{"gene":"SCN2B","run_date":"2026-04-28T20:42:07","timeline":{"discoveries":[{"year":2009,"finding":"SCN2B mutations R28Q and R28W reduce SCN5A-mediated sodium current and alter channel gating when co-expressed in heterologous cells, identifying SCN2B as a loss-of-function atrial fibrillation susceptibility gene.","method":"Heterologous expression in CHO cells with patch-clamp electrophysiology","journal":"Circulation. Arrhythmia and electrophysiology","confidence":"Medium","confidence_rationale":"Tier 2 — direct electrophysiology in heterologous system, single lab","pmids":["19808477"],"is_preprint":false},{"year":2009,"finding":"β2 subunit (Scn2b) increases persistent Na+ current (INaP) in HEK cells expressing Nav1.1, and this effect is counteracted by β1 subunit co-expression; in Scn1b/Scn2b null neurons, entry into inactivated states is slowed, indicating β1 and β2 have antagonistic roles in regulating Na+ channel inactivation.","method":"Whole-cell patch-clamp in HEK cells and cultured hippocampal neurons from Scn1b and Scn1b/Scn2b null mice","journal":"The Journal of neuroscience","confidence":"High","confidence_rationale":"Tier 2 — multiple cell types, knockout mice, replicated with chimeric subunit analysis","pmids":["19228957"],"is_preprint":false},{"year":2012,"finding":"The disulfide bond between the Na+ channel α subunit and β2 subunit is mediated by a single extracellular cysteine residue (Cys-26) within the immunoglobulin domain of β2; mutation of Cys-26 to alanine abolishes α-β2 covalent linkage and disrupts β2 targeting to nodes of Ranvier and the axon initial segment in neurons, and disrupts β2 association with the neuronal cytoskeleton.","method":"Site-directed mutagenesis, myelinating co-culture system, primary hippocampal neuron imaging, detergent extraction assay","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 — mutagenesis with multiple orthogonal functional readouts including localization and cytoskeletal association","pmids":["22992729"],"is_preprint":false},{"year":2013,"finding":"A missense mutation in β2 (D211G, encoded by SCN2B) reduces Nav1.5 sodium current density by approximately 39% without affecting unitary channel conductance; protein membrane detection experiments suggest β2-D211G decreases Nav1.5 cell surface expression, establishing SCN2B as a Brugada syndrome candidate gene.","method":"Heterologous co-expression with patch-clamp electrophysiology (whole-cell and single-channel), cell surface biotinylation","journal":"Human mutation","confidence":"High","confidence_rationale":"Tier 1-2 — multiple electrophysiology methods plus surface expression assay, single lab","pmids":["23559163"],"is_preprint":false},{"year":2008,"finding":"Scn2b null mice have reduced Na+ channel cell surface expression in neurons, compromised action potential conduction, and are neuroprotected in experimental autoimmune encephalomyelitis (EAE), consistent with β2 functioning to chaperone Na+ channel α subunits to the plasma membrane.","method":"Scn2b knockout mouse model; EAE induction; assessment of axonal degeneration, immune infiltration, symptom severity","journal":"Molecular and cellular neurosciences","confidence":"High","confidence_rationale":"Tier 2 — clean KO with specific phenotypic readouts, immune function controls, consistent with parallel neuronal data","pmids":["19013247"],"is_preprint":false},{"year":2010,"finding":"β2 subunit (Scn2b) modulates the pharmacological properties of Na+ channels: in Scn2b null CA1 neurons, carbamazepine effects on persistent Na+ current (INaP) are altered, demonstrating that β2 subunits modify not only biophysical but also pharmacological properties of the Na+ channel complex.","method":"Whole-cell patch-clamp on hippocampal CA1 neurons from Scn2b null mice; current-clamp and computational modeling","journal":"The Journal of neuroscience","confidence":"High","confidence_rationale":"Tier 2 — knockout mouse model with electrophysiology and computational validation","pmids":["20573896"],"is_preprint":false},{"year":2016,"finding":"Scn2b null mice exhibit reduced sodium and potassium current densities in ventricular myocytes, conduction slowing in the right ventricular outflow tract, spontaneous polymorphic ventricular tachycardia via functional reentry, and increased susceptibility to atrial fibrillation with increased fibrosis; Nav1.5 protein levels are unchanged, consistent with β2 chaperoning Na+ channel α subunits to the plasma membrane in the heart.","method":"Scn2b knockout mouse model; patch-clamp electrophysiology; in vivo cardiac electrophysiology; western blotting; histology","journal":"Circulation. Arrhythmia and electrophysiology","confidence":"High","confidence_rationale":"Tier 2 — clean KO with multiple orthogonal cardiac and molecular phenotypic readouts","pmids":["27932425"],"is_preprint":false},{"year":2011,"finding":"In nociceptive dorsal root ganglion neurons, Scn2b selectively regulates TTX-sensitive α subunit mRNA and protein expression, ultimately resulting in changes in pain sensitivity, as demonstrated in Scn2b null mice.","method":"Scn2b knockout mouse DRG neurons; patch-clamp electrophysiology; behavioral pain assays referenced in context","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 — knockout mice with electrophysiology, single lab; DRG-specific finding","pmids":["21555511"],"is_preprint":false},{"year":2011,"finding":"Post-transcriptional silencing of SCN2B by siRNA in ventricular cardiomyocytes increases late Na+ current (INaL) density and slows its decay, an effect opposite to that of SCN1B silencing, demonstrating that β2 and β1 subunits exert opposing modulation of INaL without changing Nav1.5 (INaT) in both normal and failing dog hearts.","method":"Virally delivered siRNA knockdown in isolated canine cardiomyocytes; whole-cell and perforated patch-clamp; RT-PCR; western blot","journal":"American journal of physiology. Heart and circulatory physiology","confidence":"High","confidence_rationale":"Tier 2 — siRNA KD with multiple methods (electrophysiology, mRNA, protein), normal and HF conditions tested","pmids":["21705762"],"is_preprint":false},{"year":2017,"finding":"β2 subunit promotes Nav1.5 localization to the cell surface in both MDCK and HL-1 cells; the BrS-associated β2 mutation D211G reaches the plasma membrane normally but is defective in promoting Nav1.5 surface localization, indicating the mutation specifically disrupts β2's trafficking function for the α subunit.","method":"Polarized MDCK and HL-1 cell expression; confocal immunofluorescence; surface biotinylation","journal":"Biology of the cell","confidence":"High","confidence_rationale":"Tier 2 — multiple cell lines, WT vs. mutant comparison, two orthogonal localization methods","pmids":["28597987"],"is_preprint":false},{"year":2019,"finding":"β2 subunit (SCN2B) is N-glycosylated at residues Asn-42, Asn-66, and Asn-74, with sialylation only at Asn-42; fully nonglycosylated β2 is retained in the ER and is defective in promoting Nav1.5 surface localization, demonstrating that N-linked glycosylation is required for efficient β2 trafficking to the plasma membrane and for β2-mediated surface delivery of Nav1.5.","method":"Site-directed mutagenesis of N-glycosylation sites; heterologous expression in MDCK cells; biochemical glycosylation assays; FRAP; surface biotinylation","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 — mutagenesis with multiple biochemical and imaging readouts in polarized cell system","pmids":["31511323"],"is_preprint":false},{"year":2021,"finding":"β2 subunit (SCN2B) is S-palmitoylated at Cys-182; palmitoylation increases β2 association with detergent-resistant membranes (lipid rafts) and influences its polarized apical localization; cholesterol depletion causes β2 mislocalization to the basolateral domain; palmitoylation is not required for promoting Nav1.5 surface localization but is linked to lipid raft association.","method":"Acyl-biotin exchange assay; cholesterol depletion; FRAP; lipid raft fractionation; confocal imaging in polarized MDCK cells","journal":"Journal of cell science","confidence":"High","confidence_rationale":"Tier 1-2 — direct biochemical detection of PTM plus multiple functional consequences tested","pmids":["33602743"],"is_preprint":false},{"year":2024,"finding":"β2 subunit (SCN2B) forms homodimers and requires its cytoplasmic tail, extracellular loop, and transmembrane domain for proper folding and export to the cell surface; deletion of any domain causes ER retention and impaired complex N-glycosylation; NaV1.5 does not influence β2 trafficking or surface localization.","method":"Domain deletion mutagenesis; heterologous expression in MDCK cells; co-immunoprecipitation; glycosylation assays; confocal imaging","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1-2 — systematic mutagenesis with biochemical and imaging validation","pmids":["39343005"],"is_preprint":false},{"year":2020,"finding":"Crystal structure of the SCN2B-encoded β2 subunit (R137H variant) reveals structural changes at the mutation site without overall protein destabilization; electrophysiology shows R137H does not alter NaV1.5 activity, suggesting this variant may act through other NaV channel subtypes present in cardiac tissue.","method":"X-ray crystallography; patch-clamp electrophysiology on NaV1.5","journal":"Bioelectricity","confidence":"Medium","confidence_rationale":"Tier 1 — crystal structure obtained, but functional conclusion is negative (no effect on NaV1.5), single lab","pmids":["34476357"],"is_preprint":false},{"year":2023,"finding":"In a β-subunit-null human cell line (BeHAPe), each β subunit including β2 (SCN2B) imparts unique gating properties to NaV1.5; co-expression of β1 and β2 together generates hybrid gating properties distinct from either subunit alone, revealing an expanded regulatory role of β2 on NaV1.5 activity.","method":"CRISPR-engineered β-subunit-null haploid human cells (BeHAPe); heterologous expression; whole-cell patch-clamp","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 — rigorous null cell background eliminates endogenous subunit confounds; multiple subunit combinations tested","pmids":["37544648"],"is_preprint":false},{"year":2017,"finding":"Navβ2 knockdown in APP/PS1 Alzheimer's disease model mice partially reverses abnormal Navβ2 cleavage by BACE1, restores sodium current density in hippocampal neurons, shifts APP metabolism toward non-amyloidogenic processing, and improves cognitive performance, establishing SCN2B as a BACE1 substrate that influences APP processing.","method":"Transgenic Navβ2 knockdown in APP/PS1 mice; patch-clamp; EEG; Morris water maze; western blot","journal":"Oncotarget","confidence":"Medium","confidence_rationale":"Tier 2 — in vivo knockdown with multiple readouts, single lab","pmids":["29245901"],"is_preprint":false},{"year":2014,"finding":"β2 subunit (encoded by SCN2B) functions as a cell adhesion molecule in prostate cancer cells, interacting with laminin; overexpression of β2 enhances PCa cell migration, invasion, and binding affinity to laminin as measured by atomic force microscopy, and enhances association with nerve axons in an ex vivo spinal cord co-culture model.","method":"β2 overexpression in LNCaP cells; ex vivo organotypic spinal cord co-culture; atomic force microscopy; migration/invasion assays","journal":"PloS one","confidence":"Medium","confidence_rationale":"Tier 2-3 — multiple functional assays in cell model, single lab, no endogenous control KD","pmids":["24892658"],"is_preprint":false},{"year":2020,"finding":"miR-449a directly targets the 3'-UTR of SCN2B mRNA (confirmed by dual-luciferase reporter assay and anti-Ago co-immunoprecipitation/microarray) and regulates SCN2B expression; inhibition of SCN2B or overexpression of miR-449a promotes hippocampal neuron extension, placing miR-449a upstream of SCN2B in a brain aging regulatory axis.","method":"Dual-luciferase reporter assay; anti-Ago co-immunoprecipitation with Affymetrix microarray; miR-449a overexpression in neurons; miRNA microarray in SAMP8 mice","journal":"International journal of molecular medicine","confidence":"Medium","confidence_rationale":"Tier 2 — biochemical validation of miRNA-target interaction with multiple methods, single lab","pmids":["32124967"],"is_preprint":false},{"year":2024,"finding":"miR-6954-3p directly binds the 3'-UTR of Scn2b mRNA (confirmed by luciferase assay); miR-6954-3p is downregulated in the trigeminal ganglion after chronic constriction injury of the infraorbital nerve, leading to upregulation of SCN2B protein; SCN2B silencing in TG reduces orofacial pain hypersensitivity, identifying SCN2B as a downstream effector of miR-6954-3p in neuropathic pain.","method":"CCI-ION mouse model; luciferase assay; siRNA knockdown; FISH; immunofluorescence; von Frey testing","journal":"The journal of pain","confidence":"Medium","confidence_rationale":"Tier 2 — validated miRNA-target interaction plus in vivo KD with behavioral outcome, single lab","pmids":["38866121"],"is_preprint":false}],"current_model":"SCN2B encodes the voltage-gated sodium channel β2 subunit, which covalently associates with α subunits via a single extracellular disulfide bond (Cys-26), chaperoning Na+ channel α subunits (Nav1.5, Nav1.1, and others) to the plasma membrane; β2 undergoes N-glycosylation (required for ER export) and S-palmitoylation (mediating lipid raft association and polarized localization), promotes Nav1.5 surface expression through a trafficking function disrupted by arrhythmia-linked mutations (e.g., D211G), opposes β1-mediated inactivation by increasing persistent Na+ current, modulates both biophysical and pharmacological properties of Na+ channels, and also functions as a cell adhesion molecule of the immunoglobulin superfamily; loss of β2 in vivo reduces Na+ channel surface expression in neurons and cardiomyocytes, causing ventricular and atrial arrhythmias, altered pain sensitivity, and neuroprotection in demyelinating disease."},"narrative":{"teleology":[{"year":2008,"claim":"The in vivo requirement for β2 was established: Scn2b-null mice showed reduced neuronal Na+ channel surface expression, impaired conduction, and unexpected neuroprotection in EAE, demonstrating that β2 functions as an essential chaperone for α subunit plasma membrane delivery in the nervous system.","evidence":"Scn2b knockout mouse with EAE induction, axonal degeneration assessment, and electrophysiology","pmids":["19013247"],"confidence":"High","gaps":["Mechanism by which reduced surface Na+ channels confer neuroprotection was not resolved","Cardiac phenotype of the knockout was not yet examined"]},{"year":2009,"claim":"Two complementary studies defined β2's biophysical role and disease relevance: β2 increases persistent Na+ current (INaP) in opposition to β1-mediated inactivation, and SCN2B mutations (R28Q, R28W) that reduce sodium current density were linked to atrial fibrillation susceptibility.","evidence":"Patch-clamp in HEK cells and hippocampal neurons from Scn1b/Scn2b null mice; heterologous expression of mutant β2 with Nav1.5 in CHO cells","pmids":["19228957","19808477"],"confidence":"High","gaps":["Whether AF-linked mutations disrupt trafficking versus gating was unresolved","Antagonistic β1/β2 interplay was not yet tested in cardiac cells"]},{"year":2010,"claim":"β2 was shown to modulate not only biophysical but also pharmacological properties of Na+ channels, as carbamazepine effects on INaP were altered in Scn2b-null hippocampal neurons, expanding the functional scope of β2 beyond gating.","evidence":"Whole-cell patch-clamp on CA1 neurons from Scn2b-null mice with computational modeling","pmids":["20573896"],"confidence":"High","gaps":["Whether β2 alters drug binding directly or indirectly through channel conformation was not distinguished"]},{"year":2011,"claim":"β2's opposing role to β1 was confirmed in cardiac myocytes, and its regulation of neuronal α subunit expression in nociceptors was identified: SCN2B knockdown in ventricular cardiomyocytes increased late Na+ current, while Scn2b-null DRG neurons showed selective changes in TTX-sensitive α subunit expression affecting pain sensitivity.","evidence":"siRNA knockdown in canine cardiomyocytes with patch-clamp; Scn2b-null mouse DRG neuron electrophysiology and behavioral assays","pmids":["21705762","21555511"],"confidence":"High","gaps":["Mechanism by which β2 regulates α subunit mRNA levels in DRG was not identified","Whether β1/β2 opposition in late current applies to all cardiac α subunit isoforms was untested"]},{"year":2012,"claim":"The molecular basis of α–β2 covalent association was pinpointed: Cys-26 in the Ig domain forms the single disulfide bond to α subunits, and this linkage is required for β2 targeting to nodes of Ranvier, the axon initial segment, and cytoskeletal association.","evidence":"Site-directed mutagenesis of Cys-26; myelinating co-cultures; primary hippocampal neuron imaging; detergent extraction","pmids":["22992729"],"confidence":"High","gaps":["Identity of the partnering cysteine on the α subunit was not mapped","Whether non-covalent β2–α interactions persist in Cys-26 mutants was not fully resolved"]},{"year":2013,"claim":"The Brugada syndrome-associated β2 mutation D211G was shown to reduce Nav1.5 surface expression without affecting unitary conductance, establishing that disease-linked β2 variants can specifically disrupt the trafficking function for α subunits.","evidence":"Heterologous co-expression; whole-cell and single-channel patch-clamp; surface biotinylation","pmids":["23559163"],"confidence":"High","gaps":["Whether D211G disrupts β2 folding, dimerization, or α subunit interaction was unknown"]},{"year":2016,"claim":"The cardiac phenotype of Scn2b loss was comprehensively characterized: null mice exhibited reduced Na+ and K+ current densities, right ventricular conduction slowing, spontaneous polymorphic VT, and atrial fibrillation with fibrosis, with unchanged total Nav1.5 protein—confirming β2's cardiac trafficking role in vivo.","evidence":"Scn2b knockout mouse; patch-clamp; in vivo cardiac electrophysiology; western blot; histology","pmids":["27932425"],"confidence":"High","gaps":["Mechanism of K+ current reduction in β2-null cardiomyocytes was unexplained","Basis of atrial fibrosis was not resolved"]},{"year":2017,"claim":"Two studies expanded β2 biology: β2 D211G was shown to reach the plasma membrane itself but fail to promote Nav1.5 surface delivery, dissociating β2 self-trafficking from its α-chaperoning function; separately, β2 was identified as a BACE1 substrate whose cleavage in AD models alters APP processing and cognition.","evidence":"Polarized MDCK/HL-1 cells with confocal imaging and surface biotinylation; Nav β2 knockdown in APP/PS1 mice with electrophysiology, EEG, and behavioral testing","pmids":["28597987","29245901"],"confidence":"High","gaps":["D211G structural defect was not identified at atomic resolution","BACE1 cleavage site on β2 was not mapped","AD-related findings from a single lab"]},{"year":2019,"claim":"N-glycosylation at Asn-42, Asn-66, and Asn-74 was mapped, with sialylation restricted to Asn-42; complete loss of glycosylation caused ER retention of β2 and failure to promote Nav1.5 surface delivery, establishing glycosylation as a prerequisite for β2 trafficking competence.","evidence":"N-glycosylation site mutagenesis; biochemical glycosylation assays; FRAP; surface biotinylation in polarized MDCK cells","pmids":["31511323"],"confidence":"High","gaps":["Contribution of individual glycosylation sites to trafficking efficiency was not fully resolved","Whether glycosylation affects β2 interaction with specific α subunits was untested"]},{"year":2020,"claim":"A crystal structure of β2 (R137H variant) was obtained, revealing local structural changes at the mutation site without global destabilization; R137H had no effect on Nav1.5, suggesting it may act through other α subunit subtypes.","evidence":"X-ray crystallography; patch-clamp electrophysiology on Nav1.5","pmids":["34476357"],"confidence":"Medium","gaps":["Wild-type β2 structure was not determined for comparison","Effect of R137H on non-Nav1.5 α subunits was not tested","Structure was of a disease variant, not wild-type"]},{"year":2021,"claim":"S-palmitoylation at Cys-182 was identified as a post-translational modification that directs β2 to lipid rafts and controls its polarized localization, independent of its α-chaperoning function.","evidence":"Acyl-biotin exchange; cholesterol depletion; lipid raft fractionation; FRAP; confocal imaging in polarized MDCK cells","pmids":["33602743"],"confidence":"High","gaps":["Palmitoylating enzyme(s) for β2 were not identified","Whether palmitoylation affects β2 function in cardiomyocytes or neurons was not tested in vivo"]},{"year":2023,"claim":"Using a CRISPR-engineered β-subunit-null human cell line, each β subunit was shown to confer unique gating properties to Nav1.5, and co-expression of β1+β2 produced hybrid gating distinct from either alone—providing a clean demonstration of combinatorial β subunit regulation.","evidence":"β-subunit-null haploid human cells (BeHAPe); heterologous expression; whole-cell patch-clamp","pmids":["37544648"],"confidence":"High","gaps":["Whether hybrid gating occurs in native cardiomyocytes was not verified","Stoichiometry of β1/β2 in the native complex was not determined"]},{"year":2024,"claim":"β2 was shown to form homodimers, and systematic domain deletion revealed that the cytoplasmic tail, extracellular Ig loop, and transmembrane domain are each required for proper folding and ER export, while Nav1.5 does not influence β2 trafficking—establishing that β2 traffics autonomously.","evidence":"Domain deletion mutagenesis; co-immunoprecipitation; glycosylation assays; confocal imaging in MDCK cells","pmids":["39343005"],"confidence":"High","gaps":["Homodimer interface residues were not mapped at atomic resolution","Functional significance of homodimerization for α subunit chaperoning was not determined"]},{"year":null,"claim":"Key unresolved questions include: the structural basis of β2-mediated α subunit trafficking (no co-structure with an α subunit exists), the identity of palmitoylating enzymes, the physiological significance of β2 homodimerization, the mechanism by which β2 loss leads to cardiac fibrosis, and whether BACE1 cleavage of β2 is pathophysiologically relevant in human Alzheimer's disease.","evidence":"","pmids":[],"confidence":"Low","gaps":["No α–β2 co-crystal or cryo-EM structure","Palmitoyl acyltransferase identity unknown","In vivo significance of β2 homodimerization untested","BACE1–β2 axis in human AD not validated"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[1,5,8,14]},{"term_id":"GO:0098631","term_label":"cell adhesion mediator activity","supporting_discovery_ids":[2,16]},{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[3,9,10]}],"localization":[{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[2,3,9,10,11,12]},{"term_id":"GO:0005783","term_label":"endoplasmic reticulum","supporting_discovery_ids":[10,12]}],"pathway":[{"term_id":"R-HSA-112316","term_label":"Neuronal System","supporting_discovery_ids":[1,4,5,7]},{"term_id":"R-HSA-9609507","term_label":"Protein localization","supporting_discovery_ids":[3,9,10,12]},{"term_id":"R-HSA-382551","term_label":"Transport of small molecules","supporting_discovery_ids":[1,6,8,14]}],"complexes":["voltage-gated sodium channel complex"],"partners":["SCN5A","SCN1A","SCN1B","BACE1"],"other_free_text":[]},"mechanistic_narrative":"SCN2B encodes the voltage-gated sodium channel β2 subunit, an immunoglobulin-superfamily transmembrane glycoprotein that covalently associates with pore-forming α subunits via an extracellular disulfide bond at Cys-26 and functions as a chaperone, gating modulator, and cell adhesion molecule. β2 promotes surface delivery of Nav1.5 and neuronal Nav α subunits through a trafficking mechanism that requires N-glycosylation for ER export, involves homodimerization and integrity of all three protein domains, and is disrupted by arrhythmia-associated mutations such as D211G [PMID:31511323, PMID:39343005, PMID:28597987]. β2 opposes β1-mediated inactivation by increasing persistent sodium current, and co-expression of β1 and β2 produces hybrid gating distinct from either subunit alone, while also modifying pharmacological sensitivity of the channel complex [PMID:19228957, PMID:37544648, PMID:20573896]. Loss of β2 in vivo reduces neuronal and cardiac sodium channel surface expression, causing ventricular arrhythmias, atrial fibrillation susceptibility, altered pain sensitivity, and neuroprotection in demyelinating disease [PMID:27932425, PMID:19013247, PMID:21555511]."},"prefetch_data":{"uniprot":{"accession":"O60939","full_name":"Sodium channel regulatory subunit beta-2","aliases":[],"length_aa":215,"mass_kda":24.3,"function":"Regulatory subunit of multiple voltage-gated sodium (Nav) channels directly mediating the depolarization of excitable membranes (PubMed:19808477, PubMed:23559163, PubMed:26894959, PubMed:30765605, PubMed:30765606, PubMed:35277491, PubMed:36823201). Navs, also called VGSCs (voltage-gated sodium channels) or VDSCs (voltage-dependent sodium channels), operate by switching between closed and open conformations depending on the voltage difference across the membrane. In the open conformation they allow Na(+) ions to selectively pass through the pore, along their electrochemical gradient. The influx of Na+ ions provokes membrane depolarization, initiating the propagation of electrical signals throughout cells and tissues (PubMed:19808477, PubMed:23559163, PubMed:26894959). The accessory beta subunits participate in localization and functional modulation of the Nav channels (PubMed:19808477, PubMed:23559163). Modulates the activity of SCN1A/Nav1.1, SCN2A/Nav1.2, SCN2A/Nav1.3, SCN5A/Nav1.5, SCN8A/Nav1.6, SCN9A/Nav1.7 and SCN10A/Nav1.8 (PubMed:19808477, PubMed:23559163, PubMed:26894959, PubMed:30765605, PubMed:30765606, PubMed:35277491, PubMed:36823201)","subcellular_location":"Cell membrane; Cell projection, axon","url":"https://www.uniprot.org/uniprotkb/O60939/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/SCN2B","classification":"Not Classified","n_dependent_lines":0,"n_total_lines":1208,"dependency_fraction":0.0},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/SCN2B","total_profiled":1310},"omim":[{"mim_id":"615378","title":"ATRIAL FIBRILLATION, FAMILIAL, 14; ATFB14","url":"https://www.omim.org/entry/615378"},{"mim_id":"615377","title":"ATRIAL FIBRILLATION, FAMILIAL, 13; ATFB13","url":"https://www.omim.org/entry/615377"},{"mim_id":"611819","title":"LONG QT SYNDROME 10; LQT10","url":"https://www.omim.org/entry/611819"},{"mim_id":"608583","title":"ATRIAL FIBRILLATION, FAMILIAL, 1; ATFB1","url":"https://www.omim.org/entry/608583"},{"mim_id":"608256","title":"SODIUM VOLTAGE-GATED CHANNEL, BETA SUBUNIT 4; SCN4B","url":"https://www.omim.org/entry/608256"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"","locations":[],"tissue_specificity":"Tissue enriched","tissue_distribution":"Detected in many","driving_tissues":[{"tissue":"brain","ntpm":48.3}],"url":"https://www.proteinatlas.org/search/SCN2B"},"hgnc":{"alias_symbol":[],"prev_symbol":[]},"alphafold":{"accession":"O60939","domains":[{"cath_id":"2.60.40.10","chopping":"31-146","consensus_level":"high","plddt":96.1161,"start":31,"end":146}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/O60939","model_url":"https://alphafold.ebi.ac.uk/files/AF-O60939-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-O60939-F1-predicted_aligned_error_v6.png","plddt_mean":85.81},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=SCN2B","jax_strain_url":"https://www.jax.org/strain/search?query=SCN2B"},"sequence":{"accession":"O60939","fasta_url":"https://rest.uniprot.org/uniprotkb/O60939.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/O60939/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/O60939"}},"corpus_meta":[{"pmid":"19808477","id":"PMC_19808477","title":"Mutations in sodium channel β1- and β2-subunits associated with atrial fibrillation.","date":"2009","source":"Circulation. Arrhythmia and electrophysiology","url":"https://pubmed.ncbi.nlm.nih.gov/19808477","citation_count":186,"is_preprint":false},{"pmid":"14738421","id":"PMC_14738421","title":"Mutations of neuronal voltage-gated Na+ channel alpha 1 subunit gene SCN1A in core severe myoclonic epilepsy in infancy (SMEI) and in borderline SMEI (SMEB).","date":"2004","source":"Epilepsia","url":"https://pubmed.ncbi.nlm.nih.gov/14738421","citation_count":157,"is_preprint":false},{"pmid":"19228957","id":"PMC_19228957","title":"Regulation of persistent Na current by interactions between beta subunits of voltage-gated Na channels.","date":"2009","source":"The Journal of neuroscience : the official journal of the Society for Neuroscience","url":"https://pubmed.ncbi.nlm.nih.gov/19228957","citation_count":144,"is_preprint":false},{"pmid":"12011299","id":"PMC_12011299","title":"Generalized epilepsy with febrile seizures plus: mutation of the sodium channel subunit SCN1B.","date":"2002","source":"Neurology","url":"https://pubmed.ncbi.nlm.nih.gov/12011299","citation_count":119,"is_preprint":false},{"pmid":"19041953","id":"PMC_19041953","title":"A novel adhesion molecule in human breast cancer cells: voltage-gated Na+ channel beta1 subunit.","date":"2008","source":"The international journal of biochemistry & cell biology","url":"https://pubmed.ncbi.nlm.nih.gov/19041953","citation_count":94,"is_preprint":false},{"pmid":"23559163","id":"PMC_23559163","title":"A missense mutation in the sodium channel β2 subunit reveals SCN2B as a new candidate gene for Brugada syndrome.","date":"2013","source":"Human mutation","url":"https://pubmed.ncbi.nlm.nih.gov/23559163","citation_count":83,"is_preprint":false},{"pmid":"32392183","id":"PMC_32392183","title":"Genetic regulatory subnetworks and key regulating genes in rat hippocampus perturbed by prenatal malnutrition: implications for major brain disorders.","date":"2020","source":"Aging","url":"https://pubmed.ncbi.nlm.nih.gov/32392183","citation_count":67,"is_preprint":false},{"pmid":"20558140","id":"PMC_20558140","title":"Functional dominant-negative mutation of sodium channel subunit gene SCN3B associated with atrial fibrillation in a Chinese GeneID population.","date":"2010","source":"Biochemical and biophysical research communications","url":"https://pubmed.ncbi.nlm.nih.gov/20558140","citation_count":65,"is_preprint":false},{"pmid":"22992729","id":"PMC_22992729","title":"Identification of the cysteine residue responsible for disulfide linkage of Na+ channel α and β2 subunits.","date":"2012","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/22992729","citation_count":64,"is_preprint":false},{"pmid":"20573896","id":"PMC_20573896","title":"Efficacy loss of the anticonvulsant carbamazepine in mice lacking sodium channel beta subunits via paradoxical effects on persistent sodium currents.","date":"2010","source":"The Journal of neuroscience : the official journal of the Society for Neuroscience","url":"https://pubmed.ncbi.nlm.nih.gov/20573896","citation_count":58,"is_preprint":false},{"pmid":"23604097","id":"PMC_23604097","title":"Mutations of the SCN4B-encoded sodium channel β4 subunit in familial atrial fibrillation.","date":"2013","source":"International journal of molecular medicine","url":"https://pubmed.ncbi.nlm.nih.gov/23604097","citation_count":56,"is_preprint":false},{"pmid":"34332113","id":"PMC_34332113","title":"Extracellular matrix remodeling precedes atrial fibrillation: Results of the PREDICT-AF trial.","date":"2021","source":"Heart rhythm","url":"https://pubmed.ncbi.nlm.nih.gov/34332113","citation_count":46,"is_preprint":false},{"pmid":"26728597","id":"PMC_26728597","title":"Regulation of SCN3B/scn3b by Interleukin 2 (IL-2): IL-2 modulates SCN3B/scn3b transcript expression and increases sodium current in myocardial cells.","date":"2016","source":"BMC cardiovascular disorders","url":"https://pubmed.ncbi.nlm.nih.gov/26728597","citation_count":45,"is_preprint":false},{"pmid":"19013247","id":"PMC_19013247","title":"Loss of Na+ channel beta2 subunits is neuroprotective in a mouse model of multiple sclerosis.","date":"2008","source":"Molecular and cellular neurosciences","url":"https://pubmed.ncbi.nlm.nih.gov/19013247","citation_count":45,"is_preprint":false},{"pmid":"27932425","id":"PMC_27932425","title":"Scn2b Deletion in Mice Results in Ventricular and Atrial Arrhythmias.","date":"2016","source":"Circulation. Arrhythmia and electrophysiology","url":"https://pubmed.ncbi.nlm.nih.gov/27932425","citation_count":41,"is_preprint":false},{"pmid":"21555511","id":"PMC_21555511","title":"Na+ channel Scn1b gene regulates dorsal root ganglion nociceptor excitability in vivo.","date":"2011","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/21555511","citation_count":41,"is_preprint":false},{"pmid":"17556197","id":"PMC_17556197","title":"Exclusion of multiple candidate genes and large genomic rearrangements in SCN5A in a Dutch Brugada syndrome cohort.","date":"2007","source":"Heart rhythm","url":"https://pubmed.ncbi.nlm.nih.gov/17556197","citation_count":40,"is_preprint":false},{"pmid":"30821013","id":"PMC_30821013","title":"Genetic interpretation and clinical translation of minor genes related to Brugada syndrome.","date":"2019","source":"Human mutation","url":"https://pubmed.ncbi.nlm.nih.gov/30821013","citation_count":36,"is_preprint":false},{"pmid":"23195492","id":"PMC_23195492","title":"Prevalence of SCN1A mutations in children with suspected Dravet syndrome and intractable childhood epilepsy.","date":"2012","source":"Epilepsy research","url":"https://pubmed.ncbi.nlm.nih.gov/23195492","citation_count":33,"is_preprint":false},{"pmid":"24662403","id":"PMC_24662403","title":"A missense mutation in the sodium channel β1b subunit reveals SCN1B as a susceptibility gene underlying long QT syndrome.","date":"2014","source":"Heart rhythm","url":"https://pubmed.ncbi.nlm.nih.gov/24662403","citation_count":32,"is_preprint":false},{"pmid":"32361481","id":"PMC_32361481","title":"Genetic variants of uncertain significance: How to match scientific rigour and standard of proof in sudden cardiac death?","date":"2020","source":"Legal medicine (Tokyo, Japan)","url":"https://pubmed.ncbi.nlm.nih.gov/32361481","citation_count":32,"is_preprint":false},{"pmid":"24529773","id":"PMC_24529773","title":"Is sudden unexplained nocturnal death syndrome in Southern China a cardiac sodium channel dysfunction disorder?","date":"2014","source":"Forensic science international","url":"https://pubmed.ncbi.nlm.nih.gov/24529773","citation_count":32,"is_preprint":false},{"pmid":"24337656","id":"PMC_24337656","title":"Case-control association study of polymorphisms in the voltage-gated sodium channel genes SCN1A, SCN2A, SCN3A, SCN1B, and SCN2B and epilepsy.","date":"2013","source":"Human genetics","url":"https://pubmed.ncbi.nlm.nih.gov/24337656","citation_count":31,"is_preprint":false},{"pmid":"26857751","id":"PMC_26857751","title":"Transcriptomic investigation of meat tenderness in two Italian cattle breeds.","date":"2016","source":"Animal genetics","url":"https://pubmed.ncbi.nlm.nih.gov/26857751","citation_count":29,"is_preprint":false},{"pmid":"21705762","id":"PMC_21705762","title":"Post-transcriptional silencing of SCN1B and SCN2B genes modulates late sodium current in cardiac myocytes from normal dogs and dogs with chronic heart failure.","date":"2011","source":"American journal of physiology. Heart and circulatory physiology","url":"https://pubmed.ncbi.nlm.nih.gov/21705762","citation_count":26,"is_preprint":false},{"pmid":"36029553","id":"PMC_36029553","title":"Modulating effects of FGF12 variants on NaV1.2 and NaV1.6 being associated with developmental and epileptic encephalopathy and Autism spectrum disorder: A case series.","date":"2022","source":"EBioMedicine","url":"https://pubmed.ncbi.nlm.nih.gov/36029553","citation_count":23,"is_preprint":false},{"pmid":"30821358","id":"PMC_30821358","title":"Significant association of rare variant p.Gly8Ser in cardiac sodium channel β4-subunit SCN4B with atrial fibrillation.","date":"2019","source":"Annals of human genetics","url":"https://pubmed.ncbi.nlm.nih.gov/30821358","citation_count":23,"is_preprint":false},{"pmid":"25757662","id":"PMC_25757662","title":"The role of the sodium current complex in a nonreferred nationwide cohort of sudden infant death syndrome.","date":"2015","source":"Heart rhythm","url":"https://pubmed.ncbi.nlm.nih.gov/25757662","citation_count":22,"is_preprint":false},{"pmid":"25575679","id":"PMC_25575679","title":"Sodium Channel Voltage-Gated Beta 2 Plays a Vital Role in Brain Aging Associated with Synaptic Plasticity and Expression of COX5A and FGF-2.","date":"2015","source":"Molecular neurobiology","url":"https://pubmed.ncbi.nlm.nih.gov/25575679","citation_count":21,"is_preprint":false},{"pmid":"29245901","id":"PMC_29245901","title":"Navβ2 knockdown improves cognition in APP/PS1 mice by partially inhibiting seizures and APP amyloid processing.","date":"2017","source":"Oncotarget","url":"https://pubmed.ncbi.nlm.nih.gov/29245901","citation_count":21,"is_preprint":false},{"pmid":"24892658","id":"PMC_24892658","title":"Identification of beta-2 as a key cell adhesion molecule in PCa cell neurotropic behavior: a novel ex vivo and biophysical approach.","date":"2014","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/24892658","citation_count":20,"is_preprint":false},{"pmid":"21458573","id":"PMC_21458573","title":"Increased expression of the beta3 subunit of voltage-gated Na+ channels in the spinal cord of the SOD1G93A mouse.","date":"2011","source":"Molecular and cellular neurosciences","url":"https://pubmed.ncbi.nlm.nih.gov/21458573","citation_count":20,"is_preprint":false},{"pmid":"32124967","id":"PMC_32124967","title":"MicroRNA‑449a regulates the progression of brain aging by targeting SCN2B in SAMP8 mice.","date":"2020","source":"International journal of molecular medicine","url":"https://pubmed.ncbi.nlm.nih.gov/32124967","citation_count":19,"is_preprint":false},{"pmid":"24368131","id":"PMC_24368131","title":"The effects of eslicarbazepine on persistent Na⁺ current and the role of the Na⁺ channel β subunits.","date":"2013","source":"Epilepsy research","url":"https://pubmed.ncbi.nlm.nih.gov/24368131","citation_count":19,"is_preprint":false},{"pmid":"31278961","id":"PMC_31278961","title":"MiR-34a is differentially expressed in dorsal root ganglia in a rat model of chronic neuropathic pain.","date":"2019","source":"Neuroscience letters","url":"https://pubmed.ncbi.nlm.nih.gov/31278961","citation_count":19,"is_preprint":false},{"pmid":"28597987","id":"PMC_28597987","title":"Trafficking and localisation to the plasma membrane of Nav 1.5 promoted by the β2 subunit is defective due to a β2 mutation associated with Brugada syndrome.","date":"2017","source":"Biology of the cell","url":"https://pubmed.ncbi.nlm.nih.gov/28597987","citation_count":18,"is_preprint":false},{"pmid":"31511323","id":"PMC_31511323","title":"N-Glycosylation of the voltage-gated sodium channel β2 subunit is required for efficient trafficking of NaV1.5/β2 to the plasma membrane.","date":"2019","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/31511323","citation_count":18,"is_preprint":false},{"pmid":"31715283","id":"PMC_31715283","title":"Identification of relevant hub genes for early intervention at gene coexpression modules with altered predicted expression in schizophrenia.","date":"2019","source":"Progress in neuro-psychopharmacology & biological psychiatry","url":"https://pubmed.ncbi.nlm.nih.gov/31715283","citation_count":17,"is_preprint":false},{"pmid":"16884893","id":"PMC_16884893","title":"Phenotypes and genotypes in epilepsy with febrile seizures plus.","date":"2006","source":"Epilepsy research","url":"https://pubmed.ncbi.nlm.nih.gov/16884893","citation_count":17,"is_preprint":false},{"pmid":"35872921","id":"PMC_35872921","title":"Comprehensive Analysis of circRNA-miRNA-mRNA Regulatory Network and Novel Potential Biomarkers in Acute Myocardial Infarction.","date":"2022","source":"Frontiers in cardiovascular medicine","url":"https://pubmed.ncbi.nlm.nih.gov/35872921","citation_count":16,"is_preprint":false},{"pmid":"10976944","id":"PMC_10976944","title":"The voltage-gated sodium channel beta2-subunit gene and idiopathic generalized epilepsy.","date":"2000","source":"Neuroreport","url":"https://pubmed.ncbi.nlm.nih.gov/10976944","citation_count":15,"is_preprint":false},{"pmid":"38001331","id":"PMC_38001331","title":"Biophysical properties of NaV1.5 channels from atrial-like and ventricular-like cardiomyocytes derived from human induced pluripotent stem cells.","date":"2023","source":"Scientific reports","url":"https://pubmed.ncbi.nlm.nih.gov/38001331","citation_count":14,"is_preprint":false},{"pmid":"31614896","id":"PMC_31614896","title":"Trafficking and Function of the Voltage-Gated Sodium Channel β2 Subunit.","date":"2019","source":"Biomolecules","url":"https://pubmed.ncbi.nlm.nih.gov/31614896","citation_count":14,"is_preprint":false},{"pmid":"30921204","id":"PMC_30921204","title":"SCN1B and SCN2B gene variants analysis in dravet syndrome patients: Analysis of 22 cases.","date":"2019","source":"Medicine","url":"https://pubmed.ncbi.nlm.nih.gov/30921204","citation_count":13,"is_preprint":false},{"pmid":"30018017","id":"PMC_30018017","title":"Intrathecal Injection of miR-133b-3p or miR-143-3p Prevents the Development of Persistent Cold and Mechanical Allodynia Following a Peripheral Nerve Injury in Rats.","date":"2018","source":"Neuroscience","url":"https://pubmed.ncbi.nlm.nih.gov/30018017","citation_count":11,"is_preprint":false},{"pmid":"38306602","id":"PMC_38306602","title":"Structural variants involving MLLT10 fusion are associated with adverse outcomes in pediatric acute myeloid leukemia.","date":"2024","source":"Blood advances","url":"https://pubmed.ncbi.nlm.nih.gov/38306602","citation_count":10,"is_preprint":false},{"pmid":"26852328","id":"PMC_26852328","title":"SCN2B in the Rat Trigeminal Ganglion and Trigeminal Sensory Nuclei.","date":"2016","source":"Cellular and molecular neurobiology","url":"https://pubmed.ncbi.nlm.nih.gov/26852328","citation_count":8,"is_preprint":false},{"pmid":"34329989","id":"PMC_34329989","title":"RNA-sequence reveals differentially expressed genes affecting the crested trait of Wumeng crested chicken.","date":"2021","source":"Poultry science","url":"https://pubmed.ncbi.nlm.nih.gov/34329989","citation_count":7,"is_preprint":false},{"pmid":"33602743","id":"PMC_33602743","title":"The voltage-gated sodium channel β2 subunit associates with lipid rafts by S-palmitoylation.","date":"2021","source":"Journal of cell science","url":"https://pubmed.ncbi.nlm.nih.gov/33602743","citation_count":7,"is_preprint":false},{"pmid":"36406589","id":"PMC_36406589","title":"Reduced Expression of Voltage-Gated Sodium Channel Beta 2 Restores Neuronal Injury and Improves Cognitive Dysfunction Induced by Aβ1-42.","date":"2022","source":"Neural plasticity","url":"https://pubmed.ncbi.nlm.nih.gov/36406589","citation_count":6,"is_preprint":false},{"pmid":"36362949","id":"PMC_36362949","title":"Two Novel Functional Mutations in Promoter Region of SCN3B Gene Associated with Atrial Fibrillation.","date":"2022","source":"Life (Basel, Switzerland)","url":"https://pubmed.ncbi.nlm.nih.gov/36362949","citation_count":6,"is_preprint":false},{"pmid":"38482382","id":"PMC_38482382","title":"Transcriptome-wide 1-methyladenosine functional profiling of messenger RNA and long non-coding RNA in bladder cancer.","date":"2024","source":"Frontiers in genetics","url":"https://pubmed.ncbi.nlm.nih.gov/38482382","citation_count":5,"is_preprint":false},{"pmid":"26149132","id":"PMC_26149132","title":"Functions of miR-9 and miR-9* during Aging in SAMP8 Mice and Their Possible Mechanisms.","date":"2015","source":"Zhongguo yi xue ke xue yuan xue bao. Acta Academiae Medicinae Sinicae","url":"https://pubmed.ncbi.nlm.nih.gov/26149132","citation_count":5,"is_preprint":false},{"pmid":"37891420","id":"PMC_37891420","title":"Comprehensive analyses identify potential biomarkers for encephalitis in HIV infection.","date":"2023","source":"Scientific reports","url":"https://pubmed.ncbi.nlm.nih.gov/37891420","citation_count":5,"is_preprint":false},{"pmid":"28327445","id":"PMC_28327445","title":"Nine differentially expressed genes from a post mortem study and their association with suicidal status in a sample of suicide completers, attempters and controls.","date":"2017","source":"Journal of psychiatric research","url":"https://pubmed.ncbi.nlm.nih.gov/28327445","citation_count":5,"is_preprint":false},{"pmid":"38094680","id":"PMC_38094680","title":"Decreased FAM13B Expression Increases Atrial Fibrillation Susceptibility by Regulating Sodium Current and Calcium Handling.","date":"2023","source":"JACC. Basic to translational science","url":"https://pubmed.ncbi.nlm.nih.gov/38094680","citation_count":4,"is_preprint":false},{"pmid":"20137763","id":"PMC_20137763","title":"A novel microsatellite polymorphism of sodium channel beta1-subunit gene (SCN1B) may underlie abnormal cardiac excitation manifested by coved-type ST-elevation compatible with Brugada syndrome in Japanese.","date":"2010","source":"International journal of clinical pharmacology and therapeutics","url":"https://pubmed.ncbi.nlm.nih.gov/20137763","citation_count":4,"is_preprint":false},{"pmid":"9887383","id":"PMC_9887383","title":"Exclusion of the SCN2B gene as candidate for CMT4B.","date":"1998","source":"European journal of human genetics : EJHG","url":"https://pubmed.ncbi.nlm.nih.gov/9887383","citation_count":3,"is_preprint":false},{"pmid":"20730464","id":"PMC_20730464","title":"Mutational analysis of SCN2B, SCN3B and SCN4B in a large Chinese Han family with generalized tonic-clonic seizure.","date":"2010","source":"Neurological sciences : official journal of the Italian Neurological Society and of the Italian Society of Clinical Neurophysiology","url":"https://pubmed.ncbi.nlm.nih.gov/20730464","citation_count":3,"is_preprint":false},{"pmid":"37544648","id":"PMC_37544648","title":"Beta-subunit-eliminated eHAP expression (BeHAPe) cells reveal subunit regulation of the cardiac voltage-gated sodium channel.","date":"2023","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/37544648","citation_count":3,"is_preprint":false},{"pmid":"38236765","id":"PMC_38236765","title":"Comparative Gene Signature of Nociceptors Innervating Mouse Molar Teeth, Cranial Meninges, and Cornea.","date":"2024","source":"Anesthesia and analgesia","url":"https://pubmed.ncbi.nlm.nih.gov/38236765","citation_count":3,"is_preprint":false},{"pmid":"37336636","id":"PMC_37336636","title":"Multi-animal-model study reveals mutations in neural plasticity and nociception genes linked to excessive alcohol drinking.","date":"2023","source":"Alcohol, clinical & experimental research","url":"https://pubmed.ncbi.nlm.nih.gov/37336636","citation_count":3,"is_preprint":false},{"pmid":"36305047","id":"PMC_36305047","title":"Identification of potential lncRNA-miRNA-mRNA regulatory network contributing to aldosterone-producing adenoma.","date":"2022","source":"Journal of cellular and molecular medicine","url":"https://pubmed.ncbi.nlm.nih.gov/36305047","citation_count":3,"is_preprint":false},{"pmid":"38136997","id":"PMC_38136997","title":"A Contemporary Review of the Genomic Associations of Coronary Artery Myocardial Bridging.","date":"2023","source":"Genes","url":"https://pubmed.ncbi.nlm.nih.gov/38136997","citation_count":3,"is_preprint":false},{"pmid":"27896052","id":"PMC_27896052","title":"Mutation analysis of the candidate genes SCN1B-4B, FHL1, and LMNA in patients with arrhythmogenic right ventricular cardiomyopathy.","date":"2012","source":"Applied & translational genomics","url":"https://pubmed.ncbi.nlm.nih.gov/27896052","citation_count":2,"is_preprint":false},{"pmid":"38866121","id":"PMC_38866121","title":"MicroRNA-6954-3p Downregulation Contributes to Orofacial Neuropathic Pain in Mice Via Targeting Voltage-Gated Sodium Channel β2 Subunit Protein.","date":"2024","source":"The journal of pain","url":"https://pubmed.ncbi.nlm.nih.gov/38866121","citation_count":1,"is_preprint":false},{"pmid":"39343005","id":"PMC_39343005","title":"Role of protein domains in trafficking and localization of the voltage-gated sodium channel β2 subunit.","date":"2024","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/39343005","citation_count":1,"is_preprint":false},{"pmid":"34476357","id":"PMC_34476357","title":"Biophysical Investigation of Sodium Channel Interaction with β-Subunit Variants Associated with Arrhythmias.","date":"2020","source":"Bioelectricity","url":"https://pubmed.ncbi.nlm.nih.gov/34476357","citation_count":1,"is_preprint":false},{"pmid":"29453527","id":"PMC_29453527","title":"Effects of 4,9-anhydrotetrodotoxin on voltage-gated Na+ channels of mouse vas deferens myocytes and recombinant NaV1.6 channels.","date":"2018","source":"Naunyn-Schmiedeberg's archives of pharmacology","url":"https://pubmed.ncbi.nlm.nih.gov/29453527","citation_count":1,"is_preprint":false},{"pmid":"33953878","id":"PMC_33953878","title":"Computational study of zebrafish immune-targeted microarray data for prediction of preventive drug candidates.","date":"2021","source":"Veterinary research forum : an international quarterly journal","url":"https://pubmed.ncbi.nlm.nih.gov/33953878","citation_count":1,"is_preprint":false},{"pmid":"40223983","id":"PMC_40223983","title":"Relationship between the expression of striated preferentially expressed gene (SPEG) and the development of atrial fibrillation.","date":"2025","source":"Journal of thoracic disease","url":"https://pubmed.ncbi.nlm.nih.gov/40223983","citation_count":0,"is_preprint":false},{"pmid":"41271115","id":"PMC_41271115","title":"From genes to lifestyle: A multi-dimensional framework for Alzheimer's disease prevention and therapy.","date":"2025","source":"Ageing research reviews","url":"https://pubmed.ncbi.nlm.nih.gov/41271115","citation_count":0,"is_preprint":false},{"pmid":"41471362","id":"PMC_41471362","title":"PIK3R1 as the Hidden Hand in Arrhythmogenic Right Ventricular Cardiomyopathy Inflammation: Weaving Transcriptomic Signatures with Structural Therapeutic Insights.","date":"2025","source":"Pharmaceuticals (Basel, Switzerland)","url":"https://pubmed.ncbi.nlm.nih.gov/41471362","citation_count":0,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":40886,"output_tokens":4583,"usd":0.095701},"stage2":{"model":"claude-opus-4-6","input_tokens":8222,"output_tokens":3498,"usd":0.19284},"total_usd":0.288541,"stage1_batch_id":"msgbatch_011rkcQdVV1RaFq9XhcG6df6","stage2_batch_id":"msgbatch_01RzgrJafdF4EWHhj5mNi6dh","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2009,\n      \"finding\": \"SCN2B mutations R28Q and R28W reduce SCN5A-mediated sodium current and alter channel gating when co-expressed in heterologous cells, identifying SCN2B as a loss-of-function atrial fibrillation susceptibility gene.\",\n      \"method\": \"Heterologous expression in CHO cells with patch-clamp electrophysiology\",\n      \"journal\": \"Circulation. Arrhythmia and electrophysiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — direct electrophysiology in heterologous system, single lab\",\n      \"pmids\": [\"19808477\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"β2 subunit (Scn2b) increases persistent Na+ current (INaP) in HEK cells expressing Nav1.1, and this effect is counteracted by β1 subunit co-expression; in Scn1b/Scn2b null neurons, entry into inactivated states is slowed, indicating β1 and β2 have antagonistic roles in regulating Na+ channel inactivation.\",\n      \"method\": \"Whole-cell patch-clamp in HEK cells and cultured hippocampal neurons from Scn1b and Scn1b/Scn2b null mice\",\n      \"journal\": \"The Journal of neuroscience\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple cell types, knockout mice, replicated with chimeric subunit analysis\",\n      \"pmids\": [\"19228957\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"The disulfide bond between the Na+ channel α subunit and β2 subunit is mediated by a single extracellular cysteine residue (Cys-26) within the immunoglobulin domain of β2; mutation of Cys-26 to alanine abolishes α-β2 covalent linkage and disrupts β2 targeting to nodes of Ranvier and the axon initial segment in neurons, and disrupts β2 association with the neuronal cytoskeleton.\",\n      \"method\": \"Site-directed mutagenesis, myelinating co-culture system, primary hippocampal neuron imaging, detergent extraction assay\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — mutagenesis with multiple orthogonal functional readouts including localization and cytoskeletal association\",\n      \"pmids\": [\"22992729\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"A missense mutation in β2 (D211G, encoded by SCN2B) reduces Nav1.5 sodium current density by approximately 39% without affecting unitary channel conductance; protein membrane detection experiments suggest β2-D211G decreases Nav1.5 cell surface expression, establishing SCN2B as a Brugada syndrome candidate gene.\",\n      \"method\": \"Heterologous co-expression with patch-clamp electrophysiology (whole-cell and single-channel), cell surface biotinylation\",\n      \"journal\": \"Human mutation\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — multiple electrophysiology methods plus surface expression assay, single lab\",\n      \"pmids\": [\"23559163\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"Scn2b null mice have reduced Na+ channel cell surface expression in neurons, compromised action potential conduction, and are neuroprotected in experimental autoimmune encephalomyelitis (EAE), consistent with β2 functioning to chaperone Na+ channel α subunits to the plasma membrane.\",\n      \"method\": \"Scn2b knockout mouse model; EAE induction; assessment of axonal degeneration, immune infiltration, symptom severity\",\n      \"journal\": \"Molecular and cellular neurosciences\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — clean KO with specific phenotypic readouts, immune function controls, consistent with parallel neuronal data\",\n      \"pmids\": [\"19013247\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"β2 subunit (Scn2b) modulates the pharmacological properties of Na+ channels: in Scn2b null CA1 neurons, carbamazepine effects on persistent Na+ current (INaP) are altered, demonstrating that β2 subunits modify not only biophysical but also pharmacological properties of the Na+ channel complex.\",\n      \"method\": \"Whole-cell patch-clamp on hippocampal CA1 neurons from Scn2b null mice; current-clamp and computational modeling\",\n      \"journal\": \"The Journal of neuroscience\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — knockout mouse model with electrophysiology and computational validation\",\n      \"pmids\": [\"20573896\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"Scn2b null mice exhibit reduced sodium and potassium current densities in ventricular myocytes, conduction slowing in the right ventricular outflow tract, spontaneous polymorphic ventricular tachycardia via functional reentry, and increased susceptibility to atrial fibrillation with increased fibrosis; Nav1.5 protein levels are unchanged, consistent with β2 chaperoning Na+ channel α subunits to the plasma membrane in the heart.\",\n      \"method\": \"Scn2b knockout mouse model; patch-clamp electrophysiology; in vivo cardiac electrophysiology; western blotting; histology\",\n      \"journal\": \"Circulation. Arrhythmia and electrophysiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — clean KO with multiple orthogonal cardiac and molecular phenotypic readouts\",\n      \"pmids\": [\"27932425\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"In nociceptive dorsal root ganglion neurons, Scn2b selectively regulates TTX-sensitive α subunit mRNA and protein expression, ultimately resulting in changes in pain sensitivity, as demonstrated in Scn2b null mice.\",\n      \"method\": \"Scn2b knockout mouse DRG neurons; patch-clamp electrophysiology; behavioral pain assays referenced in context\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — knockout mice with electrophysiology, single lab; DRG-specific finding\",\n      \"pmids\": [\"21555511\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"Post-transcriptional silencing of SCN2B by siRNA in ventricular cardiomyocytes increases late Na+ current (INaL) density and slows its decay, an effect opposite to that of SCN1B silencing, demonstrating that β2 and β1 subunits exert opposing modulation of INaL without changing Nav1.5 (INaT) in both normal and failing dog hearts.\",\n      \"method\": \"Virally delivered siRNA knockdown in isolated canine cardiomyocytes; whole-cell and perforated patch-clamp; RT-PCR; western blot\",\n      \"journal\": \"American journal of physiology. Heart and circulatory physiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — siRNA KD with multiple methods (electrophysiology, mRNA, protein), normal and HF conditions tested\",\n      \"pmids\": [\"21705762\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"β2 subunit promotes Nav1.5 localization to the cell surface in both MDCK and HL-1 cells; the BrS-associated β2 mutation D211G reaches the plasma membrane normally but is defective in promoting Nav1.5 surface localization, indicating the mutation specifically disrupts β2's trafficking function for the α subunit.\",\n      \"method\": \"Polarized MDCK and HL-1 cell expression; confocal immunofluorescence; surface biotinylation\",\n      \"journal\": \"Biology of the cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple cell lines, WT vs. mutant comparison, two orthogonal localization methods\",\n      \"pmids\": [\"28597987\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"β2 subunit (SCN2B) is N-glycosylated at residues Asn-42, Asn-66, and Asn-74, with sialylation only at Asn-42; fully nonglycosylated β2 is retained in the ER and is defective in promoting Nav1.5 surface localization, demonstrating that N-linked glycosylation is required for efficient β2 trafficking to the plasma membrane and for β2-mediated surface delivery of Nav1.5.\",\n      \"method\": \"Site-directed mutagenesis of N-glycosylation sites; heterologous expression in MDCK cells; biochemical glycosylation assays; FRAP; surface biotinylation\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — mutagenesis with multiple biochemical and imaging readouts in polarized cell system\",\n      \"pmids\": [\"31511323\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"β2 subunit (SCN2B) is S-palmitoylated at Cys-182; palmitoylation increases β2 association with detergent-resistant membranes (lipid rafts) and influences its polarized apical localization; cholesterol depletion causes β2 mislocalization to the basolateral domain; palmitoylation is not required for promoting Nav1.5 surface localization but is linked to lipid raft association.\",\n      \"method\": \"Acyl-biotin exchange assay; cholesterol depletion; FRAP; lipid raft fractionation; confocal imaging in polarized MDCK cells\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — direct biochemical detection of PTM plus multiple functional consequences tested\",\n      \"pmids\": [\"33602743\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"β2 subunit (SCN2B) forms homodimers and requires its cytoplasmic tail, extracellular loop, and transmembrane domain for proper folding and export to the cell surface; deletion of any domain causes ER retention and impaired complex N-glycosylation; NaV1.5 does not influence β2 trafficking or surface localization.\",\n      \"method\": \"Domain deletion mutagenesis; heterologous expression in MDCK cells; co-immunoprecipitation; glycosylation assays; confocal imaging\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — systematic mutagenesis with biochemical and imaging validation\",\n      \"pmids\": [\"39343005\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"Crystal structure of the SCN2B-encoded β2 subunit (R137H variant) reveals structural changes at the mutation site without overall protein destabilization; electrophysiology shows R137H does not alter NaV1.5 activity, suggesting this variant may act through other NaV channel subtypes present in cardiac tissue.\",\n      \"method\": \"X-ray crystallography; patch-clamp electrophysiology on NaV1.5\",\n      \"journal\": \"Bioelectricity\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 — crystal structure obtained, but functional conclusion is negative (no effect on NaV1.5), single lab\",\n      \"pmids\": [\"34476357\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"In a β-subunit-null human cell line (BeHAPe), each β subunit including β2 (SCN2B) imparts unique gating properties to NaV1.5; co-expression of β1 and β2 together generates hybrid gating properties distinct from either subunit alone, revealing an expanded regulatory role of β2 on NaV1.5 activity.\",\n      \"method\": \"CRISPR-engineered β-subunit-null haploid human cells (BeHAPe); heterologous expression; whole-cell patch-clamp\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — rigorous null cell background eliminates endogenous subunit confounds; multiple subunit combinations tested\",\n      \"pmids\": [\"37544648\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"Navβ2 knockdown in APP/PS1 Alzheimer's disease model mice partially reverses abnormal Navβ2 cleavage by BACE1, restores sodium current density in hippocampal neurons, shifts APP metabolism toward non-amyloidogenic processing, and improves cognitive performance, establishing SCN2B as a BACE1 substrate that influences APP processing.\",\n      \"method\": \"Transgenic Navβ2 knockdown in APP/PS1 mice; patch-clamp; EEG; Morris water maze; western blot\",\n      \"journal\": \"Oncotarget\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — in vivo knockdown with multiple readouts, single lab\",\n      \"pmids\": [\"29245901\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"β2 subunit (encoded by SCN2B) functions as a cell adhesion molecule in prostate cancer cells, interacting with laminin; overexpression of β2 enhances PCa cell migration, invasion, and binding affinity to laminin as measured by atomic force microscopy, and enhances association with nerve axons in an ex vivo spinal cord co-culture model.\",\n      \"method\": \"β2 overexpression in LNCaP cells; ex vivo organotypic spinal cord co-culture; atomic force microscopy; migration/invasion assays\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 — multiple functional assays in cell model, single lab, no endogenous control KD\",\n      \"pmids\": [\"24892658\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"miR-449a directly targets the 3'-UTR of SCN2B mRNA (confirmed by dual-luciferase reporter assay and anti-Ago co-immunoprecipitation/microarray) and regulates SCN2B expression; inhibition of SCN2B or overexpression of miR-449a promotes hippocampal neuron extension, placing miR-449a upstream of SCN2B in a brain aging regulatory axis.\",\n      \"method\": \"Dual-luciferase reporter assay; anti-Ago co-immunoprecipitation with Affymetrix microarray; miR-449a overexpression in neurons; miRNA microarray in SAMP8 mice\",\n      \"journal\": \"International journal of molecular medicine\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — biochemical validation of miRNA-target interaction with multiple methods, single lab\",\n      \"pmids\": [\"32124967\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"miR-6954-3p directly binds the 3'-UTR of Scn2b mRNA (confirmed by luciferase assay); miR-6954-3p is downregulated in the trigeminal ganglion after chronic constriction injury of the infraorbital nerve, leading to upregulation of SCN2B protein; SCN2B silencing in TG reduces orofacial pain hypersensitivity, identifying SCN2B as a downstream effector of miR-6954-3p in neuropathic pain.\",\n      \"method\": \"CCI-ION mouse model; luciferase assay; siRNA knockdown; FISH; immunofluorescence; von Frey testing\",\n      \"journal\": \"The journal of pain\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — validated miRNA-target interaction plus in vivo KD with behavioral outcome, single lab\",\n      \"pmids\": [\"38866121\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"SCN2B encodes the voltage-gated sodium channel β2 subunit, which covalently associates with α subunits via a single extracellular disulfide bond (Cys-26), chaperoning Na+ channel α subunits (Nav1.5, Nav1.1, and others) to the plasma membrane; β2 undergoes N-glycosylation (required for ER export) and S-palmitoylation (mediating lipid raft association and polarized localization), promotes Nav1.5 surface expression through a trafficking function disrupted by arrhythmia-linked mutations (e.g., D211G), opposes β1-mediated inactivation by increasing persistent Na+ current, modulates both biophysical and pharmacological properties of Na+ channels, and also functions as a cell adhesion molecule of the immunoglobulin superfamily; loss of β2 in vivo reduces Na+ channel surface expression in neurons and cardiomyocytes, causing ventricular and atrial arrhythmias, altered pain sensitivity, and neuroprotection in demyelinating disease.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"SCN2B encodes the voltage-gated sodium channel β2 subunit, an immunoglobulin-superfamily transmembrane glycoprotein that covalently associates with pore-forming α subunits via an extracellular disulfide bond at Cys-26 and functions as a chaperone, gating modulator, and cell adhesion molecule. β2 promotes surface delivery of Nav1.5 and neuronal Nav α subunits through a trafficking mechanism that requires N-glycosylation for ER export, involves homodimerization and integrity of all three protein domains, and is disrupted by arrhythmia-associated mutations such as D211G [PMID:31511323, PMID:39343005, PMID:28597987]. β2 opposes β1-mediated inactivation by increasing persistent sodium current, and co-expression of β1 and β2 produces hybrid gating distinct from either subunit alone, while also modifying pharmacological sensitivity of the channel complex [PMID:19228957, PMID:37544648, PMID:20573896]. Loss of β2 in vivo reduces neuronal and cardiac sodium channel surface expression, causing ventricular arrhythmias, atrial fibrillation susceptibility, altered pain sensitivity, and neuroprotection in demyelinating disease [PMID:27932425, PMID:19013247, PMID:21555511].\",\n  \"teleology\": [\n    {\n      \"year\": 2008,\n      \"claim\": \"The in vivo requirement for β2 was established: Scn2b-null mice showed reduced neuronal Na+ channel surface expression, impaired conduction, and unexpected neuroprotection in EAE, demonstrating that β2 functions as an essential chaperone for α subunit plasma membrane delivery in the nervous system.\",\n      \"evidence\": \"Scn2b knockout mouse with EAE induction, axonal degeneration assessment, and electrophysiology\",\n      \"pmids\": [\"19013247\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism by which reduced surface Na+ channels confer neuroprotection was not resolved\", \"Cardiac phenotype of the knockout was not yet examined\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Two complementary studies defined β2's biophysical role and disease relevance: β2 increases persistent Na+ current (INaP) in opposition to β1-mediated inactivation, and SCN2B mutations (R28Q, R28W) that reduce sodium current density were linked to atrial fibrillation susceptibility.\",\n      \"evidence\": \"Patch-clamp in HEK cells and hippocampal neurons from Scn1b/Scn2b null mice; heterologous expression of mutant β2 with Nav1.5 in CHO cells\",\n      \"pmids\": [\"19228957\", \"19808477\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether AF-linked mutations disrupt trafficking versus gating was unresolved\", \"Antagonistic β1/β2 interplay was not yet tested in cardiac cells\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"β2 was shown to modulate not only biophysical but also pharmacological properties of Na+ channels, as carbamazepine effects on INaP were altered in Scn2b-null hippocampal neurons, expanding the functional scope of β2 beyond gating.\",\n      \"evidence\": \"Whole-cell patch-clamp on CA1 neurons from Scn2b-null mice with computational modeling\",\n      \"pmids\": [\"20573896\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether β2 alters drug binding directly or indirectly through channel conformation was not distinguished\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"β2's opposing role to β1 was confirmed in cardiac myocytes, and its regulation of neuronal α subunit expression in nociceptors was identified: SCN2B knockdown in ventricular cardiomyocytes increased late Na+ current, while Scn2b-null DRG neurons showed selective changes in TTX-sensitive α subunit expression affecting pain sensitivity.\",\n      \"evidence\": \"siRNA knockdown in canine cardiomyocytes with patch-clamp; Scn2b-null mouse DRG neuron electrophysiology and behavioral assays\",\n      \"pmids\": [\"21705762\", \"21555511\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism by which β2 regulates α subunit mRNA levels in DRG was not identified\", \"Whether β1/β2 opposition in late current applies to all cardiac α subunit isoforms was untested\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"The molecular basis of α–β2 covalent association was pinpointed: Cys-26 in the Ig domain forms the single disulfide bond to α subunits, and this linkage is required for β2 targeting to nodes of Ranvier, the axon initial segment, and cytoskeletal association.\",\n      \"evidence\": \"Site-directed mutagenesis of Cys-26; myelinating co-cultures; primary hippocampal neuron imaging; detergent extraction\",\n      \"pmids\": [\"22992729\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Identity of the partnering cysteine on the α subunit was not mapped\", \"Whether non-covalent β2–α interactions persist in Cys-26 mutants was not fully resolved\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"The Brugada syndrome-associated β2 mutation D211G was shown to reduce Nav1.5 surface expression without affecting unitary conductance, establishing that disease-linked β2 variants can specifically disrupt the trafficking function for α subunits.\",\n      \"evidence\": \"Heterologous co-expression; whole-cell and single-channel patch-clamp; surface biotinylation\",\n      \"pmids\": [\"23559163\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether D211G disrupts β2 folding, dimerization, or α subunit interaction was unknown\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"The cardiac phenotype of Scn2b loss was comprehensively characterized: null mice exhibited reduced Na+ and K+ current densities, right ventricular conduction slowing, spontaneous polymorphic VT, and atrial fibrillation with fibrosis, with unchanged total Nav1.5 protein—confirming β2's cardiac trafficking role in vivo.\",\n      \"evidence\": \"Scn2b knockout mouse; patch-clamp; in vivo cardiac electrophysiology; western blot; histology\",\n      \"pmids\": [\"27932425\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism of K+ current reduction in β2-null cardiomyocytes was unexplained\", \"Basis of atrial fibrosis was not resolved\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Two studies expanded β2 biology: β2 D211G was shown to reach the plasma membrane itself but fail to promote Nav1.5 surface delivery, dissociating β2 self-trafficking from its α-chaperoning function; separately, β2 was identified as a BACE1 substrate whose cleavage in AD models alters APP processing and cognition.\",\n      \"evidence\": \"Polarized MDCK/HL-1 cells with confocal imaging and surface biotinylation; Nav β2 knockdown in APP/PS1 mice with electrophysiology, EEG, and behavioral testing\",\n      \"pmids\": [\"28597987\", \"29245901\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"D211G structural defect was not identified at atomic resolution\", \"BACE1 cleavage site on β2 was not mapped\", \"AD-related findings from a single lab\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"N-glycosylation at Asn-42, Asn-66, and Asn-74 was mapped, with sialylation restricted to Asn-42; complete loss of glycosylation caused ER retention of β2 and failure to promote Nav1.5 surface delivery, establishing glycosylation as a prerequisite for β2 trafficking competence.\",\n      \"evidence\": \"N-glycosylation site mutagenesis; biochemical glycosylation assays; FRAP; surface biotinylation in polarized MDCK cells\",\n      \"pmids\": [\"31511323\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Contribution of individual glycosylation sites to trafficking efficiency was not fully resolved\", \"Whether glycosylation affects β2 interaction with specific α subunits was untested\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"A crystal structure of β2 (R137H variant) was obtained, revealing local structural changes at the mutation site without global destabilization; R137H had no effect on Nav1.5, suggesting it may act through other α subunit subtypes.\",\n      \"evidence\": \"X-ray crystallography; patch-clamp electrophysiology on Nav1.5\",\n      \"pmids\": [\"34476357\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Wild-type β2 structure was not determined for comparison\", \"Effect of R137H on non-Nav1.5 α subunits was not tested\", \"Structure was of a disease variant, not wild-type\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"S-palmitoylation at Cys-182 was identified as a post-translational modification that directs β2 to lipid rafts and controls its polarized localization, independent of its α-chaperoning function.\",\n      \"evidence\": \"Acyl-biotin exchange; cholesterol depletion; lipid raft fractionation; FRAP; confocal imaging in polarized MDCK cells\",\n      \"pmids\": [\"33602743\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Palmitoylating enzyme(s) for β2 were not identified\", \"Whether palmitoylation affects β2 function in cardiomyocytes or neurons was not tested in vivo\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Using a CRISPR-engineered β-subunit-null human cell line, each β subunit was shown to confer unique gating properties to Nav1.5, and co-expression of β1+β2 produced hybrid gating distinct from either alone—providing a clean demonstration of combinatorial β subunit regulation.\",\n      \"evidence\": \"β-subunit-null haploid human cells (BeHAPe); heterologous expression; whole-cell patch-clamp\",\n      \"pmids\": [\"37544648\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether hybrid gating occurs in native cardiomyocytes was not verified\", \"Stoichiometry of β1/β2 in the native complex was not determined\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"β2 was shown to form homodimers, and systematic domain deletion revealed that the cytoplasmic tail, extracellular Ig loop, and transmembrane domain are each required for proper folding and ER export, while Nav1.5 does not influence β2 trafficking—establishing that β2 traffics autonomously.\",\n      \"evidence\": \"Domain deletion mutagenesis; co-immunoprecipitation; glycosylation assays; confocal imaging in MDCK cells\",\n      \"pmids\": [\"39343005\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Homodimer interface residues were not mapped at atomic resolution\", \"Functional significance of homodimerization for α subunit chaperoning was not determined\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"Key unresolved questions include: the structural basis of β2-mediated α subunit trafficking (no co-structure with an α subunit exists), the identity of palmitoylating enzymes, the physiological significance of β2 homodimerization, the mechanism by which β2 loss leads to cardiac fibrosis, and whether BACE1 cleavage of β2 is pathophysiologically relevant in human Alzheimer's disease.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"No α–β2 co-crystal or cryo-EM structure\", \"Palmitoyl acyltransferase identity unknown\", \"In vivo significance of β2 homodimerization untested\", \"BACE1–β2 axis in human AD not validated\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [1, 5, 8, 14]},\n      {\"term_id\": \"GO:0098631\", \"supporting_discovery_ids\": [2, 16]},\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [3, 9, 10]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [2, 3, 9, 10, 11, 12]},\n      {\"term_id\": \"GO:0005783\", \"supporting_discovery_ids\": [10, 12]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-112316\", \"supporting_discovery_ids\": [1, 4, 5, 7]},\n      {\"term_id\": \"R-HSA-9609507\", \"supporting_discovery_ids\": [3, 9, 10, 12]},\n      {\"term_id\": \"R-HSA-382551\", \"supporting_discovery_ids\": [1, 6, 8, 14]}\n    ],\n    \"complexes\": [\n      \"voltage-gated sodium channel complex\"\n    ],\n    \"partners\": [\n      \"SCN5A\",\n      \"SCN1A\",\n      \"SCN1B\",\n      \"BACE1\"\n    ],\n    \"other_free_text\": []\n  }\n}\n```"}