{"gene":"CACNA1I","run_date":"2026-06-09T22:57:17","timeline":{"discoveries":[{"year":2016,"finding":"The de novo missense variant R1346H in hCaV3.3 (CACNA1I) reduces protein glycosylation, lowers membrane surface levels, and reduces whole-cell hCaV3.3 currents to ~50% of wild-type without altering channel biophysical properties. Computer modeling showed that reducing CaV3.3 current density by 22% or more eliminates rebound bursting in model thalamic reticular nucleus (TRN) neurons.","method":"Biochemical analysis (western blot, glycosylation assay), whole-cell patch-clamp electrophysiology in human cell lines, NEURON computational modeling","journal":"Scientific reports","confidence":"High","confidence_rationale":"Tier 1-2 / Moderate — multiple orthogonal methods (biochemistry, electrophysiology, computational modeling) in a single rigorous study","pmids":["27756899"],"is_preprint":false},{"year":2020,"finding":"CaV3.3-R1346H knock-in mice show altered cellular excitability in thalamic reticular nucleus (TRN) neurons and marked deficits in sleep spindle occurrence and morphology during NREM sleep, establishing that CaV3.3 channel function in TRN is required for normal sleep spindle generation.","method":"Knock-in mouse model, electrophysiology in TRN neurons, polysomnographic EEG recording","journal":"Translational psychiatry","confidence":"High","confidence_rationale":"Tier 2 / Moderate — in vivo knock-in model with defined cellular (TRN excitability) and systems-level (EEG spindle) phenotypic readouts","pmids":["32066662"],"is_preprint":false},{"year":2021,"finding":"Gain-of-function missense variants in CACNA1I (p.Ile860Met, p.Ile860Asn, p.Ile1306Thr, p.Met1425Ile) at cytoplasmic ends of S5/S6 segments slow activation, inactivation, and deactivation kinetics, cause hyperpolarizing shifts in voltage-dependence of activation and inactivation, increase window currents (calcium influx), and shift mouse chromaffin cell firing from low-threshold spikes/rebound bursting to slow oscillations, establishing a gain-of-function mechanism for CaV3.3-related neurodevelopmental disorders.","method":"Patch-clamp electrophysiology in HEK293T cells, site-directed mutagenesis, structural modeling, expression in mouse chromaffin cells, computational modeling of TRN neurons","journal":"Brain : a journal of neurology","confidence":"High","confidence_rationale":"Tier 1-2 / Strong — multiple orthogonal methods including mutagenesis, electrophysiology, structural modeling, and native cell expression","pmids":["33704440"],"is_preprint":false},{"year":2025,"finding":"Two substitutions at A398 of CaV3.3 have opposite functional effects: A398E causes gain-of-function (left-shifted voltage-dependence, slowed inactivation, increased neuronal excitability), while A398V causes partial loss-of-function (decreased current density, accelerated gating kinetics, decreased neuronal excitability). Both M1425V and M1425I substitutions cause gain-of-function. Seizures in patients correlate with gain-of-function variants increasing neuronal excitability.","method":"Site-directed mutagenesis, voltage-clamp electrophysiology, computational modeling of neuronal excitability, structural modeling","journal":"PLoS genetics","confidence":"High","confidence_rationale":"Tier 1-2 / Moderate — multiple orthogonal methods (mutagenesis, electrophysiology, computational and structural modeling) in a single rigorous study","pmids":["40825030"],"is_preprint":false},{"year":2007,"finding":"Gαq/11-coupled muscarinic acetylcholine receptors (M1, M3, M5 but not Gi-coupled M2/M4) selectively inhibit CaV3.3 T-type calcium currents via Gαq/11 signaling, with no effect or stimulatory effect on CaV3.1 and CaV3.2. Chimeric channel analysis identified two distinct regions of CaV3.3 necessary and sufficient for M1 receptor-mediated inhibition.","method":"Perforated patch-clamp recordings, co-expression with mAChR subtypes, genetically encoded Gα/Gβγ antagonists and gain-of-function constructs, Cav3.1-Cav3.3 chimeric channels","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1-2 / Moderate — multiple orthogonal methods (pharmacology, genetic antagonists, chimeric channel mapping) in a single study","pmids":["17535809"],"is_preprint":false},{"year":2004,"finding":"Alternative splicing of CACNA1I affects CaV3.3 channel gating: deletion of 13 amino acids (Δ33) from exon 33 slows channel opening; addition of exon 9 has little effect alone but slows both activation and inactivation when combined with Δ33, suggesting a direct interaction between the intracellular regions after repeats I and IV in controlling channel gating.","method":"RT-PCR cloning from human brain, whole-cell patch-clamp, neuronal firing modeling","journal":"Journal of neurophysiology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — electrophysiology with splice-variant constructs and computational modeling in single lab","pmids":["15254077"],"is_preprint":false},{"year":2004,"finding":"The slow activation and inactivation kinetics distinctive to CaV3.3 are not determined by any single structural domain but require multiple structural elements distributed throughout the channel; swapping any one region of CaV3.1 into CaV3.3 (or vice versa) is insufficient to fully transfer kinetic properties.","method":"Chimeric channel construction between CaV3.1 and CaV3.3, expression in Xenopus oocytes, kinetic analysis by electrophysiology","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — systematic chimeric channel analysis with multiple constructs, single lab","pmids":["15016809"],"is_preprint":false},{"year":2006,"finding":"Domain IV of CaV3.3 is the major structural determinant of activation time constant and recovery from inactivation; domains I and IV together are major determinants of half-activation potential; simultaneous substitution of domains I+IV partially transfers inactivation kinetics between CaV3.1 and CaV3.3.","method":"Chimeric channel construction (domain-swapping between CaV3.1 and CaV3.3), expression in tsA-201 cells, whole-cell patch-clamp","journal":"Neuroscience","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — systematic chimeric channel analysis with multiple constructs, single lab","pmids":["16996222"],"is_preprint":false},{"year":2006,"finding":"CaV3.3 window current is the critical trigger for spontaneous membrane potential oscillations and intracellular Ca2+ oscillations in NG108-15 cells; the channel produces low-threshold calcium action potentials that sustain pacemaker activity, with AP duration and plateau potential controlled by the sustained CaV3.3 current.","method":"Whole-cell patch-clamp, calcium imaging, pharmacological block (nickel, mibefradil), manipulation of external Ca2+ to shift window current range","journal":"The European journal of neuroscience","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple electrophysiology and imaging methods, pharmacological validation, single lab","pmids":["16706840"],"is_preprint":false},{"year":2016,"finding":"CaV3.3 channels dominate nRt (nucleus reticularis thalami) rhythmogenesis and burst firing; deletion of CaV3.3 fully abolishes low-threshold Ca2+ currents and bursting in nRt and suppresses burst-mediated inhibitory responses in thalamocortical cells, while CaV3.2 deletion alone leaves nRt discharge largely unaltered. CaV3.3 KO suppresses NREM sleep EEG sigma band power (sleep spindles).","method":"CaV3.2KO and CaV3.2/CaV3.3 double-KO mice, patch-clamp in thalamic brain slices, polysomnographic EEG recording","journal":"Sleep","confidence":"High","confidence_rationale":"Tier 2 / Strong — clean genetic KO with defined cellular (burst firing) and systems-level (EEG) phenotypic readouts, replicated with double-KO strategy","pmids":["26612388"],"is_preprint":false},{"year":2013,"finding":"Endogenous polyunsaturated lipids (anandamide, NAGly, NASer, NADA, NATau, NA-5HT) inhibit CaV3.3 current and compete with the synthetic T-channel inhibitor TTA-A2 for the same binding site on CaV3.3, sharing a common molecular mechanism of inhibition. Saturated lipid analogs that do not inhibit current also do not displace TTA-A2 binding.","method":"Patch-clamp electrophysiology, radioligand binding assay with [3H]TTA-A1 on CaV3.3-expressing cell membranes, pharmacological competition experiments","journal":"Molecular pharmacology","confidence":"Medium","confidence_rationale":"Tier 1-2 / Moderate — electrophysiology plus radioligand binding with multiple lipid structures, single lab","pmids":["24214826"],"is_preprint":false},{"year":2003,"finding":"CaV3.3 protein exists as distinct isoforms with different apparent molecular masses in different brain regions (midbrain/diencephalon: ~230 kDa and ~190 kDa doublet; other regions: ~190 kDa only) and at different developmental stages (neonatal: ~260 kDa; adult: smaller form), with strong immunoreactivity in olfactory bulb and midbrain. Expression is present from embryonic day 14 in brain and spinal cord.","method":"Western blotting with affinity-purified anti-peptide antibodies, immunohistochemistry on mouse/rat/human brain and spinal cord dissections at multiple developmental stages","journal":"Neuroscience","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — validated antibody-based protein localization and developmental expression, replicated across multiple tissues and species","pmids":["12614673"],"is_preprint":false},{"year":2007,"finding":"CaV3.3 (α1I) is modified by N-glycosylation, and differential glycosylation (including polysialylation of the neonatal form) fully accounts for the large molecular mass difference (~260 kDa neonatal vs. ~190 kDa adult) between developmental isoforms detected in mouse brain.","method":"PNGase F treatment (removes N-linked polysaccharides), endoneuraminidase-N treatment (removes polysialic acid), western blotting of recombinant and endogenous CaV3.3","journal":"Neuroscience","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — biochemical enzymatic deglycosylation with orthogonal enzymes, single lab","pmids":["17317015"],"is_preprint":false},{"year":2017,"finding":"Neuritin increases surface expression of CaV3.3 α-subunit in medial prefrontal cortex neurons via activation of insulin receptor (IR) and downstream MEK/ERK signaling, leading to increased miniature EPSC frequency and glutamate release; inhibition of IR, MEK/ERK, or T-type channels abolished these effects.","method":"Electrophysiology (mEPSC recording), HPLC for glutamate measurement, western blotting of membrane proteins, pharmacological inhibitors of IR/MEK/ERK and T-type channels, intracellular protein transport inhibitor","journal":"Cerebral cortex","confidence":"Medium","confidence_rationale":"Tier 2-3 / Moderate — multiple pharmacological interventions and biochemical readouts, single lab, mechanistic pathway partially inferred from inhibitor studies","pmids":["28475719"],"is_preprint":false},{"year":2022,"finding":"TET1 regulates Cav3.3 expression in TM3 Leydig cells through DNA hydroxymethylation of the Cav3.3 locus; BPA exposure reduces TET1 and Cav3.3 expression, while TET1 overexpression restores Cav3.3 mRNA levels and cell viability, as confirmed by MeDIP and hMeDIP assays.","method":"Adenoviral overexpression/knockdown of TET1, qRT-PCR, western blot, MeDIP and hMeDIP assays, cell viability and apoptosis assays","journal":"Chemosphere","confidence":"Medium","confidence_rationale":"Tier 2-3 / Moderate — MeDIP/hMeDIP provide direct epigenetic evidence, combined with functional overexpression/knockdown, single lab","pmids":["36370755"],"is_preprint":false},{"year":2022,"finding":"Rare Cav3.3 variants (p.R111G, p.M128L, p.D302G, p.R307H, p.Q1158H) identified in hemiplegic migraine patients alter channel biophysical properties compared to WT, with Q1158H showing the greatest effect (reduced current density, right-shifted voltage-dependence of activation and inactivation, slower kinetics). R307H and Q1158H also show altered conductance under acidic/alkaline conditions.","method":"Patch-clamp electrophysiology in HEK293T cells expressing WT or variant Cav3.3","journal":"Frontiers in molecular neuroscience","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct electrophysiological characterization of multiple disease variants, single lab","pmids":["35928792"],"is_preprint":false},{"year":2017,"finding":"Silencing Cav3.3 in dorsal root ganglion neurons reduces CaMKIIγ mRNA and protein expression, and decreases ropivacaine-induced neurotoxicity; Cav3.3 overexpression aggravates toxicity and increases CaMKIIγ. This establishes a regulatory link between Cav3.3 channel expression and CaMKIIγ in sensory neurons.","method":"Adenoviral knockdown/overexpression in neonatal rat DRG neurons, qRT-PCR, western blot, cell viability/apoptosis assays","journal":"Artificial cells, nanomedicine, and biotechnology","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single lab, indirect functional link between Cav3.3 and CaMKIIγ inferred from overexpression/knockdown without direct mechanistic assay","pmids":["28974111"],"is_preprint":false}],"current_model":"CaV3.3 (CACNA1I) is a low-voltage-activated T-type calcium channel whose slow gating kinetics are encoded by multiple distributed structural domains (particularly domain IV for activation), and whose activity in GABAergic thalamic reticular nucleus neurons drives rebound burst firing, sleep spindle rhythmogenesis, and pacemaker oscillations via a critical window current; the channel is selectively inhibited by Gαq/11-coupled muscarinic receptors and endogenous polyunsaturated lipids acting at a shared binding site, regulated by neuritin/IR/ERK-dependent surface trafficking and TET1-mediated DNA hydroxymethylation, and disease-causing gain-of-function variants in the channel gate region cause neurodevelopmental disorders by increasing calcium influx and neuronal hyperexcitability, while loss-of-function variants reduce TRN excitability and impair sleep spindle generation with implications for schizophrenia pathophysiology."},"narrative":{"mechanistic_narrative":"CACNA1I encodes CaV3.3, a low-voltage-activated T-type calcium channel whose hallmark slow gating drives rebound burst firing and pacemaker oscillations in GABAergic neurons of the thalamic reticular nucleus, where it is required for normal sleep spindle generation during NREM sleep [PMID:32066662, PMID:26612388]. The channel's distinctively slow activation and inactivation kinetics are not assigned to any single structural element but emerge from multiple distributed domains, with domain IV serving as the major determinant of activation time constant and recovery from inactivation, and domains I and IV jointly setting the half-activation potential [PMID:15016809, PMID:16996222]; alternative splicing of exons 9 and 33 further tunes these gating properties [PMID:15254077]. A sustained window current generated by CaV3.3 acts as the critical trigger for spontaneous membrane potential and intracellular Ca2+ oscillations, and genetic deletion of CaV3.3 abolishes low-threshold Ca2+ currents and bursting in reticular thalamic neurons and suppresses sleep-spindle sigma-band EEG power [PMID:16706840, PMID:26612388]. Channel activity is negatively regulated by Gaq/11-coupled muscarinic receptors (M1/M3/M5) and by endogenous polyunsaturated lipids that compete with synthetic T-channel inhibitors at a shared binding site [PMID:17535809, PMID:24214826], while surface expression is controlled by neuritin acting through insulin receptor and MEK/ERK signaling [PMID:28475719] and channel gene expression by TET1-mediated DNA hydroxymethylation [PMID:36370755]. Disease-causing variants act bidirectionally: gain-of-function substitutions at the cytoplasmic ends of S5/S6 segments and at the channel gate slow gating, left-shift voltage dependence, and increase window current and neuronal excitability, causing neurodevelopmental disorders and seizures, whereas loss-of-function variants reduce current density and excitability [PMID:27756899, PMID:33704440, PMID:40825030].","teleology":[{"year":2003,"claim":"Establishing where and when the CaV3.3 protein is expressed was a prerequisite for assigning physiological function, and protein-level detection showed region- and developmental-stage-specific isoforms.","evidence":"Affinity-purified antibody western blotting and immunohistochemistry across mouse, rat, and human brain and spinal cord at multiple developmental stages","pmids":["12614673"],"confidence":"Medium","gaps":["Did not resolve molecular basis of the isoform mass differences","No functional consequence of differential expression established"]},{"year":2004,"claim":"It was unknown what structural features make CaV3.3 gating so slow; chimera and splicing analyses showed the kinetics are encoded by multiple distributed regions rather than a single domain.","evidence":"CaV3.1/CaV3.3 chimeric channels in Xenopus oocytes and splice-variant constructs (exon 9, delta33) by whole-cell patch-clamp","pmids":["15016809","15254077"],"confidence":"Medium","gaps":["Did not identify the specific residues responsible","Interaction between intracellular regions inferred, not structurally resolved"]},{"year":2006,"claim":"Refining which domains dominate gating, domain IV was identified as the major determinant of activation and recovery kinetics, and the window current was shown to drive autonomous oscillatory activity.","evidence":"Domain-swap chimeras in tsA-201 cells, and whole-cell patch-clamp plus calcium imaging with pharmacological block in NG108-15 cells","pmids":["16996222","16706840"],"confidence":"Medium","gaps":["Domain contributions only partially transfer kinetics","Oscillation mechanism characterized in a cell line, not native neurons"]},{"year":2007,"claim":"How CaV3.3 is acutely modulated and post-translationally processed was unknown; muscarinic Gaq/11 signaling was shown to selectively inhibit CaV3.3, and N-glycosylation/polysialylation was shown to account for isoform mass differences.","evidence":"Perforated patch-clamp with mAChR subtypes and G-protein antagonists plus chimeric mapping; enzymatic deglycosylation (PNGase F, endoneuraminidase-N) with western blotting","pmids":["17535809","17317015"],"confidence":"High","gaps":["Downstream effector linking Gaq/11 to channel inhibition not defined","Functional role of polysialylation on channel activity untested"]},{"year":2013,"claim":"Whether endogenous ligands modulate CaV3.3 was unclear; polyunsaturated lipids were shown to inhibit the channel at a binding site shared with synthetic T-channel blockers.","evidence":"Patch-clamp electrophysiology and [3H]TTA-A1 radioligand competition binding with multiple lipid structures","pmids":["24214826"],"confidence":"Medium","gaps":["Binding site not structurally localized","Physiological relevance of endogenous lipid inhibition in vivo not shown"]},{"year":2016,"claim":"The in vivo role of CaV3.3 in thalamic rhythmogenesis was untested; a clinical variant and clean knockouts established that CaV3.3 function is required for reticular thalamic bursting and sleep spindle generation.","evidence":"R1346H biochemistry and patch-clamp with NEURON modeling; CaV3.2 and CaV3.2/CaV3.3 double-KO mice with thalamic slice recording and polysomnographic EEG","pmids":["27756899","26612388"],"confidence":"High","gaps":["Behavioral/cognitive consequences of spindle loss not fully resolved","Did not address gain-of-function disease mechanisms"]},{"year":2017,"claim":"Mechanisms controlling CaV3.3 surface availability were unknown; neuritin was shown to increase channel surface expression via IR and MEK/ERK signaling, linking it to glutamate release.","evidence":"mEPSC recording, membrane-protein western blotting, HPLC, and pharmacological inhibition of IR/MEK/ERK and T-type channels in prefrontal cortex neurons","pmids":["28475719"],"confidence":"Medium","gaps":["Direct interaction between neuritin/IR and CaV3.3 not demonstrated","Trafficking pathway inferred from inhibitor effects"]},{"year":2021,"claim":"Whether CACNA1I disease variants act by gain or loss of function was unresolved; gain-of-function variants at S5/S6 cytoplasmic ends were shown to slow gating, increase window current, and elevate excitability.","evidence":"Site-directed mutagenesis, patch-clamp in HEK293T, structural modeling, native mouse chromaffin cell expression, and computational TRN modeling","pmids":["33704440"],"confidence":"High","gaps":["No in vivo model of the gain-of-function variants","Structural basis of gating slowing inferred from modeling"]},{"year":2022,"claim":"Additional disease and regulatory contexts were tested: rare variants alter biophysics in hemiplegic migraine, and TET1-mediated DNA hydroxymethylation controls Cav3.3 transcription.","evidence":"Patch-clamp of variant channels in HEK293T; TET1 overexpression/knockdown with MeDIP/hMeDIP and viability assays in Leydig cells","pmids":["35928792","36370755"],"confidence":"Medium","gaps":["Causality of migraine variants not established beyond biophysics","TET1 regulation shown in a non-neuronal cell line"]},{"year":2025,"claim":"Whether the same residue can yield opposite functional outcomes was unknown; paired substitutions at A398 produced gain- versus loss-of-function, correlating seizures with gain-of-function excitability increases.","evidence":"Site-directed mutagenesis, voltage-clamp electrophysiology, and computational and structural modeling","pmids":["40825030"],"confidence":"High","gaps":["Genotype-phenotype correlation based on modeling, not patient-derived neurons","No therapeutic intervention tested"]},{"year":null,"claim":"The structural basis for CaV3.3's distributed slow-gating mechanism and the precise molecular link between Gaq/11 or lipid binding and channel inhibition remain undefined.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No high-resolution structure of the channel or ligand-binding site","Direct effectors coupling receptor signaling to channel gating unidentified","In vivo disease models for most variants lacking"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0005215","term_label":"transporter activity","supporting_discovery_ids":[2,8,9]}],"localization":[{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[0,13]}],"pathway":[{"term_id":"R-HSA-112316","term_label":"Neuronal System","supporting_discovery_ids":[1,9]},{"term_id":"R-HSA-382551","term_label":"Transport of small molecules","supporting_discovery_ids":[2,8]}],"complexes":[],"partners":[],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q9P0X4","full_name":"Voltage-dependent T-type calcium channel subunit alpha-1I","aliases":["Voltage-gated calcium channel subunit alpha Cav3.3","Ca(v)3.3"],"length_aa":2223,"mass_kda":245.1,"function":"Voltage-sensitive calcium channels (VSCC) mediate the entry of calcium ions into excitable cells and are also involved in a variety of calcium-dependent processes, including muscle contraction, hormone or neurotransmitter release, gene expression, cell motility, cell division and cell death. This channel gives rise to T-type calcium currents. T-type calcium channels belong to the 'low-voltage activated (LVA)' group and are strongly blocked by nickel and mibefradil. A particularity of this type of channels is an opening at quite negative potentials, and a voltage-dependent inactivation. T-type channels serve pacemaking functions in both central neurons and cardiac nodal cells and support calcium signaling in secretory cells and vascular smooth muscle. They may also be involved in the modulation of firing patterns of neurons which is important for information processing as well as in cell growth processes. Gates in voltage ranges similar to, but higher than alpha 1G or alpha 1H Voltage-sensitive calcium channels (VSCC) mediate the entry of calcium ions into excitable cells and are also involved in a variety of calcium-dependent processes, including muscle contraction, hormone or neurotransmitter release, gene expression, cell motility, cell division and cell death. This channel gives rise to T-type calcium currents Voltage-sensitive calcium channels (VSCC) mediate the entry of calcium ions into excitable cells and are also involved in a variety of calcium-dependent processes, including muscle contraction, hormone or neurotransmitter release, gene expression, cell motility, cell division and cell death. This channel gives rise to T-type calcium currents","subcellular_location":"Membrane","url":"https://www.uniprot.org/uniprotkb/Q9P0X4/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/CACNA1I","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/CACNA1I","total_profiled":1310},"omim":[{"mim_id":"620114","title":"NEURODEVELOPMENTAL DISORDER WITH SPEECH IMPAIRMENT AND WITH OR WITHOUT SEIZURES; NEDSIS","url":"https://www.omim.org/entry/620114"},{"mim_id":"609120","title":"CATION CHANNEL, SPERM-ASSOCIATED, 3; CATSPER3","url":"https://www.omim.org/entry/609120"},{"mim_id":"608230","title":"CALCIUM CHANNEL, VOLTAGE-DEPENDENT, T TYPE, ALPHA-1I SUBUNIT; CACNA1I","url":"https://www.omim.org/entry/608230"},{"mim_id":"607904","title":"CALCIUM CHANNEL, VOLTAGE-DEPENDENT, T TYPE, ALPHA-1H SUBUNIT; CACNA1H","url":"https://www.omim.org/entry/607904"},{"mim_id":"604065","title":"CALCIUM CHANNEL, VOLTAGE-DEPENDENT, T TYPE, ALPHA-1G SUBUNIT; CACNA1G","url":"https://www.omim.org/entry/604065"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Plasma membrane","reliability":"Approved"},{"location":"Cell Junctions","reliability":"Additional"},{"location":"Acrosome","reliability":"Additional"}],"tissue_specificity":"Tissue enhanced","tissue_distribution":"Detected in some","driving_tissues":[{"tissue":"brain","ntpm":9.7},{"tissue":"thyroid gland","ntpm":5.1}],"url":"https://www.proteinatlas.org/search/CACNA1I"},"hgnc":{"alias_symbol":["Cav3.3"],"prev_symbol":[]},"alphafold":{"accession":"Q9P0X4","domains":[{"cath_id":"1.20.120.350","chopping":"58-192","consensus_level":"high","plddt":83.508,"start":58,"end":192},{"cath_id":"1.20.120.350","chopping":"635-745","consensus_level":"medium","plddt":80.6718,"start":635,"end":745},{"cath_id":"1.10.287.70","chopping":"761-877","consensus_level":"medium","plddt":79.4421,"start":761,"end":877},{"cath_id":"1.20.120.350","chopping":"1142-1289","consensus_level":"medium","plddt":80.1974,"start":1142,"end":1289},{"cath_id":"1.20.120.350","chopping":"1471-1602","consensus_level":"high","plddt":83.5681,"start":1471,"end":1602}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9P0X4","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q9P0X4-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q9P0X4-F1-predicted_aligned_error_v6.png","plddt_mean":59.66},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=CACNA1I","jax_strain_url":"https://www.jax.org/strain/search?query=CACNA1I"},"sequence":{"accession":"Q9P0X4","fasta_url":"https://rest.uniprot.org/uniprotkb/Q9P0X4.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q9P0X4/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9P0X4"}},"corpus_meta":[{"pmid":"30718321","id":"PMC_30718321","title":"Genome-Wide Association Studies of Impulsive Personality Traits (BIS-11 and UPPS-P) and Drug Experimentation in up to 22,861 Adult Research Participants Identify Loci in the CACNA1I and CADM2 genes.","date":"2019","source":"The Journal of neuroscience : the official journal of the Society for Neuroscience","url":"https://pubmed.ncbi.nlm.nih.gov/30718321","citation_count":116,"is_preprint":false},{"pmid":"12614673","id":"PMC_12614673","title":"Immunological characterization of T-type voltage-dependent calcium channel CaV3.1 (alpha 1G) and CaV3.3 (alpha 1I) isoforms reveal differences in their localization, expression, and neural development.","date":"2003","source":"Neuroscience","url":"https://pubmed.ncbi.nlm.nih.gov/12614673","citation_count":72,"is_preprint":false},{"pmid":"27756899","id":"PMC_27756899","title":"A rare schizophrenia risk variant of CACNA1I disrupts CaV3.3 channel activity.","date":"2016","source":"Scientific reports","url":"https://pubmed.ncbi.nlm.nih.gov/27756899","citation_count":58,"is_preprint":false},{"pmid":"33704440","id":"PMC_33704440","title":"CACNA1I gain-of-function mutations differentially affect channel gating and cause neurodevelopmental disorders.","date":"2021","source":"Brain : a journal of neurology","url":"https://pubmed.ncbi.nlm.nih.gov/33704440","citation_count":45,"is_preprint":false},{"pmid":"15254077","id":"PMC_15254077","title":"Functional impact of alternative splicing of human T-type Cav3.3 calcium channels.","date":"2004","source":"Journal of neurophysiology","url":"https://pubmed.ncbi.nlm.nih.gov/15254077","citation_count":42,"is_preprint":false},{"pmid":"26612388","id":"PMC_26612388","title":"Suppression of Sleep Spindle Rhythmogenesis in Mice with Deletion of CaV3.2 and CaV3.3 T-type Ca(2+) Channels.","date":"2016","source":"Sleep","url":"https://pubmed.ncbi.nlm.nih.gov/26612388","citation_count":41,"is_preprint":false},{"pmid":"17535809","id":"PMC_17535809","title":"Selective inhibition of Cav3.3 T-type calcium channels by Galphaq/11-coupled muscarinic acetylcholine receptors.","date":"2007","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/17535809","citation_count":41,"is_preprint":false},{"pmid":"16706840","id":"PMC_16706840","title":"T-type CaV3.3 calcium channels produce spontaneous low-threshold action potentials and intracellular calcium oscillations.","date":"2006","source":"The European journal of neuroscience","url":"https://pubmed.ncbi.nlm.nih.gov/16706840","citation_count":39,"is_preprint":false},{"pmid":"32066662","id":"PMC_32066662","title":"Effects of a patient-derived de novo coding alteration of CACNA1I in mice connect a schizophrenia risk gene with sleep spindle deficits.","date":"2020","source":"Translational psychiatry","url":"https://pubmed.ncbi.nlm.nih.gov/32066662","citation_count":35,"is_preprint":false},{"pmid":"16996222","id":"PMC_16996222","title":"Determinants of the differential gating properties of Cav3.1 and Cav3.3 T-type channels: a role of domain IV?","date":"2006","source":"Neuroscience","url":"https://pubmed.ncbi.nlm.nih.gov/16996222","citation_count":22,"is_preprint":false},{"pmid":"15016809","id":"PMC_15016809","title":"Multiple structural elements contribute to the slow kinetics of the Cav3.3 T-type channel.","date":"2004","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/15016809","citation_count":19,"is_preprint":false},{"pmid":"28475719","id":"PMC_28475719","title":"Neuritin Enhances Synaptic Transmission in Medial Prefrontal Cortex in Mice by Increasing CaV3.3 Surface Expression.","date":"2017","source":"Cerebral cortex (New York, N.Y. : 1991)","url":"https://pubmed.ncbi.nlm.nih.gov/28475719","citation_count":17,"is_preprint":false},{"pmid":"35928792","id":"PMC_35928792","title":"Investigation of CACNA1I Cav3.3 Dysfunction in Hemiplegic Migraine.","date":"2022","source":"Frontiers in molecular neuroscience","url":"https://pubmed.ncbi.nlm.nih.gov/35928792","citation_count":14,"is_preprint":false},{"pmid":"36786913","id":"PMC_36786913","title":"Whole Exome Sequencing of Hemiplegic Migraine Patients Shows an Increased Burden of Missense Variants in CACNA1H and CACNA1I Genes.","date":"2023","source":"Molecular neurobiology","url":"https://pubmed.ncbi.nlm.nih.gov/36786913","citation_count":14,"is_preprint":false},{"pmid":"29308060","id":"PMC_29308060","title":"Further evidence for the genetic association between CACNA1I and schizophrenia.","date":"2018","source":"Hereditas","url":"https://pubmed.ncbi.nlm.nih.gov/29308060","citation_count":13,"is_preprint":false},{"pmid":"16939858","id":"PMC_16939858","title":"CACNA1I is not associated with childhood absence epilepsy in the Chinese Han population.","date":"2006","source":"Pediatric neurology","url":"https://pubmed.ncbi.nlm.nih.gov/16939858","citation_count":13,"is_preprint":false},{"pmid":"24214826","id":"PMC_24214826","title":"Cross-modulation and molecular interaction at the Cav3.3 protein between the endogenous lipids and the T-type calcium channel antagonist TTA-A2.","date":"2013","source":"Molecular pharmacology","url":"https://pubmed.ncbi.nlm.nih.gov/24214826","citation_count":12,"is_preprint":false},{"pmid":"28974111","id":"PMC_28974111","title":"In vitro neurotoxicity by ropivacaine is reduced by silencing Cav3.3 T-type calcium subunits in neonatal rat sensory neurons.","date":"2017","source":"Artificial cells, nanomedicine, and biotechnology","url":"https://pubmed.ncbi.nlm.nih.gov/28974111","citation_count":12,"is_preprint":false},{"pmid":"28725167","id":"PMC_28725167","title":"Genetic risk between the CACNA1I gene and schizophrenia in Chinese Uygur population.","date":"2017","source":"Hereditas","url":"https://pubmed.ncbi.nlm.nih.gov/28725167","citation_count":10,"is_preprint":false},{"pmid":"17317015","id":"PMC_17317015","title":"Site-directed antibodies to low-voltage-activated calcium channel CaV3.3 (alpha1I) subunit also target neural cell adhesion molecule-180.","date":"2007","source":"Neuroscience","url":"https://pubmed.ncbi.nlm.nih.gov/17317015","citation_count":9,"is_preprint":false},{"pmid":"36370755","id":"PMC_36370755","title":"TET1 involved in bisphenol A induced TM3 Leydig cell toxicity by regulating Cav3.3 hydroxymethylation.","date":"2022","source":"Chemosphere","url":"https://pubmed.ncbi.nlm.nih.gov/36370755","citation_count":8,"is_preprint":false},{"pmid":"30197701","id":"PMC_30197701","title":"Functional Exploration Of T-Type Calcium Channels (Cav3.2 And Cav3.3) And Their Sensitivity To Zinc.","date":"2018","source":"The open microbiology 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forebrain","date":"2025-08-22","source":"bioRxiv","url":"https://doi.org/10.1101/2025.08.18.670814","citation_count":0,"is_preprint":true},{"pmid":null,"id":"bio_10.1101_2025.08.26.672495","title":"Transcriptional Readthrough at  <i>Atf4</i>  Locus Suppresses  <i>Rps19bp1</i>  and Impairs Heart Development","date":"2025-08-29","source":"bioRxiv","url":"https://doi.org/10.1101/2025.08.26.672495","citation_count":0,"is_preprint":true}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":17623,"output_tokens":4533,"usd":0.060432,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":12533,"output_tokens":3508,"usd":0.075182,"stage2_stop_reason":"end_turn"},"total_usd":0.135614,"stage1_batch_id":"msgbatch_01ACAxJQabDsht39JXeWG22d","stage2_batch_id":"msgbatch_01QEU22A9U5sbPTgsMzTmvSf","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2016,\n      \"finding\": \"The de novo missense variant R1346H in hCaV3.3 (CACNA1I) reduces protein glycosylation, lowers membrane surface levels, and reduces whole-cell hCaV3.3 currents to ~50% of wild-type without altering channel biophysical properties. Computer modeling showed that reducing CaV3.3 current density by 22% or more eliminates rebound bursting in model thalamic reticular nucleus (TRN) neurons.\",\n      \"method\": \"Biochemical analysis (western blot, glycosylation assay), whole-cell patch-clamp electrophysiology in human cell lines, NEURON computational modeling\",\n      \"journal\": \"Scientific reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Moderate — multiple orthogonal methods (biochemistry, electrophysiology, computational modeling) in a single rigorous study\",\n      \"pmids\": [\"27756899\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"CaV3.3-R1346H knock-in mice show altered cellular excitability in thalamic reticular nucleus (TRN) neurons and marked deficits in sleep spindle occurrence and morphology during NREM sleep, establishing that CaV3.3 channel function in TRN is required for normal sleep spindle generation.\",\n      \"method\": \"Knock-in mouse model, electrophysiology in TRN neurons, polysomnographic EEG recording\",\n      \"journal\": \"Translational psychiatry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vivo knock-in model with defined cellular (TRN excitability) and systems-level (EEG spindle) phenotypic readouts\",\n      \"pmids\": [\"32066662\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"Gain-of-function missense variants in CACNA1I (p.Ile860Met, p.Ile860Asn, p.Ile1306Thr, p.Met1425Ile) at cytoplasmic ends of S5/S6 segments slow activation, inactivation, and deactivation kinetics, cause hyperpolarizing shifts in voltage-dependence of activation and inactivation, increase window currents (calcium influx), and shift mouse chromaffin cell firing from low-threshold spikes/rebound bursting to slow oscillations, establishing a gain-of-function mechanism for CaV3.3-related neurodevelopmental disorders.\",\n      \"method\": \"Patch-clamp electrophysiology in HEK293T cells, site-directed mutagenesis, structural modeling, expression in mouse chromaffin cells, computational modeling of TRN neurons\",\n      \"journal\": \"Brain : a journal of neurology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Strong — multiple orthogonal methods including mutagenesis, electrophysiology, structural modeling, and native cell expression\",\n      \"pmids\": [\"33704440\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"Two substitutions at A398 of CaV3.3 have opposite functional effects: A398E causes gain-of-function (left-shifted voltage-dependence, slowed inactivation, increased neuronal excitability), while A398V causes partial loss-of-function (decreased current density, accelerated gating kinetics, decreased neuronal excitability). Both M1425V and M1425I substitutions cause gain-of-function. Seizures in patients correlate with gain-of-function variants increasing neuronal excitability.\",\n      \"method\": \"Site-directed mutagenesis, voltage-clamp electrophysiology, computational modeling of neuronal excitability, structural modeling\",\n      \"journal\": \"PLoS genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Moderate — multiple orthogonal methods (mutagenesis, electrophysiology, computational and structural modeling) in a single rigorous study\",\n      \"pmids\": [\"40825030\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"Gαq/11-coupled muscarinic acetylcholine receptors (M1, M3, M5 but not Gi-coupled M2/M4) selectively inhibit CaV3.3 T-type calcium currents via Gαq/11 signaling, with no effect or stimulatory effect on CaV3.1 and CaV3.2. Chimeric channel analysis identified two distinct regions of CaV3.3 necessary and sufficient for M1 receptor-mediated inhibition.\",\n      \"method\": \"Perforated patch-clamp recordings, co-expression with mAChR subtypes, genetically encoded Gα/Gβγ antagonists and gain-of-function constructs, Cav3.1-Cav3.3 chimeric channels\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Moderate — multiple orthogonal methods (pharmacology, genetic antagonists, chimeric channel mapping) in a single study\",\n      \"pmids\": [\"17535809\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"Alternative splicing of CACNA1I affects CaV3.3 channel gating: deletion of 13 amino acids (Δ33) from exon 33 slows channel opening; addition of exon 9 has little effect alone but slows both activation and inactivation when combined with Δ33, suggesting a direct interaction between the intracellular regions after repeats I and IV in controlling channel gating.\",\n      \"method\": \"RT-PCR cloning from human brain, whole-cell patch-clamp, neuronal firing modeling\",\n      \"journal\": \"Journal of neurophysiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — electrophysiology with splice-variant constructs and computational modeling in single lab\",\n      \"pmids\": [\"15254077\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"The slow activation and inactivation kinetics distinctive to CaV3.3 are not determined by any single structural domain but require multiple structural elements distributed throughout the channel; swapping any one region of CaV3.1 into CaV3.3 (or vice versa) is insufficient to fully transfer kinetic properties.\",\n      \"method\": \"Chimeric channel construction between CaV3.1 and CaV3.3, expression in Xenopus oocytes, kinetic analysis by electrophysiology\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — systematic chimeric channel analysis with multiple constructs, single lab\",\n      \"pmids\": [\"15016809\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"Domain IV of CaV3.3 is the major structural determinant of activation time constant and recovery from inactivation; domains I and IV together are major determinants of half-activation potential; simultaneous substitution of domains I+IV partially transfers inactivation kinetics between CaV3.1 and CaV3.3.\",\n      \"method\": \"Chimeric channel construction (domain-swapping between CaV3.1 and CaV3.3), expression in tsA-201 cells, whole-cell patch-clamp\",\n      \"journal\": \"Neuroscience\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — systematic chimeric channel analysis with multiple constructs, single lab\",\n      \"pmids\": [\"16996222\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"CaV3.3 window current is the critical trigger for spontaneous membrane potential oscillations and intracellular Ca2+ oscillations in NG108-15 cells; the channel produces low-threshold calcium action potentials that sustain pacemaker activity, with AP duration and plateau potential controlled by the sustained CaV3.3 current.\",\n      \"method\": \"Whole-cell patch-clamp, calcium imaging, pharmacological block (nickel, mibefradil), manipulation of external Ca2+ to shift window current range\",\n      \"journal\": \"The European journal of neuroscience\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple electrophysiology and imaging methods, pharmacological validation, single lab\",\n      \"pmids\": [\"16706840\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"CaV3.3 channels dominate nRt (nucleus reticularis thalami) rhythmogenesis and burst firing; deletion of CaV3.3 fully abolishes low-threshold Ca2+ currents and bursting in nRt and suppresses burst-mediated inhibitory responses in thalamocortical cells, while CaV3.2 deletion alone leaves nRt discharge largely unaltered. CaV3.3 KO suppresses NREM sleep EEG sigma band power (sleep spindles).\",\n      \"method\": \"CaV3.2KO and CaV3.2/CaV3.3 double-KO mice, patch-clamp in thalamic brain slices, polysomnographic EEG recording\",\n      \"journal\": \"Sleep\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — clean genetic KO with defined cellular (burst firing) and systems-level (EEG) phenotypic readouts, replicated with double-KO strategy\",\n      \"pmids\": [\"26612388\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"Endogenous polyunsaturated lipids (anandamide, NAGly, NASer, NADA, NATau, NA-5HT) inhibit CaV3.3 current and compete with the synthetic T-channel inhibitor TTA-A2 for the same binding site on CaV3.3, sharing a common molecular mechanism of inhibition. Saturated lipid analogs that do not inhibit current also do not displace TTA-A2 binding.\",\n      \"method\": \"Patch-clamp electrophysiology, radioligand binding assay with [3H]TTA-A1 on CaV3.3-expressing cell membranes, pharmacological competition experiments\",\n      \"journal\": \"Molecular pharmacology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1-2 / Moderate — electrophysiology plus radioligand binding with multiple lipid structures, single lab\",\n      \"pmids\": [\"24214826\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"CaV3.3 protein exists as distinct isoforms with different apparent molecular masses in different brain regions (midbrain/diencephalon: ~230 kDa and ~190 kDa doublet; other regions: ~190 kDa only) and at different developmental stages (neonatal: ~260 kDa; adult: smaller form), with strong immunoreactivity in olfactory bulb and midbrain. Expression is present from embryonic day 14 in brain and spinal cord.\",\n      \"method\": \"Western blotting with affinity-purified anti-peptide antibodies, immunohistochemistry on mouse/rat/human brain and spinal cord dissections at multiple developmental stages\",\n      \"journal\": \"Neuroscience\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — validated antibody-based protein localization and developmental expression, replicated across multiple tissues and species\",\n      \"pmids\": [\"12614673\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"CaV3.3 (α1I) is modified by N-glycosylation, and differential glycosylation (including polysialylation of the neonatal form) fully accounts for the large molecular mass difference (~260 kDa neonatal vs. ~190 kDa adult) between developmental isoforms detected in mouse brain.\",\n      \"method\": \"PNGase F treatment (removes N-linked polysaccharides), endoneuraminidase-N treatment (removes polysialic acid), western blotting of recombinant and endogenous CaV3.3\",\n      \"journal\": \"Neuroscience\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — biochemical enzymatic deglycosylation with orthogonal enzymes, single lab\",\n      \"pmids\": [\"17317015\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"Neuritin increases surface expression of CaV3.3 α-subunit in medial prefrontal cortex neurons via activation of insulin receptor (IR) and downstream MEK/ERK signaling, leading to increased miniature EPSC frequency and glutamate release; inhibition of IR, MEK/ERK, or T-type channels abolished these effects.\",\n      \"method\": \"Electrophysiology (mEPSC recording), HPLC for glutamate measurement, western blotting of membrane proteins, pharmacological inhibitors of IR/MEK/ERK and T-type channels, intracellular protein transport inhibitor\",\n      \"journal\": \"Cerebral cortex\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 / Moderate — multiple pharmacological interventions and biochemical readouts, single lab, mechanistic pathway partially inferred from inhibitor studies\",\n      \"pmids\": [\"28475719\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"TET1 regulates Cav3.3 expression in TM3 Leydig cells through DNA hydroxymethylation of the Cav3.3 locus; BPA exposure reduces TET1 and Cav3.3 expression, while TET1 overexpression restores Cav3.3 mRNA levels and cell viability, as confirmed by MeDIP and hMeDIP assays.\",\n      \"method\": \"Adenoviral overexpression/knockdown of TET1, qRT-PCR, western blot, MeDIP and hMeDIP assays, cell viability and apoptosis assays\",\n      \"journal\": \"Chemosphere\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 / Moderate — MeDIP/hMeDIP provide direct epigenetic evidence, combined with functional overexpression/knockdown, single lab\",\n      \"pmids\": [\"36370755\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"Rare Cav3.3 variants (p.R111G, p.M128L, p.D302G, p.R307H, p.Q1158H) identified in hemiplegic migraine patients alter channel biophysical properties compared to WT, with Q1158H showing the greatest effect (reduced current density, right-shifted voltage-dependence of activation and inactivation, slower kinetics). R307H and Q1158H also show altered conductance under acidic/alkaline conditions.\",\n      \"method\": \"Patch-clamp electrophysiology in HEK293T cells expressing WT or variant Cav3.3\",\n      \"journal\": \"Frontiers in molecular neuroscience\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct electrophysiological characterization of multiple disease variants, single lab\",\n      \"pmids\": [\"35928792\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"Silencing Cav3.3 in dorsal root ganglion neurons reduces CaMKIIγ mRNA and protein expression, and decreases ropivacaine-induced neurotoxicity; Cav3.3 overexpression aggravates toxicity and increases CaMKIIγ. This establishes a regulatory link between Cav3.3 channel expression and CaMKIIγ in sensory neurons.\",\n      \"method\": \"Adenoviral knockdown/overexpression in neonatal rat DRG neurons, qRT-PCR, western blot, cell viability/apoptosis assays\",\n      \"journal\": \"Artificial cells, nanomedicine, and biotechnology\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single lab, indirect functional link between Cav3.3 and CaMKIIγ inferred from overexpression/knockdown without direct mechanistic assay\",\n      \"pmids\": [\"28974111\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"CaV3.3 (CACNA1I) is a low-voltage-activated T-type calcium channel whose slow gating kinetics are encoded by multiple distributed structural domains (particularly domain IV for activation), and whose activity in GABAergic thalamic reticular nucleus neurons drives rebound burst firing, sleep spindle rhythmogenesis, and pacemaker oscillations via a critical window current; the channel is selectively inhibited by Gαq/11-coupled muscarinic receptors and endogenous polyunsaturated lipids acting at a shared binding site, regulated by neuritin/IR/ERK-dependent surface trafficking and TET1-mediated DNA hydroxymethylation, and disease-causing gain-of-function variants in the channel gate region cause neurodevelopmental disorders by increasing calcium influx and neuronal hyperexcitability, while loss-of-function variants reduce TRN excitability and impair sleep spindle generation with implications for schizophrenia pathophysiology.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"CACNA1I encodes CaV3.3, a low-voltage-activated T-type calcium channel whose hallmark slow gating drives rebound burst firing and pacemaker oscillations in GABAergic neurons of the thalamic reticular nucleus, where it is required for normal sleep spindle generation during NREM sleep [#1, #9]. The channel's distinctively slow activation and inactivation kinetics are not assigned to any single structural element but emerge from multiple distributed domains, with domain IV serving as the major determinant of activation time constant and recovery from inactivation, and domains I and IV jointly setting the half-activation potential [#6, #7]; alternative splicing of exons 9 and 33 further tunes these gating properties [#5]. A sustained window current generated by CaV3.3 acts as the critical trigger for spontaneous membrane potential and intracellular Ca2+ oscillations, and genetic deletion of CaV3.3 abolishes low-threshold Ca2+ currents and bursting in reticular thalamic neurons and suppresses sleep-spindle sigma-band EEG power [#8, #9]. Channel activity is negatively regulated by Gaq/11-coupled muscarinic receptors (M1/M3/M5) and by endogenous polyunsaturated lipids that compete with synthetic T-channel inhibitors at a shared binding site [#4, #10], while surface expression is controlled by neuritin acting through insulin receptor and MEK/ERK signaling [#13] and channel gene expression by TET1-mediated DNA hydroxymethylation [#14]. Disease-causing variants act bidirectionally: gain-of-function substitutions at the cytoplasmic ends of S5/S6 segments and at the channel gate slow gating, left-shift voltage dependence, and increase window current and neuronal excitability, causing neurodevelopmental disorders and seizures, whereas loss-of-function variants reduce current density and excitability [#0, #2, #3].\",\n  \"teleology\": [\n    {\n      \"year\": 2003,\n      \"claim\": \"Establishing where and when the CaV3.3 protein is expressed was a prerequisite for assigning physiological function, and protein-level detection showed region- and developmental-stage-specific isoforms.\",\n      \"evidence\": \"Affinity-purified antibody western blotting and immunohistochemistry across mouse, rat, and human brain and spinal cord at multiple developmental stages\",\n      \"pmids\": [\"12614673\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Did not resolve molecular basis of the isoform mass differences\", \"No functional consequence of differential expression established\"]\n    },\n    {\n      \"year\": 2004,\n      \"claim\": \"It was unknown what structural features make CaV3.3 gating so slow; chimera and splicing analyses showed the kinetics are encoded by multiple distributed regions rather than a single domain.\",\n      \"evidence\": \"CaV3.1/CaV3.3 chimeric channels in Xenopus oocytes and splice-variant constructs (exon 9, delta33) by whole-cell patch-clamp\",\n      \"pmids\": [\"15016809\", \"15254077\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Did not identify the specific residues responsible\", \"Interaction between intracellular regions inferred, not structurally resolved\"]\n    },\n    {\n      \"year\": 2006,\n      \"claim\": \"Refining which domains dominate gating, domain IV was identified as the major determinant of activation and recovery kinetics, and the window current was shown to drive autonomous oscillatory activity.\",\n      \"evidence\": \"Domain-swap chimeras in tsA-201 cells, and whole-cell patch-clamp plus calcium imaging with pharmacological block in NG108-15 cells\",\n      \"pmids\": [\"16996222\", \"16706840\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Domain contributions only partially transfer kinetics\", \"Oscillation mechanism characterized in a cell line, not native neurons\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"How CaV3.3 is acutely modulated and post-translationally processed was unknown; muscarinic Gaq/11 signaling was shown to selectively inhibit CaV3.3, and N-glycosylation/polysialylation was shown to account for isoform mass differences.\",\n      \"evidence\": \"Perforated patch-clamp with mAChR subtypes and G-protein antagonists plus chimeric mapping; enzymatic deglycosylation (PNGase F, endoneuraminidase-N) with western blotting\",\n      \"pmids\": [\"17535809\", \"17317015\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Downstream effector linking Gaq/11 to channel inhibition not defined\", \"Functional role of polysialylation on channel activity untested\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Whether endogenous ligands modulate CaV3.3 was unclear; polyunsaturated lipids were shown to inhibit the channel at a binding site shared with synthetic T-channel blockers.\",\n      \"evidence\": \"Patch-clamp electrophysiology and [3H]TTA-A1 radioligand competition binding with multiple lipid structures\",\n      \"pmids\": [\"24214826\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Binding site not structurally localized\", \"Physiological relevance of endogenous lipid inhibition in vivo not shown\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"The in vivo role of CaV3.3 in thalamic rhythmogenesis was untested; a clinical variant and clean knockouts established that CaV3.3 function is required for reticular thalamic bursting and sleep spindle generation.\",\n      \"evidence\": \"R1346H biochemistry and patch-clamp with NEURON modeling; CaV3.2 and CaV3.2/CaV3.3 double-KO mice with thalamic slice recording and polysomnographic EEG\",\n      \"pmids\": [\"27756899\", \"26612388\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Behavioral/cognitive consequences of spindle loss not fully resolved\", \"Did not address gain-of-function disease mechanisms\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Mechanisms controlling CaV3.3 surface availability were unknown; neuritin was shown to increase channel surface expression via IR and MEK/ERK signaling, linking it to glutamate release.\",\n      \"evidence\": \"mEPSC recording, membrane-protein western blotting, HPLC, and pharmacological inhibition of IR/MEK/ERK and T-type channels in prefrontal cortex neurons\",\n      \"pmids\": [\"28475719\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct interaction between neuritin/IR and CaV3.3 not demonstrated\", \"Trafficking pathway inferred from inhibitor effects\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Whether CACNA1I disease variants act by gain or loss of function was unresolved; gain-of-function variants at S5/S6 cytoplasmic ends were shown to slow gating, increase window current, and elevate excitability.\",\n      \"evidence\": \"Site-directed mutagenesis, patch-clamp in HEK293T, structural modeling, native mouse chromaffin cell expression, and computational TRN modeling\",\n      \"pmids\": [\"33704440\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No in vivo model of the gain-of-function variants\", \"Structural basis of gating slowing inferred from modeling\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Additional disease and regulatory contexts were tested: rare variants alter biophysics in hemiplegic migraine, and TET1-mediated DNA hydroxymethylation controls Cav3.3 transcription.\",\n      \"evidence\": \"Patch-clamp of variant channels in HEK293T; TET1 overexpression/knockdown with MeDIP/hMeDIP and viability assays in Leydig cells\",\n      \"pmids\": [\"35928792\", \"36370755\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Causality of migraine variants not established beyond biophysics\", \"TET1 regulation shown in a non-neuronal cell line\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Whether the same residue can yield opposite functional outcomes was unknown; paired substitutions at A398 produced gain- versus loss-of-function, correlating seizures with gain-of-function excitability increases.\",\n      \"evidence\": \"Site-directed mutagenesis, voltage-clamp electrophysiology, and computational and structural modeling\",\n      \"pmids\": [\"40825030\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Genotype-phenotype correlation based on modeling, not patient-derived neurons\", \"No therapeutic intervention tested\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"The structural basis for CaV3.3's distributed slow-gating mechanism and the precise molecular link between Gaq/11 or lipid binding and channel inhibition remain undefined.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No high-resolution structure of the channel or ligand-binding site\", \"Direct effectors coupling receptor signaling to channel gating unidentified\", \"In vivo disease models for most variants lacking\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0005215\", \"supporting_discovery_ids\": [2, 8, 9]},\n      {\"term_id\": \"GO:0005216\", \"supporting_discovery_ids\": [2, 6, 8]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [0, 13]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-112316\", \"supporting_discovery_ids\": [1, 9]},\n      {\"term_id\": \"R-HSA-382551\", \"supporting_discovery_ids\": [2, 8]}\n    ],\n    \"complexes\": [],\n    \"partners\": [],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":5,"faith_total":5,"faith_pct":100.0}}