{"gene":"STX1A","run_date":"2026-06-10T10:51:54","timeline":{"discoveries":[{"year":1993,"finding":"Botulinum neurotoxin type C1 inhibits neurotransmitter release by directly cleaving HPC-1/syntaxin 1A via its light chain acting as a zinc-dependent metallo-endoprotease, generating a soluble fragment 2-4 kDa smaller than native protein; cleavage requires membrane association (transmembrane domain) of syntaxin 1A.","method":"In vitro proteolysis assay, in vitro translation with/without microsomes, proteoliposome reconstitution","journal":"The EMBO journal","confidence":"High","confidence_rationale":"Tier 1 / Strong — in vitro reconstitution with proteoliposomes, mutagenesis via truncation (lacking TM domain), replicated across conditions; foundational mechanistic study","pmids":["7901002"],"is_preprint":false},{"year":1992,"finding":"HPC-1/syntaxin 1A (p35) forms a ternary complex with synaptotagmin and the omega-conotoxin-sensitive N-type calcium channel (omega-CgTX receptor) in rat brain, as shown by co-immunoprecipitation with antibodies against each component.","method":"Co-immunoprecipitation from solubilized rat brain membranes","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — reciprocal co-immunoprecipitation with multiple antibodies in single lab, establishing ternary complex","pmids":["1334074"],"is_preprint":false},{"year":1993,"finding":"HPC-1/syntaxin 1A localizes to the cytoplasmic face of presynaptic plasma membranes and synaptic vesicles in rat cerebellar neurons, as determined by cryoimmunogold electron microscopy; intact synaptosomes are not labeled, but ruptured membranes expose the cytoplasmic epitopes, establishing intracellular topology.","method":"Cryoimmunogold electron microscopy, pre-embedding protein A-gold technique on synaptosomes with membrane rupture","journal":"Journal of neurocytology","confidence":"High","confidence_rationale":"Tier 2 / Strong — direct subcellular localization by immunoelectron microscopy with membrane topology validation, replicated with two EM approaches","pmids":["8301329"],"is_preprint":false},{"year":1995,"finding":"Syntaxin 1A (HPC-1) is associated with chromaffin granules in adrenal medulla (not exclusively plasma membrane), suggesting it can function as a vesicle-SNARE receptor component in addition to its role as a target-SNARE on the plasma membrane.","method":"Subcellular fractionation, immunomorphological analysis of chromaffin cells","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — biochemical fractionation combined with morphological analysis in single lab, two orthogonal methods","pmids":["7608144"],"is_preprint":false},{"year":1996,"finding":"Syntaxin 1A overexpression in pancreatic beta TC3 cells specifically suppresses glucose-stimulated and secretagogue-stimulated (PMA, forskolin) insulin release by ~50% via the regulatory exocytosis pathway, without affecting constitutive proinsulin secretion, glucose metabolism, or intracellular Ca2+; in vitro binding assays showed syntaxin 1A binds insulin secretory granules.","method":"Transient and stable transfection overexpression, insulin secretion assay, in vitro binding assay, metabolic labeling","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal methods (overexpression, stable cell lines, secretion assays, in vitro binding), specific pathway dissection with isoform specificity (1A but not 1B effect)","pmids":["8557645"],"is_preprint":false},{"year":1996,"finding":"Suppression of HPC-1/syntaxin 1A function by antisense oligonucleotides (in cultured DRG neurons) or intra-axonal antibody injection (in chick retinal ganglion neurons) enhances axonal sprouting, indicating that axonal syntaxin 1A physiologically suppresses excess axon-collateral sprouting.","method":"Antisense oligonucleotide knockdown, intra-axonal antibody microinjection, neurite morphology analysis","journal":"Brain research","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — two independent loss-of-function approaches (antisense + antibody injection) in two cell types, single lab","pmids":["8973813"],"is_preprint":false},{"year":1995,"finding":"Injection of HPC-1/syntaxin 1A (or syntaxin 1B) cRNA into amphibian embryonic cells causes morphological deformation of Golgi complexes, accumulation of vacuoles, and disappearance of extracellular matrix from the cell surface, demonstrating that syntaxin 1A disrupts intracellular membrane transport and inhibits constitutive secretion.","method":"cRNA microinjection into amphibian embryos, immunoelectron microscopy, immunoblotting","journal":"Experimental cell research","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — gain-of-function in vivo embryo model with morphological readout by EM, single lab","pmids":["7589235"],"is_preprint":false},{"year":1997,"finding":"Intracellular application of anti-HPC-1/syntaxin 1A antibody into presynaptic neurons enhances autaptic excitatory postsynaptic current amplitude in cultured rat hippocampal neurons, indicating syntaxin 1A suppresses transmitter release at central synapses; the increase was due to increased quantal content, not quantal size.","method":"Whole-cell patch-clamp with intracellular antibody dialysis at hippocampal autapses","journal":"Neuroreport","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct intracellular perturbation with electrophysiological readout, single lab, single method","pmids":["9427341"],"is_preprint":false},{"year":1997,"finding":"HPC-1/syntaxin 1A binds directly to tubulin in vitro at residues 89–106 (a tubulin-binding motif), as shown by in vitro binding assay and competitive inhibition with synthetic peptides covering that region.","method":"In vitro binding assay (recombinant and brain-derived syntaxin 1A with tubulin), synthetic peptide competition","journal":"Biochemical and biophysical research communications","confidence":"Medium","confidence_rationale":"Tier 1 / Weak — in vitro reconstitution with peptide competition identifying binding site, single lab, single study","pmids":["9070277"],"is_preprint":false},{"year":1997,"finding":"HPC-1/syntaxin 1A in rat brain membranes is phosphorylated specifically on serine residues (not threonine or tyrosine), as detected by affinity purification and antiphosphoserine immunoblotting.","method":"Affinity column purification with isoform-specific monoclonal antibody 14D8, antiphosphoserine/threonine/tyrosine immunoblotting","journal":"Journal of molecular neuroscience : MN","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — biochemical characterization of PTM from native brain tissue, single lab, single method","pmids":["9061612"],"is_preprint":false},{"year":1998,"finding":"The C-terminal hydrophobic domain of HPC-1/syntaxin 1A functions as a membrane anchor directing localization first to the ER then to the plasma membrane via the exocytic pathway; truncation of this domain results in cytoplasmic mislocalization, and a chimeric protein with just the last 24 amino acids recapitulates transmembrane topology and exocytic pathway localization.","method":"Transient expression of deletion/chimeric mutants in COS cells, subcellular fractionation, N-glycosylation assay for ER topology, immunofluorescence","journal":"Journal of biochemistry","confidence":"High","confidence_rationale":"Tier 1 / Moderate — domain mutagenesis with multiple orthogonal methods (glycosylation assay, fractionation, imaging), single lab","pmids":["9685720"],"is_preprint":false},{"year":1999,"finding":"Reduction of syntaxin 1A expression in PC12h cells (by stable antisense transfection) enhances depolarization-evoked dopamine release, with a strong inverse correlation between syntaxin 1A protein level and dopamine release, indicating syntaxin 1A suppresses exocytosis; Ca2+ influx was unaffected.","method":"Stable antisense transfection, dopamine release assay, intracellular Ca2+ measurement","journal":"Journal of biochemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — stable knockdown with defined functional readout (dopamine secretion), Ca2+ exclusion control, single lab","pmids":["10101280"],"is_preprint":false},{"year":1999,"finding":"Syntaxin 1C, a soluble alternative splice variant of STX1A lacking the transmembrane domain, is expressed in human astroglioma cells and its expression is upregulated by PMA through a PKC-dependent signaling pathway.","method":"RT-PCR, immunoblotting, PKC inhibitor treatment","journal":"FEBS letters","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — biochemical characterization with inhibitor confirmation, single lab","pmids":["12586365"],"is_preprint":false},{"year":2001,"finding":"Intracellular delivery of the H3 domain of HPC-1/syntaxin 1A fused to HIV-1 Tat PTD suppresses transmitter release from PC12 cells, demonstrating that the H3 domain is functionally important for exocytosis regulation.","method":"Tat-fusion protein transduction into PC12 cells, transmitter release assay","journal":"Biochimica et biophysica acta","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — cell-permeable dominant-negative approach with functional readout, single lab, single method","pmids":["11420120"],"is_preprint":false},{"year":2002,"finding":"Introduction of the H3 domain peptide of HPC-1/syntaxin 1A into presynaptic hippocampal neurons via patch electrode depresses inhibitory neurotransmitter release in a stimulation-frequency-dependent manner and slows recovery from vesicle depletion after tetanic stimulation, suggesting the H3 domain regulates refilling of the readily releasable pool.","method":"Paired whole-cell patch-clamp recording with intracellular peptide dialysis in hippocampal neuronal cultures","journal":"Neuroscience letters","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct intracellular perturbation with electrophysiological readout, mechanistic interpretation supported by stimulation protocol, single lab","pmids":["12183029"],"is_preprint":false},{"year":2003,"finding":"The C-terminal membrane-anchoring region of HPC-1/syntaxin 1A (23 amino acids) does not traverse the lipid bilayer as a classical transmembrane segment; the C-terminal tail (8 amino acids) is essential for plasma membrane anchoring. These conclusions were established using the substituted-cysteine-accessibility method (SCAM) and isoform-specific monoclonal antibodies combined with subcellular fractionation.","method":"Substituted-cysteine-accessibility method (SCAM), monoclonal antibody epitope accessibility, subcellular fractionation, immunocytochemistry of transmembrane mutants","journal":"Journal of biochemistry","confidence":"High","confidence_rationale":"Tier 1 / Moderate — SCAM mutagenesis (topology determination) combined with multiple orthogonal approaches (antibody accessibility, fractionation, immunocytochemistry), single lab","pmids":["12761168"],"is_preprint":false},{"year":2004,"finding":"Syntaxin 1C (soluble splice variant of STX1A) overexpression or PMA-induced endogenous upregulation suppresses glucose uptake in astroglioma (T98G) cells by reducing GLUT-1 at the plasma membrane (Vmax decreased, Km unchanged), acting through inhibition of GLUT-1 intracellular trafficking rather than altering transporter kinetics.","method":"Overexpression, glucose uptake assay (2-deoxyglucose), immunofluorescence localization of GLUT-1, PMA stimulation","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — overexpression and endogenous induction approaches with kinetic and imaging readouts, single lab","pmids":["15037634"],"is_preprint":false},{"year":2006,"finding":"STX1A knockout mice show impaired long-term potentiation (LTP) in hippocampal CA1 slices and deficits in conditioned fear memory consolidation and extinction, while basic synaptic transmission is normal; other SNARE proteins are unaffected, establishing a specific role for STX1A in synaptic plasticity.","method":"Targeted gene disruption (knockout mice), hippocampal slice LTP recordings, behavioral tests (Morris water maze, fear conditioning), immunoblotting","journal":"The Journal of neuroscience","confidence":"High","confidence_rationale":"Tier 2 / Strong — complete KO with multiple orthogonal readouts (electrophysiology, behavior), controls for SNARE compensation, replicated by same and other labs","pmids":["16723534"],"is_preprint":false},{"year":1999,"finding":"In vitro binding assays show that syntaxin 1A binds insulin secretory granules, and syntaxin 1A overexpression specifically inhibits the regulatory (stimulated) insulin release pathway in beta TC3 cells without affecting constitutive proinsulin secretion, glucose transport, or intracellular Ca2+ levels.","method":"In vitro granule binding assay, stable overexpression in beta TC3 cells, insulin secretion assay, 2-deoxyglucose uptake, fura-2 Ca2+ imaging","journal":"Biochemical and biophysical research communications","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple functional readouts with multiple controls in established cell line, single lab","pmids":["9070225"],"is_preprint":false},{"year":2007,"finding":"STX1A knockout mice show enhanced mechanical allodynia and significantly greater excitatory synaptic transmission (increased evoked EPSC amplitude, increased aEPSC and mEPSC frequency) in spinal cord dorsal horn after peripheral nerve injury compared to wild-type mice, revealing a role for STX1A in modulating synaptic plasticity in nociceptive pathways.","method":"Partial sciatic nerve ligation, von Frey filament behavioral test, whole-cell patch-clamp recordings from spinal cord slices","journal":"The European journal of neuroscience","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — KO model with behavioral and electrophysiological readouts, single lab","pmids":["17953616"],"is_preprint":false},{"year":2011,"finding":"Munc18-1 exerts dual functions through its central cavity: (1) chaperone activity via interaction with monomeric syntaxin 1A (STX1A), and (2) activation of SNARE-mediated membrane fusion via binding to assembled SNARE complexes. A novel Munc18-1 mutant with reduced STX1A interaction retains SNARE complex binding and promotes liposome fusion, while soluble STX1A H3 domain blocks Munc18-1 activation of liposome fusion by occupying the central cavity.","method":"Munc18-1 mutagenesis, liposome fusion reconstitution assay, pulldown/binding assays, secretion assay in neuroendocrine cells","journal":"Molecular biology of the cell","confidence":"High","confidence_rationale":"Tier 1 / Moderate — in vitro reconstitution (liposome fusion), mutagenesis, and cell-based secretion assay; multiple orthogonal methods, single lab","pmids":["21900493"],"is_preprint":false},{"year":2012,"finding":"LTP impairment in STX1A knockout mice results from reduced catecholamine (noradrenaline, dopamine) release from dense-core vesicles, leading to suppressed cAMP/PKA signaling; LTP is rescued by forskolin (adenylyl cyclase activator) or by exogenous noradrenaline/dopamine, and catecholamine depletion in wild-type mice reduces LTP, placing STX1A upstream of catecholaminergic neuromodulation of LTP.","method":"Hippocampal slice LTP recordings, HPLC catecholamine measurement, pharmacological rescue experiments (forskolin, noradrenaline, dopamine, catecholamine depletion), STX1A KO mice","journal":"The Journal of neuroscience","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic KO with multiple pharmacological rescue paradigms and biochemical measurement, establishing epistatic pathway position","pmids":["22219298"],"is_preprint":false},{"year":2014,"finding":"STX1B (not STX1A) is required for neuronal survival; STX1B knockout mice die before postnatal day 14 with impaired brain development. STX1B is required in glial cells for BDNF secretion: conditioned medium from STX1B-/- glia fails to support neuronal survival, BDNF localization in STX1B-/- glia is disrupted, and BDNF or NT-3 rescues STX1B-/- neuron survival, establishing a distinct role for STX1B versus STX1A.","method":"Targeted gene disruption (STX1B KO mice), conditioned medium assay, BDNF immunolocalization, neuronal survival counts, exogenous neurotrophin rescue","journal":"Journal of neurochemistry","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic KO with multiple orthogonal functional and biochemical readouts establishing isoform-specific role; includes rescue experiments","pmids":["24666284"],"is_preprint":false},{"year":2015,"finding":"An autism-associated STX1A variant (R26Q) shows decreased phosphorylation at Ser14 by casein kinase 2 and reduced STX1A/DAT (dopamine transporter) interaction, both of which converge to inhibit reverse transport of dopamine and alter dopamine-associated behaviors.","method":"Autism patient variant characterization, biophysical/biochemical assays of DAT function, animal models, kinase assay for Ser14 phosphorylation by CK2, co-immunoprecipitation of STX1A/DAT","journal":"EBioMedicine","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple biophysical and biochemical approaches in single study, identified specific phosphorylation writer (CK2) and interaction partner (DAT), single lab","pmids":["25774383"],"is_preprint":false},{"year":2016,"finding":"Unusual social behavior in STX1A KO mice is caused by reduced dopamine-induced oxytocin (OXT) release in the CNS; in vivo microdialysis shows lower extracellular OXT in STX1A KO, intracerebroventricular OXT partially rescues social behavior, and dopamine-stimulated OXT release from amygdala is reduced.","method":"STX1A KO mice, social novelty preference test, intracerebroventricular OXT administration, in vivo microdialysis for OXT measurement","journal":"Journal of neurochemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — KO + in vivo pharmacological rescue + in vivo microdialysis, single lab","pmids":["27059771"],"is_preprint":false},{"year":1999,"finding":"In vitro binding assays demonstrate that syntaxin 1A inhibits the regulatory (stimulated) insulin release pathway by interacting with vesicular proteins on secretory granules, without affecting glucose metabolism or intracellular Ca2+.","method":"In vitro granule binding assay, insulin secretion assay in stable overexpressing beta TC3 cells","journal":"Biochemical and biophysical research communications","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — binding assay plus functional secretion assay, single lab; this finding is largely replicated by PMID 8557645","pmids":["9070225"],"is_preprint":false},{"year":1999,"finding":"In vitro inhibition of microtubule polymerization by HPC-1/syntaxin 1A: affinity chromatography shows direct tubulin binding; synthetic peptides covering residues 89-106 competitively block binding; chemical cross-linking shows 1:1 stoichiometry (one syntaxin 1A molecule per tubulin monomer); light scattering and dark-field microscopy show decreased microtubule growth rate; a mutant lacking the tubulin-binding sequence (residues 1-97) does not suppress polymerization.","method":"Affinity column chromatography, synthetic peptide competition, chemical cross-linking (EDC), light scattering microtubule polymerization assay, dark-field microscopy","journal":"Cell structure and function","confidence":"High","confidence_rationale":"Tier 1 / Moderate — in vitro reconstitution with multiple orthogonal biochemical methods and mutagenesis confirming binding site, single lab","pmids":["15216893"],"is_preprint":false},{"year":2019,"finding":"JNK2 interacts with STX1A at presynaptic terminals, and this interaction is required for NMDA receptor-evoked glutamate release; a cell-permeable peptide (JGRi1) that disrupts the JNK2/STX1A interaction reduces NMDA-evoked glutamate release in vitro and ex vivo.","method":"Co-immunoprecipitation, cell-permeable interfering peptide, glutamate release assay in vitro and ex vivo, intraperitoneal administration with brain diffusion assay","journal":"Scientific reports","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — co-IP plus functional peptide interference with glutamate release readout, two experimental systems (in vitro and ex vivo), single lab","pmids":["31073146"],"is_preprint":false},{"year":2022,"finding":"De novo missense variants in STX1A (associated with epilepsy) are predicted in silico to weaken the inhibitory STX1A-STXBP1 (Munc18-1) interaction, while inframe single-amino-acid deletions (associated with intellectual disability/autism) are predicted to impair SNARE complex formation, suggesting two distinct pathogenic mechanisms.","method":"In silico structural modeling of STX1A missense and deletion variants; clinical cohort assembly (8 individuals with ultra-rare STX1A variants)","journal":"European journal of human genetics : EJHG","confidence":"Low","confidence_rationale":"Tier 4 / Weak — mechanistic interpretation is in silico modeling only, no direct biochemical validation of the predicted protein-protein interaction changes reported in the abstract","pmids":["36564538"],"is_preprint":false},{"year":2023,"finding":"SNAP23 competitively inhibits insulin secretion by blocking SNAP25 binding to STX1A; full-length SNAP23 (requiring both N- and C-terminal SNARE binding domains) is needed for competition; SNAP23 serine 95 phosphorylation enhances the SNAP23-STX1A interaction and thereby further inhibits insulin secretion.","method":"SNAP23 overexpression/knockdown in INS-1 cells, insulin secretion assay, co-immunoprecipitation of SNAP23/SNAP25/STX1A, domain deletion analysis, phospho-mimetic/phospho-dead mutants","journal":"Bioscience reports","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — co-IP with domain mapping and phospho-mutants plus functional secretion assay, single lab","pmids":["37057886"],"is_preprint":false},{"year":2025,"finding":"STX1A localizes predominantly to lysosomes (and a cohort to the plasma membrane) in HeLa cells; STX1A knockdown causes accumulation of lysosomes beneath the cell surface with reduced lysosome exocytosis and proteolytic activity, while overexpression decreases lysosome number with peripheral dispersion; STX1A forms a SNARE complex with SNAP23 or SNAP25 (Qbc) and VAMP2 (R) to mediate lysosomal fusion with the plasma membrane. STX1A also localizes to LLOMe-induced damaged lysosomes and reduces their number by enhancing exocytosis.","method":"GFP-STX1A overexpression, siRNA knockdown, TIRF imaging, LAMP1 immunostaining, lysosome exocytosis assay, proteolytic activity assay, co-immunoprecipitation for SNARE complex, LLOMe-induced lysosome damage assay","journal":"Molecular biology of the cell","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal methods (TIRF, SNARE co-IP, gain- and loss-of-function, functional exocytosis assay, damage response), single lab but comprehensive","pmids":["41123944"],"is_preprint":false},{"year":2025,"finding":"STX1A is localized to mitochondria in gastric cancer cells; STX1A knockdown impairs mitochondrial respiration, increases oxidative stress, and induces ferroptosis; targeting STX1A or mitochondrial function reverses acquired 5-fluorouracil and cisplatin resistance by inducing ferroptosis.","method":"STX1A knockdown, mitochondrial respiration assay (Seahorse), oxidative stress measurement, cell viability/ferroptosis assay, drug resistance assay, subcellular fractionation/localization","journal":"Human cell","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — knockdown with functional readouts and novel localization, single lab, single study; mitochondrial localization is novel and not yet replicated","pmids":["40056239"],"is_preprint":false}],"current_model":"STX1A (HPC-1/syntaxin 1A) is a membrane-anchored t-SNARE that forms the core SNARE complex (with SNAP-25 and VAMP2/synaptobrevin) to drive calcium-triggered exocytosis of synaptic vesicles and dense-core vesicles at neuronal and neuroendocrine membranes; it is cleaved and inactivated by botulinum neurotoxin C1 (a zinc-metallo-endoprotease), binds monomeric syntaxin 1A as a chaperone through Munc18-1, directly interacts with the N-type calcium channel/synaptotagmin complex, is phosphorylated on serine (including Ser14 by casein kinase 2), and also localizes to lysosomes where it forms a SNARE complex with SNAP23/SNAP25 and VAMP2 to mediate lysosomal exocytosis; loss of STX1A specifically impairs dense-core vesicle release of catecholamines and oxytocin, synaptic LTP, and fear memory, while paradoxically suppressing (rather than facilitating) certain modes of exocytosis including stimulated insulin secretion."},"narrative":{"mechanistic_narrative":"STX1A (HPC-1/syntaxin 1A) is a membrane-anchored t-SNARE that governs regulated exocytosis at neuronal and neuroendocrine membranes, where it nucleates the core SNARE machinery together with SNAP-25/SNAP23 and VAMP2 [PMID:41123944]. It localizes to the cytoplasmic face of presynaptic plasma membranes and synaptic vesicles, and is also found on dense-core secretory granules including chromaffin granules and insulin granules [PMID:8301329, PMID:7608144, PMID:8557645]. Its C-terminal hydrophobic tail anchors the protein, directing trafficking from the ER to the plasma membrane via the exocytic pathway, and this membrane association is required for cleavage and inactivation by botulinum neurotoxin C1, a zinc-dependent metallo-endoprotease that thereby blocks transmitter release [PMID:7901002, PMID:9685720, PMID:12761168]. STX1A interacts with the synaptic-vesicle release apparatus, assembling into a ternary complex with synaptotagmin and the N-type calcium channel [PMID:1334074], and its function is gated by Munc18-1 (STXBP1), which uses its central cavity both to chaperone monomeric STX1A and to activate SNARE-mediated membrane fusion [PMID:21900493]. Genetic ablation in mice produces specific deficits in synaptic plasticity—impaired hippocampal LTP and fear memory—that trace to reduced dense-core-vesicle release of catecholamines and consequent loss of cAMP/PKA neuromodulation, and to reduced dopamine-induced oxytocin release underlying social behavior [PMID:16723534, PMID:22219298, PMID:27059771]. Paradoxically, in several secretory systems STX1A acts as a brake on exocytosis: its overexpression suppresses stimulated insulin secretion while reducing its level enhances depolarization-evoked dopamine release and synaptic transmitter output [PMID:8557645, PMID:10101280, PMID:9427341]. STX1A additionally binds tubulin and inhibits microtubule polymerization in vitro [PMID:15216893], and mediates lysosomal fusion with the plasma membrane through a SNAP23/SNAP25–VAMP2 SNARE complex that supports lysosomal exocytosis and the clearance of damaged lysosomes [PMID:41123944]. Variants in STX1A are linked to autism, intellectual disability, and epilepsy, with a disease-associated R26Q variant reducing Ser14 phosphorylation by casein kinase 2 and STX1A–dopamine-transporter interaction [PMID:25774383].","teleology":[{"year":1992,"claim":"Establishing how syntaxin 1A is physically coupled to the calcium-sensing release machinery answered where in the exocytic apparatus it acts.","evidence":"Co-immunoprecipitation from solubilized rat brain membranes showing a ternary complex with synaptotagmin and the N-type calcium channel","pmids":["1334074"],"confidence":"Medium","gaps":["Stoichiometry and direct versus bridged interactions not resolved","Functional consequence of the ternary complex on Ca2+-triggered fusion not demonstrated"]},{"year":1993,"claim":"Pinpointing how botulinum neurotoxin C1 blocks neurotransmission identified syntaxin 1A as a direct proteolytic substrate and defined a requirement for membrane anchoring.","evidence":"In vitro proteolysis and proteoliposome reconstitution with TM-domain truncation mutants","pmids":["7901002"],"confidence":"High","gaps":["Exact scissile bond/cleavage residues not defined in this entry","Link between cleavage and SNARE assembly failure not directly shown"]},{"year":1993,"claim":"Defining the subcellular topology of syntaxin 1A established it as a cytoplasmic-facing protein on presynaptic plasma membranes and synaptic vesicles.","evidence":"Cryoimmunogold electron microscopy with membrane-rupture topology validation on synaptosomes","pmids":["8301329"],"confidence":"High","gaps":["Quantitative partitioning between plasma membrane and vesicles not established","Did not address non-neuronal localization"]},{"year":1996,"claim":"Testing whether syntaxin 1A is positive or negative for regulated secretion revealed a counterintuitive suppressive role in endocrine exocytosis.","evidence":"Overexpression in beta TC3 cells with insulin secretion assays, isoform comparison, and in vitro granule binding","pmids":["8557645","9070225"],"confidence":"High","gaps":["Molecular basis of suppression (sequestration vs. dominant-negative SNARE) not defined","Overexpression may not reflect endogenous stoichiometry"]},{"year":1997,"claim":"Loss-of-function and dominant-negative perturbations at central synapses confirmed that syntaxin 1A restrains transmitter release rather than simply enabling it.","evidence":"Intracellular antibody dialysis and H3-domain peptide delivery at hippocampal/PC12 synapses with electrophysiological and release readouts","pmids":["9427341","11420120","10101280"],"confidence":"Medium","gaps":["Reconciliation with the obligatory SNARE-fusion role not provided","Acute perturbation effects vs. chronic adaptation not separated"]},{"year":1998,"claim":"Mapping the membrane-targeting determinant explained how syntaxin 1A reaches the plasma membrane through the secretory pathway.","evidence":"Deletion/chimeric mutants in COS cells with N-glycosylation topology, fractionation, and immunofluorescence; later SCAM topology analysis","pmids":["9685720","12761168"],"confidence":"High","gaps":["Trafficking machinery directing ER-to-PM transit not identified","Regulation of anchoring not addressed"]},{"year":1999,"claim":"Characterizing the tubulin interaction revealed a SNARE-independent cytoskeletal activity of syntaxin 1A.","evidence":"Affinity chromatography, peptide competition mapping residues 89-106, cross-linking, and microtubule polymerization assays with binding-site deletion mutant","pmids":["15216893","9070277"],"confidence":"High","gaps":["In vivo relevance of microtubule inhibition not established","Relationship to axonal sprouting suppression not directly tied"]},{"year":2006,"claim":"Genetic ablation in mice defined the in vivo phenotype, isolating a specific requirement for STX1A in synaptic plasticity rather than baseline transmission.","evidence":"STX1A knockout mice with hippocampal LTP recordings, fear conditioning, and SNARE immunoblot controls","pmids":["16723534"],"confidence":"High","gaps":["Cellular locus of the plasticity defect not yet identified in this entry","Possible developmental compensation by STX1B not excluded"]},{"year":2011,"claim":"Dissecting Munc18-1 function clarified how STX1A is chaperoned as a monomer yet permits SNARE-driven fusion downstream.","evidence":"Munc18-1 mutagenesis, liposome fusion reconstitution, binding assays, and neuroendocrine secretion assays","pmids":["21900493"],"confidence":"High","gaps":["Transition from Munc18-bound monomer to assembled SNARE complex in vivo not temporally resolved","Role of STX1A phosphorylation in this switch not tested"]},{"year":2012,"claim":"Pharmacological epistasis placed STX1A upstream of catecholaminergic neuromodulation, mechanistically explaining the LTP deficit through dense-core-vesicle release.","evidence":"STX1A KO LTP recordings with forskolin and catecholamine rescue plus HPLC catecholamine measurement","pmids":["22219298"],"confidence":"High","gaps":["Whether STX1A acts in the catecholaminergic neurons themselves or postsynaptically not fully resolved","Selectivity for dense-core over synaptic-vesicle pools not mechanistically explained"]},{"year":2015,"claim":"Characterizing a disease variant connected STX1A phosphorylation and a transporter interaction to dopamine handling and behavior.","evidence":"Autism R26Q variant analysis with CK2 Ser14 kinase assay, STX1A/DAT co-IP, DAT reverse-transport assays, and animal models","pmids":["25774383"],"confidence":"Medium","gaps":["Direct demonstration that Ser14 phosphorylation controls DAT binding under physiological conditions limited","Generalizability beyond the single variant unknown"]},{"year":2016,"claim":"Linking STX1A to oxytocin secretion explained its contribution to social behavior at the neuroendocrine level.","evidence":"STX1A KO with in vivo microdialysis of oxytocin and intracerebroventricular OXT behavioral rescue","pmids":["27059771"],"confidence":"Medium","gaps":["Direct measurement of STX1A-dependent OXT vesicle fusion not shown","Circuit locus of the defect not pinpointed"]},{"year":2023,"claim":"Identifying SNAP23 as a competitive inhibitor of SNAP25 binding clarified a regulatory node controlling STX1A-dependent insulin exocytosis.","evidence":"SNAP23 gain/loss in INS-1 cells, co-IP with SNAP25/STX1A, domain mapping, and phospho-mutant insulin secretion assays","pmids":["37057886"],"confidence":"Medium","gaps":["Whether this competition operates in primary beta cells in vivo not shown","Kinase responsible for SNAP23 Ser95 phosphorylation not identified"]},{"year":2025,"claim":"Discovering lysosomal STX1A extended its t-SNARE role beyond classical secretory vesicles to lysosomal exocytosis and damage clearance.","evidence":"GFP-STX1A overexpression, siRNA knockdown, TIRF imaging, SNARE co-IP, lysosome exocytosis/proteolytic assays, and LLOMe damage assays in HeLa cells","pmids":["41123944"],"confidence":"High","gaps":["Whether lysosomal STX1A function operates in neurons/endocrine cells not tested","Regulation switching STX1A between plasma-membrane and lysosomal pools unknown"]},{"year":2025,"claim":"A reported mitochondrial localization tied STX1A to respiration and ferroptosis-mediated chemoresistance in cancer cells.","evidence":"STX1A knockdown with Seahorse respiration, oxidative stress and ferroptosis assays, and drug-resistance assays in gastric cancer cells","pmids":["40056239"],"confidence":"Medium","gaps":["Mitochondrial localization is novel and not independently replicated","Mechanism by which a t-SNARE influences respiration not defined"]},{"year":null,"claim":"How a single t-SNARE simultaneously functions as an obligatory fusion component and a suppressor of regulated exocytosis, and what governs its partitioning across plasma membrane, secretory granules, lysosomes, and reported mitochondria, remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No unified model reconciling facilitatory SNARE assembly with negative regulation of release","Trafficking/regulatory signals directing STX1A to distinct membranes not defined","Structural basis of disease-variant effects on STXBP1 binding and SNARE assembly not biochemically validated"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0005198","term_label":"structural molecule activity","supporting_discovery_ids":[30,20,0]},{"term_id":"GO:0008092","term_label":"cytoskeletal protein binding","supporting_discovery_ids":[26,8]},{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[20]}],"localization":[{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[2,10,15,30]},{"term_id":"GO:0031410","term_label":"cytoplasmic 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kikanshi","url":"https://pubmed.ncbi.nlm.nih.gov/9403817","citation_count":5,"is_preprint":false},{"pmid":"37057886","id":"PMC_37057886","title":"SNAP23 decreases insulin secretion by competitively inhibiting the interaction between SNAP25 and STX1A.","date":"2023","source":"Bioscience reports","url":"https://pubmed.ncbi.nlm.nih.gov/37057886","citation_count":4,"is_preprint":false},{"pmid":"29880035","id":"PMC_29880035","title":"Multiplex PCR for the simultaneous detection of the Enterobacterial gene wecA, the Shiga Toxin genes (stx1 and stx2) and the Intimin gene (eae).","date":"2018","source":"BMC research notes","url":"https://pubmed.ncbi.nlm.nih.gov/29880035","citation_count":3,"is_preprint":false},{"pmid":"26443836","id":"PMC_26443836","title":"Different roles of the C-terminal end of Stx1A and Stx2A for AB5 complex integrity and retrograde transport of Stx in HeLa cells.","date":"2015","source":"Pathogens and 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\"method\": \"In vitro proteolysis assay, in vitro translation with/without microsomes, proteoliposome reconstitution\",\n      \"journal\": \"The EMBO journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — in vitro reconstitution with proteoliposomes, mutagenesis via truncation (lacking TM domain), replicated across conditions; foundational mechanistic study\",\n      \"pmids\": [\"7901002\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1992,\n      \"finding\": \"HPC-1/syntaxin 1A (p35) forms a ternary complex with synaptotagmin and the omega-conotoxin-sensitive N-type calcium channel (omega-CgTX receptor) in rat brain, as shown by co-immunoprecipitation with antibodies against each component.\",\n      \"method\": \"Co-immunoprecipitation from solubilized rat brain membranes\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — reciprocal co-immunoprecipitation with multiple antibodies in single lab, establishing ternary complex\",\n      \"pmids\": [\"1334074\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1993,\n      \"finding\": \"HPC-1/syntaxin 1A localizes to the cytoplasmic face of presynaptic plasma membranes and synaptic vesicles in rat cerebellar neurons, as determined by cryoimmunogold electron microscopy; intact synaptosomes are not labeled, but ruptured membranes expose the cytoplasmic epitopes, establishing intracellular topology.\",\n      \"method\": \"Cryoimmunogold electron microscopy, pre-embedding protein A-gold technique on synaptosomes with membrane rupture\",\n      \"journal\": \"Journal of neurocytology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — direct subcellular localization by immunoelectron microscopy with membrane topology validation, replicated with two EM approaches\",\n      \"pmids\": [\"8301329\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1995,\n      \"finding\": \"Syntaxin 1A (HPC-1) is associated with chromaffin granules in adrenal medulla (not exclusively plasma membrane), suggesting it can function as a vesicle-SNARE receptor component in addition to its role as a target-SNARE on the plasma membrane.\",\n      \"method\": \"Subcellular fractionation, immunomorphological analysis of chromaffin cells\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — biochemical fractionation combined with morphological analysis in single lab, two orthogonal methods\",\n      \"pmids\": [\"7608144\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1996,\n      \"finding\": \"Syntaxin 1A overexpression in pancreatic beta TC3 cells specifically suppresses glucose-stimulated and secretagogue-stimulated (PMA, forskolin) insulin release by ~50% via the regulatory exocytosis pathway, without affecting constitutive proinsulin secretion, glucose metabolism, or intracellular Ca2+; in vitro binding assays showed syntaxin 1A binds insulin secretory granules.\",\n      \"method\": \"Transient and stable transfection overexpression, insulin secretion assay, in vitro binding assay, metabolic labeling\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal methods (overexpression, stable cell lines, secretion assays, in vitro binding), specific pathway dissection with isoform specificity (1A but not 1B effect)\",\n      \"pmids\": [\"8557645\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1996,\n      \"finding\": \"Suppression of HPC-1/syntaxin 1A function by antisense oligonucleotides (in cultured DRG neurons) or intra-axonal antibody injection (in chick retinal ganglion neurons) enhances axonal sprouting, indicating that axonal syntaxin 1A physiologically suppresses excess axon-collateral sprouting.\",\n      \"method\": \"Antisense oligonucleotide knockdown, intra-axonal antibody microinjection, neurite morphology analysis\",\n      \"journal\": \"Brain research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — two independent loss-of-function approaches (antisense + antibody injection) in two cell types, single lab\",\n      \"pmids\": [\"8973813\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1995,\n      \"finding\": \"Injection of HPC-1/syntaxin 1A (or syntaxin 1B) cRNA into amphibian embryonic cells causes morphological deformation of Golgi complexes, accumulation of vacuoles, and disappearance of extracellular matrix from the cell surface, demonstrating that syntaxin 1A disrupts intracellular membrane transport and inhibits constitutive secretion.\",\n      \"method\": \"cRNA microinjection into amphibian embryos, immunoelectron microscopy, immunoblotting\",\n      \"journal\": \"Experimental cell research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — gain-of-function in vivo embryo model with morphological readout by EM, single lab\",\n      \"pmids\": [\"7589235\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1997,\n      \"finding\": \"Intracellular application of anti-HPC-1/syntaxin 1A antibody into presynaptic neurons enhances autaptic excitatory postsynaptic current amplitude in cultured rat hippocampal neurons, indicating syntaxin 1A suppresses transmitter release at central synapses; the increase was due to increased quantal content, not quantal size.\",\n      \"method\": \"Whole-cell patch-clamp with intracellular antibody dialysis at hippocampal autapses\",\n      \"journal\": \"Neuroreport\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct intracellular perturbation with electrophysiological readout, single lab, single method\",\n      \"pmids\": [\"9427341\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1997,\n      \"finding\": \"HPC-1/syntaxin 1A binds directly to tubulin in vitro at residues 89–106 (a tubulin-binding motif), as shown by in vitro binding assay and competitive inhibition with synthetic peptides covering that region.\",\n      \"method\": \"In vitro binding assay (recombinant and brain-derived syntaxin 1A with tubulin), synthetic peptide competition\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Weak — in vitro reconstitution with peptide competition identifying binding site, single lab, single study\",\n      \"pmids\": [\"9070277\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1997,\n      \"finding\": \"HPC-1/syntaxin 1A in rat brain membranes is phosphorylated specifically on serine residues (not threonine or tyrosine), as detected by affinity purification and antiphosphoserine immunoblotting.\",\n      \"method\": \"Affinity column purification with isoform-specific monoclonal antibody 14D8, antiphosphoserine/threonine/tyrosine immunoblotting\",\n      \"journal\": \"Journal of molecular neuroscience : MN\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — biochemical characterization of PTM from native brain tissue, single lab, single method\",\n      \"pmids\": [\"9061612\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1998,\n      \"finding\": \"The C-terminal hydrophobic domain of HPC-1/syntaxin 1A functions as a membrane anchor directing localization first to the ER then to the plasma membrane via the exocytic pathway; truncation of this domain results in cytoplasmic mislocalization, and a chimeric protein with just the last 24 amino acids recapitulates transmembrane topology and exocytic pathway localization.\",\n      \"method\": \"Transient expression of deletion/chimeric mutants in COS cells, subcellular fractionation, N-glycosylation assay for ER topology, immunofluorescence\",\n      \"journal\": \"Journal of biochemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — domain mutagenesis with multiple orthogonal methods (glycosylation assay, fractionation, imaging), single lab\",\n      \"pmids\": [\"9685720\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1999,\n      \"finding\": \"Reduction of syntaxin 1A expression in PC12h cells (by stable antisense transfection) enhances depolarization-evoked dopamine release, with a strong inverse correlation between syntaxin 1A protein level and dopamine release, indicating syntaxin 1A suppresses exocytosis; Ca2+ influx was unaffected.\",\n      \"method\": \"Stable antisense transfection, dopamine release assay, intracellular Ca2+ measurement\",\n      \"journal\": \"Journal of biochemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — stable knockdown with defined functional readout (dopamine secretion), Ca2+ exclusion control, single lab\",\n      \"pmids\": [\"10101280\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1999,\n      \"finding\": \"Syntaxin 1C, a soluble alternative splice variant of STX1A lacking the transmembrane domain, is expressed in human astroglioma cells and its expression is upregulated by PMA through a PKC-dependent signaling pathway.\",\n      \"method\": \"RT-PCR, immunoblotting, PKC inhibitor treatment\",\n      \"journal\": \"FEBS letters\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — biochemical characterization with inhibitor confirmation, single lab\",\n      \"pmids\": [\"12586365\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2001,\n      \"finding\": \"Intracellular delivery of the H3 domain of HPC-1/syntaxin 1A fused to HIV-1 Tat PTD suppresses transmitter release from PC12 cells, demonstrating that the H3 domain is functionally important for exocytosis regulation.\",\n      \"method\": \"Tat-fusion protein transduction into PC12 cells, transmitter release assay\",\n      \"journal\": \"Biochimica et biophysica acta\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — cell-permeable dominant-negative approach with functional readout, single lab, single method\",\n      \"pmids\": [\"11420120\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"Introduction of the H3 domain peptide of HPC-1/syntaxin 1A into presynaptic hippocampal neurons via patch electrode depresses inhibitory neurotransmitter release in a stimulation-frequency-dependent manner and slows recovery from vesicle depletion after tetanic stimulation, suggesting the H3 domain regulates refilling of the readily releasable pool.\",\n      \"method\": \"Paired whole-cell patch-clamp recording with intracellular peptide dialysis in hippocampal neuronal cultures\",\n      \"journal\": \"Neuroscience letters\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct intracellular perturbation with electrophysiological readout, mechanistic interpretation supported by stimulation protocol, single lab\",\n      \"pmids\": [\"12183029\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"The C-terminal membrane-anchoring region of HPC-1/syntaxin 1A (23 amino acids) does not traverse the lipid bilayer as a classical transmembrane segment; the C-terminal tail (8 amino acids) is essential for plasma membrane anchoring. These conclusions were established using the substituted-cysteine-accessibility method (SCAM) and isoform-specific monoclonal antibodies combined with subcellular fractionation.\",\n      \"method\": \"Substituted-cysteine-accessibility method (SCAM), monoclonal antibody epitope accessibility, subcellular fractionation, immunocytochemistry of transmembrane mutants\",\n      \"journal\": \"Journal of biochemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — SCAM mutagenesis (topology determination) combined with multiple orthogonal approaches (antibody accessibility, fractionation, immunocytochemistry), single lab\",\n      \"pmids\": [\"12761168\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"Syntaxin 1C (soluble splice variant of STX1A) overexpression or PMA-induced endogenous upregulation suppresses glucose uptake in astroglioma (T98G) cells by reducing GLUT-1 at the plasma membrane (Vmax decreased, Km unchanged), acting through inhibition of GLUT-1 intracellular trafficking rather than altering transporter kinetics.\",\n      \"method\": \"Overexpression, glucose uptake assay (2-deoxyglucose), immunofluorescence localization of GLUT-1, PMA stimulation\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — overexpression and endogenous induction approaches with kinetic and imaging readouts, single lab\",\n      \"pmids\": [\"15037634\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"STX1A knockout mice show impaired long-term potentiation (LTP) in hippocampal CA1 slices and deficits in conditioned fear memory consolidation and extinction, while basic synaptic transmission is normal; other SNARE proteins are unaffected, establishing a specific role for STX1A in synaptic plasticity.\",\n      \"method\": \"Targeted gene disruption (knockout mice), hippocampal slice LTP recordings, behavioral tests (Morris water maze, fear conditioning), immunoblotting\",\n      \"journal\": \"The Journal of neuroscience\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — complete KO with multiple orthogonal readouts (electrophysiology, behavior), controls for SNARE compensation, replicated by same and other labs\",\n      \"pmids\": [\"16723534\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1999,\n      \"finding\": \"In vitro binding assays show that syntaxin 1A binds insulin secretory granules, and syntaxin 1A overexpression specifically inhibits the regulatory (stimulated) insulin release pathway in beta TC3 cells without affecting constitutive proinsulin secretion, glucose transport, or intracellular Ca2+ levels.\",\n      \"method\": \"In vitro granule binding assay, stable overexpression in beta TC3 cells, insulin secretion assay, 2-deoxyglucose uptake, fura-2 Ca2+ imaging\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple functional readouts with multiple controls in established cell line, single lab\",\n      \"pmids\": [\"9070225\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"STX1A knockout mice show enhanced mechanical allodynia and significantly greater excitatory synaptic transmission (increased evoked EPSC amplitude, increased aEPSC and mEPSC frequency) in spinal cord dorsal horn after peripheral nerve injury compared to wild-type mice, revealing a role for STX1A in modulating synaptic plasticity in nociceptive pathways.\",\n      \"method\": \"Partial sciatic nerve ligation, von Frey filament behavioral test, whole-cell patch-clamp recordings from spinal cord slices\",\n      \"journal\": \"The European journal of neuroscience\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — KO model with behavioral and electrophysiological readouts, single lab\",\n      \"pmids\": [\"17953616\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"Munc18-1 exerts dual functions through its central cavity: (1) chaperone activity via interaction with monomeric syntaxin 1A (STX1A), and (2) activation of SNARE-mediated membrane fusion via binding to assembled SNARE complexes. A novel Munc18-1 mutant with reduced STX1A interaction retains SNARE complex binding and promotes liposome fusion, while soluble STX1A H3 domain blocks Munc18-1 activation of liposome fusion by occupying the central cavity.\",\n      \"method\": \"Munc18-1 mutagenesis, liposome fusion reconstitution assay, pulldown/binding assays, secretion assay in neuroendocrine cells\",\n      \"journal\": \"Molecular biology of the cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro reconstitution (liposome fusion), mutagenesis, and cell-based secretion assay; multiple orthogonal methods, single lab\",\n      \"pmids\": [\"21900493\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"LTP impairment in STX1A knockout mice results from reduced catecholamine (noradrenaline, dopamine) release from dense-core vesicles, leading to suppressed cAMP/PKA signaling; LTP is rescued by forskolin (adenylyl cyclase activator) or by exogenous noradrenaline/dopamine, and catecholamine depletion in wild-type mice reduces LTP, placing STX1A upstream of catecholaminergic neuromodulation of LTP.\",\n      \"method\": \"Hippocampal slice LTP recordings, HPLC catecholamine measurement, pharmacological rescue experiments (forskolin, noradrenaline, dopamine, catecholamine depletion), STX1A KO mice\",\n      \"journal\": \"The Journal of neuroscience\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic KO with multiple pharmacological rescue paradigms and biochemical measurement, establishing epistatic pathway position\",\n      \"pmids\": [\"22219298\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"STX1B (not STX1A) is required for neuronal survival; STX1B knockout mice die before postnatal day 14 with impaired brain development. STX1B is required in glial cells for BDNF secretion: conditioned medium from STX1B-/- glia fails to support neuronal survival, BDNF localization in STX1B-/- glia is disrupted, and BDNF or NT-3 rescues STX1B-/- neuron survival, establishing a distinct role for STX1B versus STX1A.\",\n      \"method\": \"Targeted gene disruption (STX1B KO mice), conditioned medium assay, BDNF immunolocalization, neuronal survival counts, exogenous neurotrophin rescue\",\n      \"journal\": \"Journal of neurochemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic KO with multiple orthogonal functional and biochemical readouts establishing isoform-specific role; includes rescue experiments\",\n      \"pmids\": [\"24666284\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"An autism-associated STX1A variant (R26Q) shows decreased phosphorylation at Ser14 by casein kinase 2 and reduced STX1A/DAT (dopamine transporter) interaction, both of which converge to inhibit reverse transport of dopamine and alter dopamine-associated behaviors.\",\n      \"method\": \"Autism patient variant characterization, biophysical/biochemical assays of DAT function, animal models, kinase assay for Ser14 phosphorylation by CK2, co-immunoprecipitation of STX1A/DAT\",\n      \"journal\": \"EBioMedicine\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple biophysical and biochemical approaches in single study, identified specific phosphorylation writer (CK2) and interaction partner (DAT), single lab\",\n      \"pmids\": [\"25774383\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"Unusual social behavior in STX1A KO mice is caused by reduced dopamine-induced oxytocin (OXT) release in the CNS; in vivo microdialysis shows lower extracellular OXT in STX1A KO, intracerebroventricular OXT partially rescues social behavior, and dopamine-stimulated OXT release from amygdala is reduced.\",\n      \"method\": \"STX1A KO mice, social novelty preference test, intracerebroventricular OXT administration, in vivo microdialysis for OXT measurement\",\n      \"journal\": \"Journal of neurochemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — KO + in vivo pharmacological rescue + in vivo microdialysis, single lab\",\n      \"pmids\": [\"27059771\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1999,\n      \"finding\": \"In vitro binding assays demonstrate that syntaxin 1A inhibits the regulatory (stimulated) insulin release pathway by interacting with vesicular proteins on secretory granules, without affecting glucose metabolism or intracellular Ca2+.\",\n      \"method\": \"In vitro granule binding assay, insulin secretion assay in stable overexpressing beta TC3 cells\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — binding assay plus functional secretion assay, single lab; this finding is largely replicated by PMID 8557645\",\n      \"pmids\": [\"9070225\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1999,\n      \"finding\": \"In vitro inhibition of microtubule polymerization by HPC-1/syntaxin 1A: affinity chromatography shows direct tubulin binding; synthetic peptides covering residues 89-106 competitively block binding; chemical cross-linking shows 1:1 stoichiometry (one syntaxin 1A molecule per tubulin monomer); light scattering and dark-field microscopy show decreased microtubule growth rate; a mutant lacking the tubulin-binding sequence (residues 1-97) does not suppress polymerization.\",\n      \"method\": \"Affinity column chromatography, synthetic peptide competition, chemical cross-linking (EDC), light scattering microtubule polymerization assay, dark-field microscopy\",\n      \"journal\": \"Cell structure and function\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro reconstitution with multiple orthogonal biochemical methods and mutagenesis confirming binding site, single lab\",\n      \"pmids\": [\"15216893\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"JNK2 interacts with STX1A at presynaptic terminals, and this interaction is required for NMDA receptor-evoked glutamate release; a cell-permeable peptide (JGRi1) that disrupts the JNK2/STX1A interaction reduces NMDA-evoked glutamate release in vitro and ex vivo.\",\n      \"method\": \"Co-immunoprecipitation, cell-permeable interfering peptide, glutamate release assay in vitro and ex vivo, intraperitoneal administration with brain diffusion assay\",\n      \"journal\": \"Scientific reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — co-IP plus functional peptide interference with glutamate release readout, two experimental systems (in vitro and ex vivo), single lab\",\n      \"pmids\": [\"31073146\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"De novo missense variants in STX1A (associated with epilepsy) are predicted in silico to weaken the inhibitory STX1A-STXBP1 (Munc18-1) interaction, while inframe single-amino-acid deletions (associated with intellectual disability/autism) are predicted to impair SNARE complex formation, suggesting two distinct pathogenic mechanisms.\",\n      \"method\": \"In silico structural modeling of STX1A missense and deletion variants; clinical cohort assembly (8 individuals with ultra-rare STX1A variants)\",\n      \"journal\": \"European journal of human genetics : EJHG\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 4 / Weak — mechanistic interpretation is in silico modeling only, no direct biochemical validation of the predicted protein-protein interaction changes reported in the abstract\",\n      \"pmids\": [\"36564538\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"SNAP23 competitively inhibits insulin secretion by blocking SNAP25 binding to STX1A; full-length SNAP23 (requiring both N- and C-terminal SNARE binding domains) is needed for competition; SNAP23 serine 95 phosphorylation enhances the SNAP23-STX1A interaction and thereby further inhibits insulin secretion.\",\n      \"method\": \"SNAP23 overexpression/knockdown in INS-1 cells, insulin secretion assay, co-immunoprecipitation of SNAP23/SNAP25/STX1A, domain deletion analysis, phospho-mimetic/phospho-dead mutants\",\n      \"journal\": \"Bioscience reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — co-IP with domain mapping and phospho-mutants plus functional secretion assay, single lab\",\n      \"pmids\": [\"37057886\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"STX1A localizes predominantly to lysosomes (and a cohort to the plasma membrane) in HeLa cells; STX1A knockdown causes accumulation of lysosomes beneath the cell surface with reduced lysosome exocytosis and proteolytic activity, while overexpression decreases lysosome number with peripheral dispersion; STX1A forms a SNARE complex with SNAP23 or SNAP25 (Qbc) and VAMP2 (R) to mediate lysosomal fusion with the plasma membrane. STX1A also localizes to LLOMe-induced damaged lysosomes and reduces their number by enhancing exocytosis.\",\n      \"method\": \"GFP-STX1A overexpression, siRNA knockdown, TIRF imaging, LAMP1 immunostaining, lysosome exocytosis assay, proteolytic activity assay, co-immunoprecipitation for SNARE complex, LLOMe-induced lysosome damage assay\",\n      \"journal\": \"Molecular biology of the cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal methods (TIRF, SNARE co-IP, gain- and loss-of-function, functional exocytosis assay, damage response), single lab but comprehensive\",\n      \"pmids\": [\"41123944\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"STX1A is localized to mitochondria in gastric cancer cells; STX1A knockdown impairs mitochondrial respiration, increases oxidative stress, and induces ferroptosis; targeting STX1A or mitochondrial function reverses acquired 5-fluorouracil and cisplatin resistance by inducing ferroptosis.\",\n      \"method\": \"STX1A knockdown, mitochondrial respiration assay (Seahorse), oxidative stress measurement, cell viability/ferroptosis assay, drug resistance assay, subcellular fractionation/localization\",\n      \"journal\": \"Human cell\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — knockdown with functional readouts and novel localization, single lab, single study; mitochondrial localization is novel and not yet replicated\",\n      \"pmids\": [\"40056239\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"STX1A (HPC-1/syntaxin 1A) is a membrane-anchored t-SNARE that forms the core SNARE complex (with SNAP-25 and VAMP2/synaptobrevin) to drive calcium-triggered exocytosis of synaptic vesicles and dense-core vesicles at neuronal and neuroendocrine membranes; it is cleaved and inactivated by botulinum neurotoxin C1 (a zinc-metallo-endoprotease), binds monomeric syntaxin 1A as a chaperone through Munc18-1, directly interacts with the N-type calcium channel/synaptotagmin complex, is phosphorylated on serine (including Ser14 by casein kinase 2), and also localizes to lysosomes where it forms a SNARE complex with SNAP23/SNAP25 and VAMP2 to mediate lysosomal exocytosis; loss of STX1A specifically impairs dense-core vesicle release of catecholamines and oxytocin, synaptic LTP, and fear memory, while paradoxically suppressing (rather than facilitating) certain modes of exocytosis including stimulated insulin secretion.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"STX1A (HPC-1/syntaxin 1A) is a membrane-anchored t-SNARE that governs regulated exocytosis at neuronal and neuroendocrine membranes, where it nucleates the core SNARE machinery together with SNAP-25/SNAP23 and VAMP2 [#30]. It localizes to the cytoplasmic face of presynaptic plasma membranes and synaptic vesicles, and is also found on dense-core secretory granules including chromaffin granules and insulin granules [#2, #3, #4]. Its C-terminal hydrophobic tail anchors the protein, directing trafficking from the ER to the plasma membrane via the exocytic pathway, and this membrane association is required for cleavage and inactivation by botulinum neurotoxin C1, a zinc-dependent metallo-endoprotease that thereby blocks transmitter release [#0, #10, #15]. STX1A interacts with the synaptic-vesicle release apparatus, assembling into a ternary complex with synaptotagmin and the N-type calcium channel [#1], and its function is gated by Munc18-1 (STXBP1), which uses its central cavity both to chaperone monomeric STX1A and to activate SNARE-mediated membrane fusion [#20]. Genetic ablation in mice produces specific deficits in synaptic plasticity—impaired hippocampal LTP and fear memory—that trace to reduced dense-core-vesicle release of catecholamines and consequent loss of cAMP/PKA neuromodulation, and to reduced dopamine-induced oxytocin release underlying social behavior [#17, #21, #24]. Paradoxically, in several secretory systems STX1A acts as a brake on exocytosis: its overexpression suppresses stimulated insulin secretion while reducing its level enhances depolarization-evoked dopamine release and synaptic transmitter output [#4, #11, #7]. STX1A additionally binds tubulin and inhibits microtubule polymerization in vitro [#26], and mediates lysosomal fusion with the plasma membrane through a SNAP23/SNAP25–VAMP2 SNARE complex that supports lysosomal exocytosis and the clearance of damaged lysosomes [#30]. Variants in STX1A are linked to autism, intellectual disability, and epilepsy, with a disease-associated R26Q variant reducing Ser14 phosphorylation by casein kinase 2 and STX1A–dopamine-transporter interaction [#23].\",\n  \"teleology\": [\n    {\n      \"year\": 1992,\n      \"claim\": \"Establishing how syntaxin 1A is physically coupled to the calcium-sensing release machinery answered where in the exocytic apparatus it acts.\",\n      \"evidence\": \"Co-immunoprecipitation from solubilized rat brain membranes showing a ternary complex with synaptotagmin and the N-type calcium channel\",\n      \"pmids\": [\"1334074\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Stoichiometry and direct versus bridged interactions not resolved\", \"Functional consequence of the ternary complex on Ca2+-triggered fusion not demonstrated\"]\n    },\n    {\n      \"year\": 1993,\n      \"claim\": \"Pinpointing how botulinum neurotoxin C1 blocks neurotransmission identified syntaxin 1A as a direct proteolytic substrate and defined a requirement for membrane anchoring.\",\n      \"evidence\": \"In vitro proteolysis and proteoliposome reconstitution with TM-domain truncation mutants\",\n      \"pmids\": [\"7901002\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Exact scissile bond/cleavage residues not defined in this entry\", \"Link between cleavage and SNARE assembly failure not directly shown\"]\n    },\n    {\n      \"year\": 1993,\n      \"claim\": \"Defining the subcellular topology of syntaxin 1A established it as a cytoplasmic-facing protein on presynaptic plasma membranes and synaptic vesicles.\",\n      \"evidence\": \"Cryoimmunogold electron microscopy with membrane-rupture topology validation on synaptosomes\",\n      \"pmids\": [\"8301329\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Quantitative partitioning between plasma membrane and vesicles not established\", \"Did not address non-neuronal localization\"]\n    },\n    {\n      \"year\": 1996,\n      \"claim\": \"Testing whether syntaxin 1A is positive or negative for regulated secretion revealed a counterintuitive suppressive role in endocrine exocytosis.\",\n      \"evidence\": \"Overexpression in beta TC3 cells with insulin secretion assays, isoform comparison, and in vitro granule binding\",\n      \"pmids\": [\"8557645\", \"9070225\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular basis of suppression (sequestration vs. dominant-negative SNARE) not defined\", \"Overexpression may not reflect endogenous stoichiometry\"]\n    },\n    {\n      \"year\": 1997,\n      \"claim\": \"Loss-of-function and dominant-negative perturbations at central synapses confirmed that syntaxin 1A restrains transmitter release rather than simply enabling it.\",\n      \"evidence\": \"Intracellular antibody dialysis and H3-domain peptide delivery at hippocampal/PC12 synapses with electrophysiological and release readouts\",\n      \"pmids\": [\"9427341\", \"11420120\", \"10101280\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Reconciliation with the obligatory SNARE-fusion role not provided\", \"Acute perturbation effects vs. chronic adaptation not separated\"]\n    },\n    {\n      \"year\": 1998,\n      \"claim\": \"Mapping the membrane-targeting determinant explained how syntaxin 1A reaches the plasma membrane through the secretory pathway.\",\n      \"evidence\": \"Deletion/chimeric mutants in COS cells with N-glycosylation topology, fractionation, and immunofluorescence; later SCAM topology analysis\",\n      \"pmids\": [\"9685720\", \"12761168\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Trafficking machinery directing ER-to-PM transit not identified\", \"Regulation of anchoring not addressed\"]\n    },\n    {\n      \"year\": 1999,\n      \"claim\": \"Characterizing the tubulin interaction revealed a SNARE-independent cytoskeletal activity of syntaxin 1A.\",\n      \"evidence\": \"Affinity chromatography, peptide competition mapping residues 89-106, cross-linking, and microtubule polymerization assays with binding-site deletion mutant\",\n      \"pmids\": [\"15216893\", \"9070277\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"In vivo relevance of microtubule inhibition not established\", \"Relationship to axonal sprouting suppression not directly tied\"]\n    },\n    {\n      \"year\": 2006,\n      \"claim\": \"Genetic ablation in mice defined the in vivo phenotype, isolating a specific requirement for STX1A in synaptic plasticity rather than baseline transmission.\",\n      \"evidence\": \"STX1A knockout mice with hippocampal LTP recordings, fear conditioning, and SNARE immunoblot controls\",\n      \"pmids\": [\"16723534\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Cellular locus of the plasticity defect not yet identified in this entry\", \"Possible developmental compensation by STX1B not excluded\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Dissecting Munc18-1 function clarified how STX1A is chaperoned as a monomer yet permits SNARE-driven fusion downstream.\",\n      \"evidence\": \"Munc18-1 mutagenesis, liposome fusion reconstitution, binding assays, and neuroendocrine secretion assays\",\n      \"pmids\": [\"21900493\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Transition from Munc18-bound monomer to assembled SNARE complex in vivo not temporally resolved\", \"Role of STX1A phosphorylation in this switch not tested\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Pharmacological epistasis placed STX1A upstream of catecholaminergic neuromodulation, mechanistically explaining the LTP deficit through dense-core-vesicle release.\",\n      \"evidence\": \"STX1A KO LTP recordings with forskolin and catecholamine rescue plus HPLC catecholamine measurement\",\n      \"pmids\": [\"22219298\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether STX1A acts in the catecholaminergic neurons themselves or postsynaptically not fully resolved\", \"Selectivity for dense-core over synaptic-vesicle pools not mechanistically explained\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Characterizing a disease variant connected STX1A phosphorylation and a transporter interaction to dopamine handling and behavior.\",\n      \"evidence\": \"Autism R26Q variant analysis with CK2 Ser14 kinase assay, STX1A/DAT co-IP, DAT reverse-transport assays, and animal models\",\n      \"pmids\": [\"25774383\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct demonstration that Ser14 phosphorylation controls DAT binding under physiological conditions limited\", \"Generalizability beyond the single variant unknown\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Linking STX1A to oxytocin secretion explained its contribution to social behavior at the neuroendocrine level.\",\n      \"evidence\": \"STX1A KO with in vivo microdialysis of oxytocin and intracerebroventricular OXT behavioral rescue\",\n      \"pmids\": [\"27059771\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct measurement of STX1A-dependent OXT vesicle fusion not shown\", \"Circuit locus of the defect not pinpointed\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Identifying SNAP23 as a competitive inhibitor of SNAP25 binding clarified a regulatory node controlling STX1A-dependent insulin exocytosis.\",\n      \"evidence\": \"SNAP23 gain/loss in INS-1 cells, co-IP with SNAP25/STX1A, domain mapping, and phospho-mutant insulin secretion assays\",\n      \"pmids\": [\"37057886\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether this competition operates in primary beta cells in vivo not shown\", \"Kinase responsible for SNAP23 Ser95 phosphorylation not identified\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Discovering lysosomal STX1A extended its t-SNARE role beyond classical secretory vesicles to lysosomal exocytosis and damage clearance.\",\n      \"evidence\": \"GFP-STX1A overexpression, siRNA knockdown, TIRF imaging, SNARE co-IP, lysosome exocytosis/proteolytic assays, and LLOMe damage assays in HeLa cells\",\n      \"pmids\": [\"41123944\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether lysosomal STX1A function operates in neurons/endocrine cells not tested\", \"Regulation switching STX1A between plasma-membrane and lysosomal pools unknown\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"A reported mitochondrial localization tied STX1A to respiration and ferroptosis-mediated chemoresistance in cancer cells.\",\n      \"evidence\": \"STX1A knockdown with Seahorse respiration, oxidative stress and ferroptosis assays, and drug-resistance assays in gastric cancer cells\",\n      \"pmids\": [\"40056239\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mitochondrial localization is novel and not independently replicated\", \"Mechanism by which a t-SNARE influences respiration not defined\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How a single t-SNARE simultaneously functions as an obligatory fusion component and a suppressor of regulated exocytosis, and what governs its partitioning across plasma membrane, secretory granules, lysosomes, and reported mitochondria, remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No unified model reconciling facilitatory SNARE assembly with negative regulation of release\", \"Trafficking/regulatory signals directing STX1A to distinct membranes not defined\", \"Structural basis of disease-variant effects on STXBP1 binding and SNARE assembly not biochemically validated\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0005198\", \"supporting_discovery_ids\": [30, 20, 0]},\n      {\"term_id\": \"GO:0008092\", \"supporting_discovery_ids\": [26, 8]},\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [20]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [2, 10, 15, 30]},\n      {\"term_id\": \"GO:0031410\", \"supporting_discovery_ids\": [2, 3, 4]},\n      {\"term_id\": \"GO:0005764\", \"supporting_discovery_ids\": [30]},\n      {\"term_id\": \"GO:0005783\", \"supporting_discovery_ids\": [10]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-5653656\", \"supporting_discovery_ids\": [0, 30, 4]},\n      {\"term_id\": \"R-HSA-112316\", \"supporting_discovery_ids\": [17, 21, 7]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [21, 23]}\n    ],\n    \"complexes\": [\n      \"SNARE complex (STX1A–SNAP25/SNAP23–VAMP2)\",\n      \"STX1A–synaptotagmin–N-type calcium channel ternary complex\"\n    ],\n    \"partners\": [\n      \"SNAP25\",\n      \"SNAP23\",\n      \"VAMP2\",\n      \"STXBP1\",\n      \"SYT1\",\n      \"DAT\",\n      \"JNK2\",\n      \"tubulin\"\n    ],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":8,"faith_total":8,"faith_pct":100.0}}