Affinage

CACNA2D4

Voltage-dependent calcium channel subunit alpha-2/delta-4 · UniProt Q7Z3S7

Length
1137 aa
Mass
127.9 kDa
Annotated
2026-06-09
36 papers in source corpus 10 papers cited in narrative 10 extracted findings
Cross-family judge vs UniProt: Affinage preferred faithfulness: 6/6 claims corpus-supported (100%)

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

CACNA2D4 encodes α2δ-4, an auxiliary subunit of voltage-gated CaV1.4 L-type calcium channels that is essential for the molecular and structural organization of rod and cone photoreceptor ribbon synapses (PMID:29875267). Full-length α2δ-4 increases CaV1.4-mediated calcium currents, a function that depends on its C-terminal portion, since naturally occurring truncated and alternatively spliced variants fail to potentiate the current (PMID:26218913). Loss of α2δ-4 in knockout mice abolishes ribbons in rod terminals early in development, disrupts triadic synaptic organization, and produces progressive depletion of presynaptic CaV1.4 channels first in rods then in cones, culminating in absent ERG b-waves (PMID:29875267); this requirement for delivering CaV1.4 to the synaptic membrane is evolutionarily conserved, as zebrafish cacna2d4 knockout reduces CaV1.4 expression and produces ectopic, untethered ribbons (PMID:31834350). At photoreceptor terminals α2δ-4-dependent organization also supports the functional coupling of CaV1.4 to TMEM16A calcium-activated chloride channels, with mutant rods showing impaired chloride currents despite preserved TMEM16A protein (PMID:26557056), and broader calcium dysregulation including depleted internal stores (PMID:36361866). Disruptive mutations cause retinal degeneration: a homozygous frameshift in mouse Cacna2d4 produces abnormal rod and cone ribbon synapses with loss of retinal signaling (PMID:16877424), and a homozygous nonsense mutation in human CACNA2D4 causes autosomal recessive cone dystrophy (PMID:17033974). Beyond the retina, α2δ-4 is transcriptionally driven by Egr1 and modulates hippocampal network activity and seizure susceptibility (PMID:30792272), and its loss produces sensorimotor gating deficits and hyperactivity (PMID:35353835), indicating broader CNS roles.

Mechanistic history

Synthesis pass · year-by-year structured walk · 10 steps
  1. 2006 High

    Established that Cacna2d4 is required for normal photoreceptor synapse morphology and retinal signaling, linking the gene to ribbon synapse integrity.

    Evidence Positional cloning of a spontaneous frameshift mouse mutant with linkage, sequencing, Northern blot, RT-PCR and immunohistochemistry

    PMID:16877424

    Open questions at the time
    • Did not define the molecular function of α2δ-4 at the channel level
    • Mechanism of ribbon disorganization unresolved
  2. 2006 Medium

    Extended the retinal phenotype to humans, establishing CACNA2D4 as a disease gene for autosomal recessive cone dystrophy.

    Evidence Direct sequencing and clinical electroretinography in affected siblings

    PMID:17033974

    Open questions at the time
    • Single family
    • Did not establish the cellular mechanism connecting mutation to cone degeneration
  3. 2015 Medium

    Defined the channel-modulatory function of α2δ-4 and localized it to the C-terminus, explaining why disease-associated truncations are pathogenic.

    Evidence Whole-cell patch-clamp of CaV1.4/β3 with full-length versus truncated/spliced α2δ-4 in HEK293T cells, with splicing and minigene analysis

    PMID:26218913

    Open questions at the time
    • In vitro reconstitution only; native trafficking role not addressed
    • Single lab
  4. 2015 Medium

    Connected α2δ-4 to a second synaptic conductance by showing CaV1.4 physically associates with TMEM16A and that the mutation impairs chloride currents.

    Evidence Reciprocal co-immunoprecipitation from retina, heterologous expression, and patch-clamp in Cacna2d4 mutant rods

    PMID:26557056

    Open questions at the time
    • Functional disruption observed despite intact physical TMEM16A levels; mechanism of uncoupling unclear
    • Single lab
  5. 2018 High

    Demonstrated with a clean knockout that α2δ-4 organizes ribbon synapse architecture and stabilizes presynaptic CaV1.4, establishing its developmental and structural role.

    Evidence CRISPR/Cas9 KO mice analyzed by SBF-SEM, immunohistochemistry, ERG and visual behavior

    PMID:29875267

    Open questions at the time
    • Molecular steps linking α2δ-4 to ribbon assembly not defined
    • Single lab
  6. 2019 Medium

    Showed the CaV1.4-targeting function is evolutionarily conserved and dissected paralog-specific contributions in zebrafish.

    Evidence CRISPR/Cas9 KO of cacna2d4a and cacna2d4b with ERG, IHC, EM and in situ hybridization

    PMID:31834350

    Open questions at the time
    • Paralog functional redundancy in mammals not addressed
    • Single lab
  7. 2019 Medium

    Revealed an extra-retinal regulatory axis, identifying Egr1 as a transcriptional driver of α2δ-4 and linking the subunit to hippocampal excitability and seizure susceptibility.

    Evidence ChIP and reporter assays, viral overexpression in mouse hippocampus, seizure susceptibility testing, and qPCR in human epilepsy biopsies

    PMID:30792272

    Open questions at the time
    • Channel partner mediating hippocampal effects not identified
    • Single lab
  8. 2022 Medium

    Showed calcium dysregulation in mutant rods extends beyond VGCC loss to depleted internal stores and upregulated cationic conductance, broadening the mechanistic interpretation of the phenotype.

    Evidence Patch-clamp and calcium imaging in isolated mouse rod photoreceptors

    PMID:36361866

    Open questions at the time
    • Causal relationship between store depletion and channel loss unresolved
    • Single study
  9. 2022 Medium

    Documented behavioral CNS roles for α2δ-4 beyond the retina, including sensorimotor gating and activity phenotypes.

    Evidence Behavioral phenotyping battery and auditory brainstem response in α2δ-4 KO mice

    PMID:35353835

    Open questions at the time
    • Neural circuit and molecular basis of behavioral deficits unknown
    • Single lab
  10. 2026 Medium

    Characterized pharmacological modulation of α2δ-4-supported CaV1.4 channels and mapped a structural determinant distinguishing CaV1.4 from CaV1.2.

    Evidence Patch-clamp of reconstituted CaV1.4/β2x13/α2δ-4 in HEK293T cells with mutagenesis and structure-based modeling

    PMID:41489546

    Open questions at the time
    • Determinant defined in the α1 pore subunit, not α2δ-4 itself
    • In vitro only

Open questions

Synthesis pass · forward-looking unresolved questions
  • The molecular mechanism by which α2δ-4 nucleates ribbon synapse assembly and traffics CaV1.4 to the presynaptic membrane remains undefined.
  • No structural model of α2δ-4 bound to CaV1.4
  • Trafficking/anchoring partners at the ribbon unidentified
  • Mechanism linking calcium store depletion to channel loss unresolved

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0098772 molecular function regulator activity 1
Localization
GO:0005886 plasma membrane 2
Pathway
R-HSA-112316 Neuronal System 2 R-HSA-9709957 Sensory Perception 2
Partners
CACNA1FEGR1TMEM16A
Complex memberships
CaV1.4 L-type calcium channel complex

Evidence

Reading pass · 10 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
2006 A homozygous frameshift mutation (c.2367insC) in Cacna2d4 causes a premature stop codon truncating one-third of the predicted protein, leads to severe reduction in Cacna2d4 transcript levels, and results in loss of retinal signaling with abnormal morphology of ribbon synapses in rods and cones in a spontaneous mouse mutant. Genome-wide linkage analysis, positional candidate gene screening, Northern blot analysis, RT-PCR, immunohistochemistry Investigative ophthalmology & visual science High 16877424
2006 A homozygous nucleotide substitution (c.2406C→A) in human CACNA2D4 introduces a premature stop codon truncating one-third of the protein and causes autosomal recessive cone dystrophy in humans, establishing CACNA2D4 as a disease gene for retinal degeneration. Mutation analysis by direct sequencing in patients, clinical electroretinography American journal of human genetics Medium 17033974
2015 TMEM16A (a calcium-activated chloride channel) associates physically with CaV1.4 (the α1 subunit of voltage-gated calcium channels) in the retina, as shown by co-immunoprecipitation; this interaction is disrupted in its functional consequence (but not physical association) by the Cacna2d4 mutation, which disorganizes synaptic terminals and impairs calcium-activated chloride currents in rods despite normal TMEM16A protein levels. Co-immunoprecipitation from retina, heterologous expression in tsA-201 cells, patch-clamp electrophysiology, immunohistochemistry in Cacna2d4 mutant mice Frontiers in cellular neuroscience Medium 26557056
2015 Full-length α2δ4 increases CaV1.4/β3-mediated calcium currents in electrophysiological recordings; truncated or alternatively spliced α2δ4 variants (including a naturally occurring E25b isoform that mimics the c.2451insC mutation) do not increase CaV1.4-mediated currents, demonstrating that the C-terminal portion of α2δ4 is required for its channel modulatory function. Whole-cell patch-clamp recordings in HEK293T cells transfected with CaV1.4/β3 plus various α2δ4 variants; RT-PCR splicing analysis in mouse retina and minigene assays Investigative ophthalmology & visual science Medium 26218913
2018 α2δ-4 is required for the molecular and structural organization of rod and cone photoreceptor ribbon synapses; α2δ-4 knockout mice lack ribbons in rod spherules early in development, show abnormal horizontal and bipolar cell process extension into the outer nuclear layer, have less than one-third of cone ribbon sites with expected triadic organization, and progressively lose CaV1.4 channels first in rod terminals then in cone terminals, resulting in absent b-waves on ERG. CRISPR/Cas9 genome editing to generate α2δ-4 KO mice, electroretinography, serial block-face scanning electron microscopy, immunohistochemistry, visually guided behavior assays The Journal of neuroscience High 29875267
2019 The transcription factor Early Growth Response 1 (Egr1) drives expression of the CACNA2D4-encoded α2δ4 subunit; α2δ4 levels are augmented early and persistently after pilocarpine-induced status epilepticus, and increasing α2δ4 levels in the hippocampal CA1 region elevates seizure susceptibility by slightly decreasing local network activity. Chromatin immunoprecipitation and promoter reporter assays for Egr1 binding; stereotactic viral α2δ4 overexpression in mouse hippocampus; in vivo seizure susceptibility testing; qPCR in human epilepsy biopsies The Journal of neuroscience Medium 30792272
2019 In zebrafish, knockout of cacna2d4b (but not cacna2d4a) reduces expression of Cacna1fa (the pore-forming CaV1.4 subunit) and causes ectopic punctate expression of both Cacna1fa and Ribeyeb (a ribbon protein); only double knockout of both paralogs impairs cone-mediated ERG b-wave amplitude and increases 'floating' (untethered) ribbons, indicating that increasing CaV1.4 expression at the synaptic membrane is an evolutionarily conserved function of Cacna2d4. CRISPR/Cas9 mutagenesis of zebrafish cacna2d4a and cacna2d4b; electroretinography; immunohistochemistry; electron microscopy; RNA in situ hybridization Investigative ophthalmology & visual science Medium 31834350
2022 In Cacna2d4 frameshift mutant rod photoreceptors, calcium dysregulation extends beyond reduced VGCC calcium entry: internal calcium stores are depleted and calcium entry via non-selective cationic channels (CSC) is upregulated, suggesting the primary defect may lie in defective calcium stores rather than solely in VGCC loss. Whole-cell patch-clamp recordings and calcium imaging in isolated mouse rod photoreceptors from Cacna2d4 mutant and wild-type mice International journal of molecular sciences Medium 36361866
2022 α2δ-4 knockout mice exhibit impaired prepulse inhibition (sensorimotor gating), hyperactivity, sex-dependent motor coordination deficits (females only), and anxiolytic/anti-depressive behaviors, revealing extra-retinal roles for α2δ-4 in CNS function. Behavioral phenotyping of α2δ-4 KO mice: prepulse inhibition, open field, rotarod, elevated plus maze, tail suspension test; auditory brainstem response PloS one Medium 35353835
2026 In HEK293T cells transfected with CaV1.4 plus auxiliary β2x13 and α2δ-4 subunits, the CaV3 antagonists Z944 and ML218 inhibit CaV1.4 Ca2+ currents (IC50 ~30 µM and ~2 µM, respectively); structure-based modeling and mutagenesis identified a cluster of methionine residues (particularly M1004) within the dihydropyridine-binding site as critical for ML218 sensitivity, distinguishing CaV1.4 from CaV1.2. Whole-cell patch-clamp in HEK293T cells expressing CaV1.4/β2x13/α2δ-4; site-directed mutagenesis; structure-based computational modeling The Journal of general physiology Medium 41489546

Source papers

Stage 0 corpus · 36 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2006 Mutation in the auxiliary calcium-channel subunit CACNA2D4 causes autosomal recessive cone dystrophy. American journal of human genetics 131 17033974
2006 Structural and functional abnormalities of retinal ribbon synapses due to Cacna2d4 mutation. Investigative ophthalmology & visual science 109 16877424
2016 Epigenetic signatures of childhood abuse and neglect: Implications for psychiatric vulnerability. Journal of psychiatric research 80 27643477
2012 Ultrafast genome-wide scan for SNP-SNP interactions in common complex disease. Genome research 80 22767386
2018 α2δ-4 Is Required for the Molecular and Structural Organization of Rod and Cone Photoreceptor Synapses. The Journal of neuroscience : the official journal of the Society for Neuroscience 61 29875267
2019 circRNA/lncRNA-miRNA-mRNA Network in Oxidized, Low-Density, Lipoprotein-Induced Foam Cells. DNA and cell biology 56 31804889
2020 Transcriptome and methylome analysis reveals three cellular origins of pituitary tumors. Scientific reports 53 33168897
2014 Emerging evidence for specific neuronal functions of auxiliary calcium channel α₂δ subunits. General physiology and biophysics 52 25504062
2020 Genetic associations between voltage-gated calcium channels and autism spectrum disorder: a systematic review. Molecular brain 49 32571372
2014 Whole-exome sequencing in familial atrial fibrillation. European heart journal 37 24727801
2009 Genotyping microarray for CSNB-associated genes. Investigative ophthalmology & visual science 37 19578023
2022 Genome-Wide Placental Gene Methylations in Gestational Diabetes Mellitus, Fetal Growth and Metabolic Health Biomarkers in Cord Blood. Frontiers in endocrinology 32 35721735
2014 L-type calcium channel blockers and substance P induce angiogenesis of cortical vessels associated with beta-amyloid plaques in an Alzheimer mouse model. Neurobiology of aging 29 25619662
2019 Calcium Channel Subunit α2δ4 Is Regulated by Early Growth Response 1 and Facilitates Epileptogenesis. The Journal of neuroscience : the official journal of the Society for Neuroscience 27 30792272
2015 A Naturally Occurring Canine Model of Autosomal Recessive Congenital Stationary Night Blindness. PloS one 27 26368928
2010 1.39 Mb inherited interstitial deletion in 12p13.33 associated with developmental delay. European journal of medical genetics 26 21144913
2015 TMEM16A is associated with voltage-gated calcium channels in mouse retina and its function is disrupted upon mutation of the auxiliary α2δ4 subunit. Frontiers in cellular neuroscience 23 26557056
2017 Whole Genome Sequencing Revealed Mutations in Two Independent Genes as the Underlying Cause of Retinal Degeneration in an Ashkenazi Jewish Pedigree. Genes 17 28837078
2022 Functional assays of non-canonical splice-site variants in inherited retinal dystrophies genes. Scientific reports 16 34996991
2015 A New Splicing Isoform of Cacna2d4 Mimicking the Effects of c.2451insC Mutation in the Retina: Novel Molecular and Electrophysiological Insights. Investigative ophthalmology & visual science 16 26218913
2013 Analysis of cell surface markers specific for transplantable rod photoreceptors. Molecular vision 16 24146539
2019 A New Zebrafish Model for CACNA2D4-Dysfunction. Investigative ophthalmology & visual science 13 31834350
2020 Comprehensive analysis of differential immunocyte infiltration and the potential ceRNA networks during epicardial adipose tissue development in congenital heart disease. Journal of translational medicine 11 32122382
2019 Metastatic colorectal cancer and severe hypocalcemia following irinotecan administration in a patient with X-linked agammaglobulinemia: a case report. BMC medical genetics 11 31510946
2020 Molecular alterations in non-functioning pituitary adenomas. Cancer biomarkers : section A of Disease markers 9 32224525
2022 The voltage-gated Ca2+ channel subunit α2δ-4 regulates locomotor behavior and sensorimotor gating in mice. PloS one 8 35353835
2023 Identification of methylation-regulated genes modulating microglial phagocytosis in hyperhomocysteinemia-exacerbated Alzheimer's disease. Alzheimer's research & therapy 7 37789414
2021 Novel compound heterozygous missense variants (c.G955A and c.A1822C) of CACNA2D4 likely causing autosomal recessive retinitis pigmentosa in a Chinese patient. 3 Biotech 5 33927996
2023 Integration of GWAS and eGWAS to screen candidate genes underlying green head traits in male ducks. Animal genetics 4 37194451
2021 Alterations in the Ca2+ toolkit in oesophageal adenocarcinoma. Exploration of targeted anti-tumor therapy 4 36046118
2022 Depleted Calcium Stores and Increased Calcium Entry in Rod Photoreceptors of the Cacna2d4 Mouse Model of Cone-Rod Dystrophy RCD4. International journal of molecular sciences 3 36361866
2024 Genomic analysis of an aggressive hepatic leiomyosarcoma case following treatment for hepatocellular carcinoma. Hepatology research : the official journal of the Japan Society of Hepatology 2 38459823
2025 Intrafamilial variability of phenotype in CACNA2D4-associated retinal dysfunction: more or less. Documenta ophthalmologica. Advances in ophthalmology 1 40883544
2026 Inhibition of CaV1.4 channels by CaV3 channel antagonists ML218 and Z944. The Journal of general physiology 0 41489546
2026 DNA methylation signatures associated with bipolar disorder in peripheral blood improve prediction models. EBioMedicine 0 42105630
2023 Identification of candidate genes for developmental colour agnosia in a single unique family. PloS one 0 37672513

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