{"gene":"SEPTIN5","run_date":"2026-06-10T07:46:30","timeline":{"discoveries":[{"year":1999,"finding":"SEPTIN5 (CDCrel-1) directly binds syntaxin-1A via the SNARE interaction domain, associates with synaptic vesicle membrane fractions, and co-immunoprecipitates with syntaxin and Nedd5. Overexpression of wild-type CDCrel-1 inhibited secretion in HIT-T15 cells, whereas GTPase dominant-negative mutants enhanced secretion, establishing SEPTIN5 as an inhibitor of exocytosis acting through syntaxin.","method":"Subcellular fractionation, co-immunoprecipitation, direct binding assay, transfection with wild-type and dominant-negative GTPase mutants in HIT-T15 cells","journal":"Nature neuroscience","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal Co-IP, direct binding, functional secretion assay with mutants; replicated across multiple subsequent studies","pmids":["10321247"],"is_preprint":false},{"year":2000,"finding":"Parkin acts as an E3 ubiquitin-protein ligase (through its C-terminal RING-finger domains, with E2 enzyme UbcH8) that ubiquitinates and promotes proteasomal degradation of SEPTIN5 (CDCrel-1). Parkin binds SEPTIN5 through its RING-finger domains. Familial Parkinson's disease-linked parkin mutations disrupt this ubiquitin ligase function and impair SEPTIN5 degradation.","method":"In vitro ubiquitination assay, co-immunoprecipitation, cell-based degradation assay, site-directed mutagenesis of Parkin RING domains","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 1 / Strong — in vitro reconstitution of ubiquitination, Co-IP binding, mutagenesis; independently replicated by multiple labs","pmids":["11078524"],"is_preprint":false},{"year":2002,"finding":"SEPTIN5 (CDCrel-1) forms a heteromeric complex with septins Nedd5 and CDC10 in neurons. CDCrel-1 null mice show altered expression of other septins, suggesting functional redundancy within the septin complex. CDCrel-1 expression rises at synaptic maturation. Homozygous CDCrel-1 knockout mice display normal synaptic properties and hippocampal neuron growth in vitro.","method":"Co-immunoprecipitation, generation of CDCrel-1 knockout mice, electrophysiological and morphological analysis","journal":"Molecular and cellular biology","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal Co-IP of complex, genetic knockout with defined negative phenotype and compensatory septin expression changes","pmids":["11739749"],"is_preprint":false},{"year":2002,"finding":"SEPTIN5 (CDCrel-1) physically interacts with KIAA0202 (another human septin), as demonstrated by yeast two-hybrid and confirmed by GST pull-down and co-immunoprecipitation from the K-562 human leukemia cell line.","method":"Yeast two-hybrid, GST pull-down, co-immunoprecipitation","journal":"FEBS letters","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — two orthogonal binding methods (pull-down and Co-IP) from a single lab","pmids":["12023038"],"is_preprint":false},{"year":2003,"finding":"SEPT5_v2, a splice variant of SEPTIN5, is a parkin-binding protein. It binds parkin at the amino terminus and ring finger domains. Parkin ubiquitinates SEPT5_v2 in vitro, and both SEPT5_v1 and SEPT5_v2 accumulate in brains of autosomal-recessive juvenile parkinsonism patients, indicating parkin is essential for their normal turnover.","method":"Yeast two-hybrid screen, co-immunoprecipitation from human substantia nigra lysates, in vitro ubiquitination assay, post-mortem brain protein analysis","journal":"Brain research. Molecular brain research","confidence":"High","confidence_rationale":"Tier 1 / Moderate — in vitro ubiquitination, Co-IP from human tissue, yeast two-hybrid; multiple methods in single lab study","pmids":["14559152"],"is_preprint":false},{"year":2003,"finding":"Overexpression of SEPTIN5 (CDCrel-1) in the substantia nigra via AAV-mediated gene transfer causes progressive loss of dopaminergic neurons in a dopamine-dependent manner. SEPTIN5 inhibits dopamine release from PC12 cells, and pharmacological inhibition of dopamine synthesis prevents CDCrel-1-induced neurodegeneration in vivo.","method":"AAV-mediated in vivo gene transfer to rat substantia nigra, dopaminergic neuron counting, striatal dopamine measurement, PC12 cell dopamine release assay, pharmacological inhibition","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 2 / Moderate — in vivo loss-of-function model with defined neurochemical phenotype, in vitro secretion assay, pharmacological rescue; multiple methods","pmids":["14530399"],"is_preprint":false},{"year":2005,"finding":"SEPTIN5 (Sept5) binds syntaxin within the assembled SNARE complex (7S complex), but cannot bind an nSec1-syntaxin complex. Alpha-SNAP binding to the SNARE complex occludes Sept5 binding, indicating Sept5 and alpha-SNAP compete for binding to the syntaxin-containing 7S complex, suggesting a regulatory role for Sept5 in SNARE availability.","method":"In vitro binding assays mapping Sept5 domains required for syntaxin binding, competitive binding assays with purified SNARE complexes and alpha-SNAP","journal":"The Biochemical journal","confidence":"High","confidence_rationale":"Tier 1 / Moderate — in vitro reconstitution of competitive binding with purified proteins, domain mapping; mechanistically rigorous single-lab study","pmids":["15355307"],"is_preprint":false},{"year":2006,"finding":"SEPTIN5 (SEPT5) interacts with SEPT11 in human endothelial cells. The interaction requires the GTP-binding domain and C-terminal extension of SEPT11, confirmed by yeast two-hybrid, co-precipitation from JURKAT cell lysates, and FRET. Both proteins are co-expressed in HUVECs.","method":"Yeast two-hybrid, co-immunoprecipitation, FRET, domain deletion analysis","journal":"The Journal of pathology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reciprocal Co-IP and FRET for interaction confirmation, domain mapping; single lab","pmids":["16767699"],"is_preprint":false},{"year":2007,"finding":"Cyclin-dependent kinase 5 (Cdk5)/p35 phosphorylates SEPTIN5 (Sept5_v1) at Ser17 in vitro and in mouse brain. Phosphorylation at Ser17 decreases binding of Sept5_v1 to syntaxin-1, as shown by co-immunoprecipitation from synaptosomal fractions and GST-syntaxin-1A pull-down assays.","method":"Mass spectrometry identification of Cdk5 substrates, in vitro kinase assay, site-directed mutagenesis (Ser17), GST pull-down, co-immunoprecipitation from synaptosomal fractions","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Moderate — in vitro kinase assay with mutagenesis, in vivo brain fractionation Co-IP, GST pull-down; multiple orthogonal methods","pmids":["17224448"],"is_preprint":false},{"year":2007,"finding":"Sept3 directly binds Sept5 and Sept7 and forms a heteromeric complex at nerve terminals in mature neurons, adjacent to synaptophysin-positive synaptic vesicle regions, as demonstrated by direct binding assays and co-localization in hippocampal neurons.","method":"Direct binding assay, co-localization by immunofluorescence in primary neurons, Sept3 knockout mouse generation","journal":"Journal of neurochemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct binding demonstrated, co-localization in neurons; single lab, two methods","pmids":["17564677"],"is_preprint":false},{"year":2008,"finding":"Cdk5/p35 phosphorylates human SEPTIN5 (hCDCrel-1) at Ser327. Phosphorylation at S327 decreases SEPTIN5 binding to syntaxin-1 (shown by Co-IP from synaptic vesicle fractions and Cdk5 knockout lysates). A non-phosphorylatable S327A mutant binds syntaxin more efficiently than wild-type and potentiates regulated exocytosis more than wild-type when expressed in PC12 cells.","method":"Yeast two-hybrid screen, GST pull-down, co-immunoprecipitation, in vitro and in vivo phosphorylation assay, site-directed mutagenesis (S327A), PC12 cell exocytosis assay","journal":"The Journal of neuroscience","confidence":"High","confidence_rationale":"Tier 1 / Moderate — in vitro kinase assay, mutagenesis, Co-IP from KO vs WT lysates, functional secretion assay; multiple orthogonal methods","pmids":["18385322"],"is_preprint":false},{"year":2010,"finding":"ARMS/Kidins220 interacts with SEPTIN5 (Sept5) through the N-terminal region of Sept5. The interaction was confirmed by co-immunoprecipitation from HEK-293 cells. Endogenous proteins co-localize at the plasma membrane and neurite tips in hippocampal neurons and NGF-treated PC12 cells.","method":"Yeast two-hybrid, co-immunoprecipitation from transfected HEK-293 cells, domain mapping, co-localization in primary neurons and PC12 cells","journal":"Molecules and cells","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — Co-IP and co-localization, domain mapping; single lab","pmids":["20680483"],"is_preprint":false},{"year":2020,"finding":"Downregulation of SEPTIN5 reduces levels of APP C-terminal fragments (APP CTFs) and Aβ in neuronal cells and in Septin5 knockout mouse cortex. Mechanistically, SEPTIN5 knockdown increases degradation of APP CTFs via the autophagosomal pathway, without affecting APP secretory trafficking or endocytosis, and enhances autophagosomal activity as indicated by altered autophagosomal marker levels.","method":"shRNA knockdown, Septin5 knockout mice, APP CTF and Aβ measurement by ELISA/Western blot, autophagy marker analysis, APP trafficking assay","journal":"Cells","confidence":"High","confidence_rationale":"Tier 2 / Moderate — in vitro and in vivo knockdown/knockout with defined molecular readouts, autophagy pathway analysis; multiple orthogonal methods in single lab","pmids":["33203136"],"is_preprint":false},{"year":2021,"finding":"SEPTIN5 S327 phosphorylation status affects APP processing and autophagy markers in primary cortical neurons (assessed using lentiviral phosphomutants S327A and S327D). S327 phosphorylation status also influences short-term synaptic plasticity at the CA3-CA1 synapse ex vivo, linking this post-translational modification to synaptic function.","method":"Lentiviral transduction of primary mouse cortical neurons with wild-type SEPTIN5 and phosphomutants (S327A, S327D), APP processing assays, autophagy marker quantification, ex vivo electrophysiology (CA3-CA1)","journal":"Neurobiology of disease","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — phosphomutant functional analysis in neurons and ex vivo, multiple readouts; single lab","pmids":["34954322"],"is_preprint":false},{"year":2024,"finding":"SEPTIN5 (CDCrel-1) interacts with VMAT2 in rat striatum, and binge methamphetamine alters this interaction as well as the subcellular localization of SEPTIN5.","method":"Co-immunoprecipitation from rat striatal tissue, subcellular fractionation, in vivo METH treatment model","journal":"International journal of molecular sciences","confidence":"Medium","confidence_rationale":"Tier 3 / Weak — single Co-IP from tissue, single lab, no mutagenesis or reconstitution","pmids":["39684782"],"is_preprint":false},{"year":2024,"finding":"Co-expression of Sept8-204 with SEPT5 induces formation of small vesicle-like structures that co-localize with synaptophysin. This vesicle-like structure and co-localization require palmitoylation of Sept8-204 (controlled by ZDHHC17/PPT1); loss of palmitoylation causes Sept8-204/SEPT5 to form large puncta that do not co-localize with synaptophysin.","method":"Fluorescence microscopy of co-expressed septins, palmitoylation inhibition (2-BP), ZDHHC17 and PPT1 knockouts, co-localization with synaptophysin marker","journal":"Journal of cellular biochemistry","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — subcellular localization with functional consequence (synaptic marker association), multiple genetic/pharmacological manipulations; single lab","pmids":["38308620"],"is_preprint":false},{"year":2025,"finding":"In pancreatic β-cells, SEPTIN5 is preferentially assembled at microtubule-plasma membrane contact sites in a microtubule-dependent manner, where it anchors secretory granules. Septin5 deletion destabilizes the cortical microtubule meshwork, increases insulin granule dynamics and access to the plasma membrane, increases releasable granule pool clustering on L-type Ca2+ channels, and dramatically enhances glucose-stimulated insulin secretion including in type 2 diabetes.","method":"Super-resolution imaging, Septin5 knockout rodent model, live-cell imaging of granule dynamics, Ca2+ channel co-localization analysis, insulin secretion assay in rodent and human islets","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 2 / Strong — super-resolution localization with functional consequence, genetic KO with defined mechanistic phenotype, multiple orthogonal readouts","pmids":["40108136"],"is_preprint":false},{"year":1998,"finding":"SEPTIN5 (hCDCrel-1) protein localizes to neurons in adult human brain and co-purifies with synaptosomes marked by SNAP-25 and synaptophysin, indicating a presynaptic localization.","method":"Immunohistochemistry, subcellular fractionation/co-purification with synaptosomal markers","journal":"Neuroreport","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — subcellular fractionation with synaptosomal co-purification; replicated in subsequent studies","pmids":["9760144"],"is_preprint":false}],"current_model":"SEPTIN5 (CDCrel-1/SEPT5) is a presynaptic GTPase that inhibits regulated exocytosis by directly binding syntaxin-1A via its SNARE interaction domain and competing with alpha-SNAP for access to the assembled SNARE complex; this interaction is negatively regulated by Cdk5/p35-mediated phosphorylation at Ser17 (adult isoform) and Ser327, which reduces syntaxin binding and modulates secretion. SEPTIN5 localizes to microtubule-plasma membrane contact sites in secretory cells where it tethers granules away from the plasma membrane, and its deletion enhances exocytosis by destabilizing the cortical microtubule meshwork. Parkin acts as an E3 ubiquitin ligase (with E2 UbcH8) that ubiquitinates and degrades SEPTIN5; familial Parkinson's disease mutations in parkin impair this activity, leading to SEPTIN5 accumulation and dopamine-dependent neurotoxicity. SEPTIN5 also forms heteromeric complexes with other septins (Nedd5, CDC10, Sept3, Sept7, Sept11, KIAA0202) and interacts with VMAT2 and ARMS/Kidins220, and its downregulation promotes autophagy-mediated degradation of APP C-terminal fragments, reducing Aβ levels."},"narrative":{"mechanistic_narrative":"SEPTIN5 (CDCrel-1/SEPT5) is a presynaptic GTPase of the septin family that acts as a brake on regulated exocytosis by physically gating the SNARE machinery [PMID:10321247, PMID:9760144]. It binds syntaxin-1A directly through a defined SNARE interaction domain, and the GTPase activity is required for its inhibitory effect: wild-type SEPTIN5 suppresses secretion whereas dominant-negative GTPase mutants enhance it [PMID:10321247]. Mechanistically, SEPTIN5 engages syntaxin within the assembled 7S SNARE complex but is excluded by alpha-SNAP, with which it competes for access, thereby regulating SNARE availability [PMID:15355307]. This inhibitory binding is switched off by Cdk5/p35-mediated phosphorylation at Ser17 and Ser327, which lowers syntaxin affinity; non-phosphorylatable mutants bind syntaxin more tightly and potentiate exocytosis, linking the modification to secretion and to short-term synaptic plasticity [PMID:17224448, PMID:18385322, PMID:34954322]. Beyond the SNARE interface, SEPTIN5 assembles into heteromeric septin filaments with Nedd5, CDC10, Sept3, Sept7, and Sept11 and localizes to microtubule–plasma membrane contact sites, where in pancreatic beta-cells it anchors secretory granules away from the plasma membrane; its deletion destabilizes the cortical microtubule meshwork and markedly enhances glucose-stimulated insulin secretion [PMID:11739749, PMID:17564677, PMID:40108136]. SEPTIN5 is a substrate of the E3 ubiquitin ligase parkin (with E2 UbcH8), which ubiquitinates it for proteasomal degradation; familial Parkinson's disease parkin mutations impair this turnover, and SEPTIN5 accumulation drives dopamine-dependent dopaminergic neurodegeneration [PMID:11078524, PMID:14559152, PMID:14530399]. Downregulation of SEPTIN5 additionally promotes autophagosomal degradation of APP C-terminal fragments and lowers Aβ, connecting it to amyloid processing [PMID:33203136].","teleology":[{"year":1998,"claim":"Establishing where SEPTIN5 acts was the first step: localizing the protein to presynaptic terminals framed it as a candidate regulator of neurotransmission.","evidence":"Immunohistochemistry and synaptosomal co-purification with SNAP-25 and synaptophysin in human brain","pmids":["9760144"],"confidence":"Medium","gaps":["Did not define a molecular partner or function","Subcellular resolution limited to fractionation"]},{"year":1999,"claim":"This defined SEPTIN5's core function — it binds syntaxin-1A and inhibits exocytosis in a GTPase-dependent manner, identifying it as a SNARE-targeting brake on secretion.","evidence":"Co-IP, direct binding, and wild-type vs dominant-negative GTPase mutant secretion assays in HIT-T15 cells","pmids":["10321247"],"confidence":"High","gaps":["Did not resolve whether binding is to free or assembled syntaxin","GTP cycle regulation of the interaction unmapped"]},{"year":2000,"claim":"Identifying parkin as the E3 ligase for SEPTIN5 connected its turnover to the proteasome and to Parkinson's disease genetics.","evidence":"In vitro ubiquitination with UbcH8, Co-IP, cell-based degradation assay, and parkin RING-domain mutagenesis","pmids":["11078524"],"confidence":"High","gaps":["Did not show SEPTIN5 accumulation drives neuronal death","Ubiquitination site on SEPTIN5 not mapped"]},{"year":2002,"claim":"Genetic knockout and complex analysis tested whether SEPTIN5 is essential and revealed it operates within redundant heteromeric septin filaments.","evidence":"Co-IP of Nedd5/CDC10 complexes, KIAA0202 yeast two-hybrid/pull-down, and CDCrel-1 knockout mouse phenotyping","pmids":["11739749","12023038"],"confidence":"High","gaps":["Knockout had no overt synaptic phenotype, leaving in vivo function ambiguous","Compensation by other septins not directly proven"]},{"year":2003,"claim":"Linking parkin-dependent SEPTIN5 turnover to disease showed that SEPTIN5 accumulates in patient brain and is neurotoxic when overexpressed, establishing causal relevance to dopaminergic degeneration.","evidence":"Co-IP from human substantia nigra, in vitro ubiquitination of splice variants, post-mortem brain analysis, and AAV overexpression in rat substantia nigra with dopamine-dependent rescue","pmids":["14559152","14530399"],"confidence":"High","gaps":["Mechanism linking accumulation to dopamine toxicity not fully defined","Endogenous SEPTIN5 levels in sporadic PD not addressed"]},{"year":2005,"claim":"Defining the binding interface mechanistically showed SEPTIN5 targets the assembled 7S SNARE complex and competes with alpha-SNAP, explaining how it gates SNARE recycling/availability.","evidence":"In vitro domain mapping and competitive binding assays with purified SNARE complexes and alpha-SNAP","pmids":["15355307"],"confidence":"High","gaps":["Stoichiometry of competition in vivo unknown","Effect on SNARE disassembly kinetics not measured"]},{"year":2007,"claim":"Discovery of Cdk5/p35 phosphorylation at Ser17 provided the regulatory switch that detaches SEPTIN5 from syntaxin, coupling the brake to a kinase signal.","evidence":"MS substrate identification, in vitro kinase assay, Ser17 mutagenesis, GST pull-down and synaptosomal Co-IP","pmids":["17224448"],"confidence":"High","gaps":["Functional secretion consequence of Ser17 not directly assayed here","Isoform specificity of the site"]},{"year":2007,"claim":"Mapping further septin partners (Sept3, Sept7) at nerve terminals reinforced that SEPTIN5 functions as part of synaptic septin filaments near vesicle pools.","evidence":"Direct binding assays and co-localization with synaptophysin in hippocampal neurons; Sept3 knockout","pmids":["17564677"],"confidence":"Medium","gaps":["Filament architecture not resolved","Functional output of the Sept3/5/7 complex untested"]},{"year":2008,"claim":"A second Cdk5 site (Ser327) was shown to functionally tune exocytosis, with a phospho-dead mutant binding syntaxin better and potentiating secretion — directly tying phosphorylation to release.","evidence":"Kinase assays, S327A mutagenesis, Co-IP from Cdk5 KO vs WT lysates, PC12 exocytosis assay","pmids":["18385322"],"confidence":"High","gaps":["Relative contribution of Ser17 vs Ser327 in vivo unresolved","Upstream signals activating Cdk5 toward SEPTIN5 unknown"]},{"year":2010,"claim":"Identifying ARMS/Kidins220 as an N-terminal partner extended SEPTIN5's interactome to neurite-tip and plasma-membrane signaling scaffolds.","evidence":"Yeast two-hybrid, Co-IP from HEK-293, domain mapping, co-localization in neurons and PC12 cells","pmids":["20680483"],"confidence":"Medium","gaps":["Functional consequence of the interaction undefined","Single-lab Co-IP without reciprocal endogenous validation"]},{"year":2020,"claim":"A new functional axis emerged: SEPTIN5 loss promotes autophagosomal clearance of APP C-terminal fragments and lowers Aβ, implicating it in amyloid metabolism independent of trafficking.","evidence":"shRNA knockdown and Septin5 KO mouse cortex, APP CTF/Aβ measurement, autophagy marker analysis, trafficking assays","pmids":["33203136"],"confidence":"High","gaps":["Direct molecular link between SEPTIN5 and autophagy machinery not identified","Whether effect requires syntaxin/SNARE function unknown"]},{"year":2021,"claim":"Phosphomutant analysis tied the Ser327 modification to both APP processing/autophagy and to short-term synaptic plasticity, integrating SEPTIN5's secretory and amyloid roles under one regulatory mark.","evidence":"Lentiviral S327A/S327D in cortical neurons, APP and autophagy readouts, ex vivo CA3-CA1 electrophysiology","pmids":["34954322"],"confidence":"Medium","gaps":["Causal chain from phosphorylation to autophagy unresolved","Single-lab functional correlations"]},{"year":2024,"claim":"New interactions with VMAT2 and palmitoylated Sept8 connected SEPTIN5 to monoamine handling and to vesicle-like structure formation, broadening its secretory-organelle associations.","evidence":"Co-IP from rat striatum with METH model; co-expression imaging with Sept8-204 palmitoylation manipulation (ZDHHC17/PPT1)","pmids":["39684782","38308620"],"confidence":"Medium","gaps":["VMAT2 interaction shown by single Co-IP without reconstitution","Functional significance of Sept8/SEPT5 vesicle structures untested"]},{"year":2025,"claim":"Super-resolution and KO work in beta-cells unified the localization and secretory-brake themes: SEPTIN5 sits at microtubule–plasma membrane contact sites anchoring granules, and its loss destabilizes cortical microtubules to dramatically enhance insulin secretion.","evidence":"Super-resolution imaging, Septin5 KO rodent model, live granule dynamics, Ca2+ channel co-localization, insulin secretion in rodent and human islets","pmids":["40108136"],"confidence":"High","gaps":["How GTP state controls contact-site assembly unknown","Link between microtubule role and SNARE-binding role not mechanistically bridged"]},{"year":null,"claim":"It remains unresolved how SEPTIN5's two mechanistic faces — direct SNARE/syntaxin gating and cortical microtubule/granule anchoring — are coordinated, and how its GTPase cycle and phosphorylation jointly switch between them.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No structure of SEPTIN5 bound to the SNARE complex","GTP-cycle regulation of filament assembly vs syntaxin binding undefined","Direct effector linking SEPTIN5 to autophagy unidentified"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0003924","term_label":"GTPase activity","supporting_discovery_ids":[0]},{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[0,6]},{"term_id":"GO:0005198","term_label":"structural molecule activity","supporting_discovery_ids":[2,9,16]}],"localization":[{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[11,16,17]},{"term_id":"GO:0005856","term_label":"cytoskeleton","supporting_discovery_ids":[16]},{"term_id":"GO:0031410","term_label":"cytoplasmic vesicle","supporting_discovery_ids":[9,15]}],"pathway":[{"term_id":"R-HSA-5653656","term_label":"Vesicle-mediated transport","supporting_discovery_ids":[0,6,16]},{"term_id":"R-HSA-112316","term_label":"Neuronal System","supporting_discovery_ids":[13,17]},{"term_id":"R-HSA-9612973","term_label":"Autophagy","supporting_discovery_ids":[12]}],"complexes":["septin heteromeric complex (Sept3/Sept5/Sept7)","SNARE/7S complex (interacting)"],"partners":["STX1A","PARK2","SEPT11","SEPT3","SEPT7","KIDINS220","SLC18A2","NEDD5"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q99719","full_name":"Septin-5","aliases":["Cell division control-related protein 1","CDCrel-1","Peanut-like protein 1"],"length_aa":369,"mass_kda":42.8,"function":"Filament-forming cytoskeletal GTPase (By similarity). May play a role in cytokinesis (Potential). May play a role in platelet secretion (By similarity)","subcellular_location":"Cytoplasm; Cytoplasm, cytoskeleton","url":"https://www.uniprot.org/uniprotkb/Q99719/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/SEPTIN5","classification":"Not Classified","n_dependent_lines":5,"n_total_lines":1090,"dependency_fraction":0.0045871559633027525},"opencell":{"profiled":true,"resolved_as":"","ensg_id":"ENSG00000184702","cell_line_id":"CID001922","localizations":[{"compartment":"membrane","grade":3},{"compartment":"cytoskeleton","grade":2}],"interactors":[{"gene":"SEPT8","stoichiometry":4.0},{"gene":"COPB2","stoichiometry":0.2},{"gene":"COPE","stoichiometry":0.2},{"gene":"SEPT11","stoichiometry":0.2},{"gene":"SEPT2","stoichiometry":0.2},{"gene":"SEPT7","stoichiometry":0.2},{"gene":"SEPT9","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/target/CID001922","total_profiled":1310},"omim":[],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Nucleoplasm","reliability":"Approved"},{"location":"Actin filaments","reliability":"Approved"},{"location":"Cytosol","reliability":"Approved"}],"tissue_specificity":"Tissue enhanced","tissue_distribution":"Detected in all","driving_tissues":[{"tissue":"brain","ntpm":531.3}],"url":"https://www.proteinatlas.org/search/SEPTIN5"},"hgnc":{"alias_symbol":["HCDCREL-1","H5","Septin-5","CDCREL-1"],"prev_symbol":["PNUTL1","SEPT5"]},"alphafold":{"accession":"Q99719","domains":[{"cath_id":"3.40.50.300","chopping":"39-69_77-314","consensus_level":"high","plddt":83.3577,"start":39,"end":314}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q99719","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q99719-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q99719-F1-predicted_aligned_error_v6.png","plddt_mean":77.5},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=SEPTIN5","jax_strain_url":"https://www.jax.org/strain/search?query=SEPTIN5"},"sequence":{"accession":"Q99719","fasta_url":"https://rest.uniprot.org/uniprotkb/Q99719.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q99719/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q99719"}},"corpus_meta":[{"pmid":"11078524","id":"PMC_11078524","title":"Parkin functions as an E2-dependent ubiquitin- protein ligase and promotes the degradation of the synaptic vesicle-associated protein, CDCrel-1.","date":"2000","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/11078524","citation_count":775,"is_preprint":false},{"pmid":"10321247","id":"PMC_10321247","title":"The septin CDCrel-1 binds syntaxin and inhibits exocytosis.","date":"1999","source":"Nature neuroscience","url":"https://pubmed.ncbi.nlm.nih.gov/10321247","citation_count":316,"is_preprint":false},{"pmid":"11739749","id":"PMC_11739749","title":"The septin CDCrel-1 is dispensable for normal development and neurotransmitter release.","date":"2002","source":"Molecular and cellular biology","url":"https://pubmed.ncbi.nlm.nih.gov/11739749","citation_count":105,"is_preprint":false},{"pmid":"14530399","id":"PMC_14530399","title":"Dopamine-dependent neurodegeneration in rats induced by viral vector-mediated overexpression of the parkin target protein, CDCrel-1.","date":"2003","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/14530399","citation_count":94,"is_preprint":false},{"pmid":"14559152","id":"PMC_14559152","title":"SEPT5_v2 is a parkin-binding protein.","date":"2003","source":"Brain research. Molecular brain research","url":"https://pubmed.ncbi.nlm.nih.gov/14559152","citation_count":88,"is_preprint":false},{"pmid":"15355307","id":"PMC_15355307","title":"The septin Sept5/CDCrel-1 competes with alpha-SNAP for binding to the SNARE complex.","date":"2005","source":"The Biochemical journal","url":"https://pubmed.ncbi.nlm.nih.gov/15355307","citation_count":81,"is_preprint":false},{"pmid":"19240081","id":"PMC_19240081","title":"Sept5 deficiency exerts pleiotropic influence on affective behaviors and cognitive functions in mice.","date":"2009","source":"Human molecular genetics","url":"https://pubmed.ncbi.nlm.nih.gov/19240081","citation_count":69,"is_preprint":false},{"pmid":"18385322","id":"PMC_18385322","title":"Cyclin-dependent kinase 5 phosphorylation of human septin SEPT5 (hCDCrel-1) modulates exocytosis.","date":"2008","source":"The Journal of neuroscience : the official journal of the Society for Neuroscience","url":"https://pubmed.ncbi.nlm.nih.gov/18385322","citation_count":61,"is_preprint":false},{"pmid":"17564677","id":"PMC_17564677","title":"Targeted disruption of Sept3, a heteromeric assembly partner of Sept5 and Sept7 in axons, has no effect on developing CNS neurons.","date":"2007","source":"Journal of neurochemistry","url":"https://pubmed.ncbi.nlm.nih.gov/17564677","citation_count":58,"is_preprint":false},{"pmid":"16092945","id":"PMC_16092945","title":"Neurotoxicity and behavioral deficits associated with Septin 5 accumulation in dopaminergic neurons.","date":"2005","source":"Journal of neurochemistry","url":"https://pubmed.ncbi.nlm.nih.gov/16092945","citation_count":55,"is_preprint":false},{"pmid":"22589251","id":"PMC_22589251","title":"Alterations of social interaction through genetic and environmental manipulation of the 22q11.2 gene Sept5 in the mouse brain.","date":"2012","source":"Human molecular 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infiltration.","date":"2022","source":"International journal of biological sciences","url":"https://pubmed.ncbi.nlm.nih.gov/36439885","citation_count":17,"is_preprint":false},{"pmid":"33203136","id":"PMC_33203136","title":"Presynaptic Vesicle Protein SEPTIN5 Regulates the Degradation of APP C-Terminal Fragments and the Levels of Aβ.","date":"2020","source":"Cells","url":"https://pubmed.ncbi.nlm.nih.gov/33203136","citation_count":14,"is_preprint":false},{"pmid":"10940632","id":"PMC_10940632","title":"Expression of Cdcrel-1 (Pnutl1), a gene frequently deleted in velo-cardio-facial syndrome/DiGeorge syndrome.","date":"2000","source":"Mechanisms of development","url":"https://pubmed.ncbi.nlm.nih.gov/10940632","citation_count":13,"is_preprint":false},{"pmid":"20680483","id":"PMC_20680483","title":"Ankyrin repeat-rich membrane spanning/Kidins220 protein interacts with mammalian Septin 5.","date":"2010","source":"Molecules and 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disease","url":"https://pubmed.ncbi.nlm.nih.gov/34954322","citation_count":10,"is_preprint":false},{"pmid":"22562816","id":"PMC_22562816","title":"Septin 4, the drosophila ortholog of human CDCrel-1, accumulates in parkin mutant brains and is functionally related to the Nedd4 E3 ubiquitin ligase.","date":"2012","source":"Journal of molecular neuroscience : MN","url":"https://pubmed.ncbi.nlm.nih.gov/22562816","citation_count":10,"is_preprint":false},{"pmid":"15923366","id":"PMC_15923366","title":"Immunoreactivity of the septins SEPT4, SEPT5, and SEPT8 in the human eye.","date":"2005","source":"The journal of histochemistry and cytochemistry : official journal of the Histochemistry Society","url":"https://pubmed.ncbi.nlm.nih.gov/15923366","citation_count":9,"is_preprint":false},{"pmid":"23725386","id":"PMC_23725386","title":"MLL-SEPT5 fusion transcript in infant acute myeloid leukemia with t(11;22)(q23;q11).","date":"2013","source":"Leukemia & lymphoma","url":"https://pubmed.ncbi.nlm.nih.gov/23725386","citation_count":9,"is_preprint":false},{"pmid":"28895884","id":"PMC_28895884","title":"Interaction of Recombinant Gallus gallus SEPT5 and Brain Proteins of H5N1-Avian Influenza Virus-Infected Chickens.","date":"2017","source":"Proteomes","url":"https://pubmed.ncbi.nlm.nih.gov/28895884","citation_count":6,"is_preprint":false},{"pmid":"29326822","id":"PMC_29326822","title":"Acute myeloid leukemia with KMT2A-SEPT5 translocation: A case report and review of the literature.","date":"2018","source":"SAGE open medical case reports","url":"https://pubmed.ncbi.nlm.nih.gov/29326822","citation_count":4,"is_preprint":false},{"pmid":"35004749","id":"PMC_35004749","title":"MLL-SEPT5 Fusion Transcript in Myelodysplastic Syndrome Patient With t(11;22)(q23;q11).","date":"2021","source":"Frontiers in medicine","url":"https://pubmed.ncbi.nlm.nih.gov/35004749","citation_count":3,"is_preprint":false},{"pmid":"24932261","id":"PMC_24932261","title":"Mixed lineage leukemia-septin 5 fusion transcript in de novo adult acute myeloid leukemia with t(11;22)(q23;q11.2): A case report.","date":"2014","source":"Oncology letters","url":"https://pubmed.ncbi.nlm.nih.gov/24932261","citation_count":3,"is_preprint":false},{"pmid":"40108136","id":"PMC_40108136","title":"Septin5 deletion enhances β-cell exocytosis by releasing microtubule-tethered insulin granules onto plasma membrane.","date":"2025","source":"Nature communications","url":"https://pubmed.ncbi.nlm.nih.gov/40108136","citation_count":2,"is_preprint":false},{"pmid":"38308620","id":"PMC_38308620","title":"Palmitoylation is required for Sept8-204 and Sept5 to form vesicle-like structure and colocalize with synaptophysin.","date":"2024","source":"Journal of cellular 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Overexpression of wild-type CDCrel-1 inhibited secretion in HIT-T15 cells, whereas GTPase dominant-negative mutants enhanced secretion, establishing SEPTIN5 as an inhibitor of exocytosis acting through syntaxin.\",\n      \"method\": \"Subcellular fractionation, co-immunoprecipitation, direct binding assay, transfection with wild-type and dominant-negative GTPase mutants in HIT-T15 cells\",\n      \"journal\": \"Nature neuroscience\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal Co-IP, direct binding, functional secretion assay with mutants; replicated across multiple subsequent studies\",\n      \"pmids\": [\"10321247\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2000,\n      \"finding\": \"Parkin acts as an E3 ubiquitin-protein ligase (through its C-terminal RING-finger domains, with E2 enzyme UbcH8) that ubiquitinates and promotes proteasomal degradation of SEPTIN5 (CDCrel-1). Parkin binds SEPTIN5 through its RING-finger domains. Familial Parkinson's disease-linked parkin mutations disrupt this ubiquitin ligase function and impair SEPTIN5 degradation.\",\n      \"method\": \"In vitro ubiquitination assay, co-immunoprecipitation, cell-based degradation assay, site-directed mutagenesis of Parkin RING domains\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — in vitro reconstitution of ubiquitination, Co-IP binding, mutagenesis; independently replicated by multiple labs\",\n      \"pmids\": [\"11078524\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"SEPTIN5 (CDCrel-1) forms a heteromeric complex with septins Nedd5 and CDC10 in neurons. CDCrel-1 null mice show altered expression of other septins, suggesting functional redundancy within the septin complex. CDCrel-1 expression rises at synaptic maturation. Homozygous CDCrel-1 knockout mice display normal synaptic properties and hippocampal neuron growth in vitro.\",\n      \"method\": \"Co-immunoprecipitation, generation of CDCrel-1 knockout mice, electrophysiological and morphological analysis\",\n      \"journal\": \"Molecular and cellular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal Co-IP of complex, genetic knockout with defined negative phenotype and compensatory septin expression changes\",\n      \"pmids\": [\"11739749\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"SEPTIN5 (CDCrel-1) physically interacts with KIAA0202 (another human septin), as demonstrated by yeast two-hybrid and confirmed by GST pull-down and co-immunoprecipitation from the K-562 human leukemia cell line.\",\n      \"method\": \"Yeast two-hybrid, GST pull-down, co-immunoprecipitation\",\n      \"journal\": \"FEBS letters\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — two orthogonal binding methods (pull-down and Co-IP) from a single lab\",\n      \"pmids\": [\"12023038\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"SEPT5_v2, a splice variant of SEPTIN5, is a parkin-binding protein. It binds parkin at the amino terminus and ring finger domains. Parkin ubiquitinates SEPT5_v2 in vitro, and both SEPT5_v1 and SEPT5_v2 accumulate in brains of autosomal-recessive juvenile parkinsonism patients, indicating parkin is essential for their normal turnover.\",\n      \"method\": \"Yeast two-hybrid screen, co-immunoprecipitation from human substantia nigra lysates, in vitro ubiquitination assay, post-mortem brain protein analysis\",\n      \"journal\": \"Brain research. Molecular brain research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro ubiquitination, Co-IP from human tissue, yeast two-hybrid; multiple methods in single lab study\",\n      \"pmids\": [\"14559152\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"Overexpression of SEPTIN5 (CDCrel-1) in the substantia nigra via AAV-mediated gene transfer causes progressive loss of dopaminergic neurons in a dopamine-dependent manner. SEPTIN5 inhibits dopamine release from PC12 cells, and pharmacological inhibition of dopamine synthesis prevents CDCrel-1-induced neurodegeneration in vivo.\",\n      \"method\": \"AAV-mediated in vivo gene transfer to rat substantia nigra, dopaminergic neuron counting, striatal dopamine measurement, PC12 cell dopamine release assay, pharmacological inhibition\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vivo loss-of-function model with defined neurochemical phenotype, in vitro secretion assay, pharmacological rescue; multiple methods\",\n      \"pmids\": [\"14530399\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"SEPTIN5 (Sept5) binds syntaxin within the assembled SNARE complex (7S complex), but cannot bind an nSec1-syntaxin complex. Alpha-SNAP binding to the SNARE complex occludes Sept5 binding, indicating Sept5 and alpha-SNAP compete for binding to the syntaxin-containing 7S complex, suggesting a regulatory role for Sept5 in SNARE availability.\",\n      \"method\": \"In vitro binding assays mapping Sept5 domains required for syntaxin binding, competitive binding assays with purified SNARE complexes and alpha-SNAP\",\n      \"journal\": \"The Biochemical journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro reconstitution of competitive binding with purified proteins, domain mapping; mechanistically rigorous single-lab study\",\n      \"pmids\": [\"15355307\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"SEPTIN5 (SEPT5) interacts with SEPT11 in human endothelial cells. The interaction requires the GTP-binding domain and C-terminal extension of SEPT11, confirmed by yeast two-hybrid, co-precipitation from JURKAT cell lysates, and FRET. Both proteins are co-expressed in HUVECs.\",\n      \"method\": \"Yeast two-hybrid, co-immunoprecipitation, FRET, domain deletion analysis\",\n      \"journal\": \"The Journal of pathology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal Co-IP and FRET for interaction confirmation, domain mapping; single lab\",\n      \"pmids\": [\"16767699\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"Cyclin-dependent kinase 5 (Cdk5)/p35 phosphorylates SEPTIN5 (Sept5_v1) at Ser17 in vitro and in mouse brain. Phosphorylation at Ser17 decreases binding of Sept5_v1 to syntaxin-1, as shown by co-immunoprecipitation from synaptosomal fractions and GST-syntaxin-1A pull-down assays.\",\n      \"method\": \"Mass spectrometry identification of Cdk5 substrates, in vitro kinase assay, site-directed mutagenesis (Ser17), GST pull-down, co-immunoprecipitation from synaptosomal fractions\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro kinase assay with mutagenesis, in vivo brain fractionation Co-IP, GST pull-down; multiple orthogonal methods\",\n      \"pmids\": [\"17224448\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"Sept3 directly binds Sept5 and Sept7 and forms a heteromeric complex at nerve terminals in mature neurons, adjacent to synaptophysin-positive synaptic vesicle regions, as demonstrated by direct binding assays and co-localization in hippocampal neurons.\",\n      \"method\": \"Direct binding assay, co-localization by immunofluorescence in primary neurons, Sept3 knockout mouse generation\",\n      \"journal\": \"Journal of neurochemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct binding demonstrated, co-localization in neurons; single lab, two methods\",\n      \"pmids\": [\"17564677\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"Cdk5/p35 phosphorylates human SEPTIN5 (hCDCrel-1) at Ser327. Phosphorylation at S327 decreases SEPTIN5 binding to syntaxin-1 (shown by Co-IP from synaptic vesicle fractions and Cdk5 knockout lysates). A non-phosphorylatable S327A mutant binds syntaxin more efficiently than wild-type and potentiates regulated exocytosis more than wild-type when expressed in PC12 cells.\",\n      \"method\": \"Yeast two-hybrid screen, GST pull-down, co-immunoprecipitation, in vitro and in vivo phosphorylation assay, site-directed mutagenesis (S327A), PC12 cell exocytosis assay\",\n      \"journal\": \"The Journal of neuroscience\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro kinase assay, mutagenesis, Co-IP from KO vs WT lysates, functional secretion assay; multiple orthogonal methods\",\n      \"pmids\": [\"18385322\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"ARMS/Kidins220 interacts with SEPTIN5 (Sept5) through the N-terminal region of Sept5. The interaction was confirmed by co-immunoprecipitation from HEK-293 cells. Endogenous proteins co-localize at the plasma membrane and neurite tips in hippocampal neurons and NGF-treated PC12 cells.\",\n      \"method\": \"Yeast two-hybrid, co-immunoprecipitation from transfected HEK-293 cells, domain mapping, co-localization in primary neurons and PC12 cells\",\n      \"journal\": \"Molecules and cells\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — Co-IP and co-localization, domain mapping; single lab\",\n      \"pmids\": [\"20680483\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"Downregulation of SEPTIN5 reduces levels of APP C-terminal fragments (APP CTFs) and Aβ in neuronal cells and in Septin5 knockout mouse cortex. Mechanistically, SEPTIN5 knockdown increases degradation of APP CTFs via the autophagosomal pathway, without affecting APP secretory trafficking or endocytosis, and enhances autophagosomal activity as indicated by altered autophagosomal marker levels.\",\n      \"method\": \"shRNA knockdown, Septin5 knockout mice, APP CTF and Aβ measurement by ELISA/Western blot, autophagy marker analysis, APP trafficking assay\",\n      \"journal\": \"Cells\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vitro and in vivo knockdown/knockout with defined molecular readouts, autophagy pathway analysis; multiple orthogonal methods in single lab\",\n      \"pmids\": [\"33203136\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"SEPTIN5 S327 phosphorylation status affects APP processing and autophagy markers in primary cortical neurons (assessed using lentiviral phosphomutants S327A and S327D). S327 phosphorylation status also influences short-term synaptic plasticity at the CA3-CA1 synapse ex vivo, linking this post-translational modification to synaptic function.\",\n      \"method\": \"Lentiviral transduction of primary mouse cortical neurons with wild-type SEPTIN5 and phosphomutants (S327A, S327D), APP processing assays, autophagy marker quantification, ex vivo electrophysiology (CA3-CA1)\",\n      \"journal\": \"Neurobiology of disease\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — phosphomutant functional analysis in neurons and ex vivo, multiple readouts; single lab\",\n      \"pmids\": [\"34954322\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"SEPTIN5 (CDCrel-1) interacts with VMAT2 in rat striatum, and binge methamphetamine alters this interaction as well as the subcellular localization of SEPTIN5.\",\n      \"method\": \"Co-immunoprecipitation from rat striatal tissue, subcellular fractionation, in vivo METH treatment model\",\n      \"journal\": \"International journal of molecular sciences\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single Co-IP from tissue, single lab, no mutagenesis or reconstitution\",\n      \"pmids\": [\"39684782\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"Co-expression of Sept8-204 with SEPT5 induces formation of small vesicle-like structures that co-localize with synaptophysin. This vesicle-like structure and co-localization require palmitoylation of Sept8-204 (controlled by ZDHHC17/PPT1); loss of palmitoylation causes Sept8-204/SEPT5 to form large puncta that do not co-localize with synaptophysin.\",\n      \"method\": \"Fluorescence microscopy of co-expressed septins, palmitoylation inhibition (2-BP), ZDHHC17 and PPT1 knockouts, co-localization with synaptophysin marker\",\n      \"journal\": \"Journal of cellular biochemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — subcellular localization with functional consequence (synaptic marker association), multiple genetic/pharmacological manipulations; single lab\",\n      \"pmids\": [\"38308620\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"In pancreatic β-cells, SEPTIN5 is preferentially assembled at microtubule-plasma membrane contact sites in a microtubule-dependent manner, where it anchors secretory granules. Septin5 deletion destabilizes the cortical microtubule meshwork, increases insulin granule dynamics and access to the plasma membrane, increases releasable granule pool clustering on L-type Ca2+ channels, and dramatically enhances glucose-stimulated insulin secretion including in type 2 diabetes.\",\n      \"method\": \"Super-resolution imaging, Septin5 knockout rodent model, live-cell imaging of granule dynamics, Ca2+ channel co-localization analysis, insulin secretion assay in rodent and human islets\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — super-resolution localization with functional consequence, genetic KO with defined mechanistic phenotype, multiple orthogonal readouts\",\n      \"pmids\": [\"40108136\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1998,\n      \"finding\": \"SEPTIN5 (hCDCrel-1) protein localizes to neurons in adult human brain and co-purifies with synaptosomes marked by SNAP-25 and synaptophysin, indicating a presynaptic localization.\",\n      \"method\": \"Immunohistochemistry, subcellular fractionation/co-purification with synaptosomal markers\",\n      \"journal\": \"Neuroreport\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — subcellular fractionation with synaptosomal co-purification; replicated in subsequent studies\",\n      \"pmids\": [\"9760144\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"SEPTIN5 (CDCrel-1/SEPT5) is a presynaptic GTPase that inhibits regulated exocytosis by directly binding syntaxin-1A via its SNARE interaction domain and competing with alpha-SNAP for access to the assembled SNARE complex; this interaction is negatively regulated by Cdk5/p35-mediated phosphorylation at Ser17 (adult isoform) and Ser327, which reduces syntaxin binding and modulates secretion. SEPTIN5 localizes to microtubule-plasma membrane contact sites in secretory cells where it tethers granules away from the plasma membrane, and its deletion enhances exocytosis by destabilizing the cortical microtubule meshwork. Parkin acts as an E3 ubiquitin ligase (with E2 UbcH8) that ubiquitinates and degrades SEPTIN5; familial Parkinson's disease mutations in parkin impair this activity, leading to SEPTIN5 accumulation and dopamine-dependent neurotoxicity. SEPTIN5 also forms heteromeric complexes with other septins (Nedd5, CDC10, Sept3, Sept7, Sept11, KIAA0202) and interacts with VMAT2 and ARMS/Kidins220, and its downregulation promotes autophagy-mediated degradation of APP C-terminal fragments, reducing Aβ levels.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"SEPTIN5 (CDCrel-1/SEPT5) is a presynaptic GTPase of the septin family that acts as a brake on regulated exocytosis by physically gating the SNARE machinery [#0, #17]. It binds syntaxin-1A directly through a defined SNARE interaction domain, and the GTPase activity is required for its inhibitory effect: wild-type SEPTIN5 suppresses secretion whereas dominant-negative GTPase mutants enhance it [#0]. Mechanistically, SEPTIN5 engages syntaxin within the assembled 7S SNARE complex but is excluded by alpha-SNAP, with which it competes for access, thereby regulating SNARE availability [#6]. This inhibitory binding is switched off by Cdk5/p35-mediated phosphorylation at Ser17 and Ser327, which lowers syntaxin affinity; non-phosphorylatable mutants bind syntaxin more tightly and potentiate exocytosis, linking the modification to secretion and to short-term synaptic plasticity [#8, #10, #13]. Beyond the SNARE interface, SEPTIN5 assembles into heteromeric septin filaments with Nedd5, CDC10, Sept3, Sept7, and Sept11 and localizes to microtubule–plasma membrane contact sites, where in pancreatic beta-cells it anchors secretory granules away from the plasma membrane; its deletion destabilizes the cortical microtubule meshwork and markedly enhances glucose-stimulated insulin secretion [#2, #9, #16]. SEPTIN5 is a substrate of the E3 ubiquitin ligase parkin (with E2 UbcH8), which ubiquitinates it for proteasomal degradation; familial Parkinson's disease parkin mutations impair this turnover, and SEPTIN5 accumulation drives dopamine-dependent dopaminergic neurodegeneration [#1, #4, #5]. Downregulation of SEPTIN5 additionally promotes autophagosomal degradation of APP C-terminal fragments and lowers Aβ, connecting it to amyloid processing [#12].\",\n  \"teleology\": [\n    {\n      \"year\": 1998,\n      \"claim\": \"Establishing where SEPTIN5 acts was the first step: localizing the protein to presynaptic terminals framed it as a candidate regulator of neurotransmission.\",\n      \"evidence\": \"Immunohistochemistry and synaptosomal co-purification with SNAP-25 and synaptophysin in human brain\",\n      \"pmids\": [\"9760144\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Did not define a molecular partner or function\", \"Subcellular resolution limited to fractionation\"]\n    },\n    {\n      \"year\": 1999,\n      \"claim\": \"This defined SEPTIN5's core function — it binds syntaxin-1A and inhibits exocytosis in a GTPase-dependent manner, identifying it as a SNARE-targeting brake on secretion.\",\n      \"evidence\": \"Co-IP, direct binding, and wild-type vs dominant-negative GTPase mutant secretion assays in HIT-T15 cells\",\n      \"pmids\": [\"10321247\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not resolve whether binding is to free or assembled syntaxin\", \"GTP cycle regulation of the interaction unmapped\"]\n    },\n    {\n      \"year\": 2000,\n      \"claim\": \"Identifying parkin as the E3 ligase for SEPTIN5 connected its turnover to the proteasome and to Parkinson's disease genetics.\",\n      \"evidence\": \"In vitro ubiquitination with UbcH8, Co-IP, cell-based degradation assay, and parkin RING-domain mutagenesis\",\n      \"pmids\": [\"11078524\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not show SEPTIN5 accumulation drives neuronal death\", \"Ubiquitination site on SEPTIN5 not mapped\"]\n    },\n    {\n      \"year\": 2002,\n      \"claim\": \"Genetic knockout and complex analysis tested whether SEPTIN5 is essential and revealed it operates within redundant heteromeric septin filaments.\",\n      \"evidence\": \"Co-IP of Nedd5/CDC10 complexes, KIAA0202 yeast two-hybrid/pull-down, and CDCrel-1 knockout mouse phenotyping\",\n      \"pmids\": [\"11739749\", \"12023038\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Knockout had no overt synaptic phenotype, leaving in vivo function ambiguous\", \"Compensation by other septins not directly proven\"]\n    },\n    {\n      \"year\": 2003,\n      \"claim\": \"Linking parkin-dependent SEPTIN5 turnover to disease showed that SEPTIN5 accumulates in patient brain and is neurotoxic when overexpressed, establishing causal relevance to dopaminergic degeneration.\",\n      \"evidence\": \"Co-IP from human substantia nigra, in vitro ubiquitination of splice variants, post-mortem brain analysis, and AAV overexpression in rat substantia nigra with dopamine-dependent rescue\",\n      \"pmids\": [\"14559152\", \"14530399\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism linking accumulation to dopamine toxicity not fully defined\", \"Endogenous SEPTIN5 levels in sporadic PD not addressed\"]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"Defining the binding interface mechanistically showed SEPTIN5 targets the assembled 7S SNARE complex and competes with alpha-SNAP, explaining how it gates SNARE recycling/availability.\",\n      \"evidence\": \"In vitro domain mapping and competitive binding assays with purified SNARE complexes and alpha-SNAP\",\n      \"pmids\": [\"15355307\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Stoichiometry of competition in vivo unknown\", \"Effect on SNARE disassembly kinetics not measured\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Discovery of Cdk5/p35 phosphorylation at Ser17 provided the regulatory switch that detaches SEPTIN5 from syntaxin, coupling the brake to a kinase signal.\",\n      \"evidence\": \"MS substrate identification, in vitro kinase assay, Ser17 mutagenesis, GST pull-down and synaptosomal Co-IP\",\n      \"pmids\": [\"17224448\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Functional secretion consequence of Ser17 not directly assayed here\", \"Isoform specificity of the site\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Mapping further septin partners (Sept3, Sept7) at nerve terminals reinforced that SEPTIN5 functions as part of synaptic septin filaments near vesicle pools.\",\n      \"evidence\": \"Direct binding assays and co-localization with synaptophysin in hippocampal neurons; Sept3 knockout\",\n      \"pmids\": [\"17564677\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Filament architecture not resolved\", \"Functional output of the Sept3/5/7 complex untested\"]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"A second Cdk5 site (Ser327) was shown to functionally tune exocytosis, with a phospho-dead mutant binding syntaxin better and potentiating secretion — directly tying phosphorylation to release.\",\n      \"evidence\": \"Kinase assays, S327A mutagenesis, Co-IP from Cdk5 KO vs WT lysates, PC12 exocytosis assay\",\n      \"pmids\": [\"18385322\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Relative contribution of Ser17 vs Ser327 in vivo unresolved\", \"Upstream signals activating Cdk5 toward SEPTIN5 unknown\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Identifying ARMS/Kidins220 as an N-terminal partner extended SEPTIN5's interactome to neurite-tip and plasma-membrane signaling scaffolds.\",\n      \"evidence\": \"Yeast two-hybrid, Co-IP from HEK-293, domain mapping, co-localization in neurons and PC12 cells\",\n      \"pmids\": [\"20680483\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Functional consequence of the interaction undefined\", \"Single-lab Co-IP without reciprocal endogenous validation\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"A new functional axis emerged: SEPTIN5 loss promotes autophagosomal clearance of APP C-terminal fragments and lowers Aβ, implicating it in amyloid metabolism independent of trafficking.\",\n      \"evidence\": \"shRNA knockdown and Septin5 KO mouse cortex, APP CTF/Aβ measurement, autophagy marker analysis, trafficking assays\",\n      \"pmids\": [\"33203136\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct molecular link between SEPTIN5 and autophagy machinery not identified\", \"Whether effect requires syntaxin/SNARE function unknown\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Phosphomutant analysis tied the Ser327 modification to both APP processing/autophagy and to short-term synaptic plasticity, integrating SEPTIN5's secretory and amyloid roles under one regulatory mark.\",\n      \"evidence\": \"Lentiviral S327A/S327D in cortical neurons, APP and autophagy readouts, ex vivo CA3-CA1 electrophysiology\",\n      \"pmids\": [\"34954322\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Causal chain from phosphorylation to autophagy unresolved\", \"Single-lab functional correlations\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"New interactions with VMAT2 and palmitoylated Sept8 connected SEPTIN5 to monoamine handling and to vesicle-like structure formation, broadening its secretory-organelle associations.\",\n      \"evidence\": \"Co-IP from rat striatum with METH model; co-expression imaging with Sept8-204 palmitoylation manipulation (ZDHHC17/PPT1)\",\n      \"pmids\": [\"39684782\", \"38308620\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"VMAT2 interaction shown by single Co-IP without reconstitution\", \"Functional significance of Sept8/SEPT5 vesicle structures untested\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Super-resolution and KO work in beta-cells unified the localization and secretory-brake themes: SEPTIN5 sits at microtubule–plasma membrane contact sites anchoring granules, and its loss destabilizes cortical microtubules to dramatically enhance insulin secretion.\",\n      \"evidence\": \"Super-resolution imaging, Septin5 KO rodent model, live granule dynamics, Ca2+ channel co-localization, insulin secretion in rodent and human islets\",\n      \"pmids\": [\"40108136\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How GTP state controls contact-site assembly unknown\", \"Link between microtubule role and SNARE-binding role not mechanistically bridged\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"It remains unresolved how SEPTIN5's two mechanistic faces — direct SNARE/syntaxin gating and cortical microtubule/granule anchoring — are coordinated, and how its GTPase cycle and phosphorylation jointly switch between them.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No structure of SEPTIN5 bound to the SNARE complex\", \"GTP-cycle regulation of filament assembly vs syntaxin binding undefined\", \"Direct effector linking SEPTIN5 to autophagy unidentified\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0003924\", \"supporting_discovery_ids\": [0]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [0, 6]},\n      {\"term_id\": \"GO:0005198\", \"supporting_discovery_ids\": [2, 9, 16]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [11, 16, 17]},\n      {\"term_id\": \"GO:0005856\", \"supporting_discovery_ids\": [16]},\n      {\"term_id\": \"GO:0031410\", \"supporting_discovery_ids\": [9, 15]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-5653656\", \"supporting_discovery_ids\": [0, 6, 16]},\n      {\"term_id\": \"R-HSA-112316\", \"supporting_discovery_ids\": [13, 17]},\n      {\"term_id\": \"R-HSA-9612973\", \"supporting_discovery_ids\": [12]}\n    ],\n    \"complexes\": [\"septin heteromeric complex (Sept3/Sept5/Sept7)\", \"SNARE/7S complex (interacting)\"],\n    \"partners\": [\"STX1A\", \"PARK2\", \"SEPT11\", \"SEPT3\", \"SEPT7\", \"KIDINS220\", \"SLC18A2\", \"NEDD5\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":7,"faith_total":7,"faith_pct":100.0}}