SCN1A encodes the pore-forming Ξ±-subunit of Nav1.1, the most clinically important voltage-gated sodium channel in epilepsy genetics. As a 24-transmembrane domain protein, SCN1A directly mediates the depolarizing phase of action potentials through voltage-dependent conformational switching that allows selective Na+ influx along electrochemical gradients. Nav1.1 is particularly critical in GABAergic interneurons where it regulates inhibitory neuron excitability - loss-of-function mutations impair interneuron function leading to network hyperexcitability and seizures. SCN1A mutations cause >80% of Dravet syndrome cases and represent the most frequent target of epilepsy-related mutations, causing a phenotypic spectrum from febrile seizures (GEFS+) to severe developmental epileptic encephalopathy. The protein localizes to specialized membrane domains including axon initial segments, nodes of Ranvier, and neuronal cell bodies where it enables action potential initiation, propagation, and presynaptic membrane potential regulation. Understanding SCN1A pathophysiology has revealed that sodium channel blockers are contraindicated in SCN1A-related epilepsies as they worsen seizures by further impairing already compromised interneuron excitability.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0001518 voltage-gated sodium channel complex | IBA GO_REF:0000033 | ACCEPT | Summary: This annotation correctly identifies SCN1A as part of the voltage-gated sodium channel complex. As the pore-forming Ξ±-subunit, SCN1A associates with auxiliary Ξ²-subunits (SCN1B, SCN2B, SCN3B, SCN4B) to form the functional Nav1.1 complex. IBA evidence from phylogenetic analysis provides strong support for this cellular component annotation. |
| GO:0005248 voltage-gated sodium channel activity | IBA GO_REF:0000033 | ACCEPT | Summary: This is the core molecular function of SCN1A. The protein directly mediates voltage-gated sodium channel activity through conformational changes that allow selective Na+ passage. This annotation captures the essential enzymatic function supported by UniProt catalytic activity data (Na+(in) = Na+(out)) and extensive experimental evidence. Supporting Evidence: file:human/SCN1A/SCN1A-deep-research-falcon.md Nav1.1 is a **voltage-gated Na+ channel** that opens with membrane depolarization to carry inward sodium current needed for action potential initiation/propagation. |
| GO:0035725 sodium ion transmembrane transport | IBA GO_REF:0000033 | ACCEPT | Summary: This accurately describes the biological process mediated by SCN1A. The protein enables sodium ion transport across neuronal membranes, which is fundamental for action potential generation and propagation. IBA evidence from phylogenetic analysis strongly supports this core function. |
| GO:0086002 cardiac muscle cell action potential involved in contraction | IBA GO_REF:0000033 | KEEP AS NON CORE | Summary: While Nav1.1 sodium channels may be expressed in cardiac tissue, SCN1A is predominantly and specifically important in neuronal tissues, particularly GABAergic interneurons. Cardiac action potentials are primarily mediated by SCN5A (Nav1.5). This annotation represents over-annotation for SCN1A, which should be marked as peripheral to its core neuronal function. |
| GO:0099505 regulation of presynaptic membrane potential | IEA GO_REF:0000108 | KEEP AS NON CORE | Summary: This annotation is consistent with SCN1A role in presynaptic terminals where voltage-gated sodium channels regulate membrane potential and neurotransmitter release. However, IEA evidence alone is relatively weak, and this represents a more specific function than the core sodium channel activity. |
| GO:0001518 voltage-gated sodium channel complex | IEA GO_REF:0000002 | ACCEPT | Summary: Duplicate of earlier IBA annotation for the same GO term. This IEA annotation provides additional computational support for SCN1A being part of voltage-gated sodium channel complex, consistent with its role as the pore-forming Ξ±-subunit. |
| GO:0005216 monoatomic ion channel activity | IEA GO_REF:0000002 | ACCEPT | Summary: This is a broader molecular function term that encompasses sodium channel activity. While accurate, it is less informative than the specific voltage-gated sodium channel activity annotation. This represents a valid but general annotation. |
| GO:0005248 voltage-gated sodium channel activity | IEA GO_REF:0000120 | ACCEPT | Summary: Another annotation for the core molecular function of SCN1A with IEA evidence. This duplicates the IBA annotation but provides additional computational support for the essential voltage-gated sodium channel activity. |
| GO:0005261 monoatomic cation channel activity | IEA GO_REF:0000002 | ACCEPT | Summary: This is a broader molecular function term that encompasses sodium channel activity. Sodium channels are indeed monoatomic cation channels, but this annotation is less specific than voltage-gated sodium channel activity. Still accurate but general. |
| GO:0005886 plasma membrane | IEA GO_REF:0000120 | ACCEPT | Summary: Correct cellular component annotation. SCN1A is a multi-pass membrane protein embedded in the plasma membrane where it functions as a voltage-gated sodium channel. UniProt confirms this subcellular localization. |
| GO:0006811 monoatomic ion transport | IEA GO_REF:0000120 | ACCEPT | Summary: This is a broad biological process term that encompasses sodium ion transport. While accurate (sodium is a monoatomic ion), it is less informative than the more specific sodium ion transmembrane transport annotation. |
| GO:0006814 sodium ion transport | IEA GO_REF:0000120 | ACCEPT | Summary: This accurately describes a core biological process mediated by SCN1A. The protein enables sodium ion transport, which is fundamental for neuronal excitability and action potential propagation. This is a key function supported by extensive evidence. |
| GO:0016020 membrane | IEA GO_REF:0000120 | MARK AS OVER ANNOTATED | Summary: This is a very general cellular component term. While SCN1A is indeed a membrane protein, this annotation provides minimal informative value compared to the more specific plasma membrane annotation. |
| GO:0055085 transmembrane transport | IEA GO_REF:0000002 | MARK AS OVER ANNOTATED | Summary: This is a broad biological process term that encompasses the specific sodium ion transmembrane transport function. While accurate, it provides less informative value than more specific transport annotations. |
| GO:0001508 action potential | IEA GO_REF:0000117 | ACCEPT | Summary: This annotation correctly identifies SCN1A role in action potentials. As the pore-forming subunit of Nav1.1, SCN1A directly mediates the depolarizing phase of action potentials by allowing Na+ influx. This is a core biological process supported by UniProt functional data. |
| GO:0005272 sodium channel activity | IEA GO_REF:0000043 | ACCEPT | Summary: This annotation captures the core sodium channel activity of SCN1A. While slightly broader than voltage-gated sodium channel activity, it accurately describes the fundamental molecular function of the protein in enabling sodium ion passage through the membrane. |
| GO:0034220 monoatomic ion transmembrane transport | IEA GO_REF:0000043 | ACCEPT | Summary: This is a broader biological process term that encompasses sodium ion transmembrane transport. While accurate (sodium is a monoatomic ion), the more specific sodium ion transmembrane transport annotation is more informative for SCN1A function. |
| GO:0034702 monoatomic ion channel complex | IEA GO_REF:0000043 | ACCEPT | Summary: This is a broader cellular component term that encompasses voltage-gated sodium channel complex. SCN1A is indeed part of a monoatomic ion channel complex, but the more specific voltage-gated sodium channel complex annotation provides better functional specificity. |
| GO:0007628 adult walking behavior | IEA GO_REF:0000107 | MARK AS OVER ANNOTATED | Summary: This annotation is based on Ensembl orthology inference from mouse models. While SCN1A mutations can affect motor behavior through seizures and neurological impairment, adult walking behavior is a high-level phenotype not directly representative of the core molecular function. This is likely over-annotation. |
| GO:0008340 determination of adult lifespan | IEA GO_REF:0000107 | MARK AS OVER ANNOTATED | Summary: This annotation is based on Ensembl orthology inference from mouse models. While SCN1A mutations can be associated with sudden unexpected death in epilepsy (SUDEP), determination of adult lifespan is a high-level organismal phenotype not directly representative of the core sodium channel function. This represents over-annotation. |
| GO:0014704 intercalated disc | IEA GO_REF:0000107 | REMOVE | Summary: This is a cardiac-specific cellular component annotation based on Ensembl orthology inference. While sodium channels may be present in cardiac tissue, SCN1A (Nav1.1) is predominantly neuronal, whereas SCN5A (Nav1.5) is the primary cardiac sodium channel. This annotation is likely inappropriate for SCN1A. |
| GO:0019227 neuronal action potential propagation | IEA GO_REF:0000107 | ACCEPT | Summary: This annotation accurately captures a core biological process mediated by SCN1A. Nav1.1 channels are essential for neuronal action potential propagation, particularly in axon initial segments and nodes of Ranvier. This is well-supported by functional and localization data. |
| GO:0019228 neuronal action potential | IEA GO_REF:0000107 | ACCEPT | Summary: This annotation correctly identifies SCN1A role in neuronal action potentials. As the pore-forming subunit of Nav1.1, SCN1A directly mediates the depolarizing phase of neuronal action potentials. This is a core neuronal function well-supported by evidence. |
| GO:0021675 nerve development | IEA GO_REF:0000107 | KEEP AS NON CORE | Summary: This annotation is based on Ensembl orthology inference. While SCN1A may play roles during nervous system development, this is a developmental process annotation that is peripheral to the core adult function as a voltage-gated sodium channel. Evidence for direct developmental roles is limited. |
| GO:0030018 Z disc | IEA GO_REF:0000107 | REMOVE | Summary: This is a muscle-specific cellular component annotation based on Ensembl orthology inference. Z discs are structures in striated muscle. SCN1A (Nav1.1) is predominantly neuronal and this localization is not supported by evidence for the human protein. |
| GO:0030315 T-tubule | IEA GO_REF:0000107 | REMOVE | Summary: This is a muscle-specific cellular component annotation based on Ensembl orthology inference. T-tubules are structures in muscle cells for excitation-contraction coupling. SCN1A (Nav1.1) is predominantly neuronal and this localization is inappropriate. |
| GO:0030424 axon | IEA GO_REF:0000107 | ACCEPT | Summary: This annotation accurately reflects SCN1A localization. Nav1.1 channels are enriched in axons, particularly at axon initial segments and nodes of Ranvier where they are crucial for action potential initiation and propagation. This cellular component annotation is well-supported. |
| GO:0033268 node of Ranvier | IEA GO_REF:0000107 | ACCEPT | Summary: This annotation accurately reflects a key subcellular localization of SCN1A. Nav1.1 channels are highly concentrated at nodes of Ranvier where they mediate saltatory conduction and action potential propagation along myelinated axons. This is a well-established localization. |
| GO:0034706 sodium channel complex | IEA GO_REF:0000107 | ACCEPT | Summary: This annotation correctly identifies SCN1A as part of a sodium channel complex. As the pore-forming Ξ±-subunit, SCN1A associates with auxiliary Ξ²-subunits to form functional Nav1.1 sodium channel complexes. This cellular component annotation is accurate. |
| GO:0042391 regulation of membrane potential | IEA GO_REF:0000107 | ACCEPT | Summary: This annotation accurately captures a key biological process mediated by SCN1A. Voltage-gated sodium channels are fundamental regulators of membrane potential in excitable cells, controlling the depolarization phase of action potentials and overall neuronal excitability. |
| GO:0043025 neuronal cell body | IEA GO_REF:0000107 | ACCEPT | Summary: This annotation reflects SCN1A localization in neuronal cell bodies. While Nav1.1 channels are present in cell bodies, they are more highly concentrated and functionally important at axon initial segments and nodes of Ranvier. This represents a valid but less specific localization. |
| GO:0043194 axon initial segment | IEA GO_REF:0000107 | ACCEPT | Summary: This annotation accurately reflects a critical subcellular localization of SCN1A. Nav1.1 channels are highly concentrated at axon initial segments where they are essential for action potential initiation. This is one of the most functionally important localizations for SCN1A. |
| GO:0050884 neuromuscular process controlling posture | IEA GO_REF:0000107 | MARK AS OVER ANNOTATED | Summary: This annotation is based on Ensembl orthology inference from mouse models. While SCN1A mutations can indirectly affect posture through seizures and neurological impairment, this high-level behavioral annotation is not directly representative of the core sodium channel function. |
| GO:0050966 detection of mechanical stimulus involved in sensory perception of pain | IEA GO_REF:0000107 | KEEP AS NON CORE | Summary: This annotation has some support from UniProt which states that Nav1.1 contributes to sensory perception of mechanically-induced pain through controlling excitability of somatosensory neurons. However, this is a specialized function compared to the core neuronal excitability role. |
| GO:0051649 establishment of localization in cell | IEA GO_REF:0000107 | MARK AS OVER ANNOTATED | Summary: This is a very broad biological process annotation based on Ensembl orthology inference. While SCN1A protein must be localized to specific membrane compartments, this general localization process annotation provides minimal informative value about the core sodium channel function. |
| GO:0086010 membrane depolarization during action potential | IEA GO_REF:0000107 | ACCEPT | Summary: This annotation accurately describes the core biological process mediated by SCN1A. Nav1.1 channels directly mediate membrane depolarization during the rising phase of action potentials through selective sodium influx. This is a fundamental function supported by extensive evidence. |
| GO:0005654 nucleoplasm | IDA GO_REF:0000052 | REMOVE | Summary: This annotation is problematic. SCN1A encodes a multi-pass membrane protein that functions in the plasma membrane. Nuclear localization is inconsistent with its known function as a voltage-gated sodium channel. This IDA evidence may be from immunofluorescence artifacts or cross-reactivity. |
| GO:0005886 plasma membrane | IDA GO_REF:0000052 | ACCEPT | Summary: This annotation is correct and supported by direct experimental evidence (IDA). SCN1A is a multi-pass membrane protein embedded in the plasma membrane where it functions as a voltage-gated sodium channel. This is the primary functional localization. |
| GO:0016604 nuclear body | IDA GO_REF:0000052 | REMOVE | Summary: This annotation is inconsistent with SCN1A function. SCN1A encodes a voltage-gated sodium channel that functions in the plasma membrane, not in nuclear bodies. This IDA evidence may be from immunofluorescence artifacts or antibody cross-reactivity. |
| GO:0099508 voltage-gated monoatomic ion channel activity involved in regulation of presynaptic membrane potential | NAS PMID:22150645 Pure haploinsufficiency for Dravet syndrome Na(V)1.1 (SCN1A)... | ACCEPT | Summary: This annotation describes a specific molecular function of SCN1A at presynaptic terminals. The referenced study (PMID:22150645) demonstrates SCN1A role in regulating presynaptic membrane potential. While this is a specialized function, it is well-supported by experimental evidence and represents an important aspect of Nav1.1 function. Supporting Evidence: PMID:22150645 2011 Dec 9. Pure haploinsufficiency for Dravet syndrome Na(V)1.1 (SCN1A) sodium channel truncating mutations. |
| GO:0099508 voltage-gated monoatomic ion channel activity involved in regulation of presynaptic membrane potential | IDA PMID:22150645 Pure haploinsufficiency for Dravet syndrome Na(V)1.1 (SCN1A)... | ACCEPT | Summary: Duplicate annotation for the same GO term with stronger IDA evidence from PMID:22150645. This direct experimental evidence supports SCN1A role in regulating presynaptic membrane potential, which is important for neurotransmitter release and synaptic transmission. Supporting Evidence: PMID:22150645 2011 Dec 9. Pure haploinsufficiency for Dravet syndrome Na(V)1.1 (SCN1A) sodium channel truncating mutations. |
| GO:0099508 voltage-gated monoatomic ion channel activity involved in regulation of presynaptic membrane potential | IMP PMID:22150645 Pure haploinsufficiency for Dravet syndrome Na(V)1.1 (SCN1A)... | ACCEPT | Summary: Third annotation for the same GO term with IMP evidence from PMID:22150645. This mutant phenotype evidence further supports the role of SCN1A in presynaptic membrane potential regulation. The study examined SCN1A truncation mutants and their effects on channel function. Supporting Evidence: PMID:22150645 We studied the effect of two DS truncated Na(V)1.1 mutants, R222* and R1234*, on coexpressed wild-type Na(+) channels |
| GO:0005248 voltage-gated sodium channel activity | IMP PMID:14672992 Epilepsy-associated dysfunction in the voltage-gated neurona... | ACCEPT | Summary: This annotation for the core molecular function has strong IMP (mutant phenotype) evidence from PMID:14672992. This represents high-quality experimental support for the voltage-gated sodium channel activity, complementing the IBA evidence for the same function. Supporting Evidence: PMID:14672992 Mutations in SCN1A, the gene encoding the brain voltage-gated sodium channel alpha1 subunit (NaV1.1), are associated with at least two forms of epilepsy |
| GO:0005886 plasma membrane | IDA PMID:14672992 Epilepsy-associated dysfunction in the voltage-gated neurona... | ACCEPT | Summary: This annotation has strong IDA evidence from PMID:14672992 for plasma membrane localization. This complements other annotations for the same cellular component and provides experimental support for the primary functional localization of SCN1A. Supporting Evidence: PMID:14672992 Voltage-gated sodium channels are responsible for the generation and propagation of action potentials in excitable tissues |
| GO:0086010 membrane depolarization during action potential | ISS GO_REF:0000024 | ACCEPT | Summary: This annotation accurately describes the core biological process with ISS (sequence similarity) evidence. SCN1A mediates membrane depolarization during action potentials through selective sodium influx. This is a fundamental function well-conserved across species. |
| GO:0086010 membrane depolarization during action potential | IMP PMID:14672992 Epilepsy-associated dysfunction in the voltage-gated neurona... | ACCEPT | Summary: Duplicate annotation for the same core biological process with strong IMP evidence from PMID:14672992. This mutant phenotype evidence provides experimental support for SCN1A role in membrane depolarization during action potentials. Supporting Evidence: PMID:14672992 We examined the functional properties of four GEFS+ alleles and one SMEI allele using whole-cell patch-clamp analysis of heterologously expressed recombinant human SCN1A |
| GO:0086002 cardiac muscle cell action potential involved in contraction | IMP PMID:27207958 Variants of Transient Receptor Potential Melastatin Member 4... | KEEP AS NON CORE | Summary: While Nav1.1 may have some cardiac expression, this is peripheral to SCN1A's core neuronal function in GABAergic interneurons. Reason: SCN1A (Nav1.1) is predominantly neuronal while SCN5A (Nav1.5) is the main cardiac sodium channel. Any cardiac role for SCN1A is peripheral to its core function in neuronal action potentials. Supporting Evidence: PMID:27207958 Variants of Transient Receptor Potential Melastatin Member 4 in Childhood Atrioventricular Block. |
| GO:0005248 voltage-gated sodium channel activity | ISS GO_REF:0000024 | ACCEPT | Summary: Another annotation for the core molecular function with ISS evidence based on sequence similarity. This provides additional computational support for the voltage-gated sodium channel activity, which is highly conserved across orthologs. |
| GO:0050966 detection of mechanical stimulus involved in sensory perception of pain | ISS GO_REF:0000024 | KEEP AS NON CORE | Summary: Duplicate annotation for the same specialized function with ISS evidence. This provides additional computational support for SCN1A role in pain perception through controlling somatosensory neuron excitability, as mentioned in UniProt. |
| GO:0030018 Z disc | ISS GO_REF:0000024 | REMOVE | Summary: Duplicate annotation for muscle-specific Z disc localization with ISS evidence. Like the previous annotation, this is inappropriate for SCN1A (Nav1.1) which is predominantly neuronal. Z discs are structures in striated muscle not relevant to Nav1.1 function. |
| GO:0005248 voltage-gated sodium channel activity | NAS PMID:10742094 Mutations of SCN1A, encoding a neuronal sodium channel, in t... | ACCEPT | Summary: Another annotation for the core molecular function with NAS evidence from PMID:10742094, a study about SCN1A mutations in GEFS+2. This provides additional literature support for the voltage-gated sodium channel activity of SCN1A. Supporting Evidence: PMID:10742094 Mutations of SCN1A, encoding a neuronal sodium channel, in two families with GEFS+2 |
| GO:0006814 sodium ion transport | NAS PMID:10742094 Mutations of SCN1A, encoding a neuronal sodium channel, in t... | ACCEPT | Summary: This annotation for the core biological process has NAS evidence from PMID:10742094. This provides additional literature support for SCN1A role in sodium ion transport, which is fundamental to its voltage-gated sodium channel function. Supporting Evidence: PMID:10742094 Mutations of SCN1A, encoding a neuronal sodium channel, in two families with GEFS+2. |
Loading supporting contentβ¦
Download this section (compressed HTML)Q: How do different SCN1A mutations affect sodium channel gating properties and contribute to distinct epilepsy phenotypes?
Q: What determines the brain region-specific effects of SCN1A dysfunction and why is inhibitory neuron function particularly affected?
Q: How does SCN1A haploinsufficiency lead to the temperature-sensitive seizures characteristic of Dravet syndrome?
Q: What are the developmental changes in SCN1A expression and function that contribute to age-dependent seizure patterns?
Experiment: Patch-clamp electrophysiology of SCN1A variants in different neuronal subtypes to correlate biophysical properties with clinical phenotypes
Experiment: Organoid models of human brain development using patient-derived iPSCs to study SCN1A function in cortical circuit formation
Experiment: Two-photon calcium imaging in brain slices to study how SCN1A mutations affect inhibitory circuit function and excitability
Experiment: Cryo-EM structural analysis of SCN1A in different conformational states to understand mutation effects on channel structure
Loading supporting contentβ¦
Download this section (compressed HTML)Loading supporting contentβ¦
Download this section (compressed HTML)π View Pathway Visualization Interactive pathway diagram with detailed annotations