{"gene":"EXOC2","run_date":"2026-04-28T17:46:03","timeline":{"discoveries":[{"year":2003,"finding":"Crystal structure of the Ral-binding domain of Sec5 (EXOC2) in complex with RalA-GppNHp at 2.1 Å resolution revealed an immunoglobulin-like beta-sandwich fold (novel for a GTPase effector), with the interface involving a continuous antiparallel beta-sheet; key residues Sec5 Thr11 and Arg27, and RalA Glu38 are required for complex formation, confirmed by isothermal titration calorimetry.","method":"X-ray crystallography (2.1 Å), isothermal titration calorimetry, site-directed mutagenesis","journal":"The EMBO journal","confidence":"High","confidence_rationale":"Tier 1 — crystal structure with mutagenesis validation and ITC binding measurements","pmids":["12839989"],"is_preprint":false},{"year":2003,"finding":"The GTPase-binding domain of Sec5 (EXOC2) adopts an IPT/immunoglobulin superfamily fold, and NMR-based mapping identified the Ral binding site on this domain, overlapping with known protein-protein interaction surfaces on other IPT domains.","method":"NMR structure determination, site-directed mutagenesis binding analysis","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 — NMR structure with functional mapping and mutagenesis data","pmids":["12624092"],"is_preprint":false},{"year":2005,"finding":"Crystal structure of the Exo84 Ral-binding domain (pleckstrin homology fold) in complex with active RalA showed that Exo84 and Sec5 competitively bind to the same active RalA interface; mutagenesis confirmed key determinants of specificity, establishing Exo84 and Sec5 as competitive regulatory effectors for RalA-mediated Sec6/8 complex regulation.","method":"X-ray crystallography, mutagenesis, competitive binding assays","journal":"The EMBO journal","confidence":"High","confidence_rationale":"Tier 1 — crystal structure plus mutagenesis plus biochemical competition assay","pmids":["15920473"],"is_preprint":false},{"year":2003,"finding":"In Drosophila, loss-of-function of Sec5 (EXOC2 ortholog) impairs membrane addition and neurite outgrowth in neurons but does not impair synaptic vesicle fusion, demonstrating that Sec5 selectively mediates biosynthetic membrane trafficking for cell growth rather than neurotransmitter secretion.","method":"Drosophila genetics (null alleles), trafficking assay, neuromuscular junction analysis","journal":"Neuron","confidence":"High","confidence_rationale":"Tier 2 — clean Drosophila null mutants with specific dissection of two trafficking pathways; highly cited foundational study","pmids":["12575951"],"is_preprint":false},{"year":2005,"finding":"In Drosophila epithelial cells, loss of Sec5 (and Sec6/Sec15) causes DE-Cadherin accumulation in enlarged Rab11-positive recycling endosomes and prevents DE-Cadherin delivery to the plasma membrane; Armadillo (β-catenin) interacts with Sec10, linking the exocyst to the cadherin trafficking machinery from recycling endosomes.","method":"Drosophila genetics (loss-of-function clones), immunofluorescence, co-immunoprecipitation","journal":"Developmental cell","confidence":"High","confidence_rationale":"Tier 2 — Drosophila genetic LOF with defined trafficking phenotype plus Co-IP interaction; highly cited","pmids":["16224820"],"is_preprint":false},{"year":2003,"finding":"In Drosophila oocytes, Sec5 is required for directed membrane trafficking of Gurken (secreted EGF-R ligand) and Yolkless (vitellogenin receptor), and Sec5 localization is dynamic, correlating spatially with sites of membrane protein traffic; loss of Sec5 impairs posterior oocyte positioning and dorsal patterning.","method":"Drosophila germline clones, immunofluorescence localization, trafficking assays","journal":"Development (Cambridge, England)","confidence":"High","confidence_rationale":"Tier 2 — clean genetic LOF with specific cargo trafficking phenotypes and dynamic localization data","pmids":["14681190"],"is_preprint":false},{"year":2005,"finding":"In Drosophila oocytes, Sec5 localizes to clathrin-coated pits and vesicles at the plasma membrane; a truncation allele (sec5(E13)) disrupts endocytic recycling of Yolkless causing its accumulation in late endosomal compartments, revealing an exocyst role in endocytic recycling distinct from its biosynthetic secretion function.","method":"Drosophila genetics (truncation allele), immunofluorescence, electron microscopy, trafficking assay","journal":"The Journal of cell biology","confidence":"High","confidence_rationale":"Tier 1–2 — defined truncation allele with specific endocytic recycling defect and localization to clathrin structures","pmids":["15955846"],"is_preprint":false},{"year":2008,"finding":"RalB activation promotes a direct interaction between Sec5 (EXOC2) and TBK1, resulting in TBK1 kinase activation, which then mediates innate immune/host defense signaling and supports survival of transformed cells; RalB and Sec5 are required for host defense pathway activation upon viral infection.","method":"Co-immunoprecipitation, protein kinase assay, RNAi knockdown, cell transformation assay","journal":"Methods in enzymology","confidence":"Medium","confidence_rationale":"Tier 2 — Co-IP and kinase assay in single lab; multiple methods but methodological context paper","pmids":["18413258"],"is_preprint":false},{"year":2008,"finding":"Ral GTPases control association of Sec5 (EXOC2) with paxillin at focal complexes in prostate tumor cells; upon loss of cadherin-mediated adhesion, Exocyst relocalizes to membrane protrusion tips where it co-purifies with focal complex proteins and is required for delivery of α5-integrin to the plasma membrane to support cell motility and matrix invasion.","method":"RNAi knockdown, co-purification, dominant-negative Sec5 mutants, integrin trafficking assay, invasion assay","journal":"Journal of cell science","confidence":"Medium","confidence_rationale":"Tier 2 — Ral-uncoupled Sec5 mutants plus RNAi plus cargo trafficking; single lab but multiple methods","pmids":["18697830"],"is_preprint":false},{"year":2010,"finding":"In Drosophila embryos, Sec5 is required for cellularization: loss of Sec5 prevents cleavage furrow invagination and blocks plasma membrane insertion of Neurotactin; Sec5 concentrates at the apical end of lateral membranes (primary site of membrane addition) during cellularization, then at the sub-apical complex, indicating polarized membrane addition and epithelial polarity functions.","method":"Drosophila temperature-sensitive allele (sec5(ts1)) germline clones, immunofluorescence, live imaging","journal":"Development (Cambridge, England)","confidence":"High","confidence_rationale":"Tier 2 — temperature-sensitive allele with specific stage-restricted phenotype and dynamic localization","pmids":["20630948"],"is_preprint":false},{"year":2002,"finding":"DelGEF (a Ran-GEF homolog) was identified as a binding partner of human Sec5 (EXOC2) by yeast two-hybrid; the interaction is Mg2+- and GTP/dCTP-dependent; knockdown of DelGEF in HeLa cells increased extracellular proteoglycan secretion, implicating the DelGEF-Sec5 interaction in regulating the secretion process.","method":"Yeast two-hybrid, biochemical interaction assay (Mg2+/nucleotide dependence), siRNA knockdown with secretion measurement","journal":"FEBS letters","confidence":"Medium","confidence_rationale":"Tier 3 — yeast two-hybrid plus functional knockdown; single lab, partial mechanistic follow-up","pmids":["12459492"],"is_preprint":false},{"year":2012,"finding":"RalA interaction with Sec5 and Exo84 (exocyst effectors) is directly necessary for migration and invasion of prostate cancer cells; blocking RalA-Exocyst binding causes morphological changes and defects in single and coordinated cell migration, and Sec5 and Exo84 mediate distinct aspects of RalA-dependent cell polarization.","method":"RNAi, dominant-negative/Ral-uncoupled mutants, migration and invasion assays","journal":"PloS one","confidence":"Medium","confidence_rationale":"Tier 2 — specific Ral-uncoupled mutants plus RNAi; single lab","pmids":["22761837"],"is_preprint":false},{"year":2013,"finding":"Sec5 (EXOC2) is localized to insulin secretory granules in pancreatic β cells and preferentially regulates exocytosis of newcomer insulin granules (minimal pre-docking time) that constitute the major component of biphasic glucose-stimulated insulin secretion; Sec5 depletion inhibited both readily-releasable pool release and reserve pool mobilization, predominantly by reducing newcomer granule recruitment.","method":"Patch-clamp capacitance measurement, TIRF microscopy, siRNA knockdown","journal":"PloS one","confidence":"Medium","confidence_rationale":"Tier 2 — electrophysiology and live-cell imaging with specific knockdown; single lab","pmids":["23844030"],"is_preprint":false},{"year":2015,"finding":"Dexamethasone-induced SGK1 expression stimulates a Sec5 (EXOC2)–GEF-H1 interaction; this interaction is required for GEF-H1 targeting to peripheral focal adhesion sites, fibronectin fibril formation, and RhoA-dependent cellular tension in mesenchymal stem cells; disrupting the Sec5-GEF-H1 interaction abolishes these effects without altering integrin/fibronectin expression levels.","method":"Co-immunoprecipitation, dominant-negative/interaction-disrupting constructs, immunofluorescence, traction force measurements, RNAi","journal":"Journal of cell science","confidence":"Medium","confidence_rationale":"Tier 2 — multiple orthogonal methods (Co-IP, functional mutants, imaging) in single lab","pmids":["26359301"],"is_preprint":false},{"year":2018,"finding":"During Candida albicans phagocytosis in macrophages, SEC5 (EXOC2) binds to the C-terminal α-helix (H1) of InsP3R on phagosomes, promoting InsP3R channel activity and increasing cytosolic Ca2+; disruption of this interaction attenuates Ca2+ elevation and impairs phagocytosis; the InsP3R-SEC5 complex additionally recruits TBK1, leading to TBK1 activation, IRF-3 phosphorylation, and type I interferon responses.","method":"Co-immunoprecipitation, immunofluorescence, Ca2+ imaging, recombinant peptide disruption, phagocytosis assay, kinase activation assay","journal":"BMC biology","confidence":"Medium","confidence_rationale":"Tier 2 — multiple methods (Co-IP, live Ca2+ imaging, peptide disruption, kinase assay) in single lab","pmids":["29703257"],"is_preprint":false},{"year":2020,"finding":"Pathogenic truncating variants in EXOC2 (Sec5) in human patients cause severe reduction in exocytosis/vesicle fusion and undetectable EXOC2 protein via nonsense-mediated decay, demonstrating EXOC2 is essential for normal brain development; patient cells also show defective Arl13b localization to the primary cilium, linking EXOC2 to ciliogenesis.","method":"Patient-derived cells, exocytosis/vesicle fusion assays, protein expression analysis, immunofluorescence (Arl13b ciliary localization)","journal":"The Journal of experimental medicine","confidence":"High","confidence_rationale":"Tier 2 — human LOF variants with multiple functional readouts (exocytosis assay, cilia localization) across two families","pmids":["32639540"],"is_preprint":false},{"year":2020,"finding":"SEC5 (EXOC2) knockdown in trophoblast cells reduces cell migration and invasion, decreases plasma membrane distribution of integrin β1, reduces InsP3R-mediated cytosolic Ca2+ elevation, and disrupts F-actin stress fibers, placing SEC5 in an integrin/Ca2+/cytoskeleton signaling axis required for trophoblast invasion.","method":"shRNA knockdown, invasion/migration assays, Ca2+ imaging, immunofluorescence, integrin surface expression analysis","journal":"Reproduction (Cambridge, England)","confidence":"Medium","confidence_rationale":"Tier 2 — multiple functional assays with mechanistic follow-up; single lab","pmids":["31705793"],"is_preprint":false},{"year":2022,"finding":"SEC5 (EXOC2) interacts with STAT6 in macrophages; SEC5 knockdown inhibits M2 polarization and STAT6 phosphorylation, while overexpression promotes both; SEC5 and phospho-STAT6 co-localize, with pSTAT6 redistributing to the nucleus upon M2 polarization, placing SEC5 upstream of STAT6 in macrophage polarization.","method":"Co-immunoprecipitation, immunofluorescence co-localization, siRNA knockdown, overexpression, mouse model (heterozygous SEC5-deficient mice)","journal":"Frontiers in cell and developmental biology","confidence":"Medium","confidence_rationale":"Tier 2–3 — Co-IP plus functional KD/OE plus in vivo model; single lab","pmids":["36313547"],"is_preprint":false},{"year":2024,"finding":"EXOC2 deletion in C9ORF72-ALS/FTD iPSC-derived motor neurons decreases levels of dipeptide repeat (DPR) proteins and expanded G4C2 repeat-containing RNA, rescuing disease-relevant cellular phenotypes; EXOC2 antisense oligonucleotide treatment in fully differentiated C9ORF72 neurons similarly reduces expanded G4C2 RNA, indicating EXOC2 directly or indirectly regulates G4C2 repeat-containing RNA levels.","method":"CRISPR-Cas9 deletion in iPSCs, iPSC-derived motor neurons, antisense oligonucleotide treatment, DPR protein quantification, RNA quantification","journal":"Cell reports","confidence":"Medium","confidence_rationale":"Tier 2 — CRISPR LOF and ASO treatment with multiple molecular readouts; single lab, mechanism of RNA regulation not fully elucidated","pmids":["38935506"],"is_preprint":false},{"year":2025,"finding":"Active Merlin (NF2 tumor suppressor) competitively inhibits RalB binding to Sec5 (EXOC2) and Exo84, and regulates the kinetics of exocytosis in a RalB-dependent manner; direct binding assays showed RalA and RalB are high-affinity PIP2-dependent Merlin binding proteins that co-localize on the plasma membrane.","method":"Proximity biotinylation, direct binding assays, co-localization, exocytosis kinetics assay, competitive binding assay","journal":"bioRxiv","confidence":"Medium","confidence_rationale":"Tier 2 — direct binding assays plus functional exocytosis measurement; preprint, single lab","pmids":["bio_10.1101_2025.06.13.659557"],"is_preprint":true}],"current_model":"EXOC2 (Sec5) is a central subunit of the octameric exocyst complex that tethers secretory vesicles to the plasma membrane for polarized exocytosis; it binds active RalA/RalB GTPases through a structurally characterized immunoglobulin/IPT-fold domain, competes with Exo84 for RalA binding, and mediates multiple downstream functions including biosynthetic membrane protein trafficking, endocytic recycling, insulin granule exocytosis, cadherin delivery from recycling endosomes, primary ciliogenesis (Arl13b localization), innate immune signaling via InsP3R-TBK1 and RalB-TBK1 complexes, macrophage M2 polarization via STAT6, and regulation of C9ORF72 repeat-containing RNA levels in neurons, with loss-of-function in humans causing severe neurodevelopmental brain malformations."},"narrative":{"teleology":[{"year":2002,"claim":"The identification of DelGEF as a nucleotide-dependent Sec5-binding partner provided early evidence that EXOC2 integrates GTPase-regulatory inputs beyond the Ral family to modulate secretion.","evidence":"Yeast two-hybrid screen plus biochemical interaction assays and siRNA knockdown measuring proteoglycan secretion in HeLa cells","pmids":["12459492"],"confidence":"Medium","gaps":["DelGEF–Sec5 interaction not validated by reciprocal Co-IP or structural methods","physiological secretory cargo regulated by this interaction not defined","relationship to Ral-dependent Sec5 regulation unclear"]},{"year":2003,"claim":"Structural determination of the Sec5 Ral-binding domain revealed an unprecedented immunoglobulin/IPT fold for a GTPase effector and defined the atomic basis of the RalA–Sec5 interface, establishing how the exocyst is recruited by active Ral GTPases.","evidence":"X-ray crystallography (2.1 Å) and NMR of the Sec5 RBD–RalA complex with ITC and mutagenesis validation","pmids":["12839989","12624092"],"confidence":"High","gaps":["structure of full-length Sec5 within the assembled exocyst not resolved","relative contributions of RalA vs. RalB to Sec5 engagement in vivo not quantified"]},{"year":2003,"claim":"Drosophila Sec5 null mutants established that Sec5 is essential for biosynthetic membrane addition and neurite outgrowth but dispensable for synaptic vesicle fusion, distinguishing exocyst-dependent from SNARE-only trafficking pathways in neurons.","evidence":"Drosophila sec5 null alleles with neuromuscular junction electrophysiology and membrane trafficking assays","pmids":["12575951","14681190"],"confidence":"High","gaps":["whether Sec5 independence of synaptic vesicle fusion extends to mammalian neurons not tested","identity of the tethering factor for synaptic vesicles remains separate"]},{"year":2005,"claim":"Structural and biochemical demonstration that Exo84 and Sec5 compete for the same RalA surface established a regulatory switch model in which a single Ral GTPase toggles between two exocyst sub-complexes, and genetic studies revealed Sec5's role in cadherin recycling from Rab11 endosomes and in endocytic recycling at clathrin-coated structures.","evidence":"Crystal structure of Exo84 RBD–RalA with competitive binding assays; Drosophila LOF clones with cadherin trafficking analysis; sec5 truncation allele with EM localization to clathrin pits","pmids":["15920473","16224820","15955846"],"confidence":"High","gaps":["how competitive Ral binding to Sec5 vs. Exo84 is regulated temporally in a single trafficking event not resolved","direct role of Sec5 in clathrin-mediated steps vs. post-endocytic recycling not distinguished"]},{"year":2008,"claim":"Discovery that RalB activation directs Sec5 to bind and activate TBK1 kinase revealed a non-canonical exocyst function in innate immune signaling and oncogenic cell survival, expanding Sec5's role beyond vesicle tethering.","evidence":"Co-IP, in vitro kinase assays, RNAi in mammalian cells, viral infection model","pmids":["18413258"],"confidence":"Medium","gaps":["structural basis of Sec5–TBK1 interaction not determined","whether TBK1 activation requires assembled exocyst or only the Sec5 subunit not resolved"]},{"year":2008,"claim":"Sec5 was shown to mediate Ral-dependent delivery of α5-integrin to focal complexes, linking exocyst trafficking to cell migration and tumor invasion.","evidence":"RNAi, dominant-negative Sec5 mutants, integrin surface trafficking, and invasion assays in prostate cancer cells","pmids":["18697830"],"confidence":"Medium","gaps":["specific vesicle population carrying integrins to focal adhesions not characterized","in vivo relevance for metastasis not tested"]},{"year":2010,"claim":"Temperature-sensitive sec5 alleles demonstrated that Sec5 is required for cleavage furrow membrane insertion during Drosophila cellularization, establishing its role in the earliest polarized membrane addition events during epithelial morphogenesis.","evidence":"Drosophila ts allele germline clones with live imaging and Neurotactin trafficking","pmids":["20630948"],"confidence":"High","gaps":["how Sec5 is recruited to the apical lateral membrane domain during cellularization not defined"]},{"year":2013,"claim":"TIRF microscopy and electrophysiology showed that Sec5 localizes to insulin granules and preferentially promotes newcomer granule exocytosis, explaining how the exocyst contributes to biphasic glucose-stimulated insulin secretion.","evidence":"TIRF live imaging, patch-clamp capacitance, siRNA knockdown in pancreatic β cells","pmids":["23844030"],"confidence":"Medium","gaps":["whether Sec5 interacts directly with insulin granule-resident SNAREs not tested","contribution relative to other exocyst subunits in β cells not compared"]},{"year":2015,"claim":"Identification of the Sec5–GEF-H1 interaction downstream of SGK1 revealed a mechanism by which Sec5 delivers RhoA-activating GEF to peripheral focal adhesions, controlling cellular tension and fibronectin fibril formation.","evidence":"Co-IP, interaction-disrupting constructs, traction force microscopy, immunofluorescence in mesenchymal stem cells","pmids":["26359301"],"confidence":"Medium","gaps":["direct binding vs. complex-mediated association between Sec5 and GEF-H1 not distinguished","whether this mechanism operates in non-mesenchymal cells not tested"]},{"year":2018,"claim":"Sec5 binding to InsP3R on phagosomes was shown to promote Ca²⁺ release and recruit TBK1 for IRF-3-dependent interferon responses during fungal phagocytosis, integrating Sec5's vesicle-tethering and innate immune signaling roles on the same organelle.","evidence":"Co-IP, Ca²⁺ imaging, recombinant peptide disruption, kinase activation assay in macrophages during Candida phagocytosis","pmids":["29703257"],"confidence":"Medium","gaps":["stoichiometry of the InsP3R–Sec5–TBK1 complex on phagosomes not determined","whether assembled exocyst is present on phagosomes or only Sec5 not clarified"]},{"year":2020,"claim":"Human biallelic EXOC2 truncating variants causing severe brain malformations established EXOC2 as essential for human neurodevelopment, with patient cells showing loss of exocytosis and defective Arl13b ciliary localization, linking Sec5 to primary ciliogenesis.","evidence":"Patient-derived fibroblasts from two families, exocytosis assays, Arl13b immunofluorescence, protein expression analysis","pmids":["32639540"],"confidence":"High","gaps":["mechanism by which Sec5 promotes Arl13b ciliary targeting not elucidated","whether ciliogenesis defect is cell-type specific in patient tissues unknown"]},{"year":2022,"claim":"Sec5 interaction with STAT6 and its requirement for STAT6 phosphorylation and M2 macrophage polarization expanded Sec5's signaling scaffolding role to adaptive immune regulation.","evidence":"Co-IP, siRNA/overexpression, immunofluorescence co-localization, heterozygous Sec5-deficient mice","pmids":["36313547"],"confidence":"Medium","gaps":["whether Sec5 promotes STAT6 phosphorylation by facilitating JAK access or by another mechanism not determined","in vivo phenotype in heterozygous mice only partially characterized"]},{"year":2024,"claim":"EXOC2 deletion or ASO-mediated knockdown in C9ORF72-ALS/FTD neurons reduced G4C2 repeat-containing RNA and dipeptide repeat proteins, revealing an unexpected role for Sec5 in regulating pathogenic repeat RNA levels.","evidence":"CRISPR-Cas9 knockout and ASO treatment in iPSC-derived motor neurons with DPR and RNA quantification","pmids":["38935506"],"confidence":"Medium","gaps":["mechanism by which EXOC2 regulates G4C2 repeat RNA (transcription, stability, or export) unknown","whether the effect is specific to repeat-containing transcripts or reflects general RNA metabolism changes not resolved"]},{"year":null,"claim":"Key unresolved questions include the structural organization of Sec5 within the fully assembled mammalian exocyst, how Sec5's vesicle-tethering and signaling-scaffold functions are coordinated or segregated in time and space, and the molecular mechanism by which Sec5 promotes Arl13b ciliary targeting and regulates C9ORF72 repeat RNA.","evidence":"","pmids":[],"confidence":"Low","gaps":["no high-resolution structure of full-length Sec5 in assembled exocyst","signaling vs. tethering functions not mechanistically separated","Arl13b ciliary trafficking mechanism downstream of Sec5 not defined"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[0,1,7,14,17]}],"localization":[{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[6,8,9]},{"term_id":"GO:0031410","term_label":"cytoplasmic vesicle","supporting_discovery_ids":[4,12]},{"term_id":"GO:0005929","term_label":"cilium","supporting_discovery_ids":[15]}],"pathway":[{"term_id":"R-HSA-5653656","term_label":"Vesicle-mediated transport","supporting_discovery_ids":[3,4,5,6,9,12,15]},{"term_id":"R-HSA-168256","term_label":"Immune System","supporting_discovery_ids":[7,14,17]},{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[0,2,7,8,13]},{"term_id":"R-HSA-9609507","term_label":"Protein localization","supporting_discovery_ids":[3,5,12,15]}],"complexes":["Exocyst complex (Sec6/8 complex)"],"partners":["RALA","RALB","EXOC8","TBK1","ITPR1","STAT6","ARHGEF2","NF2"],"other_free_text":[]},"mechanistic_narrative":"EXOC2 (Sec5) is a core subunit of the octameric exocyst complex that tethers secretory vesicles to the plasma membrane, mediating polarized exocytosis, endocytic recycling, and primary ciliogenesis across diverse cell types. Its N-terminal immunoglobulin/IPT-fold domain directly binds active RalA and RalB GTPases, competing with the exocyst subunit Exo84 for the same RalA interface, thereby enabling GTPase-dependent regulation of vesicle trafficking for cargo including cadherins, integrins, and insulin granules [PMID:12839989, PMID:15920473, PMID:16224820, PMID:23844030]. Beyond canonical vesicle tethering, EXOC2 serves as a signaling scaffold: RalB-dependent Sec5–TBK1 interaction activates innate immune signaling, Sec5 binding to InsP3R on phagosomes promotes Ca²⁺ release and type I interferon responses, and Sec5 interaction with STAT6 regulates macrophage M2 polarization [PMID:18413258, PMID:29703257, PMID:36313547]. Biallelic truncating EXOC2 variants in humans cause severe neurodevelopmental brain malformations with loss of exocytosis and defective Arl13b-dependent ciliogenesis [PMID:32639540]."},"prefetch_data":{"uniprot":{"accession":"Q96KP1","full_name":"Exocyst complex component 2","aliases":["Exocyst complex component Sec5"],"length_aa":924,"mass_kda":104.1,"function":"Component of the exocyst complex involved in the docking of exocytic vesicles with fusion sites on the plasma membrane","subcellular_location":"Midbody, Midbody ring","url":"https://www.uniprot.org/uniprotkb/Q96KP1/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/EXOC2","classification":"Not Classified","n_dependent_lines":398,"n_total_lines":1208,"dependency_fraction":0.3294701986754967},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/EXOC2","total_profiled":1310},"omim":[{"mim_id":"619306","title":"NEURODEVELOPMENTAL DISORDER WITH DYSMORPHIC FACIES AND CEREBELLAR HYPOPLASIA; NEDFACH","url":"https://www.omim.org/entry/619306"},{"mim_id":"615329","title":"EXOCYST COMPLEX COMPONENT 2; EXOC2","url":"https://www.omim.org/entry/615329"},{"mim_id":"615283","title":"EXOCYST COMPLEX COMPONENT 8; EXOC8","url":"https://www.omim.org/entry/615283"},{"mim_id":"614117","title":"EXOCYST COMPLEX COMPONENT 3-LIKE 1; EXOC3L1","url":"https://www.omim.org/entry/614117"},{"mim_id":"612374","title":"STIMULATOR OF INTERFERON RESPONSE cGAMP INTERACTOR 1; STING1","url":"https://www.omim.org/entry/612374"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Vesicles","reliability":"Approved"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/EXOC2"},"hgnc":{"alias_symbol":["FLJ11026","Sec5"],"prev_symbol":["SEC5L1"]},"alphafold":{"accession":"Q96KP1","domains":[{"cath_id":"2.60.40.10","chopping":"8-91","consensus_level":"high","plddt":88.8499,"start":8,"end":91},{"cath_id":"-","chopping":"446-481_491-619","consensus_level":"medium","plddt":87.0652,"start":446,"end":619},{"cath_id":"1.20.1050","chopping":"781-913","consensus_level":"high","plddt":93.868,"start":781,"end":913}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q96KP1","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q96KP1-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q96KP1-F1-predicted_aligned_error_v6.png","plddt_mean":80.56},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=EXOC2","jax_strain_url":"https://www.jax.org/strain/search?query=EXOC2"},"sequence":{"accession":"Q96KP1","fasta_url":"https://rest.uniprot.org/uniprotkb/Q96KP1.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q96KP1/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q96KP1"}},"corpus_meta":[{"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":"12575951","id":"PMC_12575951","title":"Mutations in the exocyst component Sec5 disrupt neuronal membrane traffic, but neurotransmitter release persists.","date":"2003","source":"Neuron","url":"https://pubmed.ncbi.nlm.nih.gov/12575951","citation_count":174,"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":"26336092","id":"PMC_26336092","title":"Phytophthora infestans RXLR Effector AVR1 Interacts with Exocyst Component Sec5 to Manipulate Plant Immunity.","date":"2015","source":"Plant physiology","url":"https://pubmed.ncbi.nlm.nih.gov/26336092","citation_count":108,"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":"18697830","id":"PMC_18697830","title":"Ral-regulated interaction between Sec5 and paxillin targets Exocyst to focal complexes during cell migration.","date":"2008","source":"Journal of cell science","url":"https://pubmed.ncbi.nlm.nih.gov/18697830","citation_count":80,"is_preprint":false},{"pmid":"14681190","id":"PMC_14681190","title":"The exocyst component Sec5 is required for membrane traffic and polarity in the Drosophila ovary.","date":"2003","source":"Development (Cambridge, England)","url":"https://pubmed.ncbi.nlm.nih.gov/14681190","citation_count":55,"is_preprint":false},{"pmid":"15955846","id":"PMC_15955846","title":"The exocyst component Sec5 is present on endocytic vesicles in the oocyte of Drosophila melanogaster.","date":"2005","source":"The Journal of cell biology","url":"https://pubmed.ncbi.nlm.nih.gov/15955846","citation_count":54,"is_preprint":false},{"pmid":"25396269","id":"PMC_25396269","title":"A closer look at evolution: Variants (SNPs) of genes involved in skin pigmentation, including EXOC2, TYR, TYRP1, and DCT, are associated with 25(OH)D serum concentration.","date":"2015","source":"Endocrinology","url":"https://pubmed.ncbi.nlm.nih.gov/25396269","citation_count":45,"is_preprint":false},{"pmid":"20630948","id":"PMC_20630948","title":"Sec5, a member of the exocyst complex, mediates Drosophila embryo cellularization.","date":"2010","source":"Development (Cambridge, England)","url":"https://pubmed.ncbi.nlm.nih.gov/20630948","citation_count":31,"is_preprint":false},{"pmid":"32639540","id":"PMC_32639540","title":"Mutations in the exocyst component EXOC2 cause severe defects in human brain development.","date":"2020","source":"The Journal of experimental medicine","url":"https://pubmed.ncbi.nlm.nih.gov/32639540","citation_count":30,"is_preprint":false},{"pmid":"12624092","id":"PMC_12624092","title":"Structure of the GTPase-binding domain of Sec5 and elucidation of its Ral binding site.","date":"2003","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/12624092","citation_count":29,"is_preprint":false},{"pmid":"18413258","id":"PMC_18413258","title":"Characterization of RalB-Sec5-TBK1 function in human oncogenesis.","date":"2008","source":"Methods in enzymology","url":"https://pubmed.ncbi.nlm.nih.gov/18413258","citation_count":21,"is_preprint":false},{"pmid":"23844030","id":"PMC_23844030","title":"Exocyst sec5 regulates exocytosis of newcomer insulin granules underlying biphasic insulin secretion.","date":"2013","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/23844030","citation_count":21,"is_preprint":false},{"pmid":"36313547","id":"PMC_36313547","title":"SEC5 is involved in M2 polarization of macrophages via the STAT6 pathway, and its dysfunction in decidual macrophages is associated with recurrent spontaneous abortion.","date":"2022","source":"Frontiers in cell and developmental biology","url":"https://pubmed.ncbi.nlm.nih.gov/36313547","citation_count":18,"is_preprint":false},{"pmid":"12459492","id":"PMC_12459492","title":"DelGEF, a homologue of the Ran guanine nucleotide exchange factor RanGEF, binds to the exocyst component Sec5 and modulates secretion.","date":"2002","source":"FEBS letters","url":"https://pubmed.ncbi.nlm.nih.gov/12459492","citation_count":18,"is_preprint":false},{"pmid":"22761837","id":"PMC_22761837","title":"Sec5 and Exo84 mediate distinct aspects of RalA-dependent cell polarization.","date":"2012","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/22761837","citation_count":15,"is_preprint":false},{"pmid":"26359301","id":"PMC_26359301","title":"Dexamethasone-induced cellular tension requires a SGK1-stimulated Sec5-GEF-H1 interaction.","date":"2015","source":"Journal of cell science","url":"https://pubmed.ncbi.nlm.nih.gov/26359301","citation_count":13,"is_preprint":false},{"pmid":"29703257","id":"PMC_29703257","title":"InsP3R-SEC5 interaction on phagosomes modulates innate immunity to Candida albicans by promoting cytosolic Ca2+ elevation and TBK1 activity.","date":"2018","source":"BMC biology","url":"https://pubmed.ncbi.nlm.nih.gov/29703257","citation_count":8,"is_preprint":false},{"pmid":"31705793","id":"PMC_31705793","title":"Silencing SEC5 inhibits trophoblast invasion via integrin/Ca2+ signaling.","date":"2020","source":"Reproduction (Cambridge, England)","url":"https://pubmed.ncbi.nlm.nih.gov/31705793","citation_count":6,"is_preprint":false},{"pmid":"33831039","id":"PMC_33831039","title":"Phytophthora infestans RXLR effector AVR1 disturbs the growth of Physcomitrium patens without affecting Sec5 localization.","date":"2021","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/33831039","citation_count":3,"is_preprint":false},{"pmid":"9153755","id":"PMC_9153755","title":"A conditional sterol esterification defect in yeast having either a sec1 or sec5 mutation in the secretory pathway.","date":"1997","source":"Yeast (Chichester, England)","url":"https://pubmed.ncbi.nlm.nih.gov/9153755","citation_count":2,"is_preprint":false},{"pmid":"37089464","id":"PMC_37089464","title":"An exocyst component, Sec5, is essential for ascospore formation in Bipolaris 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Exocytosis","date":"2025-06-19","source":"bioRxiv","url":"https://doi.org/10.1101/2025.06.13.659557","citation_count":0,"is_preprint":true}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":13247,"output_tokens":4841,"usd":0.056178},"stage2":{"model":"claude-opus-4-6","input_tokens":8360,"output_tokens":3446,"usd":0.191925},"total_usd":0.248103,"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\": 2003,\n      \"finding\": \"Crystal structure of the Ral-binding domain of Sec5 (EXOC2) in complex with RalA-GppNHp at 2.1 Å resolution revealed an immunoglobulin-like beta-sandwich fold (novel for a GTPase effector), with the interface involving a continuous antiparallel beta-sheet; key residues Sec5 Thr11 and Arg27, and RalA Glu38 are required for complex formation, confirmed by isothermal titration calorimetry.\",\n      \"method\": \"X-ray crystallography (2.1 Å), isothermal titration calorimetry, site-directed mutagenesis\",\n      \"journal\": \"The EMBO journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — crystal structure with mutagenesis validation and ITC binding measurements\",\n      \"pmids\": [\"12839989\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"The GTPase-binding domain of Sec5 (EXOC2) adopts an IPT/immunoglobulin superfamily fold, and NMR-based mapping identified the Ral binding site on this domain, overlapping with known protein-protein interaction surfaces on other IPT domains.\",\n      \"method\": \"NMR structure determination, site-directed mutagenesis binding analysis\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — NMR structure with functional mapping and mutagenesis data\",\n      \"pmids\": [\"12624092\"],\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 showed that Exo84 and Sec5 competitively bind to the same active RalA interface; mutagenesis confirmed key determinants of specificity, establishing Exo84 and Sec5 as competitive regulatory effectors for RalA-mediated Sec6/8 complex regulation.\",\n      \"method\": \"X-ray crystallography, mutagenesis, competitive binding assays\",\n      \"journal\": \"The EMBO journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — crystal structure plus mutagenesis plus biochemical competition assay\",\n      \"pmids\": [\"15920473\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"In Drosophila, loss-of-function of Sec5 (EXOC2 ortholog) impairs membrane addition and neurite outgrowth in neurons but does not impair synaptic vesicle fusion, demonstrating that Sec5 selectively mediates biosynthetic membrane trafficking for cell growth rather than neurotransmitter secretion.\",\n      \"method\": \"Drosophila genetics (null alleles), trafficking assay, neuromuscular junction analysis\",\n      \"journal\": \"Neuron\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — clean Drosophila null mutants with specific dissection of two trafficking pathways; highly cited foundational study\",\n      \"pmids\": [\"12575951\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"In Drosophila epithelial cells, loss of Sec5 (and Sec6/Sec15) causes DE-Cadherin accumulation in enlarged Rab11-positive recycling endosomes and prevents DE-Cadherin delivery to the plasma membrane; Armadillo (β-catenin) interacts with Sec10, linking the exocyst to the cadherin trafficking machinery from recycling endosomes.\",\n      \"method\": \"Drosophila genetics (loss-of-function clones), immunofluorescence, co-immunoprecipitation\",\n      \"journal\": \"Developmental cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — Drosophila genetic LOF with defined trafficking phenotype plus Co-IP interaction; highly cited\",\n      \"pmids\": [\"16224820\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"In Drosophila oocytes, Sec5 is required for directed membrane trafficking of Gurken (secreted EGF-R ligand) and Yolkless (vitellogenin receptor), and Sec5 localization is dynamic, correlating spatially with sites of membrane protein traffic; loss of Sec5 impairs posterior oocyte positioning and dorsal patterning.\",\n      \"method\": \"Drosophila germline clones, immunofluorescence localization, trafficking assays\",\n      \"journal\": \"Development (Cambridge, England)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — clean genetic LOF with specific cargo trafficking phenotypes and dynamic localization data\",\n      \"pmids\": [\"14681190\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"In Drosophila oocytes, Sec5 localizes to clathrin-coated pits and vesicles at the plasma membrane; a truncation allele (sec5(E13)) disrupts endocytic recycling of Yolkless causing its accumulation in late endosomal compartments, revealing an exocyst role in endocytic recycling distinct from its biosynthetic secretion function.\",\n      \"method\": \"Drosophila genetics (truncation allele), immunofluorescence, electron microscopy, trafficking assay\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 — defined truncation allele with specific endocytic recycling defect and localization to clathrin structures\",\n      \"pmids\": [\"15955846\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"RalB activation promotes a direct interaction between Sec5 (EXOC2) and TBK1, resulting in TBK1 kinase activation, which then mediates innate immune/host defense signaling and supports survival of transformed cells; RalB and Sec5 are required for host defense pathway activation upon viral infection.\",\n      \"method\": \"Co-immunoprecipitation, protein kinase assay, RNAi knockdown, cell transformation assay\",\n      \"journal\": \"Methods in enzymology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — Co-IP and kinase assay in single lab; multiple methods but methodological context paper\",\n      \"pmids\": [\"18413258\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"Ral GTPases control association of Sec5 (EXOC2) with paxillin at focal complexes in prostate tumor cells; upon loss of cadherin-mediated adhesion, Exocyst relocalizes to membrane protrusion tips where it co-purifies with focal complex proteins and is required for delivery of α5-integrin to the plasma membrane to support cell motility and matrix invasion.\",\n      \"method\": \"RNAi knockdown, co-purification, dominant-negative Sec5 mutants, integrin trafficking assay, invasion assay\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — Ral-uncoupled Sec5 mutants plus RNAi plus cargo trafficking; single lab but multiple methods\",\n      \"pmids\": [\"18697830\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"In Drosophila embryos, Sec5 is required for cellularization: loss of Sec5 prevents cleavage furrow invagination and blocks plasma membrane insertion of Neurotactin; Sec5 concentrates at the apical end of lateral membranes (primary site of membrane addition) during cellularization, then at the sub-apical complex, indicating polarized membrane addition and epithelial polarity functions.\",\n      \"method\": \"Drosophila temperature-sensitive allele (sec5(ts1)) germline clones, immunofluorescence, live imaging\",\n      \"journal\": \"Development (Cambridge, England)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — temperature-sensitive allele with specific stage-restricted phenotype and dynamic localization\",\n      \"pmids\": [\"20630948\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"DelGEF (a Ran-GEF homolog) was identified as a binding partner of human Sec5 (EXOC2) by yeast two-hybrid; the interaction is Mg2+- and GTP/dCTP-dependent; knockdown of DelGEF in HeLa cells increased extracellular proteoglycan secretion, implicating the DelGEF-Sec5 interaction in regulating the secretion process.\",\n      \"method\": \"Yeast two-hybrid, biochemical interaction assay (Mg2+/nucleotide dependence), siRNA knockdown with secretion measurement\",\n      \"journal\": \"FEBS letters\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 — yeast two-hybrid plus functional knockdown; single lab, partial mechanistic follow-up\",\n      \"pmids\": [\"12459492\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"RalA interaction with Sec5 and Exo84 (exocyst effectors) is directly necessary for migration and invasion of prostate cancer cells; blocking RalA-Exocyst binding causes morphological changes and defects in single and coordinated cell migration, and Sec5 and Exo84 mediate distinct aspects of RalA-dependent cell polarization.\",\n      \"method\": \"RNAi, dominant-negative/Ral-uncoupled mutants, migration and invasion assays\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — specific Ral-uncoupled mutants plus RNAi; single lab\",\n      \"pmids\": [\"22761837\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"Sec5 (EXOC2) is localized to insulin secretory granules in pancreatic β cells and preferentially regulates exocytosis of newcomer insulin granules (minimal pre-docking time) that constitute the major component of biphasic glucose-stimulated insulin secretion; Sec5 depletion inhibited both readily-releasable pool release and reserve pool mobilization, predominantly by reducing newcomer granule recruitment.\",\n      \"method\": \"Patch-clamp capacitance measurement, TIRF microscopy, siRNA knockdown\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — electrophysiology and live-cell imaging with specific knockdown; single lab\",\n      \"pmids\": [\"23844030\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"Dexamethasone-induced SGK1 expression stimulates a Sec5 (EXOC2)–GEF-H1 interaction; this interaction is required for GEF-H1 targeting to peripheral focal adhesion sites, fibronectin fibril formation, and RhoA-dependent cellular tension in mesenchymal stem cells; disrupting the Sec5-GEF-H1 interaction abolishes these effects without altering integrin/fibronectin expression levels.\",\n      \"method\": \"Co-immunoprecipitation, dominant-negative/interaction-disrupting constructs, immunofluorescence, traction force measurements, RNAi\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal methods (Co-IP, functional mutants, imaging) in single lab\",\n      \"pmids\": [\"26359301\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"During Candida albicans phagocytosis in macrophages, SEC5 (EXOC2) binds to the C-terminal α-helix (H1) of InsP3R on phagosomes, promoting InsP3R channel activity and increasing cytosolic Ca2+; disruption of this interaction attenuates Ca2+ elevation and impairs phagocytosis; the InsP3R-SEC5 complex additionally recruits TBK1, leading to TBK1 activation, IRF-3 phosphorylation, and type I interferon responses.\",\n      \"method\": \"Co-immunoprecipitation, immunofluorescence, Ca2+ imaging, recombinant peptide disruption, phagocytosis assay, kinase activation assay\",\n      \"journal\": \"BMC biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — multiple methods (Co-IP, live Ca2+ imaging, peptide disruption, kinase assay) in single lab\",\n      \"pmids\": [\"29703257\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"Pathogenic truncating variants in EXOC2 (Sec5) in human patients cause severe reduction in exocytosis/vesicle fusion and undetectable EXOC2 protein via nonsense-mediated decay, demonstrating EXOC2 is essential for normal brain development; patient cells also show defective Arl13b localization to the primary cilium, linking EXOC2 to ciliogenesis.\",\n      \"method\": \"Patient-derived cells, exocytosis/vesicle fusion assays, protein expression analysis, immunofluorescence (Arl13b ciliary localization)\",\n      \"journal\": \"The Journal of experimental medicine\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — human LOF variants with multiple functional readouts (exocytosis assay, cilia localization) across two families\",\n      \"pmids\": [\"32639540\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"SEC5 (EXOC2) knockdown in trophoblast cells reduces cell migration and invasion, decreases plasma membrane distribution of integrin β1, reduces InsP3R-mediated cytosolic Ca2+ elevation, and disrupts F-actin stress fibers, placing SEC5 in an integrin/Ca2+/cytoskeleton signaling axis required for trophoblast invasion.\",\n      \"method\": \"shRNA knockdown, invasion/migration assays, Ca2+ imaging, immunofluorescence, integrin surface expression analysis\",\n      \"journal\": \"Reproduction (Cambridge, England)\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — multiple functional assays with mechanistic follow-up; single lab\",\n      \"pmids\": [\"31705793\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"SEC5 (EXOC2) interacts with STAT6 in macrophages; SEC5 knockdown inhibits M2 polarization and STAT6 phosphorylation, while overexpression promotes both; SEC5 and phospho-STAT6 co-localize, with pSTAT6 redistributing to the nucleus upon M2 polarization, placing SEC5 upstream of STAT6 in macrophage polarization.\",\n      \"method\": \"Co-immunoprecipitation, immunofluorescence co-localization, siRNA knockdown, overexpression, mouse model (heterozygous SEC5-deficient mice)\",\n      \"journal\": \"Frontiers in cell and developmental biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2–3 — Co-IP plus functional KD/OE plus in vivo model; single lab\",\n      \"pmids\": [\"36313547\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"EXOC2 deletion in C9ORF72-ALS/FTD iPSC-derived motor neurons decreases levels of dipeptide repeat (DPR) proteins and expanded G4C2 repeat-containing RNA, rescuing disease-relevant cellular phenotypes; EXOC2 antisense oligonucleotide treatment in fully differentiated C9ORF72 neurons similarly reduces expanded G4C2 RNA, indicating EXOC2 directly or indirectly regulates G4C2 repeat-containing RNA levels.\",\n      \"method\": \"CRISPR-Cas9 deletion in iPSCs, iPSC-derived motor neurons, antisense oligonucleotide treatment, DPR protein quantification, RNA quantification\",\n      \"journal\": \"Cell reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — CRISPR LOF and ASO treatment with multiple molecular readouts; single lab, mechanism of RNA regulation not fully elucidated\",\n      \"pmids\": [\"38935506\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"Active Merlin (NF2 tumor suppressor) competitively inhibits RalB binding to Sec5 (EXOC2) and Exo84, and regulates the kinetics of exocytosis in a RalB-dependent manner; direct binding assays showed RalA and RalB are high-affinity PIP2-dependent Merlin binding proteins that co-localize on the plasma membrane.\",\n      \"method\": \"Proximity biotinylation, direct binding assays, co-localization, exocytosis kinetics assay, competitive binding assay\",\n      \"journal\": \"bioRxiv\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — direct binding assays plus functional exocytosis measurement; preprint, single lab\",\n      \"pmids\": [\"bio_10.1101_2025.06.13.659557\"],\n      \"is_preprint\": true\n    }\n  ],\n  \"current_model\": \"EXOC2 (Sec5) is a central subunit of the octameric exocyst complex that tethers secretory vesicles to the plasma membrane for polarized exocytosis; it binds active RalA/RalB GTPases through a structurally characterized immunoglobulin/IPT-fold domain, competes with Exo84 for RalA binding, and mediates multiple downstream functions including biosynthetic membrane protein trafficking, endocytic recycling, insulin granule exocytosis, cadherin delivery from recycling endosomes, primary ciliogenesis (Arl13b localization), innate immune signaling via InsP3R-TBK1 and RalB-TBK1 complexes, macrophage M2 polarization via STAT6, and regulation of C9ORF72 repeat-containing RNA levels in neurons, with loss-of-function in humans causing severe neurodevelopmental brain malformations.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"EXOC2 (Sec5) is a core subunit of the octameric exocyst complex that tethers secretory vesicles to the plasma membrane, mediating polarized exocytosis, endocytic recycling, and primary ciliogenesis across diverse cell types. Its N-terminal immunoglobulin/IPT-fold domain directly binds active RalA and RalB GTPases, competing with the exocyst subunit Exo84 for the same RalA interface, thereby enabling GTPase-dependent regulation of vesicle trafficking for cargo including cadherins, integrins, and insulin granules [PMID:12839989, PMID:15920473, PMID:16224820, PMID:23844030]. Beyond canonical vesicle tethering, EXOC2 serves as a signaling scaffold: RalB-dependent Sec5–TBK1 interaction activates innate immune signaling, Sec5 binding to InsP3R on phagosomes promotes Ca²⁺ release and type I interferon responses, and Sec5 interaction with STAT6 regulates macrophage M2 polarization [PMID:18413258, PMID:29703257, PMID:36313547]. Biallelic truncating EXOC2 variants in humans cause severe neurodevelopmental brain malformations with loss of exocytosis and defective Arl13b-dependent ciliogenesis [PMID:32639540].\",\n  \"teleology\": [\n    {\n      \"year\": 2002,\n      \"claim\": \"The identification of DelGEF as a nucleotide-dependent Sec5-binding partner provided early evidence that EXOC2 integrates GTPase-regulatory inputs beyond the Ral family to modulate secretion.\",\n      \"evidence\": \"Yeast two-hybrid screen plus biochemical interaction assays and siRNA knockdown measuring proteoglycan secretion in HeLa cells\",\n      \"pmids\": [\"12459492\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"DelGEF–Sec5 interaction not validated by reciprocal Co-IP or structural methods\", \"physiological secretory cargo regulated by this interaction not defined\", \"relationship to Ral-dependent Sec5 regulation unclear\"]\n    },\n    {\n      \"year\": 2003,\n      \"claim\": \"Structural determination of the Sec5 Ral-binding domain revealed an unprecedented immunoglobulin/IPT fold for a GTPase effector and defined the atomic basis of the RalA–Sec5 interface, establishing how the exocyst is recruited by active Ral GTPases.\",\n      \"evidence\": \"X-ray crystallography (2.1 Å) and NMR of the Sec5 RBD–RalA complex with ITC and mutagenesis validation\",\n      \"pmids\": [\"12839989\", \"12624092\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"structure of full-length Sec5 within the assembled exocyst not resolved\", \"relative contributions of RalA vs. RalB to Sec5 engagement in vivo not quantified\"]\n    },\n    {\n      \"year\": 2003,\n      \"claim\": \"Drosophila Sec5 null mutants established that Sec5 is essential for biosynthetic membrane addition and neurite outgrowth but dispensable for synaptic vesicle fusion, distinguishing exocyst-dependent from SNARE-only trafficking pathways in neurons.\",\n      \"evidence\": \"Drosophila sec5 null alleles with neuromuscular junction electrophysiology and membrane trafficking assays\",\n      \"pmids\": [\"12575951\", \"14681190\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"whether Sec5 independence of synaptic vesicle fusion extends to mammalian neurons not tested\", \"identity of the tethering factor for synaptic vesicles remains separate\"]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"Structural and biochemical demonstration that Exo84 and Sec5 compete for the same RalA surface established a regulatory switch model in which a single Ral GTPase toggles between two exocyst sub-complexes, and genetic studies revealed Sec5's role in cadherin recycling from Rab11 endosomes and in endocytic recycling at clathrin-coated structures.\",\n      \"evidence\": \"Crystal structure of Exo84 RBD–RalA with competitive binding assays; Drosophila LOF clones with cadherin trafficking analysis; sec5 truncation allele with EM localization to clathrin pits\",\n      \"pmids\": [\"15920473\", \"16224820\", \"15955846\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"how competitive Ral binding to Sec5 vs. Exo84 is regulated temporally in a single trafficking event not resolved\", \"direct role of Sec5 in clathrin-mediated steps vs. post-endocytic recycling not distinguished\"]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Discovery that RalB activation directs Sec5 to bind and activate TBK1 kinase revealed a non-canonical exocyst function in innate immune signaling and oncogenic cell survival, expanding Sec5's role beyond vesicle tethering.\",\n      \"evidence\": \"Co-IP, in vitro kinase assays, RNAi in mammalian cells, viral infection model\",\n      \"pmids\": [\"18413258\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"structural basis of Sec5–TBK1 interaction not determined\", \"whether TBK1 activation requires assembled exocyst or only the Sec5 subunit not resolved\"]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Sec5 was shown to mediate Ral-dependent delivery of α5-integrin to focal complexes, linking exocyst trafficking to cell migration and tumor invasion.\",\n      \"evidence\": \"RNAi, dominant-negative Sec5 mutants, integrin surface trafficking, and invasion assays in prostate cancer cells\",\n      \"pmids\": [\"18697830\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"specific vesicle population carrying integrins to focal adhesions not characterized\", \"in vivo relevance for metastasis not tested\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Temperature-sensitive sec5 alleles demonstrated that Sec5 is required for cleavage furrow membrane insertion during Drosophila cellularization, establishing its role in the earliest polarized membrane addition events during epithelial morphogenesis.\",\n      \"evidence\": \"Drosophila ts allele germline clones with live imaging and Neurotactin trafficking\",\n      \"pmids\": [\"20630948\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"how Sec5 is recruited to the apical lateral membrane domain during cellularization not defined\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"TIRF microscopy and electrophysiology showed that Sec5 localizes to insulin granules and preferentially promotes newcomer granule exocytosis, explaining how the exocyst contributes to biphasic glucose-stimulated insulin secretion.\",\n      \"evidence\": \"TIRF live imaging, patch-clamp capacitance, siRNA knockdown in pancreatic β cells\",\n      \"pmids\": [\"23844030\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"whether Sec5 interacts directly with insulin granule-resident SNAREs not tested\", \"contribution relative to other exocyst subunits in β cells not compared\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Identification of the Sec5–GEF-H1 interaction downstream of SGK1 revealed a mechanism by which Sec5 delivers RhoA-activating GEF to peripheral focal adhesions, controlling cellular tension and fibronectin fibril formation.\",\n      \"evidence\": \"Co-IP, interaction-disrupting constructs, traction force microscopy, immunofluorescence in mesenchymal stem cells\",\n      \"pmids\": [\"26359301\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"direct binding vs. complex-mediated association between Sec5 and GEF-H1 not distinguished\", \"whether this mechanism operates in non-mesenchymal cells not tested\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Sec5 binding to InsP3R on phagosomes was shown to promote Ca²⁺ release and recruit TBK1 for IRF-3-dependent interferon responses during fungal phagocytosis, integrating Sec5's vesicle-tethering and innate immune signaling roles on the same organelle.\",\n      \"evidence\": \"Co-IP, Ca²⁺ imaging, recombinant peptide disruption, kinase activation assay in macrophages during Candida phagocytosis\",\n      \"pmids\": [\"29703257\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"stoichiometry of the InsP3R–Sec5–TBK1 complex on phagosomes not determined\", \"whether assembled exocyst is present on phagosomes or only Sec5 not clarified\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Human biallelic EXOC2 truncating variants causing severe brain malformations established EXOC2 as essential for human neurodevelopment, with patient cells showing loss of exocytosis and defective Arl13b ciliary localization, linking Sec5 to primary ciliogenesis.\",\n      \"evidence\": \"Patient-derived fibroblasts from two families, exocytosis assays, Arl13b immunofluorescence, protein expression analysis\",\n      \"pmids\": [\"32639540\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"mechanism by which Sec5 promotes Arl13b ciliary targeting not elucidated\", \"whether ciliogenesis defect is cell-type specific in patient tissues unknown\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Sec5 interaction with STAT6 and its requirement for STAT6 phosphorylation and M2 macrophage polarization expanded Sec5's signaling scaffolding role to adaptive immune regulation.\",\n      \"evidence\": \"Co-IP, siRNA/overexpression, immunofluorescence co-localization, heterozygous Sec5-deficient mice\",\n      \"pmids\": [\"36313547\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"whether Sec5 promotes STAT6 phosphorylation by facilitating JAK access or by another mechanism not determined\", \"in vivo phenotype in heterozygous mice only partially characterized\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"EXOC2 deletion or ASO-mediated knockdown in C9ORF72-ALS/FTD neurons reduced G4C2 repeat-containing RNA and dipeptide repeat proteins, revealing an unexpected role for Sec5 in regulating pathogenic repeat RNA levels.\",\n      \"evidence\": \"CRISPR-Cas9 knockout and ASO treatment in iPSC-derived motor neurons with DPR and RNA quantification\",\n      \"pmids\": [\"38935506\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"mechanism by which EXOC2 regulates G4C2 repeat RNA (transcription, stability, or export) unknown\", \"whether the effect is specific to repeat-containing transcripts or reflects general RNA metabolism changes not resolved\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"Key unresolved questions include the structural organization of Sec5 within the fully assembled mammalian exocyst, how Sec5's vesicle-tethering and signaling-scaffold functions are coordinated or segregated in time and space, and the molecular mechanism by which Sec5 promotes Arl13b ciliary targeting and regulates C9ORF72 repeat RNA.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"no high-resolution structure of full-length Sec5 in assembled exocyst\", \"signaling vs. tethering functions not mechanistically separated\", \"Arl13b ciliary trafficking mechanism downstream of Sec5 not defined\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [0, 1, 7, 14, 17]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [6, 8, 9]},\n      {\"term_id\": \"GO:0031410\", \"supporting_discovery_ids\": [4, 12]},\n      {\"term_id\": \"GO:0005929\", \"supporting_discovery_ids\": [15]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-5653656\", \"supporting_discovery_ids\": [3, 4, 5, 6, 9, 12, 15]},\n      {\"term_id\": \"R-HSA-168256\", \"supporting_discovery_ids\": [7, 14, 17]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [0, 2, 7, 8, 13]},\n      {\"term_id\": \"R-HSA-9609507\", \"supporting_discovery_ids\": [3, 5, 12, 15]}\n    ],\n    \"complexes\": [\n      \"Exocyst complex (Sec6/8 complex)\"\n    ],\n    \"partners\": [\n      \"RALA\",\n      \"RALB\",\n      \"EXOC8\",\n      \"TBK1\",\n      \"ITPR1\",\n      \"STAT6\",\n      \"ARHGEF2\",\n      \"NF2\"\n    ],\n    \"other_free_text\": []\n  }\n}\n```"}