates at the inside of the presynaptic plasma membrane (distinct from cytoplasmic Sec8); Sec6 is transported along neurites on secretogranin II-positive vesicles, identifying it as a cargo associated with dense-core vesicle transport to presynaptic sites.","method":"Immunolocalization (confocal), subcellular fractionation, live transport imaging in neurons and PC12 cells","journal":"Neuroscience","confidence":"Medium","confidence_rationale":"Tier 3 — localization experiments with vesicle transport correlation but limited functional manipulation","pmids":["12763070"],"is_preprint":false},{"year":2018,"finding":"EXOC3 (Sec6) knockdown in mammalian cells suppresses phosphorylation of p38 MAPK (via MKK3/6), MK2, and HSP27 at Ser78/Ser82, reduces cell migration, and promotes apoptosis after TNF-α/cycloheximide treatment, placing Sec6 upstream of the MKK3/6-p38-MK2-HSP27 signaling axis.","method":"siRNA knockdown, Western blotting for phospho-proteins, cell migration assay, apoptosis assay","journal":"Cellular signalling","confidence":"Medium","confidence_rationale":"Tier 3 — single-lab siRNA study with defined phosphoprotein readouts but no reconstitution or direct biochemical interaction","pmids":["29729335"],"is_preprint":false},{"year":2016,"finding":"EXOC3 (Sec6) knockdown in HeLa cells inhibits IκBα degradation and delays p65 nuclear translocation after TNF-α stimulation; Sec6 regulates NF-κB activity via control of ERK and p90RSK1 phosphorylation and IκBα phosphorylation at Ser32.","method":"siRNA knockdown, Western blotting, nuclear translocation assay, luciferase reporter assay","journal":"Journal of cellular physiology","confidence":"Medium","confidence_rationale":"Tier 3 — siRNA with defined signaling readouts but single lab and no direct biochemical mechanism established","pmids":["26247921"],"is_preprint":false},{"year":2014,"finding":"EXOC3 (Sec6) regulates cytoplasmic translocation and degradation of p27 by promoting p27 phosphorylation at Thr157 and through interactions with Jab1 (CSN5) and Siah1, thereby suppressing cell cycle progression.","method":"siRNA knockdown, coimmunoprecipitation, Western blotting, cell cycle analysis","journal":"Cellular signalling","confidence":"Low","confidence_rationale":"Tier 3 — co-IP plus KD but single lab with limited mechanistic depth","pmids":["24949832"],"is_preprint":false},{"year":2021,"finding":"Conditional knockout of EXOC3 in mouse megakaryocytes/platelets causes defects in platelet aggregation, integrin activation, α-granule/dense granule/lysosomal granule secretion after GPVI stimulation, and reduces surface GPVI levels; paradoxically, PAR4 activation increases dense granule secretion and integrin activation in KO platelets via enhanced ADP release; arterial thrombosis is accelerated in KO mice.","method":"Conditional knockout (Cre-lox), platelet aggregation assay, flow cytometry, phosphorylation assays, tail bleeding time, ferric chloride arterial thrombosis model","journal":"Blood advances","confidence":"High","confidence_rationale":"Tier 2 — conditional KO with multiple specific platelet function readouts and in vivo thrombosis model","pmids":["33560379"],"is_preprint":false},{"year":2020,"finding":"Tnfaip2 (mouse EXOC3 ortholog) acts epistatically upstream of vimentin (Vim) to control triacylglycerol synthesis and lipid droplet formation during ESC differentiation; Tnfaip2 KO impairs differentiation and lipid droplet induction, and supplementation with palmitic acid rescues this defect.","method":"Knockout mouse ESCs, lipid profiling, epistasis analysis, rescue with palmitic acid","journal":"EMBO reports","confidence":"Medium","confidence_rationale":"Tier 2 — genetic epistasis plus metabolic rescue, but novel/unexpected role for this exocyst subunit","pmids":["33300287"],"is_preprint":false},{"year":2023,"finding":"Crystallization of truncated human Sec6 (HuSec6 121-734 and 121-745) was achieved with >95% purity, yielding crystals with ~9 Å X-ray diffraction, providing a structural foundation for analysis of human EXOC3.","method":"Recombinant protein expression in E. coli, purification, X-ray crystallography","journal":"Studies in health technology and informatics","confidence":"Low","confidence_rationale":"Tier 1 method but only preliminary low-resolution diffraction; no functional validation","pmids":["38007759"],"is_preprint":false},{"year":2024,"finding":"Male germline-specific conditional knockout of Exoc3 (EXOC3/SEC6) in mice does not disrupt spermatogenesis, establishing that EXOC3 is dispensable for this process (unlike EXOC1/SEC3 or EXOC7/EXO70).","method":"Conditional knockout (Cre-lox), histological analysis of spermatogenesis","journal":"Experimental animals","confidence":"Medium","confidence_rationale":"Tier 2 — clean KO with specific tissue phenotype readout; negative result well-controlled by comparison with other exocyst KOs","pmids":["38325858"],"is_preprint":false}],"current_model":"EXOC3 (Sec6) is a core subunit of the octameric exocyst tethering complex that functions at the plasma membrane and TGN to direct secretory vesicle docking and fusion at polarized membrane domains; it physically interacts with SNARE proteins (promoting rather than inhibiting SNARE complex assembly), SM proteins (Sec1/Munc18), cell-cell adhesion complexes (E-cadherin, nectin), and septin filaments, is regulated upstream by Ral GTPases (competing with Sec5/Exo84 for RalA binding), and also modulates signaling cascades including p38 MAPK/HSP27, NF-κB/IκBα, and lipid metabolism relevant to stem cell differentiation, with loss of EXOC3 in platelets impairing granule secretion and GPVI signaling while paradoxically accelerating thrombosis."},"narrative":{"teleology":[{"year":1992,"claim":"Establishing that SEC6 encodes an essential soluble protein required for post-Golgi vesicle fusion with the plasma membrane defined its fundamental role in the secretory pathway.","evidence":"Yeast gene cloning by complementation, gene disruption lethality, subcellular fractionation","pmids":["1523887"],"confidence":"High","gaps":["No interacting partners identified","No structural information","Mammalian ortholog not yet characterized"]},{"year":1995,"claim":"Identifying Sec6 as a stable subunit of the multisubunit Sec6/8 complex that localizes to polarized bud tips placed it within a defined molecular machine for polarized exocytosis.","evidence":"Immobilized metal affinity chromatography, gel filtration, co-IP, and immunofluorescence in S. cerevisiae","pmids":["7615633"],"confidence":"High","gaps":["Stoichiometry and complete subunit composition of the complex not yet defined","Function of individual subunits within the complex unknown"]},{"year":1998,"claim":"Demonstrating that the Sec6/8 complex is recruited to cell-cell contacts upon calcium-dependent adhesion and specifically directs basolateral (not apical) membrane delivery in epithelial cells established the complex's role in polarized trafficking in mammalian cells.","evidence":"Function-blocking antibodies in streptolysin-O-permeabilized MDCK cells with domain-specific cargo readouts; co-IP with septin filaments in neurons","pmids":["9630218","9655500"],"confidence":"High","gaps":["Which subunit(s) mediate membrane-domain specificity remains unclear","Mechanism of recruitment to cell-cell contacts unresolved"]},{"year":2001,"claim":"Showing that the exocyst functions at both the TGN and the plasma membrane, with antibodies against each pool blocking distinct transport steps, revealed that the complex acts at multiple stations along the exocytic route.","evidence":"Antibody inhibition in semiintact cells with VSVG cargo tracking, Brefeldin A experiments","pmids":["11696560"],"confidence":"High","gaps":["How the complex transitions between TGN and PM pools is unknown","Specific contribution of Sec6 versus other subunits at each station not resolved"]},{"year":2004,"claim":"Identifying E-cadherin and nectin-2α as upstream recruiters of the exocyst to the apical junctional complex explained how adhesion controls vesicle delivery to cell-cell contacts.","evidence":"Co-IP with surface-labeled adhesion proteins; reconstitution of exocyst recruitment in fibroblasts co-expressing E-cadherin and nectin","pmids":["14709721"],"confidence":"High","gaps":["Direct binding subunit(s) within the exocyst that contact E-cadherin/nectin not mapped","Regulation of the interaction not defined"]},{"year":2005,"claim":"Structural and genetic studies established that Ral GTPases regulate the exocyst through mutually exclusive binding to Sec5 and Exo84, and that the Rab11-exocyst axis routes vesicles from recycling endosomes to the plasma membrane in epithelia.","evidence":"Crystal structures of RalA–Sec5 and RalA–Exo84 complexes; Drosophila sec6 loss-of-function showing vesicle accumulation and DE-Cadherin trapping in Rab11-positive endosomes; co-IP of Rab11–Sec15 and Armadillo–Sec10","pmids":["12839989","15920473","15897260","16224820"],"confidence":"High","gaps":["Whether Sec6 itself directly contacts Ral or Rab11 is unknown","How Ral and Rab11 signals are integrated at the level of the holo-complex remains unresolved"]},{"year":2011,"claim":"Revealing that Sec6 directly binds the SM protein Sec1 in a manner mutually exclusive with SNARE binding defined a hand-off mechanism coordinating vesicle tethering with SNARE-mediated fusion.","evidence":"In vitro pull-down and binding competition assays in yeast","pmids":["22114349"],"confidence":"High","gaps":["Temporal sequence of hand-off not demonstrated in vivo","Structural basis of mutual exclusivity not determined"]},{"year":2015,"claim":"Showing that Sec6 binds assembled SNARE complexes without inhibiting their assembly—and that disrupting this interaction impairs growth—revised the model from inhibitory gatekeeper to a positive regulator of SNARE complex formation.","evidence":"In vitro SNARE assembly kinetics, cross-linking mass spectrometry mapping the Sec6–SNARE interface, yeast mutagenesis growth assays","pmids":["26446795"],"confidence":"High","gaps":["Whether Sec6 stabilizes or activates SNARE complexes post-assembly is unclear","Interface residues not confirmed by structural methods"]},{"year":2016,"claim":"EXOC3 knockdown studies linked the exocyst subunit to NF-κB and p38 MAPK signaling cascades, suggesting broader roles beyond vesicle trafficking in cytokine-stimulated signaling.","evidence":"siRNA knockdown in HeLa cells with IκBα degradation, p65 translocation, and phospho-p38/HSP27 readouts","pmids":["26247921","29729335"],"confidence":"Medium","gaps":["No direct biochemical mechanism connecting Sec6 to kinase activation","Single-lab observations not independently replicated","Possible indirect effects via impaired trafficking of signaling receptors not excluded"]},{"year":2021,"claim":"Conditional EXOC3 knockout in platelets demonstrated its requirement for GPVI-dependent granule secretion and integrin activation, yet paradoxically accelerated thrombosis through enhanced PAR4-mediated ADP release, revealing receptor-specific roles in vivo.","evidence":"Conditional knockout mice (Cre-lox), platelet aggregation, flow cytometry, ferric chloride arterial thrombosis model","pmids":["33560379"],"confidence":"High","gaps":["Mechanism of paradoxical PAR4-pathway enhancement in the absence of EXOC3 is unexplained","Whether phenotype reflects Sec6-specific function or general exocyst disruption is unknown"]},{"year":2024,"claim":"Male germline-specific knockout showed EXOC3 is dispensable for spermatogenesis, distinguishing it from other exocyst subunits (SEC3, EXO70) and revealing functional non-equivalence among subunits in this tissue.","evidence":"Conditional knockout in mouse male germline with histological analysis","pmids":["38325858"],"confidence":"Medium","gaps":["Whether other exocyst subunits compensate in the germline is untested","Subtle fertility or sperm function defects not assessed beyond histology"]},{"year":null,"claim":"A high-resolution structure of human EXOC3 and atomic-detail understanding of how Sec6 coordinates the SNARE/SM hand-off in the context of the assembled holo-exocyst complex remain unresolved.","evidence":"Only low-resolution (~9 Å) crystals of truncated human Sec6 have been obtained","pmids":[],"confidence":"Low","gaps":["No high-resolution structure of full-length human EXOC3","No cryo-EM or crystal structure of Sec6 within the assembled mammalian exocyst","Structural basis of Sec6–SNARE and Sec6–Sec1 mutual exclusivity unresolved"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0005198","term_label":"structural molecule activity","supporting_discovery_ids":[0,1]},{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[12,13]}],"localization":[{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[2,4,14]},{"term_id":"GO:0005794","term_label":"Golgi apparatus","supporting_discovery_ids":[4]},{"term_id":"GO:0005829","term_label":"cytosol","supporting_discovery_ids":[1,2]},{"term_id":"GO:0031410","term_label":"cytoplasmic vesicle","supporting_discovery_ids":[10,11]}],"pathway":[{"term_id":"R-HSA-5653656","term_label":"Vesicle-mediated transport","supporting_discovery_ids":[1,2,4,10,11,18]},{"term_id":"R-HSA-9609507","term_label":"Protein localization","supporting_discovery_ids":[2,4,11]},{"term_id":"R-HSA-1500931","term_label":"Cell-Cell communication","supporting_discovery_ids":[2,6]},{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[15,16]},{"term_id":"R-HSA-109582","term_label":"Hemostasis","supporting_discovery_ids":[18]}],"complexes":["exocyst complex"],"partners":["EXOC2","EXOC4","SEC1","STX1A","CDH1","NECTIN2","SEPT7","RAB11A"],"other_free_text":[]},"mechanistic_narrative":"EXOC3 (Sec6) is a core subunit of the octameric exocyst tethering complex that directs the docking and fusion of secretory vesicles at polarized membrane domains, functioning at the plasma membrane and trans-Golgi network in processes ranging from basolateral cargo delivery in epithelia to granule secretion in platelets [PMID:1523887, PMID:9630218, PMID:11696560, PMID:33560379]. Sec6 directly binds SNARE complexes and the SM protein Sec1/Munc18 in a mutually exclusive manner: upon vesicle arrival, Sec6 releases the t-SNARE Sec9 and recruits Sec1, thereby promoting rather than inhibiting SNARE-mediated membrane fusion [PMID:22114349, PMID:26446795]. The exocyst complex containing EXOC3 is recruited to sites of cell-cell contact through interactions with E-cadherin and nectin and operates downstream of Rab11 and Ral GTPases to route vesicles from recycling endosomes to the cell surface [PMID:14709721, PMID:15897260, PMID:16224820]. EXOC3 knockdown also modulates p38 MAPK/HSP27 and NF-κB signaling cascades, and conditional knockout in mouse platelets disrupts GPVI-dependent granule secretion while paradoxically accelerating arterial thrombosis [PMID:29729335, PMID:26247921, PMID:33560379]."},"prefetch_data":{"uniprot":{"accession":"O60645","full_name":"Exocyst complex component 3","aliases":["Exocyst complex component Sec6"],"length_aa":745,"mass_kda":85.6,"function":"Component of the exocyst complex involved in the docking of exocytic vesicles with fusion sites on the plasma membrane","subcellular_location":"Cytoplasm; Cytoplasm, perinuclear region; Cell projection, growth cone; Midbody; Golgi apparatus; Cell projection, neuron projection","url":"https://www.uniprot.org/uniprotkb/O60645/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":true,"resolved_as":"","url":"https://depmap.org/portal/gene/EXOC3","classification":"Common Essential","n_dependent_lines":962,"n_total_lines":1208,"dependency_fraction":0.7963576158940397},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/EXOC3","total_profiled":1310},"omim":[{"mim_id":"621085","title":"EXOCYST COMPLEX COMPONENT 3-LIKE 4; EXOC3L4","url":"https://www.omim.org/entry/621085"},{"mim_id":"616927","title":"EXOCYST COMPLEX COMPONENT 3-LIKE 2; EXOC3L2","url":"https://www.omim.org/entry/616927"},{"mim_id":"614117","title":"EXOCYST COMPLEX COMPONENT 3-LIKE 1; EXOC3L1","url":"https://www.omim.org/entry/614117"},{"mim_id":"608186","title":"EXOCYST COMPLEX COMPONENT 3; EXOC3","url":"https://www.omim.org/entry/608186"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Uncertain","locations":[{"location":"Plasma membrane","reliability":"Uncertain"},{"location":"Cytosol","reliability":"Uncertain"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/EXOC3"},"hgnc":{"alias_symbol":["Sec6"],"prev_symbol":["SEC6L1"]},"alphafold":{"accession":"O60645","domains":[{"cath_id":"-","chopping":"33-243","consensus_level":"medium","plddt":86.6618,"start":33,"end":243},{"cath_id":"-","chopping":"248-372","consensus_level":"medium","plddt":94.1593,"start":248,"end":372},{"cath_id":"1.10.357.50","chopping":"377-540","consensus_level":"high","plddt":91.4301,"start":377,"end":540},{"cath_id":"1.10.357.70","chopping":"558-733","consensus_level":"high","plddt":88.592,"start":558,"end":733}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/O60645","model_url":"https://alphafold.ebi.ac.uk/files/AF-O60645-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-O60645-F1-predicted_aligned_error_v6.png","plddt_mean":88.5},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=EXOC3","jax_strain_url":"https://www.jax.org/strain/search?query=EXOC3"},"sequence":{"accession":"O60645","fasta_url":"https://rest.uniprot.org/uniprotkb/O60645.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/O60645/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/O60645"}},"corpus_meta":[{"pmid":"9630218","id":"PMC_9630218","title":"Sec6/8 complex is recruited to cell-cell contacts and specifies transport vesicle delivery to the basal-lateral membrane in epithelial cells.","date":"1998","source":"Cell","url":"https://pubmed.ncbi.nlm.nih.gov/9630218","citation_count":434,"is_preprint":false},{"pmid":"9655500","id":"PMC_9655500","title":"Subunit composition, protein interactions, and structures of the mammalian brain sec6/8 complex and septin filaments.","date":"1998","source":"Neuron","url":"https://pubmed.ncbi.nlm.nih.gov/9655500","citation_count":296,"is_preprint":false},{"pmid":"7615633","id":"PMC_7615633","title":"Sec6, Sec8, and Sec15 are components of a multisubunit complex which localizes to small bud tips in Saccharomyces cerevisiae.","date":"1995","source":"The Journal of cell biology","url":"https://pubmed.ncbi.nlm.nih.gov/7615633","citation_count":257,"is_preprint":false},{"pmid":"16224820","id":"PMC_16224820","title":"Drosophila exocyst components Sec5, Sec6, and Sec15 regulate DE-Cadherin trafficking from recycling endosomes to the plasma membrane.","date":"2005","source":"Developmental cell","url":"https://pubmed.ncbi.nlm.nih.gov/16224820","citation_count":231,"is_preprint":false},{"pmid":"11696560","id":"PMC_11696560","title":"Sec6/8 complexes on trans-Golgi network and plasma membrane regulate late stages of exocytosis in mammalian cells.","date":"2001","source":"The Journal of cell biology","url":"https://pubmed.ncbi.nlm.nih.gov/11696560","citation_count":147,"is_preprint":false},{"pmid":"14709721","id":"PMC_14709721","title":"Mechanism of recruiting Sec6/8 (exocyst) complex to the apical junctional complex during polarization of epithelial cells.","date":"2004","source":"Journal of cell science","url":"https://pubmed.ncbi.nlm.nih.gov/14709721","citation_count":142,"is_preprint":false},{"pmid":"19210702","id":"PMC_19210702","title":"Sec6-dependent sorting of fungal extracellular exosomes and laccase of Cryptococcus neoformans.","date":"2008","source":"Molecular microbiology","url":"https://pubmed.ncbi.nlm.nih.gov/19210702","citation_count":129,"is_preprint":false},{"pmid":"10203793","id":"PMC_10203793","title":"Targeting vesicles to specific sites on the plasma membrane: the role of the sec6/8 complex.","date":"1999","source":"Trends in cell biology","url":"https://pubmed.ncbi.nlm.nih.gov/10203793","citation_count":125,"is_preprint":false},{"pmid":"15920473","id":"PMC_15920473","title":"Exo84 and Sec5 are competitive regulatory Sec6/8 effectors to the RalA GTPase.","date":"2005","source":"The EMBO journal","url":"https://pubmed.ncbi.nlm.nih.gov/15920473","citation_count":122,"is_preprint":false},{"pmid":"15897260","id":"PMC_15897260","title":"Essential function of Drosophila Sec6 in apical exocytosis of epithelial photoreceptor cells.","date":"2005","source":"The Journal of cell biology","url":"https://pubmed.ncbi.nlm.nih.gov/15897260","citation_count":101,"is_preprint":false},{"pmid":"12839989","id":"PMC_12839989","title":"Structural basis of the interaction between RalA and Sec5, a subunit of the sec6/8 complex.","date":"2003","source":"The EMBO journal","url":"https://pubmed.ncbi.nlm.nih.gov/12839989","citation_count":98,"is_preprint":false},{"pmid":"11493706","id":"PMC_11493706","title":"The Sec6/8 complex in mammalian cells: characterization of mammalian Sec3, subunit interactions, and expression of subunits in polarized cells.","date":"2001","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/11493706","citation_count":95,"is_preprint":false},{"pmid":"22114349","id":"PMC_22114349","title":"Regulation of exocytosis by the exocyst subunit Sec6 and the SM protein Sec1.","date":"2011","source":"Molecular biology of the cell","url":"https://pubmed.ncbi.nlm.nih.gov/22114349","citation_count":86,"is_preprint":false},{"pmid":"10973998","id":"PMC_10973998","title":"The mammalian Sec6/8 complex interacts with Ca(2+) signaling complexes and regulates 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biology","url":"https://pubmed.ncbi.nlm.nih.gov/27457987","citation_count":16,"is_preprint":false},{"pmid":"26283729","id":"PMC_26283729","title":"Role of the Exocyst Complex Component Sec6/8 in Genomic Stability.","date":"2015","source":"Molecular and cellular biology","url":"https://pubmed.ncbi.nlm.nih.gov/26283729","citation_count":15,"is_preprint":false},{"pmid":"16185821","id":"PMC_16185821","title":"Characterization of the Saccharomyces cerevisiae sec6-4 mutation and tools to create S. cerevisiae strains containing the sec6-4 allele.","date":"2005","source":"Gene","url":"https://pubmed.ncbi.nlm.nih.gov/16185821","citation_count":14,"is_preprint":false},{"pmid":"26892009","id":"PMC_26892009","title":"Sec6/8 regulates Bcl-2 and Mcl-1, but not Bcl-xl, in malignant peripheral nerve sheath tumor cells.","date":"2016","source":"Apoptosis : an international journal on programmed cell death","url":"https://pubmed.ncbi.nlm.nih.gov/26892009","citation_count":13,"is_preprint":false},{"pmid":"33560379","id":"PMC_33560379","title":"Loss of the exocyst complex component EXOC3 promotes hemostasis and accelerates arterial thrombosis.","date":"2021","source":"Blood advances","url":"https://pubmed.ncbi.nlm.nih.gov/33560379","citation_count":12,"is_preprint":false},{"pmid":"30635445","id":"PMC_30635445","title":"Exocyst subunit Sec6 is positioned by microtubule overlaps in the moss phragmoplast prior to cell plate membrane arrival.","date":"2019","source":"Journal of cell science","url":"https://pubmed.ncbi.nlm.nih.gov/30635445","citation_count":12,"is_preprint":false},{"pmid":"18480549","id":"PMC_18480549","title":"Involvement of Exoc3l, a protein structurally related to the exocyst subunit Sec6, in insulin secretion.","date":"2008","source":"Biomedical research (Tokyo, Japan)","url":"https://pubmed.ncbi.nlm.nih.gov/18480549","citation_count":12,"is_preprint":false},{"pmid":"26002719","id":"PMC_26002719","title":"The Candida albicans Exocyst Subunit Sec6 Contributes to Cell Wall Integrity and Is a Determinant of Hyphal Branching.","date":"2015","source":"Eukaryotic cell","url":"https://pubmed.ncbi.nlm.nih.gov/26002719","citation_count":8,"is_preprint":false},{"pmid":"35483595","id":"PMC_35483595","title":"Molecular cloning, inducible expression and function analysis of Epinephelus coioides Sec6 response to SGIV infection.","date":"2022","source":"Fish & shellfish immunology","url":"https://pubmed.ncbi.nlm.nih.gov/35483595","citation_count":7,"is_preprint":false},{"pmid":"33599020","id":"PMC_33599020","title":"SEC6 exocyst subunit contributes to multiple steps of growth and development of Physcomitrella (Physcomitrium patens).","date":"2021","source":"The Plant journal : for cell and molecular 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reference bias: Making pangenomes accessible with PangyPlot","date":"2025-11-03","source":"bioRxiv","url":"https://doi.org/10.1101/2025.10.31.684064","citation_count":0,"is_preprint":true}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":19520,"output_tokens":5144,"usd":0.06786},"stage2":{"model":"claude-opus-4-6","input_tokens":8736,"output_tokens":2983,"usd":0.177382},"total_usd":0.245242,"stage1_batch_id":"msgbatch_0118RScg3WGaGkaZRtWZbtce","stage2_batch_id":"msgbatch_01Cpfzvtbj42aqp5oYZ5Te2s","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 1995,\n      \"finding\": \"Sec6 (EXOC3 ortholog in yeast) is a stable component of the Sec6/8/15 multisubunit complex (~1-2 MDa) that localizes to small bud tips in S. cerevisiae, identifying its position in the exocytic machinery at sites of polarized secretion.\",\n      \"method\": \"Immobilized metal affinity chromatography, gel filtration, sucrose velocity centrifugation, coimmunoprecipitation, immunofluorescence\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — multiple orthogonal biochemical fractionation methods plus localization, foundational study\",\n      \"pmids\": [\"7615633\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1992,\n      \"finding\": \"SEC6 encodes an 85 kDa soluble protein required for fusion of post-Golgi vesicles with the plasma membrane in yeast; SEC6 is essential for growth and its product sediments at 14S in the soluble fraction.\",\n      \"method\": \"Gene cloning by complementation, nucleotide sequencing, gene disruption, subcellular fractionation\",\n      \"journal\": \"Yeast (Chichester, England)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — genetic loss-of-function with defined secretory phenotype, essential gene confirmed by disruption\",\n      \"pmids\": [\"1523887\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1998,\n      \"finding\": \"In MDCK epithelial cells, the Sec6/8 (exocyst) complex is cytosolic in non-polarized cells and is rapidly recruited (~70%) to sites of cell-cell contact upon calcium-dependent adhesion; Sec8 antibodies in permeabilized cells inhibit LDL receptor delivery to the basolateral membrane but not apical delivery of p75NTR, demonstrating that the complex specifically directs vesicle delivery to the basolateral membrane.\",\n      \"method\": \"Immunofluorescence, streptolysin-O permeabilization assay with function-blocking antibodies, subcellular fractionation\",\n      \"journal\": \"Cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — direct functional antibody-blocking experiment with specific membrane-domain readout, highly cited foundational study\",\n      \"pmids\": [\"9630218\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1998,\n      \"finding\": \"The rat brain Sec6/8 complex coimmunoprecipitates with septin filaments (including CDC10) and adopts a 'T' or 'Y' shaped conformation by electron microscopy, establishing a physical interaction between the exocyst and septin complexes at the plasma membrane of neurons.\",\n      \"method\": \"Coimmunoprecipitation, electron microscopy of purified complexes\",\n      \"journal\": \"Neuron\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — reciprocal co-IP plus structural visualization; highly cited\",\n      \"pmids\": [\"9655500\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2001,\n      \"finding\": \"The Sec6/8 complex localizes to both the trans-Golgi network (TGN) and plasma membrane in mammalian cells and is required for multiple steps of exocytic transport; antibodies against TGN-bound or plasma membrane-bound Sec6/8 each cause cargo accumulation at distinct intracellular sites, and Brefeldin A treatment blocks plasma membrane recruitment while blocking exocytosis causes TGN accumulation.\",\n      \"method\": \"Immunofluorescence colocalization with VSVG-tsO45 cargo, Brefeldin A treatment, antibody inhibition in semiintact cells\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — function-blocking antibodies in semiintact cells with specific cargo-accumulation readout, multiple orthogonal approaches\",\n      \"pmids\": [\"11696560\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2001,\n      \"finding\": \"Human Sec3 (hSec3), the last mammalian exocyst subunit to be identified, interacts with Sec5 and Sec8 in yeast two-hybrid assays but lacks the Rho1-binding site present in yeast Sec3p; GFP-Exo70 (but not other subunits) localizes to lateral membrane cell-cell contacts in MDCK cells and its overexpression disrupts tight monolayer formation.\",\n      \"method\": \"Sequence cloning, yeast two-hybrid, GFP-fusion imaging in MDCK cells\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 — characterization of subunit interactions and localization but limited functional validation for Sec6 specifically\",\n      \"pmids\": [\"11493706\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"The Sec6/8 complex is recruited to the apical junctional complex in epithelial cells via direct interaction with E-cadherin and nectin-2α; co-expression of both adhesion proteins in fibroblasts is sufficient to recruit the complex to cell-cell contacts, placing E-cadherin/nectin complexes upstream of exocyst localization.\",\n      \"method\": \"Coimmunoprecipitation with surface-labeled E-cadherin and nectin-2α, high-molecular-mass fractionation, fibroblast reconstitution\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — reciprocal co-IP plus reconstitution in fibroblasts with defined localization readout\",\n      \"pmids\": [\"14709721\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2000,\n      \"finding\": \"In pancreatic acinar and brain cells, Sec8 coimmunoprecipitates Sec6, IP3R3, Gβγ, plasma membrane Ca2+ pump, Gαq, PLCβ1, and IP3R1; interaction between Sec6/8 and Ca2+ signaling proteins is mediated by actin filaments; anti-Sec6/Sec8 antibodies inhibit Ca2+ signaling upstream of Ca2+ release, and actin disruption causes Sec6/8 translocation to cytosol and impairs polarized Ca2+ waves.\",\n      \"method\": \"Immunoprecipitation, confocal immunolocalization, actin depolymerization (latrunculin B), antibody inhibition experiments\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple co-IP partners confirmed, actin-mediated interaction mechanism established, function-blocking antibodies with Ca2+ signaling readout\",\n      \"pmids\": [\"10973998\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"Crystal structure of the Sec5 Ral-binding domain (immunoglobulin-like β-sandwich) in complex with RalA-GppNHp at 2.1 Å reveals a nucleotide-dependent switch mechanism; key residues Sec5 Thr11, Arg27, and RalA Glu38 are required for complex formation, establishing the structural basis of GTP-dependent exocyst regulation by Ral GTPases.\",\n      \"method\": \"X-ray crystallography, isothermal titration calorimetry, mutagenesis\",\n      \"journal\": \"The EMBO journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — crystal structure plus mutagenesis and ITC binding validation\",\n      \"pmids\": [\"12839989\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"Crystal structure of the Exo84 Ral-binding domain (pleckstrin homology fold) in complex with active RalA shows that Exo84 and Sec5 competitively and mutually exclusively bind RalA via overlapping switch-region interfaces; key residues determining specificity were confirmed by mutagenesis.\",\n      \"method\": \"X-ray crystallography, mutagenesis, biochemical binding assays\",\n      \"journal\": \"The EMBO journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — crystal structure, mutagenesis, and competitive binding assays\",\n      \"pmids\": [\"15920473\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"In Drosophila epithelial cells, loss of sec6 (but not sec5 or sec8) causes accumulation at adherens junctions; in photoreceptors, reduced Sec6 leads to accumulation of secretory vesicles and failure to transport proteins to the apical rhabdomere; Rab11 forms a complex with Sec5, and Sec5 interacts with Sec6, positioning the exocyst as a Rab11 effector for apical membrane protein transport.\",\n      \"method\": \"Drosophila genetics (loss-of-function mutations), immunolocalization, coimmunoprecipitation (Rab11-Sec5-Sec6)\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — genetic loss-of-function with defined vesicle-accumulation phenotype, co-IP establishing Rab11-exocyst interaction\",\n      \"pmids\": [\"15897260\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"In Drosophila epithelial cells, sec5, sec6, and sec15 loss-of-function results in accumulation of DE-Cadherin in an enlarged Rab11-positive recycling endosomal compartment and blocks DE-Cad delivery to the plasma membrane; Rab11 interacts with Sec15 and Armadillo interacts with Sec10, placing the exocyst in a Rab11-dependent recycling endosome-to-membrane trafficking pathway.\",\n      \"method\": \"Drosophila genetics, immunofluorescence, coimmunoprecipitation\",\n      \"journal\": \"Developmental cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — genetic loss-of-function with defined trafficking phenotype plus co-IP interaction data, highly cited\",\n      \"pmids\": [\"16224820\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"Yeast Sec6 directly binds the SM protein Sec1 (Munc18 family); the Sec6-Sec1 interaction is mutually exclusive with Sec6-Sec9 (SNARE) interaction but compatible with Sec6-exocyst assembly; the Sec6-exocyst interaction is incompatible with Sec6-Sec9 binding. Upon vesicle arrival, Sec6 is proposed to release Sec9 and recruit Sec1 for coordinated SNARE complex formation.\",\n      \"method\": \"In vitro binding assays, pull-down, yeast genetics\",\n      \"journal\": \"Molecular biology of the cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — in vitro binding assays defining mutually exclusive interactions, mechanistic model supported by multiple interaction experiments\",\n      \"pmids\": [\"22114349\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"Yeast Sec6 directly binds assembled binary (Sec9-Sso1) and ternary (Sec9-Sso1-Snc2) SNARE complexes but does not inhibit SNARE assembly rate; cross-linking/mass spectrometry identified Sec6 residues at the interface, and mutation of these residues causes a growth defect, suggesting Sec6 promotes rather than inhibits SNARE complex assembly.\",\n      \"method\": \"In vitro SNARE assembly assays, cross-linking mass spectrometry, yeast mutagenesis growth assays\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — in vitro reconstitution with cross-linking/MS and mutagenesis; revises prior model\",\n      \"pmids\": [\"26446795\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"In neurons, Sec6 concentrates at the inside of the presynaptic plasma membrane (distinct from cytoplasmic Sec8); Sec6 is transported along neurites on secretogranin II-positive vesicles, identifying it as a cargo associated with dense-core vesicle transport to presynaptic sites.\",\n      \"method\": \"Immunolocalization (confocal), subcellular fractionation, live transport imaging in neurons and PC12 cells\",\n      \"journal\": \"Neuroscience\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 — localization experiments with vesicle transport correlation but limited functional manipulation\",\n      \"pmids\": [\"12763070\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"EXOC3 (Sec6) knockdown in mammalian cells suppresses phosphorylation of p38 MAPK (via MKK3/6), MK2, and HSP27 at Ser78/Ser82, reduces cell migration, and promotes apoptosis after TNF-α/cycloheximide treatment, placing Sec6 upstream of the MKK3/6-p38-MK2-HSP27 signaling axis.\",\n      \"method\": \"siRNA knockdown, Western blotting for phospho-proteins, cell migration assay, apoptosis assay\",\n      \"journal\": \"Cellular signalling\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 — single-lab siRNA study with defined phosphoprotein readouts but no reconstitution or direct biochemical interaction\",\n      \"pmids\": [\"29729335\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"EXOC3 (Sec6) knockdown in HeLa cells inhibits IκBα degradation and delays p65 nuclear translocation after TNF-α stimulation; Sec6 regulates NF-κB activity via control of ERK and p90RSK1 phosphorylation and IκBα phosphorylation at Ser32.\",\n      \"method\": \"siRNA knockdown, Western blotting, nuclear translocation assay, luciferase reporter assay\",\n      \"journal\": \"Journal of cellular physiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 — siRNA with defined signaling readouts but single lab and no direct biochemical mechanism established\",\n      \"pmids\": [\"26247921\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"EXOC3 (Sec6) regulates cytoplasmic translocation and degradation of p27 by promoting p27 phosphorylation at Thr157 and through interactions with Jab1 (CSN5) and Siah1, thereby suppressing cell cycle progression.\",\n      \"method\": \"siRNA knockdown, coimmunoprecipitation, Western blotting, cell cycle analysis\",\n      \"journal\": \"Cellular signalling\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 — co-IP plus KD but single lab with limited mechanistic depth\",\n      \"pmids\": [\"24949832\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"Conditional knockout of EXOC3 in mouse megakaryocytes/platelets causes defects in platelet aggregation, integrin activation, α-granule/dense granule/lysosomal granule secretion after GPVI stimulation, and reduces surface GPVI levels; paradoxically, PAR4 activation increases dense granule secretion and integrin activation in KO platelets via enhanced ADP release; arterial thrombosis is accelerated in KO mice.\",\n      \"method\": \"Conditional knockout (Cre-lox), platelet aggregation assay, flow cytometry, phosphorylation assays, tail bleeding time, ferric chloride arterial thrombosis model\",\n      \"journal\": \"Blood advances\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — conditional KO with multiple specific platelet function readouts and in vivo thrombosis model\",\n      \"pmids\": [\"33560379\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"Tnfaip2 (mouse EXOC3 ortholog) acts epistatically upstream of vimentin (Vim) to control triacylglycerol synthesis and lipid droplet formation during ESC differentiation; Tnfaip2 KO impairs differentiation and lipid droplet induction, and supplementation with palmitic acid rescues this defect.\",\n      \"method\": \"Knockout mouse ESCs, lipid profiling, epistasis analysis, rescue with palmitic acid\",\n      \"journal\": \"EMBO reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — genetic epistasis plus metabolic rescue, but novel/unexpected role for this exocyst subunit\",\n      \"pmids\": [\"33300287\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"Crystallization of truncated human Sec6 (HuSec6 121-734 and 121-745) was achieved with >95% purity, yielding crystals with ~9 Å X-ray diffraction, providing a structural foundation for analysis of human EXOC3.\",\n      \"method\": \"Recombinant protein expression in E. coli, purification, X-ray crystallography\",\n      \"journal\": \"Studies in health technology and informatics\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 1 method but only preliminary low-resolution diffraction; no functional validation\",\n      \"pmids\": [\"38007759\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"Male germline-specific conditional knockout of Exoc3 (EXOC3/SEC6) in mice does not disrupt spermatogenesis, establishing that EXOC3 is dispensable for this process (unlike EXOC1/SEC3 or EXOC7/EXO70).\",\n      \"method\": \"Conditional knockout (Cre-lox), histological analysis of spermatogenesis\",\n      \"journal\": \"Experimental animals\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — clean KO with specific tissue phenotype readout; negative result well-controlled by comparison with other exocyst KOs\",\n      \"pmids\": [\"38325858\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"EXOC3 (Sec6) is a core subunit of the octameric exocyst tethering complex that functions at the plasma membrane and TGN to direct secretory vesicle docking and fusion at polarized membrane domains; it physically interacts with SNARE proteins (promoting rather than inhibiting SNARE complex assembly), SM proteins (Sec1/Munc18), cell-cell adhesion complexes (E-cadherin, nectin), and septin filaments, is regulated upstream by Ral GTPases (competing with Sec5/Exo84 for RalA binding), and also modulates signaling cascades including p38 MAPK/HSP27, NF-κB/IκBα, and lipid metabolism relevant to stem cell differentiation, with loss of EXOC3 in platelets impairing granule secretion and GPVI signaling while paradoxically accelerating thrombosis.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"EXOC3 (Sec6) is a core subunit of the octameric exocyst tethering complex that directs the docking and fusion of secretory vesicles at polarized membrane domains, functioning at the plasma membrane and trans-Golgi network in processes ranging from basolateral cargo delivery in epithelia to granule secretion in platelets [PMID:1523887, PMID:9630218, PMID:11696560, PMID:33560379]. Sec6 directly binds SNARE complexes and the SM protein Sec1/Munc18 in a mutually exclusive manner: upon vesicle arrival, Sec6 releases the t-SNARE Sec9 and recruits Sec1, thereby promoting rather than inhibiting SNARE-mediated membrane fusion [PMID:22114349, PMID:26446795]. The exocyst complex containing EXOC3 is recruited to sites of cell-cell contact through interactions with E-cadherin and nectin and operates downstream of Rab11 and Ral GTPases to route vesicles from recycling endosomes to the cell surface [PMID:14709721, PMID:15897260, PMID:16224820]. EXOC3 knockdown also modulates p38 MAPK/HSP27 and NF-κB signaling cascades, and conditional knockout in mouse platelets disrupts GPVI-dependent granule secretion while paradoxically accelerating arterial thrombosis [PMID:29729335, PMID:26247921, PMID:33560379].\",\n  \"teleology\": [\n    {\n      \"year\": 1992,\n      \"claim\": \"Establishing that SEC6 encodes an essential soluble protein required for post-Golgi vesicle fusion with the plasma membrane defined its fundamental role in the secretory pathway.\",\n      \"evidence\": \"Yeast gene cloning by complementation, gene disruption lethality, subcellular fractionation\",\n      \"pmids\": [\"1523887\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No interacting partners identified\", \"No structural information\", \"Mammalian ortholog not yet characterized\"]\n    },\n    {\n      \"year\": 1995,\n      \"claim\": \"Identifying Sec6 as a stable subunit of the multisubunit Sec6/8 complex that localizes to polarized bud tips placed it within a defined molecular machine for polarized exocytosis.\",\n      \"evidence\": \"Immobilized metal affinity chromatography, gel filtration, co-IP, and immunofluorescence in S. cerevisiae\",\n      \"pmids\": [\"7615633\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Stoichiometry and complete subunit composition of the complex not yet defined\", \"Function of individual subunits within the complex unknown\"]\n    },\n    {\n      \"year\": 1998,\n      \"claim\": \"Demonstrating that the Sec6/8 complex is recruited to cell-cell contacts upon calcium-dependent adhesion and specifically directs basolateral (not apical) membrane delivery in epithelial cells established the complex's role in polarized trafficking in mammalian cells.\",\n      \"evidence\": \"Function-blocking antibodies in streptolysin-O-permeabilized MDCK cells with domain-specific cargo readouts; co-IP with septin filaments in neurons\",\n      \"pmids\": [\"9630218\", \"9655500\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Which subunit(s) mediate membrane-domain specificity remains unclear\", \"Mechanism of recruitment to cell-cell contacts unresolved\"]\n    },\n    {\n      \"year\": 2001,\n      \"claim\": \"Showing that the exocyst functions at both the TGN and the plasma membrane, with antibodies against each pool blocking distinct transport steps, revealed that the complex acts at multiple stations along the exocytic route.\",\n      \"evidence\": \"Antibody inhibition in semiintact cells with VSVG cargo tracking, Brefeldin A experiments\",\n      \"pmids\": [\"11696560\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How the complex transitions between TGN and PM pools is unknown\", \"Specific contribution of Sec6 versus other subunits at each station not resolved\"]\n    },\n    {\n      \"year\": 2004,\n      \"claim\": \"Identifying E-cadherin and nectin-2α as upstream recruiters of the exocyst to the apical junctional complex explained how adhesion controls vesicle delivery to cell-cell contacts.\",\n      \"evidence\": \"Co-IP with surface-labeled adhesion proteins; reconstitution of exocyst recruitment in fibroblasts co-expressing E-cadherin and nectin\",\n      \"pmids\": [\"14709721\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct binding subunit(s) within the exocyst that contact E-cadherin/nectin not mapped\", \"Regulation of the interaction not defined\"]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"Structural and genetic studies established that Ral GTPases regulate the exocyst through mutually exclusive binding to Sec5 and Exo84, and that the Rab11-exocyst axis routes vesicles from recycling endosomes to the plasma membrane in epithelia.\",\n      \"evidence\": \"Crystal structures of RalA–Sec5 and RalA–Exo84 complexes; Drosophila sec6 loss-of-function showing vesicle accumulation and DE-Cadherin trapping in Rab11-positive endosomes; co-IP of Rab11–Sec15 and Armadillo–Sec10\",\n      \"pmids\": [\"12839989\", \"15920473\", \"15897260\", \"16224820\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether Sec6 itself directly contacts Ral or Rab11 is unknown\", \"How Ral and Rab11 signals are integrated at the level of the holo-complex remains unresolved\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Revealing that Sec6 directly binds the SM protein Sec1 in a manner mutually exclusive with SNARE binding defined a hand-off mechanism coordinating vesicle tethering with SNARE-mediated fusion.\",\n      \"evidence\": \"In vitro pull-down and binding competition assays in yeast\",\n      \"pmids\": [\"22114349\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Temporal sequence of hand-off not demonstrated in vivo\", \"Structural basis of mutual exclusivity not determined\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Showing that Sec6 binds assembled SNARE complexes without inhibiting their assembly—and that disrupting this interaction impairs growth—revised the model from inhibitory gatekeeper to a positive regulator of SNARE complex formation.\",\n      \"evidence\": \"In vitro SNARE assembly kinetics, cross-linking mass spectrometry mapping the Sec6–SNARE interface, yeast mutagenesis growth assays\",\n      \"pmids\": [\"26446795\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether Sec6 stabilizes or activates SNARE complexes post-assembly is unclear\", \"Interface residues not confirmed by structural methods\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"EXOC3 knockdown studies linked the exocyst subunit to NF-κB and p38 MAPK signaling cascades, suggesting broader roles beyond vesicle trafficking in cytokine-stimulated signaling.\",\n      \"evidence\": \"siRNA knockdown in HeLa cells with IκBα degradation, p65 translocation, and phospho-p38/HSP27 readouts\",\n      \"pmids\": [\"26247921\", \"29729335\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No direct biochemical mechanism connecting Sec6 to kinase activation\", \"Single-lab observations not independently replicated\", \"Possible indirect effects via impaired trafficking of signaling receptors not excluded\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Conditional EXOC3 knockout in platelets demonstrated its requirement for GPVI-dependent granule secretion and integrin activation, yet paradoxically accelerated thrombosis through enhanced PAR4-mediated ADP release, revealing receptor-specific roles in vivo.\",\n      \"evidence\": \"Conditional knockout mice (Cre-lox), platelet aggregation, flow cytometry, ferric chloride arterial thrombosis model\",\n      \"pmids\": [\"33560379\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism of paradoxical PAR4-pathway enhancement in the absence of EXOC3 is unexplained\", \"Whether phenotype reflects Sec6-specific function or general exocyst disruption is unknown\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Male germline-specific knockout showed EXOC3 is dispensable for spermatogenesis, distinguishing it from other exocyst subunits (SEC3, EXO70) and revealing functional non-equivalence among subunits in this tissue.\",\n      \"evidence\": \"Conditional knockout in mouse male germline with histological analysis\",\n      \"pmids\": [\"38325858\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether other exocyst subunits compensate in the germline is untested\", \"Subtle fertility or sperm function defects not assessed beyond histology\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"A high-resolution structure of human EXOC3 and atomic-detail understanding of how Sec6 coordinates the SNARE/SM hand-off in the context of the assembled holo-exocyst complex remain unresolved.\",\n      \"evidence\": \"Only low-resolution (~9 Å) crystals of truncated human Sec6 have been obtained\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"No high-resolution structure of full-length human EXOC3\", \"No cryo-EM or crystal structure of Sec6 within the assembled mammalian exocyst\", \"Structural basis of Sec6–SNARE and Sec6–Sec1 mutual exclusivity unresolved\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0005198\", \"supporting_discovery_ids\": [0, 1]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [12, 13]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [2, 4, 14]},\n      {\"term_id\": \"GO:0005794\", \"supporting_discovery_ids\": [4]},\n      {\"term_id\": \"GO:0005829\", \"supporting_discovery_ids\": [1, 2]},\n      {\"term_id\": \"GO:0031410\", \"supporting_discovery_ids\": [10, 11]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-5653656\", \"supporting_discovery_ids\": [1, 2, 4, 10, 11, 18]},\n      {\"term_id\": \"R-HSA-9609507\", \"supporting_discovery_ids\": [2, 4, 11]},\n      {\"term_id\": \"R-HSA-1500931\", \"supporting_discovery_ids\": [2, 6]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [15, 16]},\n      {\"term_id\": \"R-HSA-109582\", \"supporting_discovery_ids\": [18]}\n    ],\n    \"complexes\": [\n      \"exocyst complex\"\n    ],\n    \"partners\": [\n      \"EXOC2\",\n      \"EXOC4\",\n      \"SEC1\",\n      \"STX1A\",\n      \"CDH1\",\n      \"NECTIN2\",\n      \"SEPT7\",\n      \"RAB11A\"\n    ],\n    \"other_free_text\": []\n  }\n}\n```"}