{"gene":"DOC2B","run_date":"2026-06-09T23:54:42","timeline":{"discoveries":[{"year":2010,"finding":"DOC2B acts as a high-affinity Ca2+ sensor for spontaneous neurotransmitter release. Doc2 proteins are cytosolic but function analogously to synaptotagmin-1, binding SNARE complexes in competition with synaptotagmin-1 and triggering spontaneous vesicle fusion with higher Ca2+ sensitivity than synaptotagmin-1.","method":"Biochemical binding assays (SNARE competition), electrophysiology in neurons, knockout mouse analysis","journal":"Science","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal binding assays, KO mice with defined phenotype, replicated across multiple methods in a high-impact study","pmids":["20150444"],"is_preprint":false},{"year":2008,"finding":"The C2A domain of DOC2B interacts directly with the plasma membrane in a calcium-dependent manner. DOC2B acts as a priming factor, increasing the number of fusion-competent vesicles, must translocate to the plasma membrane to exert its effect, and interacts with plasma membrane SNAREs to affect fusion pore kinetics during catecholamine secretion.","method":"Biochemical and biophysical measurements, electrophysiology, TIRF microscopy, morphological analysis","journal":"The Journal of Neuroscience","confidence":"High","confidence_rationale":"Tier 2 / Moderate — multiple orthogonal methods (biochemical, electrophysiological, imaging) in a single study","pmids":["18596155"],"is_preprint":false},{"year":2008,"finding":"DOC2B directly associates with syntaxin-4 in an intracellular Ca2+-dependent manner and is essential for GLUT4 vesicle fusion in adipocytes. DOC2B translocates to the plasma membrane upon insulin stimulation, and Ca2+-binding domain mutants or DOC2B knockdown inhibit insulin-stimulated glucose uptake.","method":"Yeast two-hybrid screening, immunoprecipitation, GST pull-down, confocal microscopy, GLUT4 externalization assay, glucose uptake measurement, siRNA knockdown","journal":"Diabetes","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal Co-IP, GST pulldown, functional KD and OE with defined cellular phenotype, multiple orthogonal methods","pmids":["19033398"],"is_preprint":false},{"year":2004,"finding":"A rise in intracellular Ca2+ is sufficient for Munc13-independent recruitment of DOC2B to the target membrane. Purified DOC2B binds phospholipids in a Ca2+-dependent manner via its C2 domain, and Ca2+-induced translocation occurs in neurons within 5 seconds of depolarization.","method":"Phospholipid binding assay with purified protein, live-cell fluorescence imaging (EGFP-DOC2B in neurons), Ca2+-dependent translocation assays","journal":"The Journal of Biological Chemistry","confidence":"High","confidence_rationale":"Tier 2 / Moderate — in vitro phospholipid binding with purified protein plus live-cell imaging, two orthogonal methods","pmids":["15033971"],"is_preprint":false},{"year":2013,"finding":"Doc2b binds GLUT4 exocytic SNAREs and potently accelerates SNARE-dependent fusion kinetics in a Ca2+-dependent manner. Ca2+-binding sites on both C2A and C2B domains are required. Doc2b strongly bends membrane bilayers, and this membrane-bending activity is essential for its stimulatory function in GLUT4 vesicle fusion.","method":"Reconstituted proteoliposome SNARE-dependent fusion assay, electron microscopy for membrane bending, site-directed mutagenesis of Ca2+-binding sites","journal":"Molecular Biology of the Cell","confidence":"High","confidence_rationale":"Tier 1 / Moderate — in vitro reconstitution with defined components, mutagenesis, electron microscopy, multiple orthogonal methods in one study","pmids":["23427263"],"is_preprint":false},{"year":2013,"finding":"Crystal structures of the isolated C2A and C2B domains of DOC2B were determined, and small-angle X-ray scattering characterized the solution structure of the tandem C2AB domain. C2B binds Ca2+ with considerably higher affinity than C2A. In cells, isolated C2B translocates to the plasma membrane with an EC50 of ~400 nM while C2A does not translocate at submicromolar Ca2+. C2A enhances the interaction of C2AB with the plasma membrane but C2B is the primary Ca2+ sensing unit.","method":"X-ray crystallography of C2A and C2B domains, SAXS of C2AB, Ca2+ binding kinetics, live-cell imaging of domain translocation","journal":"Journal of Molecular Biology","confidence":"High","confidence_rationale":"Tier 1 / Moderate — crystal structures plus functional validation by live-cell imaging and kinetics, multiple orthogonal methods","pmids":["23994332"],"is_preprint":false},{"year":2012,"finding":"Doc2b is required for both phases of glucose-stimulated insulin secretion and for insulin-stimulated GLUT4 vesicle translocation in skeletal muscle. Doc2b deficiency impairs Munc18c-syntaxin 4 dissociation and SNARE complex assembly. Doc2b acts as a positive regulator of Munc18c-syntaxin 4-mediated exocytosis in vivo.","method":"Doc2b heterozygous and homozygous knockout mice, in vivo glucose/insulin tolerance tests, ex vivo islet insulin secretion, skeletal muscle GLUT4 translocation assay, SNARE complex assembly assay","journal":"Diabetes","confidence":"High","confidence_rationale":"Tier 2 / Strong — KO mice with multiple defined phenotypic readouts and biochemical mechanism, replicated across tissues","pmids":["22698913"],"is_preprint":false},{"year":2015,"finding":"The C2AB domain of Doc2b directly induces membrane hemifusion in a Ca2+- and phosphatidylserine-dependent manner in a cell-free system. Doc2b-coated membrane stalks between SNARE-free synthetic membranes resist forces up to 600 pN. Phospholipid but not content mixing occurs, confirming hemifusion rather than full fusion.","method":"Optical tweezers with SNARE-free synthetic membrane beads, real-time fluorescence imaging for lipid/content mixing","journal":"Nature Communications","confidence":"High","confidence_rationale":"Tier 1 / Moderate — cell-free reconstitution with defined components, direct biophysical measurement, fluorescence imaging confirmation","pmids":["26395669"],"is_preprint":false},{"year":2017,"finding":"Doc2B plays distinct roles in two sequential vesicle priming steps in chromaffin cells. Mutating Ca2+-coordinating aspartates in C2A renders an upstream priming step Ca2+-independent. A downstream priming function depends on SNARE-binding, Ca2+-binding to C2B, interaction with ubMunc13-2, and the presence of synaptotagmin-1. A separate inhibitory function during sustained Ca2+ elevations depends on the MID-domain.","method":"Site-directed mutagenesis of Ca2+-coordinating residues, overexpression and knockdown in mouse adrenal chromaffin cells, electrophysiological exocytosis measurements, genetic epistasis with Munc13-2 and synaptotagmin-1","journal":"eLife","confidence":"High","confidence_rationale":"Tier 2 / Strong — mutagenesis, epistasis with multiple proteins, electrophysiological readout, multiple orthogonal approaches","pmids":["29274147"],"is_preprint":false},{"year":2009,"finding":"DOC2b associates with insulin vesicles and translocates to the plasma membrane upon glucose stimulation, then interacts specifically with syntaxin-4 (not syntaxin-1). DOC2b knockdown inhibits second-phase insulin secretion without affecting first-phase secretion; DOC2b overexpression enhances glucose-stimulated insulin secretion.","method":"Immunoprecipitation, subcellular fractionation/localization, siRNA knockdown, overexpression in MIN6 cells, insulin secretion assays","journal":"Biochemical and Biophysical Research Communications","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP for binding specificity, KD and OE with defined secretion phenotype, single lab","pmids":["19410553"],"is_preprint":false},{"year":2013,"finding":"Doc2b synchronizes exocytosis in chromaffin cells by augmenting the readily releasable pool (RRP) and inhibiting the sustained release component. In the absence of Doc2b, RRP refilling is faster but incomplete, leading to premature fusion. Doc2b inhibits vesicle priming during prolonged calcium elevations to protect unprimed vesicles and favor synchronized release.","method":"Doc2b knockout mice, high temporal resolution electrophysiological capacitance measurements, electron microscopy of vesicle pools, Doc2b overexpression","journal":"The Journal of Neuroscience","confidence":"High","confidence_rationale":"Tier 2 / Strong — KO and OE with high-resolution electrophysiology and EM, multiple orthogonal approaches","pmids":["24133251"],"is_preprint":false},{"year":2013,"finding":"Munc13-1 translocates to the plasma membrane in a Doc2B- and Ca2+-dependent manner in PC12 cells. Munc13-1 co-translocation requires its interaction with Doc2B and depends on diacylglycerol for accumulation. Doc2B dislocates from the membrane faster than Munc13-1 upon Ca2+ removal.","method":"Fluorescence live-cell imaging of co-expressed fluorescent-tagged proteins in PC12 cells, Munc13-1(H567K) DAG-binding mutant analysis","journal":"Frontiers in Endocrinology","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — live imaging with mutagenesis, single lab, two orthogonal approaches","pmids":["24062723"],"is_preprint":false},{"year":2014,"finding":"Doc2b serves as a scaffolding platform in pancreatic β-cells that simultaneously binds Munc18-1 (via C2A) and Munc18c (via C2B) to form a macromolecular complex. Doc2b bridges the interaction between Munc18c and Munc18-1; these two proteins fail to associate in the absence of Doc2b. This scaffold function supports both phases of glucose-stimulated insulin secretion.","method":"Co-immunoprecipitation from β-cells, in vitro GST-Doc2b interaction/competition assays, domain mapping","journal":"The Biochemical Journal","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reciprocal Co-IP and in vitro GST pulldown competition assay, single lab","pmids":["25190515"],"is_preprint":false},{"year":2005,"finding":"The Ca2+ concentration threshold for DOC2B translocation to the plasma membrane in cultured neurons is approximately 200 nM in the bulk cytoplasm. Translocation rate is slower than Ca2+ elevation rate, while detachment from the membrane is faster than Ca2+ removal. The extent of translocation reflects local submembrane Ca2+ concentration.","method":"Live-cell imaging of EGFP-DOC2B in Aplysia neurons with simultaneous Ca2+ imaging","journal":"Cell Calcium","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct live imaging with Ca2+ concentration measurement, single lab","pmids":["16305808"],"is_preprint":false},{"year":2014,"finding":"Doc2b enrichment enhances syntaxin-4-SNARE complex formation in skeletal muscle cells and increases insulin-stimulated GLUT4 vesicle accumulation at the cell surface, improving glucose tolerance and peripheral insulin sensitivity in transgenic mice overexpressing Doc2b.","method":"Tetracycline-repressible transgenic mice overexpressing Doc2b, SNARE complex assays, GLUT4 translocation assay, glucose/insulin tolerance tests","journal":"Diabetologia","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — transgenic mouse model with biochemical SNARE complex analysis and GLUT4 translocation, single lab","pmids":["24705606"],"is_preprint":false},{"year":2019,"finding":"DOC2B is phosphorylated on tyrosine (Y301) upon insulin stimulation in skeletal muscle cells, enhancing its interaction with kinesin light chain 1 (KLC1). Mutation of Y301 blocks insulin-stimulated DOC2B phosphorylation, reduces DOC2B-KLC1 interaction, and impairs insulin-stimulated GLUT4 accumulation at the plasma membrane.","method":"Co-immunoprecipitation, mass spectrometry, site-directed mutagenesis of Y301, GLUT4 translocation assays, skeletal-muscle-specific transgenic mice","journal":"Diabetologia","confidence":"High","confidence_rationale":"Tier 2 / Moderate — Co-IP, MS identification of interaction, mutagenesis with functional readout, in vitro and in vivo corroboration","pmids":["30707251"],"is_preprint":false},{"year":2019,"finding":"Syt1 and Doc2b exhibit distinct membrane-remodeling mechanisms. Both Syt1 C2AB and Doc2b C2AB can induce hemifusion of SNARE-free membranes and reduce the membrane-bending modulus in a Ca2+-dependent manner, but Doc2b is more effective when both membranes are loaded, whereas Syt1 is more effective with single-membrane loading. Significantly higher Syt1 concentrations are required for hemifusion than Doc2b.","method":"Optical tweezers with synthetic membranes, lipid-mixing confocal assay, AFM membrane-bending modulus measurement","journal":"Biophysical Journal","confidence":"Medium","confidence_rationale":"Tier 1 / Moderate — cell-free reconstitution with biophysical methods, single lab, multiple orthogonal approaches","pmids":["31952804"],"is_preprint":false},{"year":2022,"finding":"DOC2b is tyrosine-phosphorylated at Y301 within 2 minutes of glucose stimulation in β-cells, mediated by the Src family kinase YES. Y301 phosphorylation is required for DOC2b's interaction with YES kinase, increased VAMP2 at the plasma membrane, and enhanced glucose-stimulated insulin secretion. Tyrosine-phosphorylated DOC2b also increases ERM protein activation; ERM knockdown impairs DOC2b-mediated GSIS.","method":"Biochemical analysis of human islets and clonal β-cells, co-immunoprecipitation, site-directed mutagenesis of Y301, VAMP2 plasma membrane localization assay, ERM knockdown","journal":"Diabetes","confidence":"High","confidence_rationale":"Tier 2 / Moderate — Co-IP with kinase identification, mutagenesis, functional KD, multiple orthogonal methods in one study","pmids":["35377441"],"is_preprint":false},{"year":2021,"finding":"DOC2B inhibits EMT and promotes cellular senescence in cervical cancer cells via a calcium-dependent process. DOC2B interacts with CDH1 in a calcium-dependent manner, and this interaction is associated with suppression of EMT and induction of senescence.","method":"DOC2B overexpression and knockdown, calcium chelation, co-immunoprecipitation of DOC2B with CDH1, in vivo xenograft model","journal":"Cell Biology and Toxicology","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — Co-IP for CDH1 interaction, KD/OE with multiple phenotypic readouts, single lab","pmids":["33758996"],"is_preprint":false},{"year":2022,"finding":"DOC2B negatively regulates Wnt/β-catenin signaling by enhancing expression of components of the CTNNB1 destruction complex and promoting proteasomal degradation of CTNNB1 in a GSK3β-independent manner. DOC2B upregulates DKK1, and DKK1 inhibition reactivates Wnt/β-catenin signaling and reverses DOC2B-induced senescence and anti-tumor effects.","method":"DOC2B overexpression and knockdown, β-catenin protein assays, proteasome inhibitor studies, DKK1 pharmacological inhibition (WAY262611)","journal":"Pharmacological Research","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple biochemical assays and pharmacological intervention, single lab","pmids":["35500882"],"is_preprint":false},{"year":2023,"finding":"DOC2B is localized to mitochondria and induces Ca2+-mediated lipotoxicity in cervical cancer cells. DOC2B expression causes mitochondrial morphological changes, reduces mitochondrial DNA copy number, membrane potential, and complex-IV activity, and elevates intracellular Ca2+, ROS, and lipid peroxidation. These effects are Ca2+-dependent.","method":"DOC2B overexpression and knockdown, mitochondrial fractionation/localization assays, mitochondrial functional assays, Ca2+ chelation, lipid peroxidation assays","journal":"Free Radical Biology and Medicine","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — localization by fractionation with functional consequence, multiple cellular assays, single lab","pmids":["36913987"],"is_preprint":false},{"year":2025,"finding":"DOC2b enrichment attenuates cytokine-induced CXCL10 expression in β-cells and human islets by reducing IKKβ activation, reducing NF-κB p65 levels, and reducing STAT-1 activation. IKKβ, NF-κB p65, and STAT-1 physically associate with DOC2b in cytokine-challenged β-cells. DOC2b also prevents ER-stress-IKKβ and STAT-1 crosstalk.","method":"Co-immunoprecipitation, DOC2b enrichment/depletion in human islets and β-cell lines, qPCR, proteomics, immunoconfocal microscopy","journal":"Metabolism: Clinical and Experimental","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — Co-IP for protein associations, OE/KD with functional readouts, single lab","pmids":["39805534"],"is_preprint":false},{"year":2020,"finding":"Loss of Doc2b does not influence spontaneous neurotransmitter release, synaptic strength, evoked release time course, responses to sustained high-frequency stimulation, or short-term plasticity at mature Purkinje cell-to-deep cerebellar nuclei synapses under physiological conditions, despite Doc2b being the sole Doc2 isoform expressed in Purkinje cells.","method":"Doc2b knockout mice, electrophysiological recordings at PC-to-DCN synapses in acute cerebellar slices","journal":"eLife","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — KO mice with comprehensive electrophysiology; NEGATIVE result at a specific synapse type, single lab","pmids":["32347796"],"is_preprint":false},{"year":2023,"finding":"DOC2B enrichment in skeletal muscle cells prevents palmitate-induced cofilin phosphorylation, preserves insulin- and β2-adrenergic receptor-stimulated GLUT4 trafficking to the plasma membrane, and rescues glucose uptake under lipotoxic conditions.","method":"DOC2B overexpression in rat L6 skeletal muscle cells, GLUT4 translocation assay, cofilin phosphorylation assay, glucose uptake measurement under palmitate stress","journal":"International Journal of Molecular Sciences","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single lab, OE with cellular phenotype readout, no defined direct molecular mechanism for cofilin regulation","pmids":["38203312"],"is_preprint":false}],"current_model":"DOC2B is a cytosolic, high-affinity Ca2+ sensor with tandem C2 domains (C2B being the primary Ca2+-binding unit) that undergoes Ca2+- and phosphatidylserine-dependent translocation to the plasma membrane, where it promotes spontaneous and asynchronous neurotransmitter release by binding SNARE complexes in competition with synaptotagmin-1, induces membrane hemifusion and curvature, acts as a priming factor that scaffolds Munc18 isoforms and recruits Munc13-1, and in non-neuronal tissues (pancreatic β-cells, skeletal muscle, adipocytes) drives insulin granule and GLUT4 vesicle exocytosis through Ca2+-dependent syntaxin-4 binding and insulin-stimulated Y301 phosphorylation-dependent interaction with KLC1 for vesicle transport."},"narrative":{"mechanistic_narrative":"DOC2B is a cytosolic, high-affinity Ca2+ sensor built from tandem C2 domains that couples intracellular Ca2+ rises to regulated vesicle exocytosis in both neuronal and metabolic tissues [PMID:20150444, PMID:15033971]. A Ca2+ rise alone is sufficient to drive Munc13-independent translocation of DOC2B to the plasma membrane, where its C2 domains bind phospholipids in a Ca2+-dependent manner with a translocation threshold of ~200 nM; structural and domain-dissection work establishes C2B as the primary high-affinity Ca2+-sensing unit, with C2A enhancing membrane engagement [PMID:15033971, PMID:23994332, PMID:16305808]. At the membrane DOC2B acts as a Ca2+ sensor for spontaneous and asynchronous release, binding SNARE complexes in competition with synaptotagmin-1, and functions as a priming factor that augments the readily releasable pool while inhibiting sustained release to favor synchronized fusion [PMID:20150444, PMID:18596155, PMID:24133251]. Biophysically, its C2AB module directly bends membrane bilayers and drives Ca2+- and phosphatidylserine-dependent hemifusion of SNARE-free membranes, an activity essential for its stimulatory role in fusion [PMID:23427263, PMID:26395669]. DOC2B also serves as a scaffold that bridges Munc18 isoforms and recruits Munc13-1 to the membrane in a Ca2+-dependent manner, organizing the priming machinery [PMID:24062723, PMID:25190515]. In non-neuronal tissues DOC2B drives insulin-granule and GLUT4-vesicle exocytosis through Ca2+-dependent binding to syntaxin-4 and promotion of Munc18c–syntaxin-4 dissociation and SNARE assembly, and insulin/glucose stimulation triggers Src-family-kinase (YES)-mediated Y301 tyrosine phosphorylation that recruits kinesin light chain 1 and supports vesicle trafficking [PMID:19033398, PMID:22698913, PMID:30707251, PMID:35377441]. Distinct from its exocytic role, DOC2B has Ca2+-dependent tumor-suppressive activity in cervical cancer, interacting with CDH1, antagonizing Wnt/β-catenin signaling, and inducing mitochondrial dysfunction and senescence [PMID:33758996, PMID:35500882, PMID:36913987].","teleology":[{"year":2004,"claim":"Established that DOC2B is intrinsically Ca2+-responsive, answering whether its membrane recruitment requires partner proteins or follows directly from Ca2+ binding.","evidence":"Phospholipid binding with purified protein and live-cell imaging of EGFP-DOC2B translocation in neurons","pmids":["15033971"],"confidence":"High","gaps":["Did not resolve which C2 domain provides the dominant Ca2+ sensitivity","Lipid specificity of the Ca2+-dependent interaction not defined"]},{"year":2005,"claim":"Quantified the Ca2+ threshold and kinetics of DOC2B membrane translocation, defining it as a sensor reporting local submembrane Ca2+.","evidence":"Live-cell EGFP-DOC2B imaging with simultaneous Ca2+ imaging in Aplysia neurons","pmids":["16305808"],"confidence":"Medium","gaps":["Bulk vs. true submembrane Ca2+ values not directly reconciled","Functional consequence of translocation kinetics on release not measured here"]},{"year":2008,"claim":"Linked DOC2B membrane translocation to vesicle priming and fusion-pore control, and extended its role beyond neurons to insulin-stimulated GLUT4 exocytosis via Ca2+-dependent syntaxin-4 binding.","evidence":"Electrophysiology/TIRF in secretory cells and yeast two-hybrid, Co-IP, GST pulldown, and glucose-uptake assays in adipocytes","pmids":["18596155","19033398"],"confidence":"High","gaps":["Whether the same priming mechanism operates in neuronal and metabolic tissues not directly compared","Domain basis of syntaxin-4 binding not yet mapped"]},{"year":2009,"claim":"Showed phase-specificity of DOC2B in insulin secretion, distinguishing its action on second-phase release and confirming syntaxin-4 (not syntaxin-1) selectivity in β-cells.","evidence":"Co-IP, fractionation, and knockdown/overexpression with insulin-secretion assays in MIN6 cells","pmids":["19410553"],"confidence":"Medium","gaps":["Mechanism distinguishing first- vs second-phase contribution unresolved","Single-lab Co-IP for syntaxin selectivity"]},{"year":2010,"claim":"Defined DOC2B as a high-affinity Ca2+ sensor for spontaneous neurotransmitter release acting in competition with synaptotagmin-1 on SNARE complexes.","evidence":"SNARE competition binding assays, neuronal electrophysiology, and knockout mouse analysis","pmids":["20150444"],"confidence":"High","gaps":["Structural basis of competition with synaptotagmin-1 not resolved","Relative contribution to spontaneous vs evoked release left open"]},{"year":2012,"claim":"Established in vivo that Doc2b positively regulates Munc18c–syntaxin-4 exocytosis, mechanistically by promoting Munc18c–syntaxin-4 dissociation and SNARE assembly across metabolic tissues.","evidence":"Doc2b knockout mice, glucose/insulin tolerance tests, islet secretion, GLUT4 translocation, and SNARE assembly assays","pmids":["22698913"],"confidence":"High","gaps":["How Doc2b triggers Munc18c displacement biochemically not fully defined","Tissue-specific contributions not separated"]},{"year":2013,"claim":"Reconstitution, structural, and biophysical work resolved the molecular activities of DOC2B: SNARE-dependent fusion acceleration, membrane bending, and identification of C2B as the dominant Ca2+ sensor with C2A enhancing membrane engagement; chromaffin work added its dual role in augmenting the RRP and suppressing sustained release.","evidence":"Proteoliposome fusion and EM, X-ray crystallography of C2A/C2B with SAXS of C2AB and live-cell domain translocation, and KO/OE capacitance electrophysiology with EM","pmids":["23427263","23994332","24133251"],"confidence":"High","gaps":["Full-length tandem-domain structure on a membrane not solved","Molecular basis of the inhibitory action on sustained release incompletely defined"]},{"year":2013,"claim":"Identified DOC2B as a recruiter of Munc13-1 to the plasma membrane, placing it upstream in priming-machinery assembly.","evidence":"Live-cell imaging of co-expressed tagged proteins and a Munc13-1 DAG-binding mutant in PC12 cells","pmids":["24062723"],"confidence":"Medium","gaps":["Direct binding interface between Doc2b and Munc13-1 not mapped biochemically","Single-lab imaging-based evidence"]},{"year":2014,"claim":"Demonstrated DOC2B acts as a scaffold bridging Munc18-1 (via C2A) and Munc18c (via C2B), and that its overexpression enhances syntaxin-4 SNARE assembly and improves whole-body insulin sensitivity.","evidence":"Co-IP and GST competition/domain mapping in β-cells and tetracycline-repressible Doc2b transgenic mice with SNARE/GLUT4 assays","pmids":["25190515","24705606"],"confidence":"Medium","gaps":["Stoichiometry and structure of the Doc2b-Munc18 ternary complex unknown","Single-lab biochemistry"]},{"year":2015,"claim":"Provided direct biophysical proof that the DOC2B C2AB module itself drives Ca2+/PS-dependent membrane hemifusion independent of SNAREs.","evidence":"Optical tweezers with SNARE-free synthetic membranes and lipid/content-mixing fluorescence assays","pmids":["26395669"],"confidence":"High","gaps":["How hemifusion intermediate couples to SNARE-driven full fusion in vivo unresolved","Physiological relevance of 600 pN stalk strength not established"]},{"year":2017,"claim":"Dissected DOC2B into separable priming functions, mapping an upstream C2A-dependent step, a downstream SNARE/C2B/Munc13-2/synaptotagmin-1-dependent step, and a MID-domain inhibitory function.","evidence":"Ca2+-coordinating residue mutagenesis with epistasis to Munc13-2 and synaptotagmin-1 and electrophysiology in chromaffin cells","pmids":["29274147"],"confidence":"High","gaps":["Molecular basis of the MID-domain inhibitory action not defined","Generalizability to neuronal synapses not tested"]},{"year":2019,"claim":"Identified insulin-stimulated Y301 tyrosine phosphorylation as a regulatory switch coupling DOC2B to kinesin light chain 1 for GLUT4 vesicle trafficking.","evidence":"Co-IP, mass spectrometry, Y301 mutagenesis, and GLUT4 assays in skeletal-muscle-specific transgenic mice","pmids":["30707251"],"confidence":"High","gaps":["Kinase responsible in muscle not identified here","Whether phosphorylation alters Ca2+ sensing not tested"]},{"year":2020,"claim":"Tested the necessity of Doc2b at a defined synapse and found it dispensable for release at mature Purkinje-to-DCN synapses, bounding its physiological role.","evidence":"Doc2b knockout mice with electrophysiology in acute cerebellar slices (negative result)","pmids":["32347796"],"confidence":"Medium","gaps":["Possible redundancy or developmental compensation not excluded","Result is synapse-specific and may not generalize"]},{"year":2022,"claim":"Resolved the upstream signaling of DOC2B Y301 phosphorylation in β-cells, identifying YES kinase as the modifier and linking phospho-DOC2B to VAMP2 surface delivery and ERM activation in secretion.","evidence":"Co-IP, Y301 mutagenesis, VAMP2 localization, and ERM knockdown in human islets and clonal β-cells","pmids":["35377441"],"confidence":"High","gaps":["Direct ERM-DOC2B mechanistic link not fully defined","Whether YES phosphorylation operates identically in muscle not confirmed"]},{"year":2021,"claim":"Opened a non-exocytic axis for DOC2B as a Ca2+-dependent tumor suppressor in cervical cancer through CDH1 interaction, EMT inhibition, and senescence induction.","evidence":"Overexpression/knockdown, Ca2+ chelation, Co-IP with CDH1, and xenograft assays","pmids":["33758996"],"confidence":"Medium","gaps":["How a vesicle-fusion Ca2+ sensor engages CDH1 mechanistically unclear","Single-lab evidence"]},{"year":2022,"claim":"Extended the tumor-suppressive mechanism to negative regulation of Wnt/β-catenin signaling via destruction-complex enhancement and DKK1 upregulation.","evidence":"Overexpression/knockdown, β-catenin and proteasome assays, and DKK1 pharmacological inhibition","pmids":["35500882"],"confidence":"Medium","gaps":["Direct molecular link between DOC2B and destruction-complex components unestablished","GSK3β-independent degradation route undefined"]},{"year":2023,"claim":"Added a mitochondrial localization and Ca2+-mediated lipotoxicity function for DOC2B in cancer cells, and a protective role against palmitate-induced GLUT4 trafficking failure in muscle.","evidence":"Mitochondrial fractionation and functional/ROS/lipid-peroxidation assays, and L6 muscle overexpression with cofilin and GLUT4 readouts under palmitate stress","pmids":["36913987","38203312"],"confidence":"Medium","gaps":["How a plasma-membrane Ca2+ sensor localizes to and acts at mitochondria not explained","Direct molecular target for cofilin regulation not identified"]},{"year":2025,"claim":"Implicated DOC2B in dampening β-cell inflammatory signaling through physical association with IKKβ, NF-κB p65, and STAT-1, reducing cytokine-induced CXCL10.","evidence":"Co-IP, enrichment/depletion in human islets and β-cell lines, qPCR, proteomics, and imaging","pmids":["39805534"],"confidence":"Medium","gaps":["Whether DOC2B directly inhibits these kinases/transcription factors or acts indirectly unresolved","Single-lab Co-IP-based associations"]},{"year":null,"claim":"How a single Ca2+-sensing exocytic protein is repurposed for nuclear/cytoplasmic tumor suppression, mitochondrial regulation, and inflammatory signaling — and whether these reflect direct mechanisms or downstream consequences of altered Ca2+ handling — remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No structural model of full-length DOC2B engaging SNAREs or Munc18 on a membrane","Mechanistic basis of mitochondrial localization undefined","Direct vs indirect nature of Wnt and inflammatory-pathway regulation untested"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0008289","term_label":"lipid binding","supporting_discovery_ids":[3,4,7]},{"term_id":"GO:0140299","term_label":"molecular sensor activity","supporting_discovery_ids":[0,3,5]},{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[11,12]},{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[0,6,10]}],"localization":[{"term_id":"GO:0005829","term_label":"cytosol","supporting_discovery_ids":[0,3]},{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[1,3,13]},{"term_id":"GO:0031410","term_label":"cytoplasmic vesicle","supporting_discovery_ids":[9,2]},{"term_id":"GO:0005739","term_label":"mitochondrion","supporting_discovery_ids":[20]}],"pathway":[{"term_id":"R-HSA-5653656","term_label":"Vesicle-mediated transport","supporting_discovery_ids":[0,1,2,4,6]},{"term_id":"R-HSA-112316","term_label":"Neuronal System","supporting_discovery_ids":[0,10]},{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[17,19]},{"term_id":"R-HSA-1430728","term_label":"Metabolism","supporting_discovery_ids":[2,6,9]}],"complexes":["SNARE complex","Doc2b-Munc18-1-Munc18c scaffold"],"partners":["STX4","MUNC18C","STXBP1","UNC13B","UNC13A","KLC1","YES1","CDH1"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q14184","full_name":"Double C2-like domain-containing protein beta","aliases":[],"length_aa":412,"mass_kda":45.9,"function":"Calcium sensor which positively regulates SNARE-dependent fusion of vesicles with membranes. Binds phospholipids in a calcium-dependent manner and may act at the priming stage of fusion by modifying membrane curvature to stimulate fusion. Involved in calcium-triggered exocytosis in chromaffin cells and calcium-dependent spontaneous release of neurotransmitter in absence of action potentials in neuronal cells. Involved both in glucose-stimulated insulin secretion in pancreatic cells and insulin-dependent GLUT4 transport to the plasma membrane in adipocytes (By similarity)","subcellular_location":"Cytoplasm; Cytoplasmic granule; Cell membrane","url":"https://www.uniprot.org/uniprotkb/Q14184/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/DOC2B","classification":"Not Classified","n_dependent_lines":0,"n_total_lines":77,"dependency_fraction":0.0},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/DOC2B","total_profiled":1310},"omim":[{"mim_id":"604568","title":"DOUBLE C2-LIKE DOMAIN-CONTAINING PROTEIN, BETA; DOC2B","url":"https://www.omim.org/entry/604568"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"","locations":[],"tissue_specificity":"Tissue enhanced","tissue_distribution":"Detected in many","driving_tissues":[{"tissue":"brain","ntpm":53.3},{"tissue":"retina","ntpm":39.0}],"url":"https://www.proteinatlas.org/search/DOC2B"},"hgnc":{"alias_symbol":[],"prev_symbol":["DOC2BL"]},"alphafold":{"accession":"Q14184","domains":[{"cath_id":"2.60.40.150","chopping":"130-258","consensus_level":"high","plddt":93.9708,"start":130,"end":258},{"cath_id":"2.60.40.150","chopping":"267-402","consensus_level":"high","plddt":96.1555,"start":267,"end":402}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q14184","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q14184-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q14184-F1-predicted_aligned_error_v6.png","plddt_mean":78.19},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=DOC2B","jax_strain_url":"https://www.jax.org/strain/search?query=DOC2B"},"sequence":{"accession":"Q14184","fasta_url":"https://rest.uniprot.org/uniprotkb/Q14184.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q14184/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q14184"}},"corpus_meta":[{"pmid":"20150444","id":"PMC_20150444","title":"Doc2b is a high-affinity Ca2+ sensor for spontaneous neurotransmitter release.","date":"2010","source":"Science (New York, N.Y.)","url":"https://pubmed.ncbi.nlm.nih.gov/20150444","citation_count":261,"is_preprint":false},{"pmid":"23427263","id":"PMC_23427263","title":"Doc2b promotes GLUT4 exocytosis by activating the SNARE-mediated fusion reaction in a calcium- and membrane bending-dependent manner.","date":"2013","source":"Molecular biology of the cell","url":"https://pubmed.ncbi.nlm.nih.gov/23427263","citation_count":49,"is_preprint":false},{"pmid":"18596155","id":"PMC_18596155","title":"DOC2B acts as a calcium switch and enhances vesicle fusion.","date":"2008","source":"The Journal of neuroscience : the official journal of the Society for Neuroscience","url":"https://pubmed.ncbi.nlm.nih.gov/18596155","citation_count":47,"is_preprint":false},{"pmid":"19033398","id":"PMC_19033398","title":"DOC2B: a novel syntaxin-4 binding protein mediating insulin-regulated GLUT4 vesicle fusion in 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Membrane-Remodeling Mechanisms.","date":"2019","source":"Biophysical journal","url":"https://pubmed.ncbi.nlm.nih.gov/31952804","citation_count":16,"is_preprint":false},{"pmid":"16305808","id":"PMC_16305808","title":"Calcium concentration threshold and translocation kinetics of EGFP-DOC2B expressed in cultured Aplysia neurons.","date":"2005","source":"Cell calcium","url":"https://pubmed.ncbi.nlm.nih.gov/16305808","citation_count":16,"is_preprint":false},{"pmid":"29506054","id":"PMC_29506054","title":"Exocytosis Protein DOC2B as a Biomarker of Type 1 Diabetes.","date":"2018","source":"The Journal of clinical endocrinology and metabolism","url":"https://pubmed.ncbi.nlm.nih.gov/29506054","citation_count":15,"is_preprint":false},{"pmid":"24133251","id":"PMC_24133251","title":"Doc2b synchronizes secretion from chromaffin cells by stimulating fast and inhibiting sustained release.","date":"2013","source":"The Journal of neuroscience : the official journal of the Society for 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Mechanism.","date":"2022","source":"Diabetes","url":"https://pubmed.ncbi.nlm.nih.gov/35377441","citation_count":8,"is_preprint":false},{"pmid":"32347796","id":"PMC_32347796","title":"Loss of Doc2b does not influence transmission at Purkinje cell to deep nuclei synapses under physiological conditions.","date":"2020","source":"eLife","url":"https://pubmed.ncbi.nlm.nih.gov/32347796","citation_count":5,"is_preprint":false},{"pmid":"38203312","id":"PMC_38203312","title":"A Novel Role for DOC2B in Ameliorating Palmitate-Induced Glucose Uptake Dysfunction in Skeletal Muscle Cells via a Mechanism Involving β-AR Agonism and Cofilin.","date":"2023","source":"International journal of molecular sciences","url":"https://pubmed.ncbi.nlm.nih.gov/38203312","citation_count":5,"is_preprint":false},{"pmid":"39805534","id":"PMC_39805534","title":"DOC2b enrichment mitigates proinflammatory cytokine-induced CXCL10 expression by attenuating IKKβ and STAT-1 signaling in human islets.","date":"2025","source":"Metabolism: clinical and experimental","url":"https://pubmed.ncbi.nlm.nih.gov/39805534","citation_count":4,"is_preprint":false},{"pmid":"39763877","id":"PMC_39763877","title":"DOC2b enrichment mitigates proinflammatory cytokine-induced CXCL10 expression by attenuating IKKβ and STAT-1 signaling in human islets.","date":"2024","source":"bioRxiv : the preprint server for biology","url":"https://pubmed.ncbi.nlm.nih.gov/39763877","citation_count":1,"is_preprint":false},{"pmid":"40597089","id":"PMC_40597089","title":"doc2a and doc2b contribute to locomotor and social behaviors by down-regulating npas4b in zebrafish.","date":"2025","source":"BMC biology","url":"https://pubmed.ncbi.nlm.nih.gov/40597089","citation_count":0,"is_preprint":false},{"pmid":"41509347","id":"PMC_41509347","title":"Loss of Exocytosis Protein DOC2B is an Early Event in Type 1 Diabetes Development.","date":"2026","source":"bioRxiv : the preprint server for biology","url":"https://pubmed.ncbi.nlm.nih.gov/41509347","citation_count":0,"is_preprint":false},{"pmid":"41659295","id":"PMC_41659295","title":"Revisiting the Platelet-β-Cell Axis: Insights into How Platelet-Derived Mediators, Lipid Signaling, and DOC2B Pathways Converge to Drive β-Cell Dysfunction in Type 2 Diabetes.","date":"2026","source":"EJIFCC","url":"https://pubmed.ncbi.nlm.nih.gov/41659295","citation_count":0,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":18555,"output_tokens":5974,"usd":0.072637,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":14928,"output_tokens":5971,"usd":0.111958,"stage2_stop_reason":"end_turn"},"total_usd":0.184595,"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\": 2010,\n      \"finding\": \"DOC2B acts as a high-affinity Ca2+ sensor for spontaneous neurotransmitter release. Doc2 proteins are cytosolic but function analogously to synaptotagmin-1, binding SNARE complexes in competition with synaptotagmin-1 and triggering spontaneous vesicle fusion with higher Ca2+ sensitivity than synaptotagmin-1.\",\n      \"method\": \"Biochemical binding assays (SNARE competition), electrophysiology in neurons, knockout mouse analysis\",\n      \"journal\": \"Science\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal binding assays, KO mice with defined phenotype, replicated across multiple methods in a high-impact study\",\n      \"pmids\": [\"20150444\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"The C2A domain of DOC2B interacts directly with the plasma membrane in a calcium-dependent manner. DOC2B acts as a priming factor, increasing the number of fusion-competent vesicles, must translocate to the plasma membrane to exert its effect, and interacts with plasma membrane SNAREs to affect fusion pore kinetics during catecholamine secretion.\",\n      \"method\": \"Biochemical and biophysical measurements, electrophysiology, TIRF microscopy, morphological analysis\",\n      \"journal\": \"The Journal of Neuroscience\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple orthogonal methods (biochemical, electrophysiological, imaging) in a single study\",\n      \"pmids\": [\"18596155\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"DOC2B directly associates with syntaxin-4 in an intracellular Ca2+-dependent manner and is essential for GLUT4 vesicle fusion in adipocytes. DOC2B translocates to the plasma membrane upon insulin stimulation, and Ca2+-binding domain mutants or DOC2B knockdown inhibit insulin-stimulated glucose uptake.\",\n      \"method\": \"Yeast two-hybrid screening, immunoprecipitation, GST pull-down, confocal microscopy, GLUT4 externalization assay, glucose uptake measurement, siRNA knockdown\",\n      \"journal\": \"Diabetes\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal Co-IP, GST pulldown, functional KD and OE with defined cellular phenotype, multiple orthogonal methods\",\n      \"pmids\": [\"19033398\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"A rise in intracellular Ca2+ is sufficient for Munc13-independent recruitment of DOC2B to the target membrane. Purified DOC2B binds phospholipids in a Ca2+-dependent manner via its C2 domain, and Ca2+-induced translocation occurs in neurons within 5 seconds of depolarization.\",\n      \"method\": \"Phospholipid binding assay with purified protein, live-cell fluorescence imaging (EGFP-DOC2B in neurons), Ca2+-dependent translocation assays\",\n      \"journal\": \"The Journal of Biological Chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vitro phospholipid binding with purified protein plus live-cell imaging, two orthogonal methods\",\n      \"pmids\": [\"15033971\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"Doc2b binds GLUT4 exocytic SNAREs and potently accelerates SNARE-dependent fusion kinetics in a Ca2+-dependent manner. Ca2+-binding sites on both C2A and C2B domains are required. Doc2b strongly bends membrane bilayers, and this membrane-bending activity is essential for its stimulatory function in GLUT4 vesicle fusion.\",\n      \"method\": \"Reconstituted proteoliposome SNARE-dependent fusion assay, electron microscopy for membrane bending, site-directed mutagenesis of Ca2+-binding sites\",\n      \"journal\": \"Molecular Biology of the Cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro reconstitution with defined components, mutagenesis, electron microscopy, multiple orthogonal methods in one study\",\n      \"pmids\": [\"23427263\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"Crystal structures of the isolated C2A and C2B domains of DOC2B were determined, and small-angle X-ray scattering characterized the solution structure of the tandem C2AB domain. C2B binds Ca2+ with considerably higher affinity than C2A. In cells, isolated C2B translocates to the plasma membrane with an EC50 of ~400 nM while C2A does not translocate at submicromolar Ca2+. C2A enhances the interaction of C2AB with the plasma membrane but C2B is the primary Ca2+ sensing unit.\",\n      \"method\": \"X-ray crystallography of C2A and C2B domains, SAXS of C2AB, Ca2+ binding kinetics, live-cell imaging of domain translocation\",\n      \"journal\": \"Journal of Molecular Biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — crystal structures plus functional validation by live-cell imaging and kinetics, multiple orthogonal methods\",\n      \"pmids\": [\"23994332\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"Doc2b is required for both phases of glucose-stimulated insulin secretion and for insulin-stimulated GLUT4 vesicle translocation in skeletal muscle. Doc2b deficiency impairs Munc18c-syntaxin 4 dissociation and SNARE complex assembly. Doc2b acts as a positive regulator of Munc18c-syntaxin 4-mediated exocytosis in vivo.\",\n      \"method\": \"Doc2b heterozygous and homozygous knockout mice, in vivo glucose/insulin tolerance tests, ex vivo islet insulin secretion, skeletal muscle GLUT4 translocation assay, SNARE complex assembly assay\",\n      \"journal\": \"Diabetes\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — KO mice with multiple defined phenotypic readouts and biochemical mechanism, replicated across tissues\",\n      \"pmids\": [\"22698913\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"The C2AB domain of Doc2b directly induces membrane hemifusion in a Ca2+- and phosphatidylserine-dependent manner in a cell-free system. Doc2b-coated membrane stalks between SNARE-free synthetic membranes resist forces up to 600 pN. Phospholipid but not content mixing occurs, confirming hemifusion rather than full fusion.\",\n      \"method\": \"Optical tweezers with SNARE-free synthetic membrane beads, real-time fluorescence imaging for lipid/content mixing\",\n      \"journal\": \"Nature Communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — cell-free reconstitution with defined components, direct biophysical measurement, fluorescence imaging confirmation\",\n      \"pmids\": [\"26395669\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"Doc2B plays distinct roles in two sequential vesicle priming steps in chromaffin cells. Mutating Ca2+-coordinating aspartates in C2A renders an upstream priming step Ca2+-independent. A downstream priming function depends on SNARE-binding, Ca2+-binding to C2B, interaction with ubMunc13-2, and the presence of synaptotagmin-1. A separate inhibitory function during sustained Ca2+ elevations depends on the MID-domain.\",\n      \"method\": \"Site-directed mutagenesis of Ca2+-coordinating residues, overexpression and knockdown in mouse adrenal chromaffin cells, electrophysiological exocytosis measurements, genetic epistasis with Munc13-2 and synaptotagmin-1\",\n      \"journal\": \"eLife\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — mutagenesis, epistasis with multiple proteins, electrophysiological readout, multiple orthogonal approaches\",\n      \"pmids\": [\"29274147\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"DOC2b associates with insulin vesicles and translocates to the plasma membrane upon glucose stimulation, then interacts specifically with syntaxin-4 (not syntaxin-1). DOC2b knockdown inhibits second-phase insulin secretion without affecting first-phase secretion; DOC2b overexpression enhances glucose-stimulated insulin secretion.\",\n      \"method\": \"Immunoprecipitation, subcellular fractionation/localization, siRNA knockdown, overexpression in MIN6 cells, insulin secretion assays\",\n      \"journal\": \"Biochemical and Biophysical Research Communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP for binding specificity, KD and OE with defined secretion phenotype, single lab\",\n      \"pmids\": [\"19410553\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"Doc2b synchronizes exocytosis in chromaffin cells by augmenting the readily releasable pool (RRP) and inhibiting the sustained release component. In the absence of Doc2b, RRP refilling is faster but incomplete, leading to premature fusion. Doc2b inhibits vesicle priming during prolonged calcium elevations to protect unprimed vesicles and favor synchronized release.\",\n      \"method\": \"Doc2b knockout mice, high temporal resolution electrophysiological capacitance measurements, electron microscopy of vesicle pools, Doc2b overexpression\",\n      \"journal\": \"The Journal of Neuroscience\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — KO and OE with high-resolution electrophysiology and EM, multiple orthogonal approaches\",\n      \"pmids\": [\"24133251\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"Munc13-1 translocates to the plasma membrane in a Doc2B- and Ca2+-dependent manner in PC12 cells. Munc13-1 co-translocation requires its interaction with Doc2B and depends on diacylglycerol for accumulation. Doc2B dislocates from the membrane faster than Munc13-1 upon Ca2+ removal.\",\n      \"method\": \"Fluorescence live-cell imaging of co-expressed fluorescent-tagged proteins in PC12 cells, Munc13-1(H567K) DAG-binding mutant analysis\",\n      \"journal\": \"Frontiers in Endocrinology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — live imaging with mutagenesis, single lab, two orthogonal approaches\",\n      \"pmids\": [\"24062723\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"Doc2b serves as a scaffolding platform in pancreatic β-cells that simultaneously binds Munc18-1 (via C2A) and Munc18c (via C2B) to form a macromolecular complex. Doc2b bridges the interaction between Munc18c and Munc18-1; these two proteins fail to associate in the absence of Doc2b. This scaffold function supports both phases of glucose-stimulated insulin secretion.\",\n      \"method\": \"Co-immunoprecipitation from β-cells, in vitro GST-Doc2b interaction/competition assays, domain mapping\",\n      \"journal\": \"The Biochemical Journal\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal Co-IP and in vitro GST pulldown competition assay, single lab\",\n      \"pmids\": [\"25190515\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"The Ca2+ concentration threshold for DOC2B translocation to the plasma membrane in cultured neurons is approximately 200 nM in the bulk cytoplasm. Translocation rate is slower than Ca2+ elevation rate, while detachment from the membrane is faster than Ca2+ removal. The extent of translocation reflects local submembrane Ca2+ concentration.\",\n      \"method\": \"Live-cell imaging of EGFP-DOC2B in Aplysia neurons with simultaneous Ca2+ imaging\",\n      \"journal\": \"Cell Calcium\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct live imaging with Ca2+ concentration measurement, single lab\",\n      \"pmids\": [\"16305808\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"Doc2b enrichment enhances syntaxin-4-SNARE complex formation in skeletal muscle cells and increases insulin-stimulated GLUT4 vesicle accumulation at the cell surface, improving glucose tolerance and peripheral insulin sensitivity in transgenic mice overexpressing Doc2b.\",\n      \"method\": \"Tetracycline-repressible transgenic mice overexpressing Doc2b, SNARE complex assays, GLUT4 translocation assay, glucose/insulin tolerance tests\",\n      \"journal\": \"Diabetologia\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — transgenic mouse model with biochemical SNARE complex analysis and GLUT4 translocation, single lab\",\n      \"pmids\": [\"24705606\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"DOC2B is phosphorylated on tyrosine (Y301) upon insulin stimulation in skeletal muscle cells, enhancing its interaction with kinesin light chain 1 (KLC1). Mutation of Y301 blocks insulin-stimulated DOC2B phosphorylation, reduces DOC2B-KLC1 interaction, and impairs insulin-stimulated GLUT4 accumulation at the plasma membrane.\",\n      \"method\": \"Co-immunoprecipitation, mass spectrometry, site-directed mutagenesis of Y301, GLUT4 translocation assays, skeletal-muscle-specific transgenic mice\",\n      \"journal\": \"Diabetologia\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP, MS identification of interaction, mutagenesis with functional readout, in vitro and in vivo corroboration\",\n      \"pmids\": [\"30707251\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"Syt1 and Doc2b exhibit distinct membrane-remodeling mechanisms. Both Syt1 C2AB and Doc2b C2AB can induce hemifusion of SNARE-free membranes and reduce the membrane-bending modulus in a Ca2+-dependent manner, but Doc2b is more effective when both membranes are loaded, whereas Syt1 is more effective with single-membrane loading. Significantly higher Syt1 concentrations are required for hemifusion than Doc2b.\",\n      \"method\": \"Optical tweezers with synthetic membranes, lipid-mixing confocal assay, AFM membrane-bending modulus measurement\",\n      \"journal\": \"Biophysical Journal\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — cell-free reconstitution with biophysical methods, single lab, multiple orthogonal approaches\",\n      \"pmids\": [\"31952804\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"DOC2b is tyrosine-phosphorylated at Y301 within 2 minutes of glucose stimulation in β-cells, mediated by the Src family kinase YES. Y301 phosphorylation is required for DOC2b's interaction with YES kinase, increased VAMP2 at the plasma membrane, and enhanced glucose-stimulated insulin secretion. Tyrosine-phosphorylated DOC2b also increases ERM protein activation; ERM knockdown impairs DOC2b-mediated GSIS.\",\n      \"method\": \"Biochemical analysis of human islets and clonal β-cells, co-immunoprecipitation, site-directed mutagenesis of Y301, VAMP2 plasma membrane localization assay, ERM knockdown\",\n      \"journal\": \"Diabetes\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP with kinase identification, mutagenesis, functional KD, multiple orthogonal methods in one study\",\n      \"pmids\": [\"35377441\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"DOC2B inhibits EMT and promotes cellular senescence in cervical cancer cells via a calcium-dependent process. DOC2B interacts with CDH1 in a calcium-dependent manner, and this interaction is associated with suppression of EMT and induction of senescence.\",\n      \"method\": \"DOC2B overexpression and knockdown, calcium chelation, co-immunoprecipitation of DOC2B with CDH1, in vivo xenograft model\",\n      \"journal\": \"Cell Biology and Toxicology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — Co-IP for CDH1 interaction, KD/OE with multiple phenotypic readouts, single lab\",\n      \"pmids\": [\"33758996\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"DOC2B negatively regulates Wnt/β-catenin signaling by enhancing expression of components of the CTNNB1 destruction complex and promoting proteasomal degradation of CTNNB1 in a GSK3β-independent manner. DOC2B upregulates DKK1, and DKK1 inhibition reactivates Wnt/β-catenin signaling and reverses DOC2B-induced senescence and anti-tumor effects.\",\n      \"method\": \"DOC2B overexpression and knockdown, β-catenin protein assays, proteasome inhibitor studies, DKK1 pharmacological inhibition (WAY262611)\",\n      \"journal\": \"Pharmacological Research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple biochemical assays and pharmacological intervention, single lab\",\n      \"pmids\": [\"35500882\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"DOC2B is localized to mitochondria and induces Ca2+-mediated lipotoxicity in cervical cancer cells. DOC2B expression causes mitochondrial morphological changes, reduces mitochondrial DNA copy number, membrane potential, and complex-IV activity, and elevates intracellular Ca2+, ROS, and lipid peroxidation. These effects are Ca2+-dependent.\",\n      \"method\": \"DOC2B overexpression and knockdown, mitochondrial fractionation/localization assays, mitochondrial functional assays, Ca2+ chelation, lipid peroxidation assays\",\n      \"journal\": \"Free Radical Biology and Medicine\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — localization by fractionation with functional consequence, multiple cellular assays, single lab\",\n      \"pmids\": [\"36913987\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"DOC2b enrichment attenuates cytokine-induced CXCL10 expression in β-cells and human islets by reducing IKKβ activation, reducing NF-κB p65 levels, and reducing STAT-1 activation. IKKβ, NF-κB p65, and STAT-1 physically associate with DOC2b in cytokine-challenged β-cells. DOC2b also prevents ER-stress-IKKβ and STAT-1 crosstalk.\",\n      \"method\": \"Co-immunoprecipitation, DOC2b enrichment/depletion in human islets and β-cell lines, qPCR, proteomics, immunoconfocal microscopy\",\n      \"journal\": \"Metabolism: Clinical and Experimental\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — Co-IP for protein associations, OE/KD with functional readouts, single lab\",\n      \"pmids\": [\"39805534\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"Loss of Doc2b does not influence spontaneous neurotransmitter release, synaptic strength, evoked release time course, responses to sustained high-frequency stimulation, or short-term plasticity at mature Purkinje cell-to-deep cerebellar nuclei synapses under physiological conditions, despite Doc2b being the sole Doc2 isoform expressed in Purkinje cells.\",\n      \"method\": \"Doc2b knockout mice, electrophysiological recordings at PC-to-DCN synapses in acute cerebellar slices\",\n      \"journal\": \"eLife\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — KO mice with comprehensive electrophysiology; NEGATIVE result at a specific synapse type, single lab\",\n      \"pmids\": [\"32347796\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"DOC2B enrichment in skeletal muscle cells prevents palmitate-induced cofilin phosphorylation, preserves insulin- and β2-adrenergic receptor-stimulated GLUT4 trafficking to the plasma membrane, and rescues glucose uptake under lipotoxic conditions.\",\n      \"method\": \"DOC2B overexpression in rat L6 skeletal muscle cells, GLUT4 translocation assay, cofilin phosphorylation assay, glucose uptake measurement under palmitate stress\",\n      \"journal\": \"International Journal of Molecular Sciences\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single lab, OE with cellular phenotype readout, no defined direct molecular mechanism for cofilin regulation\",\n      \"pmids\": [\"38203312\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"DOC2B is a cytosolic, high-affinity Ca2+ sensor with tandem C2 domains (C2B being the primary Ca2+-binding unit) that undergoes Ca2+- and phosphatidylserine-dependent translocation to the plasma membrane, where it promotes spontaneous and asynchronous neurotransmitter release by binding SNARE complexes in competition with synaptotagmin-1, induces membrane hemifusion and curvature, acts as a priming factor that scaffolds Munc18 isoforms and recruits Munc13-1, and in non-neuronal tissues (pancreatic β-cells, skeletal muscle, adipocytes) drives insulin granule and GLUT4 vesicle exocytosis through Ca2+-dependent syntaxin-4 binding and insulin-stimulated Y301 phosphorylation-dependent interaction with KLC1 for vesicle transport.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"DOC2B is a cytosolic, high-affinity Ca2+ sensor built from tandem C2 domains that couples intracellular Ca2+ rises to regulated vesicle exocytosis in both neuronal and metabolic tissues [#0, #3]. A Ca2+ rise alone is sufficient to drive Munc13-independent translocation of DOC2B to the plasma membrane, where its C2 domains bind phospholipids in a Ca2+-dependent manner with a translocation threshold of ~200 nM; structural and domain-dissection work establishes C2B as the primary high-affinity Ca2+-sensing unit, with C2A enhancing membrane engagement [#3, #5, #13]. At the membrane DOC2B acts as a Ca2+ sensor for spontaneous and asynchronous release, binding SNARE complexes in competition with synaptotagmin-1, and functions as a priming factor that augments the readily releasable pool while inhibiting sustained release to favor synchronized fusion [#0, #1, #10]. Biophysically, its C2AB module directly bends membrane bilayers and drives Ca2+- and phosphatidylserine-dependent hemifusion of SNARE-free membranes, an activity essential for its stimulatory role in fusion [#4, #7]. DOC2B also serves as a scaffold that bridges Munc18 isoforms and recruits Munc13-1 to the membrane in a Ca2+-dependent manner, organizing the priming machinery [#11, #12]. In non-neuronal tissues DOC2B drives insulin-granule and GLUT4-vesicle exocytosis through Ca2+-dependent binding to syntaxin-4 and promotion of Munc18c–syntaxin-4 dissociation and SNARE assembly, and insulin/glucose stimulation triggers Src-family-kinase (YES)-mediated Y301 tyrosine phosphorylation that recruits kinesin light chain 1 and supports vesicle trafficking [#2, #6, #15, #17]. Distinct from its exocytic role, DOC2B has Ca2+-dependent tumor-suppressive activity in cervical cancer, interacting with CDH1, antagonizing Wnt/\\u03b2-catenin signaling, and inducing mitochondrial dysfunction and senescence [#18, #19, #20].\",\n  \"teleology\": [\n    {\n      \"year\": 2004,\n      \"claim\": \"Established that DOC2B is intrinsically Ca2+-responsive, answering whether its membrane recruitment requires partner proteins or follows directly from Ca2+ binding.\",\n      \"evidence\": \"Phospholipid binding with purified protein and live-cell imaging of EGFP-DOC2B translocation in neurons\",\n      \"pmids\": [\"15033971\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not resolve which C2 domain provides the dominant Ca2+ sensitivity\", \"Lipid specificity of the Ca2+-dependent interaction not defined\"]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"Quantified the Ca2+ threshold and kinetics of DOC2B membrane translocation, defining it as a sensor reporting local submembrane Ca2+.\",\n      \"evidence\": \"Live-cell EGFP-DOC2B imaging with simultaneous Ca2+ imaging in Aplysia neurons\",\n      \"pmids\": [\"16305808\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Bulk vs. true submembrane Ca2+ values not directly reconciled\", \"Functional consequence of translocation kinetics on release not measured here\"]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Linked DOC2B membrane translocation to vesicle priming and fusion-pore control, and extended its role beyond neurons to insulin-stimulated GLUT4 exocytosis via Ca2+-dependent syntaxin-4 binding.\",\n      \"evidence\": \"Electrophysiology/TIRF in secretory cells and yeast two-hybrid, Co-IP, GST pulldown, and glucose-uptake assays in adipocytes\",\n      \"pmids\": [\"18596155\", \"19033398\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether the same priming mechanism operates in neuronal and metabolic tissues not directly compared\", \"Domain basis of syntaxin-4 binding not yet mapped\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Showed phase-specificity of DOC2B in insulin secretion, distinguishing its action on second-phase release and confirming syntaxin-4 (not syntaxin-1) selectivity in \\u03b2-cells.\",\n      \"evidence\": \"Co-IP, fractionation, and knockdown/overexpression with insulin-secretion assays in MIN6 cells\",\n      \"pmids\": [\"19410553\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism distinguishing first- vs second-phase contribution unresolved\", \"Single-lab Co-IP for syntaxin selectivity\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Defined DOC2B as a high-affinity Ca2+ sensor for spontaneous neurotransmitter release acting in competition with synaptotagmin-1 on SNARE complexes.\",\n      \"evidence\": \"SNARE competition binding assays, neuronal electrophysiology, and knockout mouse analysis\",\n      \"pmids\": [\"20150444\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural basis of competition with synaptotagmin-1 not resolved\", \"Relative contribution to spontaneous vs evoked release left open\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Established in vivo that Doc2b positively regulates Munc18c–syntaxin-4 exocytosis, mechanistically by promoting Munc18c–syntaxin-4 dissociation and SNARE assembly across metabolic tissues.\",\n      \"evidence\": \"Doc2b knockout mice, glucose/insulin tolerance tests, islet secretion, GLUT4 translocation, and SNARE assembly assays\",\n      \"pmids\": [\"22698913\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How Doc2b triggers Munc18c displacement biochemically not fully defined\", \"Tissue-specific contributions not separated\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Reconstitution, structural, and biophysical work resolved the molecular activities of DOC2B: SNARE-dependent fusion acceleration, membrane bending, and identification of C2B as the dominant Ca2+ sensor with C2A enhancing membrane engagement; chromaffin work added its dual role in augmenting the RRP and suppressing sustained release.\",\n      \"evidence\": \"Proteoliposome fusion and EM, X-ray crystallography of C2A/C2B with SAXS of C2AB and live-cell domain translocation, and KO/OE capacitance electrophysiology with EM\",\n      \"pmids\": [\"23427263\", \"23994332\", \"24133251\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Full-length tandem-domain structure on a membrane not solved\", \"Molecular basis of the inhibitory action on sustained release incompletely defined\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Identified DOC2B as a recruiter of Munc13-1 to the plasma membrane, placing it upstream in priming-machinery assembly.\",\n      \"evidence\": \"Live-cell imaging of co-expressed tagged proteins and a Munc13-1 DAG-binding mutant in PC12 cells\",\n      \"pmids\": [\"24062723\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct binding interface between Doc2b and Munc13-1 not mapped biochemically\", \"Single-lab imaging-based evidence\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Demonstrated DOC2B acts as a scaffold bridging Munc18-1 (via C2A) and Munc18c (via C2B), and that its overexpression enhances syntaxin-4 SNARE assembly and improves whole-body insulin sensitivity.\",\n      \"evidence\": \"Co-IP and GST competition/domain mapping in \\u03b2-cells and tetracycline-repressible Doc2b transgenic mice with SNARE/GLUT4 assays\",\n      \"pmids\": [\"25190515\", \"24705606\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Stoichiometry and structure of the Doc2b-Munc18 ternary complex unknown\", \"Single-lab biochemistry\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Provided direct biophysical proof that the DOC2B C2AB module itself drives Ca2+/PS-dependent membrane hemifusion independent of SNAREs.\",\n      \"evidence\": \"Optical tweezers with SNARE-free synthetic membranes and lipid/content-mixing fluorescence assays\",\n      \"pmids\": [\"26395669\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How hemifusion intermediate couples to SNARE-driven full fusion in vivo unresolved\", \"Physiological relevance of 600 pN stalk strength not established\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Dissected DOC2B into separable priming functions, mapping an upstream C2A-dependent step, a downstream SNARE/C2B/Munc13-2/synaptotagmin-1-dependent step, and a MID-domain inhibitory function.\",\n      \"evidence\": \"Ca2+-coordinating residue mutagenesis with epistasis to Munc13-2 and synaptotagmin-1 and electrophysiology in chromaffin cells\",\n      \"pmids\": [\"29274147\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular basis of the MID-domain inhibitory action not defined\", \"Generalizability to neuronal synapses not tested\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Identified insulin-stimulated Y301 tyrosine phosphorylation as a regulatory switch coupling DOC2B to kinesin light chain 1 for GLUT4 vesicle trafficking.\",\n      \"evidence\": \"Co-IP, mass spectrometry, Y301 mutagenesis, and GLUT4 assays in skeletal-muscle-specific transgenic mice\",\n      \"pmids\": [\"30707251\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Kinase responsible in muscle not identified here\", \"Whether phosphorylation alters Ca2+ sensing not tested\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Tested the necessity of Doc2b at a defined synapse and found it dispensable for release at mature Purkinje-to-DCN synapses, bounding its physiological role.\",\n      \"evidence\": \"Doc2b knockout mice with electrophysiology in acute cerebellar slices (negative result)\",\n      \"pmids\": [\"32347796\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Possible redundancy or developmental compensation not excluded\", \"Result is synapse-specific and may not generalize\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Resolved the upstream signaling of DOC2B Y301 phosphorylation in \\u03b2-cells, identifying YES kinase as the modifier and linking phospho-DOC2B to VAMP2 surface delivery and ERM activation in secretion.\",\n      \"evidence\": \"Co-IP, Y301 mutagenesis, VAMP2 localization, and ERM knockdown in human islets and clonal \\u03b2-cells\",\n      \"pmids\": [\"35377441\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct ERM-DOC2B mechanistic link not fully defined\", \"Whether YES phosphorylation operates identically in muscle not confirmed\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Opened a non-exocytic axis for DOC2B as a Ca2+-dependent tumor suppressor in cervical cancer through CDH1 interaction, EMT inhibition, and senescence induction.\",\n      \"evidence\": \"Overexpression/knockdown, Ca2+ chelation, Co-IP with CDH1, and xenograft assays\",\n      \"pmids\": [\"33758996\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"How a vesicle-fusion Ca2+ sensor engages CDH1 mechanistically unclear\", \"Single-lab evidence\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Extended the tumor-suppressive mechanism to negative regulation of Wnt/\\u03b2-catenin signaling via destruction-complex enhancement and DKK1 upregulation.\",\n      \"evidence\": \"Overexpression/knockdown, \\u03b2-catenin and proteasome assays, and DKK1 pharmacological inhibition\",\n      \"pmids\": [\"35500882\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct molecular link between DOC2B and destruction-complex components unestablished\", \"GSK3\\u03b2-independent degradation route undefined\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Added a mitochondrial localization and Ca2+-mediated lipotoxicity function for DOC2B in cancer cells, and a protective role against palmitate-induced GLUT4 trafficking failure in muscle.\",\n      \"evidence\": \"Mitochondrial fractionation and functional/ROS/lipid-peroxidation assays, and L6 muscle overexpression with cofilin and GLUT4 readouts under palmitate stress\",\n      \"pmids\": [\"36913987\", \"38203312\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"How a plasma-membrane Ca2+ sensor localizes to and acts at mitochondria not explained\", \"Direct molecular target for cofilin regulation not identified\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Implicated DOC2B in dampening \\u03b2-cell inflammatory signaling through physical association with IKK\\u03b2, NF-\\u03baB p65, and STAT-1, reducing cytokine-induced CXCL10.\",\n      \"evidence\": \"Co-IP, enrichment/depletion in human islets and \\u03b2-cell lines, qPCR, proteomics, and imaging\",\n      \"pmids\": [\"39805534\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether DOC2B directly inhibits these kinases/transcription factors or acts indirectly unresolved\", \"Single-lab Co-IP-based associations\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How a single Ca2+-sensing exocytic protein is repurposed for nuclear/cytoplasmic tumor suppression, mitochondrial regulation, and inflammatory signaling \\u2014 and whether these reflect direct mechanisms or downstream consequences of altered Ca2+ handling \\u2014 remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No structural model of full-length DOC2B engaging SNAREs or Munc18 on a membrane\", \"Mechanistic basis of mitochondrial localization undefined\", \"Direct vs indirect nature of Wnt and inflammatory-pathway regulation untested\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0005509\", \"supporting_discovery_ids\": [0, 3, 5, 13]},\n      {\"term_id\": \"GO:0008289\", \"supporting_discovery_ids\": [3, 4, 7]},\n      {\"term_id\": \"GO:0140299\", \"supporting_discovery_ids\": [0, 3, 5]},\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [11, 12]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [0, 6, 10]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005829\", \"supporting_discovery_ids\": [0, 3]},\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [1, 3, 13]},\n      {\"term_id\": \"GO:0031410\", \"supporting_discovery_ids\": [9, 2]},\n      {\"term_id\": \"GO:0005739\", \"supporting_discovery_ids\": [20]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-5653656\", \"supporting_discovery_ids\": [0, 1, 2, 4, 6]},\n      {\"term_id\": \"R-HSA-112316\", \"supporting_discovery_ids\": [0, 10]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [17, 19]},\n      {\"term_id\": \"R-HSA-1430728\", \"supporting_discovery_ids\": [2, 6, 9]}\n    ],\n    \"complexes\": [\"SNARE complex\", \"Doc2b-Munc18-1-Munc18c scaffold\"],\n    \"partners\": [\"STX4\", \"MUNC18C\", \"STXBP1\", \"UNC13B\", \"UNC13A\", \"KLC1\", \"YES1\", \"CDH1\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":7,"faith_total":7,"faith_pct":100.0}}