{"gene":"EXOC2","run_date":"2026-06-09T23:54:43","timeline":{"discoveries":[{"year":2003,"finding":"The Ral-binding domain of EXOC2/Sec5 adopts an immunoglobulin-like beta-sandwich (IPT domain) fold and binds RalA in a GTP-dependent manner; crystal structure at 2.1 Å resolution revealed a continuous antiparallel beta-sheet interface, and Sec5 Thr11, Arg27, and RalA Glu38 were shown by isothermal titration calorimetry to be required for complex formation.","method":"X-ray crystallography (2.1 Å) plus isothermal titration calorimetry and site-directed mutagenesis","journal":"The EMBO journal","confidence":"High","confidence_rationale":"Tier 1 / Strong — crystal structure with mutagenesis validation; independently corroborated by NMR structure in same year","pmids":["12839989"],"is_preprint":false},{"year":2003,"finding":"The Ral-binding domain of Sec5 folds into an IPT (immunoglobulin superfamily) domain, representing a novel G-protein effector fold; NMR structure and site-directed mutagenesis mapped the Ral-binding surface on Sec5.","method":"NMR spectroscopy and site-directed mutagenesis","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Strong — NMR structure with mutagenesis; orthogonal confirmation of crystal structure findings from PMID:12839989","pmids":["12624092"],"is_preprint":false},{"year":2005,"finding":"Exo84 and Sec5/EXOC2 competitively and mutually exclusively bind active RalA; crystal structure of the RalA–Exo84 complex plus mutagenesis established that the two exocyst subunits share overlapping binding surfaces on RalA, making them competitive effectors.","method":"X-ray crystallography plus mutagenesis binding studies and biochemical competition assays","journal":"The EMBO journal","confidence":"High","confidence_rationale":"Tier 1 / Strong — crystal structure of competing complex plus mutagenesis demonstrating competition between Sec5 and Exo84","pmids":["15920473"],"is_preprint":false},{"year":2003,"finding":"In Drosophila, loss-of-function of sec5 (EXOC2 ortholog) impairs membrane addition and delivery of newly synthesized membrane proteins (neurite outgrowth, neuromuscular junction expansion), but does not impair synaptic vesicle fusion/neurotransmitter release, demonstrating that Sec5 differentiates between biosynthetic membrane trafficking and regulated exocytosis.","method":"Genetic null alleles in Drosophila, membrane trafficking assay, electrophysiology at neuromuscular junction","journal":"Neuron","confidence":"High","confidence_rationale":"Tier 2 / Strong — clean genetic loss-of-function with two distinct functional readouts (trafficking vs. synaptic transmission) in Drosophila","pmids":["12575951"],"is_preprint":false},{"year":2005,"finding":"Drosophila Sec5 (EXOC2 ortholog), together with Sec6 and Sec15, is required for trafficking of DE-Cadherin from Rab11-positive recycling endosomes to the plasma membrane in epithelial cells; loss of sec5 causes DE-Cad accumulation in enlarged Rab11 endosomes.","method":"Drosophila loss-of-function genetics, immunofluorescence, co-immunoprecipitation of Sec15 with Rab11 and Sec10 with Armadillo","journal":"Developmental cell","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic loss-of-function with defined trafficking phenotype plus Co-IP demonstrating molecular interactions","pmids":["16224820"],"is_preprint":false},{"year":2005,"finding":"In Drosophila oocytes, Sec5/EXOC2 is unexpectedly present in clathrin-coated pits and vesicles at the plasma membrane; a truncation allele (sec5(E13)) causes defective endocytic recycling of the vitellogenin receptor Yolkless (which accumulates in late endosomal compartments), revealing a role for Sec5 in endocytic recycling in addition to secretory trafficking.","method":"Drosophila genetics, immunolocalization, truncation allele analysis","journal":"The Journal of cell biology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic allele with defined phenotype in single study; localization data orthogonal to functional data","pmids":["15955846"],"is_preprint":false},{"year":2003,"finding":"In Drosophila oogenesis, Sec5/EXOC2 is required for directed membrane traffic of the secreted ligand Gurken and the receptor Yolkless; sec5 germline clones show defects in membrane addition, posterior oocyte positioning, dorsal patterning, and egg size, while cytoskeletal orientation remains correct.","method":"Drosophila germline clone analysis, immunofluorescence, membrane trafficking assays","journal":"Development (Cambridge, England)","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — clean genetic loss-of-function with specific cargo trafficking phenotypes in single study","pmids":["14681190"],"is_preprint":false},{"year":2010,"finding":"Sec5/EXOC2 is required for Drosophila embryo cellularization: a temperature-sensitive sec5 allele (sec5(ts1)) blocks cleavage furrow invagination and prevents membrane insertion of the zygotic protein Neurotactin; Sec5 concentrates at the apical end of lateral membranes (the major site of membrane addition) during cellularization and later at the sub-apical complex in the polarized epithelium.","method":"Temperature-sensitive Drosophila allele, immunofluorescence localization, membrane protein insertion assay","journal":"Development (Cambridge, England)","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — conditional allele with defined phenotype and subcellular localization linked to function in single study","pmids":["20630948"],"is_preprint":false},{"year":2008,"finding":"RalB activation promotes a direct interaction between Sec5/EXOC2 and TBK1, leading to TBK1 kinase activation; this RalB–Sec5–TBK1 complex is required for RalB-dependent cell survival signaling in transformed cells and for innate immune pathway activation upon virus infection.","method":"Protein complex co-purification, protein kinase assays, RNAi knockdown, cell transformation and survival assays","journal":"Methods in enzymology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — biochemical complex isolation plus kinase assay plus functional RNAi in single study/lab","pmids":["18413258"],"is_preprint":false},{"year":2008,"finding":"Ral GTPases control the association of Sec5/EXOC2 with paxillin at focal complexes in prostate tumor cells; Ral-uncoupled Sec5 mutants and RNAi knockdown of RalA or RalB disrupted Exocyst–paxillin interaction and shifted Exocyst localization from lateral membranes to protrusive extensions; this Exocyst localization is required for alpha5-integrin delivery to the plasma membrane and for tumor cell motility and matrix invasiveness.","method":"RNAi knockdown, Ral-uncoupled Sec5 mutant overexpression, co-purification, immunofluorescence, cell motility/invasion assays","journal":"Journal of cell science","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple orthogonal methods (RNAi, dominant-negative mutants, co-purification, functional invasion assay) in single study","pmids":["18697830"],"is_preprint":false},{"year":2002,"finding":"DelGEF (a RanGEF homologue) binds the human Sec5/EXOC2 protein; interaction is Mg2+-dependent and stimulated by GTP or dCTP; knockdown of DelGEF increases extracellular secretion of proteoglycans, implicating the DelGEF–Sec5 interaction in the secretion process.","method":"Yeast two-hybrid screen, biochemical binding assay, siRNA knockdown with secretion assay","journal":"FEBS letters","confidence":"Low","confidence_rationale":"Tier 3 / Weak — yeast two-hybrid identification plus single knockdown experiment; limited mechanistic follow-up","pmids":["12459492"],"is_preprint":false},{"year":2013,"finding":"Sec5/EXOC2 regulates exocytosis of newcomer insulin granules in pancreatic beta cells; Sec5 localizes to insulin granules, and siRNA-mediated knockdown in INS-1 cells selectively impairs recruitment and exocytosis of newcomer granules (which minimally dock at the plasma membrane) and mobilization of reserve-pool granules, while having little effect on predocked granules.","method":"siRNA knockdown, patch-clamp membrane capacitance measurement, total internal reflection fluorescence (TIRF) microscopy","journal":"PloS one","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — two orthogonal functional methods (capacitance + TIRF) with compartment-specific phenotype in single study","pmids":["23844030"],"is_preprint":false},{"year":2015,"finding":"Dexamethasone-induced SGK1 expression promotes interaction between Sec5/EXOC2 and GEF-H1 (a microtubule-regulated RhoA activator); this Sec5–GEF-H1 interaction is required for GEF-H1 targeting to focal adhesion sites and for dexamethasone-induced cellular tension, fibronectin fibril formation, and integrin-mediated attachment in mesenchymal stem cells.","method":"Co-immunoprecipitation, dominant-negative disruption of Sec5–GEF-H1 interaction, cellular tension measurements, immunofluorescence","journal":"Journal of cell science","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP plus functional disruption with specific phenotypic readout; single lab","pmids":["26359301"],"is_preprint":false},{"year":2018,"finding":"During Candida albicans phagocytosis, SEC5/EXOC2 binds the C-terminal α-helix (H1) of the inositol trisphosphate receptor (InsP3R) on phagosomes, promoting InsP3R channel activity and cytosolic Ca2+ elevation; disruption of this interaction with recombinant H1 peptides attenuates Ca2+ elevation and impairs phagocytosis; additionally, the InsP3R–SEC5 complex 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, IRF-3 phosphorylation assay","journal":"BMC biology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple orthogonal methods including functional disruption with defined molecular interface; single lab","pmids":["29703257"],"is_preprint":false},{"year":2020,"finding":"Pathogenic truncating variants in EXOC2 cause nonsense-mediated decay of EXOC2 transcript, undetectable EXOC2 protein, severe reduction in exocytosis and vesicle fusion in patient cells, and defective Arl13b localization to the primary cilium, establishing EXOC2 as essential for neuronal vesicle trafficking and ciliogenesis in humans.","method":"Patient-derived cell lines, Western blot, exocytosis assay, immunofluorescence of primary cilia, molecular genetics","journal":"The Journal of experimental medicine","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — human loss-of-function variants with defined molecular and cellular phenotypes; multiple patient families; single study","pmids":["32639540"],"is_preprint":false},{"year":2022,"finding":"SEC5/EXOC2 interacts with STAT6 in macrophages; SEC5 knockdown reduces STAT6 phosphorylation and M2 macrophage polarization, while overexpression promotes them; pSTAT6 and SEC5 co-localize, and SEC5 deficiency in mouse decidual macrophages leads to impaired M2 polarization and pregnancy loss.","method":"Co-immunoprecipitation, shRNA knockdown, overexpression, immunofluorescence co-localization, mouse heterozygous knockout model","journal":"Frontiers in cell and developmental biology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP with functional knockdown/overexpression and in vivo mouse model; single lab","pmids":["36313547"],"is_preprint":false},{"year":2020,"finding":"SEC5/EXOC2 knockdown in trophoblast (HTR-8/SVneo) cells reduces plasma membrane distribution of integrin β1, attenuates InsP3R-mediated cytosolic Ca2+ elevation upon serum stimulation, disrupts F-actin stress fibers, and inhibits cell migration and invasion, placing SEC5 upstream of an integrin/Ca2+/cytoskeleton axis.","method":"shRNA knockdown, Ca2+ imaging, BAPTA-AM chelation, immunofluorescence, Matrigel invasion assay","journal":"Reproduction (Cambridge, England)","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single lab, knockdown with multiple readouts but limited mechanistic resolution of direct vs. indirect effects","pmids":["31705793"],"is_preprint":false},{"year":2012,"finding":"RalA binding to Sec5/EXOC2 and Exo84 mediates distinct aspects of cell polarization; blocking RalA–Exocyst interactions causes morphological changes and defects in migration and invasion of prostate cancer cells.","method":"RalA effector mutants, RNAi, cell migration and invasion assays","journal":"PloS one","confidence":"Low","confidence_rationale":"Tier 3 / Weak — functional mutant analysis with migration assay; limited molecular resolution of Sec5-specific mechanism","pmids":["22761837"],"is_preprint":false},{"year":2024,"finding":"CRISPR-Cas9 deletion of EXOC2 in C9ORF72-ALS/FTD iPSCs (yielding truncated EXOC2 with partial exocyst function) rescues disease phenotypes by decreasing levels of dipeptide repeat (DPR) proteins and G4C2 repeat-containing RNA, indicating that EXOC2 directly or indirectly regulates G4C2 repeat RNA levels; EXOC2 antisense oligonucleotide treatment in differentiated neurons also decreased expanded G4C2 RNA.","method":"CRISPR-Cas9 deletion in patient iPSCs, iPSC-derived motor neurons, antisense oligonucleotide treatment, DPR protein and RNA quantification","journal":"Cell reports","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — two orthogonal loss-of-function approaches (CRISPR and ASO) with consistent phenotypic rescue; single study","pmids":["38935506"],"is_preprint":false},{"year":2025,"finding":"Active Merlin (NF2 tumor suppressor) competitively inhibits RalB binding to its exocyst effectors Sec5/EXOC2 and Exo84, and Merlin 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.","method":"Proximity biotinylation, direct binding assays, competitive binding assays, exocytosis kinetics assay","journal":"bioRxiv","confidence":"Low","confidence_rationale":"Tier 3 / Weak — preprint, single lab, competitive binding with functional exocytosis assay but limited orthogonal validation","pmids":["bio_10.1101_2025.06.13.659557"],"is_preprint":true}],"current_model":"EXOC2/Sec5 is a core subunit of the octameric exocyst complex that tethers secretory vesicles to specific plasma membrane sites for polarized exocytosis; its Ral-binding domain (IPT/immunoglobulin-like fold) directly binds active RalA/RalB in a GTP-dependent manner (competing with Exo84), linking upstream Ral GTPase signaling to exocyst assembly and targeting; Sec5 mediates biosynthetic membrane trafficking and recycling endosome-to-plasma membrane delivery (including E-Cadherin and integrins) but is dispensable for regulated synaptic vesicle fusion; it also forms a RalB-dependent complex with TBK1 to activate innate immune signaling, interacts with InsP3R on phagosomes to promote Ca2+ elevation, interacts with GEF-H1 to regulate RhoA activity and cytoskeletal tension, and is essential for human brain development and primary ciliogenesis (Arl13b localization)."},"narrative":{"mechanistic_narrative":"EXOC2/Sec5 is a core subunit of the octameric exocyst complex that tethers vesicles to the plasma membrane for polarized membrane trafficking, and it serves as a direct effector that couples Ral GTPase signaling to vesicle delivery [PMID:12839989, PMID:12575951]. Its Ral-binding domain adopts an immunoglobulin-like (IPT) beta-sandwich fold that binds RalA in a GTP-dependent manner through a continuous antiparallel beta-sheet interface, a binding mode mutually exclusive with the other exocyst Ral effector Exo84 [PMID:12839989, PMID:12624092, PMID:15920473]. Through this activity Sec5 directs biosynthetic delivery of newly synthesized membrane proteins and recycling-endosome cargo — including E-Cadherin, integrins, and secreted ligands — to specific membrane sites, while being dispensable for regulated synaptic vesicle fusion, establishing it as a selective tether for biosynthetic versus regulated exocytosis [PMID:12575951, PMID:16224820, PMID:18697830]. Beyond trafficking, Sec5 acts as a signaling node: RalB-dependent assembly of a Sec5–TBK1 complex activates TBK1 kinase to drive cell-survival and innate immune signaling [PMID:18413258], Sec5 binds GEF-H1 to control RhoA-dependent cytoskeletal tension and integrin-mediated attachment [PMID:26359301], and it binds the InsP3 receptor on phagosomes to promote Ca2+ elevation and TBK1/IRF-3–dependent interferon responses during phagocytosis [PMID:29703257]. In humans, biallelic truncating EXOC2 variants abolish protein expression, severely impair exocytosis, and disrupt Arl13b localization to the primary cilium, defining EXOC2 as essential for neuronal vesicle trafficking, ciliogenesis, and brain development [PMID:32639540].","teleology":[{"year":2003,"claim":"Structural and biochemical work answered how Sec5 physically connects to upstream Ral signaling, establishing it as a direct GTP-dependent RalA effector via a novel domain fold.","evidence":"X-ray crystallography at 2.1 Å, NMR, isothermal titration calorimetry, and site-directed mutagenesis of the Sec5 Ral-binding domain","pmids":["12839989","12624092"],"confidence":"High","gaps":["Did not establish how Ral binding alters exocyst assembly or membrane targeting in cells","Affinity and competition with other Ral effectors not yet resolved"]},{"year":2003,"claim":"Drosophila genetics resolved which class of exocytosis Sec5 governs, showing it is required for biosynthetic membrane addition but not for regulated synaptic vesicle fusion.","evidence":"Null alleles in Drosophila with membrane trafficking assays and neuromuscular junction electrophysiology","pmids":["12575951"],"confidence":"High","gaps":["Molecular basis for distinguishing biosynthetic from regulated vesicles not defined","Mammalian generality not tested in this study"]},{"year":2005,"claim":"Crystallography of the competing RalA–Exo84 complex established that Sec5 and Exo84 are mutually exclusive Ral effectors, implying Ral switches between distinct exocyst configurations.","evidence":"X-ray crystallography of RalA–Exo84 plus mutagenesis and biochemical competition assays","pmids":["15920473"],"confidence":"High","gaps":["Functional consequence of the Sec5-bound versus Exo84-bound state in vivo not resolved","Regulation of the switch between effectors unknown"]},{"year":2005,"claim":"Genetic studies defined the cargo and compartment specificity of Sec5-dependent trafficking, linking it to recycling-endosome-to-membrane delivery and endocytic recycling.","evidence":"Drosophila loss-of-function and truncation alleles, immunolocalization, and Co-IP of exocyst subunits with Rab11 and cargo","pmids":["16224820","15955846","14681190"],"confidence":"Medium","gaps":["Direct vs. indirect role in endocytic recycling not separated from secretory role","Mammalian cargo specificity not addressed"]},{"year":2010,"claim":"Conditional alleles tied Sec5 localization to sites of active membrane addition, showing it is required for cleavage-furrow membrane insertion during cellularization.","evidence":"Temperature-sensitive Drosophila allele with immunofluorescence and membrane protein insertion assays","pmids":["20630948"],"confidence":"Medium","gaps":["Recruitment mechanism to apical/sub-apical sites not defined","Identity of the targeting cue unknown"]},{"year":2008,"claim":"Biochemical and functional studies revealed a signaling role beyond tethering, with RalB driving a Sec5–TBK1 complex that activates kinase signaling for survival and innate immunity.","evidence":"Complex co-purification, kinase assays, and RNAi in transformed cells","pmids":["18413258"],"confidence":"Medium","gaps":["Whether full exocyst or free Sec5 mediates TBK1 binding unclear","Structural basis of Sec5–TBK1 interaction not determined"]},{"year":2008,"claim":"Ral control of Sec5 localization was linked to integrin delivery and tumor invasion, connecting exocyst targeting to cell motility.","evidence":"RNAi, Ral-uncoupled Sec5 mutants, co-purification, and motility/invasion assays in prostate tumor cells","pmids":["18697830"],"confidence":"Medium","gaps":["Direct paxillin binding partner within exocyst not defined","Mechanism of localization switch to protrusions unresolved"]},{"year":2012,"claim":"RalA effector partitioning between Sec5 and Exo84 was tied to distinct aspects of polarized migration and invasion.","evidence":"RalA effector mutants, RNAi, and migration/invasion assays","pmids":["22761837"],"confidence":"Low","gaps":["Limited resolution of Sec5-specific mechanism vs. Exo84","Direct molecular readout absent"]},{"year":2013,"claim":"TIRF and capacitance measurements refined Sec5's exocytic role to recruitment of newcomer and reserve-pool granules rather than predocked vesicles.","evidence":"siRNA, patch-clamp capacitance, and TIRF microscopy in INS-1 beta cells","pmids":["23844030"],"confidence":"Medium","gaps":["Molecular step distinguishing newcomer from predocked granules unclear","Generalizability beyond beta cells untested"]},{"year":2015,"claim":"A Sec5–GEF-H1 interaction was identified as the link between exocyst and RhoA-driven cytoskeletal tension and adhesion.","evidence":"Co-IP, dominant-negative disruption, and cellular tension/attachment assays in mesenchymal stem cells","pmids":["26359301"],"confidence":"Medium","gaps":["Direct vs. complex-mediated Sec5–GEF-H1 binding not resolved","Single lab/cell type"]},{"year":2018,"claim":"Sec5 was shown to bind the InsP3R on phagosomes via a defined helix, coupling phagocytosis to Ca2+ signaling and TBK1/IRF-3-driven interferon responses.","evidence":"Co-IP, Ca2+ imaging, recombinant peptide disruption, phagocytosis and IRF-3 phosphorylation assays","pmids":["29703257"],"confidence":"Medium","gaps":["Whether exocyst tethering and InsP3R binding are coordinated unclear","Single-lab interface mapping"]},{"year":2020,"claim":"Human loss-of-function variants established EXOC2 as essential for exocytosis, ciliogenesis, and brain development, anchoring the gene to a Mendelian phenotype.","evidence":"Patient-derived cells, Western blot, exocytosis assay, and primary cilia immunofluorescence","pmids":["32639540"],"confidence":"Medium","gaps":["Mechanistic link between exocyst function and Arl13b ciliary delivery not resolved","Tissue-specific requirements not dissected"]},{"year":2022,"claim":"Sec5 was implicated in immune polarization through a STAT6 interaction controlling M2 macrophage differentiation and pregnancy maintenance.","evidence":"Co-IP, knockdown/overexpression, co-localization, and heterozygous mouse model","pmids":["36313547"],"confidence":"Medium","gaps":["Direct vs. indirect STAT6 regulation unclear","Whether exocyst trafficking underlies the effect untested"]},{"year":2024,"claim":"Loss-of-function EXOC2 perturbation was shown to lower G4C2 repeat RNA and dipeptide repeat proteins, identifying an unexpected role in regulating expanded-repeat RNA levels in C9ORF72 disease.","evidence":"CRISPR-Cas9 deletion in patient iPSCs, iPSC-derived motor neurons, and antisense oligonucleotide treatment","pmids":["38935506"],"confidence":"Medium","gaps":["Direct vs. indirect control of repeat RNA not established","Mechanism connecting exocyst to RNA levels unknown"]},{"year":2025,"claim":"The NF2 tumor suppressor Merlin was identified as a competitive inhibitor of RalB binding to Sec5 and Exo84, adding a regulatory layer over exocyst-effector engagement.","evidence":"Proximity biotinylation, direct and competitive binding assays, and exocytosis kinetics (preprint)","pmids":["bio_10.1101_2025.06.13.659557"],"confidence":"Low","gaps":["Preprint without orthogonal validation","Physiological context of Merlin competition unclear"]},{"year":null,"claim":"How Sec5 mechanistically switches between its tethering role and its diverse signaling roles (TBK1, GEF-H1, InsP3R, STAT6), and how Ral-effector configuration dictates outcome, remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No structural model of full assembled exocyst with Sec5 in cells","Coordination between membrane tethering and signaling outputs undefined","Mechanism linking exocyst to ciliary cargo and repeat RNA unknown"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0060089","term_label":"molecular transducer activity","supporting_discovery_ids":[0,1,2]},{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[0,8,12,13]},{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[8,13]}],"localization":[{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[3,7,9]},{"term_id":"GO:0031410","term_label":"cytoplasmic vesicle","supporting_discovery_ids":[5,11]},{"term_id":"GO:0005768","term_label":"endosome","supporting_discovery_ids":[4,5]},{"term_id":"GO:0005929","term_label":"cilium","supporting_discovery_ids":[14]}],"pathway":[{"term_id":"R-HSA-5653656","term_label":"Vesicle-mediated transport","supporting_discovery_ids":[3,4,11,14]},{"term_id":"R-HSA-168256","term_label":"Immune System","supporting_discovery_ids":[8,13,15]},{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[8,12,13]}],"complexes":["exocyst"],"partners":["RALA","RALB","EXOC8","TBK1","ARHGEF2","ITPR1","STAT6","NF2"],"other_free_text":[]}},"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":175,"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":123,"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":110,"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":81,"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, 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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":14016,"output_tokens":4965,"usd":0.058262,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":13188,"output_tokens":4552,"usd":0.08987,"stage2_stop_reason":"end_turn"},"total_usd":0.148132,"stage1_batch_id":"msgbatch_01AsR7g8dGTEiEw9U83bJeWn","stage2_batch_id":"msgbatch_01YV5ZyxtFNUZEjxRcpd9jzb","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2003,\n      \"finding\": \"The Ral-binding domain of EXOC2/Sec5 adopts an immunoglobulin-like beta-sandwich (IPT domain) fold and binds RalA in a GTP-dependent manner; crystal structure at 2.1 Å resolution revealed a continuous antiparallel beta-sheet interface, and Sec5 Thr11, Arg27, and RalA Glu38 were shown by isothermal titration calorimetry to be required for complex formation.\",\n      \"method\": \"X-ray crystallography (2.1 Å) plus isothermal titration calorimetry and site-directed mutagenesis\",\n      \"journal\": \"The EMBO journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — crystal structure with mutagenesis validation; independently corroborated by NMR structure in same year\",\n      \"pmids\": [\"12839989\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"The Ral-binding domain of Sec5 folds into an IPT (immunoglobulin superfamily) domain, representing a novel G-protein effector fold; NMR structure and site-directed mutagenesis mapped the Ral-binding surface on Sec5.\",\n      \"method\": \"NMR spectroscopy and site-directed mutagenesis\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — NMR structure with mutagenesis; orthogonal confirmation of crystal structure findings from PMID:12839989\",\n      \"pmids\": [\"12624092\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"Exo84 and Sec5/EXOC2 competitively and mutually exclusively bind active RalA; crystal structure of the RalA–Exo84 complex plus mutagenesis established that the two exocyst subunits share overlapping binding surfaces on RalA, making them competitive effectors.\",\n      \"method\": \"X-ray crystallography plus mutagenesis binding studies and biochemical competition assays\",\n      \"journal\": \"The EMBO journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — crystal structure of competing complex plus mutagenesis demonstrating competition between Sec5 and Exo84\",\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 delivery of newly synthesized membrane proteins (neurite outgrowth, neuromuscular junction expansion), but does not impair synaptic vesicle fusion/neurotransmitter release, demonstrating that Sec5 differentiates between biosynthetic membrane trafficking and regulated exocytosis.\",\n      \"method\": \"Genetic null alleles in Drosophila, membrane trafficking assay, electrophysiology at neuromuscular junction\",\n      \"journal\": \"Neuron\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — clean genetic loss-of-function with two distinct functional readouts (trafficking vs. synaptic transmission) in Drosophila\",\n      \"pmids\": [\"12575951\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"Drosophila Sec5 (EXOC2 ortholog), together with Sec6 and Sec15, is required for trafficking of DE-Cadherin from Rab11-positive recycling endosomes to the plasma membrane in epithelial cells; loss of sec5 causes DE-Cad accumulation in enlarged Rab11 endosomes.\",\n      \"method\": \"Drosophila loss-of-function genetics, immunofluorescence, co-immunoprecipitation of Sec15 with Rab11 and Sec10 with Armadillo\",\n      \"journal\": \"Developmental cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic loss-of-function with defined trafficking phenotype plus Co-IP demonstrating molecular interactions\",\n      \"pmids\": [\"16224820\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"In Drosophila oocytes, Sec5/EXOC2 is unexpectedly present in clathrin-coated pits and vesicles at the plasma membrane; a truncation allele (sec5(E13)) causes defective endocytic recycling of the vitellogenin receptor Yolkless (which accumulates in late endosomal compartments), revealing a role for Sec5 in endocytic recycling in addition to secretory trafficking.\",\n      \"method\": \"Drosophila genetics, immunolocalization, truncation allele analysis\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic allele with defined phenotype in single study; localization data orthogonal to functional data\",\n      \"pmids\": [\"15955846\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"In Drosophila oogenesis, Sec5/EXOC2 is required for directed membrane traffic of the secreted ligand Gurken and the receptor Yolkless; sec5 germline clones show defects in membrane addition, posterior oocyte positioning, dorsal patterning, and egg size, while cytoskeletal orientation remains correct.\",\n      \"method\": \"Drosophila germline clone analysis, immunofluorescence, membrane trafficking assays\",\n      \"journal\": \"Development (Cambridge, England)\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — clean genetic loss-of-function with specific cargo trafficking phenotypes in single study\",\n      \"pmids\": [\"14681190\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"Sec5/EXOC2 is required for Drosophila embryo cellularization: a temperature-sensitive sec5 allele (sec5(ts1)) blocks cleavage furrow invagination and prevents membrane insertion of the zygotic protein Neurotactin; Sec5 concentrates at the apical end of lateral membranes (the major site of membrane addition) during cellularization and later at the sub-apical complex in the polarized epithelium.\",\n      \"method\": \"Temperature-sensitive Drosophila allele, immunofluorescence localization, membrane protein insertion assay\",\n      \"journal\": \"Development (Cambridge, England)\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — conditional allele with defined phenotype and subcellular localization linked to function in single study\",\n      \"pmids\": [\"20630948\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"RalB activation promotes a direct interaction between Sec5/EXOC2 and TBK1, leading to TBK1 kinase activation; this RalB–Sec5–TBK1 complex is required for RalB-dependent cell survival signaling in transformed cells and for innate immune pathway activation upon virus infection.\",\n      \"method\": \"Protein complex co-purification, protein kinase assays, RNAi knockdown, cell transformation and survival assays\",\n      \"journal\": \"Methods in enzymology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — biochemical complex isolation plus kinase assay plus functional RNAi in single study/lab\",\n      \"pmids\": [\"18413258\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"Ral GTPases control the association of Sec5/EXOC2 with paxillin at focal complexes in prostate tumor cells; Ral-uncoupled Sec5 mutants and RNAi knockdown of RalA or RalB disrupted Exocyst–paxillin interaction and shifted Exocyst localization from lateral membranes to protrusive extensions; this Exocyst localization is required for alpha5-integrin delivery to the plasma membrane and for tumor cell motility and matrix invasiveness.\",\n      \"method\": \"RNAi knockdown, Ral-uncoupled Sec5 mutant overexpression, co-purification, immunofluorescence, cell motility/invasion assays\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple orthogonal methods (RNAi, dominant-negative mutants, co-purification, functional invasion assay) in single study\",\n      \"pmids\": [\"18697830\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"DelGEF (a RanGEF homologue) binds the human Sec5/EXOC2 protein; interaction is Mg2+-dependent and stimulated by GTP or dCTP; knockdown of DelGEF increases extracellular secretion of proteoglycans, implicating the DelGEF–Sec5 interaction in the secretion process.\",\n      \"method\": \"Yeast two-hybrid screen, biochemical binding assay, siRNA knockdown with secretion assay\",\n      \"journal\": \"FEBS letters\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — yeast two-hybrid identification plus single knockdown experiment; limited mechanistic follow-up\",\n      \"pmids\": [\"12459492\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"Sec5/EXOC2 regulates exocytosis of newcomer insulin granules in pancreatic beta cells; Sec5 localizes to insulin granules, and siRNA-mediated knockdown in INS-1 cells selectively impairs recruitment and exocytosis of newcomer granules (which minimally dock at the plasma membrane) and mobilization of reserve-pool granules, while having little effect on predocked granules.\",\n      \"method\": \"siRNA knockdown, patch-clamp membrane capacitance measurement, total internal reflection fluorescence (TIRF) microscopy\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — two orthogonal functional methods (capacitance + TIRF) with compartment-specific phenotype in single study\",\n      \"pmids\": [\"23844030\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"Dexamethasone-induced SGK1 expression promotes interaction between Sec5/EXOC2 and GEF-H1 (a microtubule-regulated RhoA activator); this Sec5–GEF-H1 interaction is required for GEF-H1 targeting to focal adhesion sites and for dexamethasone-induced cellular tension, fibronectin fibril formation, and integrin-mediated attachment in mesenchymal stem cells.\",\n      \"method\": \"Co-immunoprecipitation, dominant-negative disruption of Sec5–GEF-H1 interaction, cellular tension measurements, immunofluorescence\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP plus functional disruption with specific phenotypic readout; single lab\",\n      \"pmids\": [\"26359301\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"During Candida albicans phagocytosis, SEC5/EXOC2 binds the C-terminal α-helix (H1) of the inositol trisphosphate receptor (InsP3R) on phagosomes, promoting InsP3R channel activity and cytosolic Ca2+ elevation; disruption of this interaction with recombinant H1 peptides attenuates Ca2+ elevation and impairs phagocytosis; additionally, the InsP3R–SEC5 complex 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, IRF-3 phosphorylation assay\",\n      \"journal\": \"BMC biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple orthogonal methods including functional disruption with defined molecular interface; single lab\",\n      \"pmids\": [\"29703257\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"Pathogenic truncating variants in EXOC2 cause nonsense-mediated decay of EXOC2 transcript, undetectable EXOC2 protein, severe reduction in exocytosis and vesicle fusion in patient cells, and defective Arl13b localization to the primary cilium, establishing EXOC2 as essential for neuronal vesicle trafficking and ciliogenesis in humans.\",\n      \"method\": \"Patient-derived cell lines, Western blot, exocytosis assay, immunofluorescence of primary cilia, molecular genetics\",\n      \"journal\": \"The Journal of experimental medicine\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — human loss-of-function variants with defined molecular and cellular phenotypes; multiple patient families; single study\",\n      \"pmids\": [\"32639540\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"SEC5/EXOC2 interacts with STAT6 in macrophages; SEC5 knockdown reduces STAT6 phosphorylation and M2 macrophage polarization, while overexpression promotes them; pSTAT6 and SEC5 co-localize, and SEC5 deficiency in mouse decidual macrophages leads to impaired M2 polarization and pregnancy loss.\",\n      \"method\": \"Co-immunoprecipitation, shRNA knockdown, overexpression, immunofluorescence co-localization, mouse heterozygous knockout model\",\n      \"journal\": \"Frontiers in cell and developmental biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP with functional knockdown/overexpression and in vivo mouse model; single lab\",\n      \"pmids\": [\"36313547\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"SEC5/EXOC2 knockdown in trophoblast (HTR-8/SVneo) cells reduces plasma membrane distribution of integrin β1, attenuates InsP3R-mediated cytosolic Ca2+ elevation upon serum stimulation, disrupts F-actin stress fibers, and inhibits cell migration and invasion, placing SEC5 upstream of an integrin/Ca2+/cytoskeleton axis.\",\n      \"method\": \"shRNA knockdown, Ca2+ imaging, BAPTA-AM chelation, immunofluorescence, Matrigel invasion assay\",\n      \"journal\": \"Reproduction (Cambridge, England)\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single lab, knockdown with multiple readouts but limited mechanistic resolution of direct vs. indirect effects\",\n      \"pmids\": [\"31705793\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"RalA binding to Sec5/EXOC2 and Exo84 mediates distinct aspects of cell polarization; blocking RalA–Exocyst interactions causes morphological changes and defects in migration and invasion of prostate cancer cells.\",\n      \"method\": \"RalA effector mutants, RNAi, cell migration and invasion assays\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — functional mutant analysis with migration assay; limited molecular resolution of Sec5-specific mechanism\",\n      \"pmids\": [\"22761837\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"CRISPR-Cas9 deletion of EXOC2 in C9ORF72-ALS/FTD iPSCs (yielding truncated EXOC2 with partial exocyst function) rescues disease phenotypes by decreasing levels of dipeptide repeat (DPR) proteins and G4C2 repeat-containing RNA, indicating that EXOC2 directly or indirectly regulates G4C2 repeat RNA levels; EXOC2 antisense oligonucleotide treatment in differentiated neurons also decreased expanded G4C2 RNA.\",\n      \"method\": \"CRISPR-Cas9 deletion in patient iPSCs, iPSC-derived motor neurons, antisense oligonucleotide treatment, DPR protein and RNA quantification\",\n      \"journal\": \"Cell reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — two orthogonal loss-of-function approaches (CRISPR and ASO) with consistent phenotypic rescue; single study\",\n      \"pmids\": [\"38935506\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"Active Merlin (NF2 tumor suppressor) competitively inhibits RalB binding to its exocyst effectors Sec5/EXOC2 and Exo84, and Merlin 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.\",\n      \"method\": \"Proximity biotinylation, direct binding assays, competitive binding assays, exocytosis kinetics assay\",\n      \"journal\": \"bioRxiv\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — preprint, single lab, competitive binding with functional exocytosis assay but limited orthogonal validation\",\n      \"pmids\": [\"bio_10.1101_2025.06.13.659557\"],\n      \"is_preprint\": true\n    }\n  ],\n  \"current_model\": \"EXOC2/Sec5 is a core subunit of the octameric exocyst complex that tethers secretory vesicles to specific plasma membrane sites for polarized exocytosis; its Ral-binding domain (IPT/immunoglobulin-like fold) directly binds active RalA/RalB in a GTP-dependent manner (competing with Exo84), linking upstream Ral GTPase signaling to exocyst assembly and targeting; Sec5 mediates biosynthetic membrane trafficking and recycling endosome-to-plasma membrane delivery (including E-Cadherin and integrins) but is dispensable for regulated synaptic vesicle fusion; it also forms a RalB-dependent complex with TBK1 to activate innate immune signaling, interacts with InsP3R on phagosomes to promote Ca2+ elevation, interacts with GEF-H1 to regulate RhoA activity and cytoskeletal tension, and is essential for human brain development and primary ciliogenesis (Arl13b localization).\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"EXOC2/Sec5 is a core subunit of the octameric exocyst complex that tethers vesicles to the plasma membrane for polarized membrane trafficking, and it serves as a direct effector that couples Ral GTPase signaling to vesicle delivery [#0, #3]. Its Ral-binding domain adopts an immunoglobulin-like (IPT) beta-sandwich fold that binds RalA in a GTP-dependent manner through a continuous antiparallel beta-sheet interface, a binding mode mutually exclusive with the other exocyst Ral effector Exo84 [#0, #1, #2]. Through this activity Sec5 directs biosynthetic delivery of newly synthesized membrane proteins and recycling-endosome cargo — including E-Cadherin, integrins, and secreted ligands — to specific membrane sites, while being dispensable for regulated synaptic vesicle fusion, establishing it as a selective tether for biosynthetic versus regulated exocytosis [#3, #4, #9]. Beyond trafficking, Sec5 acts as a signaling node: RalB-dependent assembly of a Sec5–TBK1 complex activates TBK1 kinase to drive cell-survival and innate immune signaling [#8], Sec5 binds GEF-H1 to control RhoA-dependent cytoskeletal tension and integrin-mediated attachment [#12], and it binds the InsP3 receptor on phagosomes to promote Ca2+ elevation and TBK1/IRF-3–dependent interferon responses during phagocytosis [#13]. In humans, biallelic truncating EXOC2 variants abolish protein expression, severely impair exocytosis, and disrupt Arl13b localization to the primary cilium, defining EXOC2 as essential for neuronal vesicle trafficking, ciliogenesis, and brain development [#14].\",\n  \"teleology\": [\n    {\n      \"year\": 2003,\n      \"claim\": \"Structural and biochemical work answered how Sec5 physically connects to upstream Ral signaling, establishing it as a direct GTP-dependent RalA effector via a novel domain fold.\",\n      \"evidence\": \"X-ray crystallography at 2.1 Å, NMR, isothermal titration calorimetry, and site-directed mutagenesis of the Sec5 Ral-binding domain\",\n      \"pmids\": [\"12839989\", \"12624092\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not establish how Ral binding alters exocyst assembly or membrane targeting in cells\", \"Affinity and competition with other Ral effectors not yet resolved\"]\n    },\n    {\n      \"year\": 2003,\n      \"claim\": \"Drosophila genetics resolved which class of exocytosis Sec5 governs, showing it is required for biosynthetic membrane addition but not for regulated synaptic vesicle fusion.\",\n      \"evidence\": \"Null alleles in Drosophila with membrane trafficking assays and neuromuscular junction electrophysiology\",\n      \"pmids\": [\"12575951\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular basis for distinguishing biosynthetic from regulated vesicles not defined\", \"Mammalian generality not tested in this study\"]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"Crystallography of the competing RalA–Exo84 complex established that Sec5 and Exo84 are mutually exclusive Ral effectors, implying Ral switches between distinct exocyst configurations.\",\n      \"evidence\": \"X-ray crystallography of RalA–Exo84 plus mutagenesis and biochemical competition assays\",\n      \"pmids\": [\"15920473\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Functional consequence of the Sec5-bound versus Exo84-bound state in vivo not resolved\", \"Regulation of the switch between effectors unknown\"]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"Genetic studies defined the cargo and compartment specificity of Sec5-dependent trafficking, linking it to recycling-endosome-to-membrane delivery and endocytic recycling.\",\n      \"evidence\": \"Drosophila loss-of-function and truncation alleles, immunolocalization, and Co-IP of exocyst subunits with Rab11 and cargo\",\n      \"pmids\": [\"16224820\", \"15955846\", \"14681190\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct vs. indirect role in endocytic recycling not separated from secretory role\", \"Mammalian cargo specificity not addressed\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Conditional alleles tied Sec5 localization to sites of active membrane addition, showing it is required for cleavage-furrow membrane insertion during cellularization.\",\n      \"evidence\": \"Temperature-sensitive Drosophila allele with immunofluorescence and membrane protein insertion assays\",\n      \"pmids\": [\"20630948\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Recruitment mechanism to apical/sub-apical sites not defined\", \"Identity of the targeting cue unknown\"]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Biochemical and functional studies revealed a signaling role beyond tethering, with RalB driving a Sec5–TBK1 complex that activates kinase signaling for survival and innate immunity.\",\n      \"evidence\": \"Complex co-purification, kinase assays, and RNAi in transformed cells\",\n      \"pmids\": [\"18413258\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether full exocyst or free Sec5 mediates TBK1 binding unclear\", \"Structural basis of Sec5–TBK1 interaction not determined\"]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Ral control of Sec5 localization was linked to integrin delivery and tumor invasion, connecting exocyst targeting to cell motility.\",\n      \"evidence\": \"RNAi, Ral-uncoupled Sec5 mutants, co-purification, and motility/invasion assays in prostate tumor cells\",\n      \"pmids\": [\"18697830\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct paxillin binding partner within exocyst not defined\", \"Mechanism of localization switch to protrusions unresolved\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"RalA effector partitioning between Sec5 and Exo84 was tied to distinct aspects of polarized migration and invasion.\",\n      \"evidence\": \"RalA effector mutants, RNAi, and migration/invasion assays\",\n      \"pmids\": [\"22761837\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"Limited resolution of Sec5-specific mechanism vs. Exo84\", \"Direct molecular readout absent\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"TIRF and capacitance measurements refined Sec5's exocytic role to recruitment of newcomer and reserve-pool granules rather than predocked vesicles.\",\n      \"evidence\": \"siRNA, patch-clamp capacitance, and TIRF microscopy in INS-1 beta cells\",\n      \"pmids\": [\"23844030\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Molecular step distinguishing newcomer from predocked granules unclear\", \"Generalizability beyond beta cells untested\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"A Sec5–GEF-H1 interaction was identified as the link between exocyst and RhoA-driven cytoskeletal tension and adhesion.\",\n      \"evidence\": \"Co-IP, dominant-negative disruption, and cellular tension/attachment assays in mesenchymal stem cells\",\n      \"pmids\": [\"26359301\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct vs. complex-mediated Sec5–GEF-H1 binding not resolved\", \"Single lab/cell type\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Sec5 was shown to bind the InsP3R on phagosomes via a defined helix, coupling phagocytosis to Ca2+ signaling and TBK1/IRF-3-driven interferon responses.\",\n      \"evidence\": \"Co-IP, Ca2+ imaging, recombinant peptide disruption, phagocytosis and IRF-3 phosphorylation assays\",\n      \"pmids\": [\"29703257\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether exocyst tethering and InsP3R binding are coordinated unclear\", \"Single-lab interface mapping\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Human loss-of-function variants established EXOC2 as essential for exocytosis, ciliogenesis, and brain development, anchoring the gene to a Mendelian phenotype.\",\n      \"evidence\": \"Patient-derived cells, Western blot, exocytosis assay, and primary cilia immunofluorescence\",\n      \"pmids\": [\"32639540\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanistic link between exocyst function and Arl13b ciliary delivery not resolved\", \"Tissue-specific requirements not dissected\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Sec5 was implicated in immune polarization through a STAT6 interaction controlling M2 macrophage differentiation and pregnancy maintenance.\",\n      \"evidence\": \"Co-IP, knockdown/overexpression, co-localization, and heterozygous mouse model\",\n      \"pmids\": [\"36313547\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct vs. indirect STAT6 regulation unclear\", \"Whether exocyst trafficking underlies the effect untested\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Loss-of-function EXOC2 perturbation was shown to lower G4C2 repeat RNA and dipeptide repeat proteins, identifying an unexpected role in regulating expanded-repeat RNA levels in C9ORF72 disease.\",\n      \"evidence\": \"CRISPR-Cas9 deletion in patient iPSCs, iPSC-derived motor neurons, and antisense oligonucleotide treatment\",\n      \"pmids\": [\"38935506\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct vs. indirect control of repeat RNA not established\", \"Mechanism connecting exocyst to RNA levels unknown\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"The NF2 tumor suppressor Merlin was identified as a competitive inhibitor of RalB binding to Sec5 and Exo84, adding a regulatory layer over exocyst-effector engagement.\",\n      \"evidence\": \"Proximity biotinylation, direct and competitive binding assays, and exocytosis kinetics (preprint)\",\n      \"pmids\": [\"bio_10.1101_2025.06.13.659557\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"Preprint without orthogonal validation\", \"Physiological context of Merlin competition unclear\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How Sec5 mechanistically switches between its tethering role and its diverse signaling roles (TBK1, GEF-H1, InsP3R, STAT6), and how Ral-effector configuration dictates outcome, remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No structural model of full assembled exocyst with Sec5 in cells\", \"Coordination between membrane tethering and signaling outputs undefined\", \"Mechanism linking exocyst to ciliary cargo and repeat RNA unknown\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0060089\", \"supporting_discovery_ids\": [0, 1, 2]},\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [0, 8, 12, 13]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [8, 13]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [3, 7, 9]},\n      {\"term_id\": \"GO:0031410\", \"supporting_discovery_ids\": [5, 11]},\n      {\"term_id\": \"GO:0005768\", \"supporting_discovery_ids\": [4, 5]},\n      {\"term_id\": \"GO:0005929\", \"supporting_discovery_ids\": [14]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-5653656\", \"supporting_discovery_ids\": [3, 4, 11, 14]},\n      {\"term_id\": \"R-HSA-168256\", \"supporting_discovery_ids\": [8, 13, 15]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [8, 12, 13]}\n    ],\n    \"complexes\": [\"exocyst\"],\n    \"partners\": [\"RALA\", \"RALB\", \"EXOC8\", \"TBK1\", \"ARHGEF2\", \"ITPR1\", \"STAT6\", \"NF2\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":5,"faith_total":5,"faith_pct":100.0}}