Affinage

GJD2

Gap junction delta-2 protein · UniProt Q9UKL4

Round 2 corrected
Length
321 aa
Mass
36.1 kDa
Annotated
2026-04-28
93 papers in source corpus 41 papers cited in narrative 41 extracted findings

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

GJD2 encodes connexin 36 (Cx36), the principal gap junction protein of neuronal electrical synapses and pancreatic beta-cells, where it forms homotypic, strongly cation-selective intercellular channels that synchronize membrane potential and Ca²⁺ oscillations (PMID:9753189, PMID:10905480, PMID:22752717). Cryo-EM structures reveal that channel gating involves an α-to-π-helix transition in TM1 that repositions N-terminal helices into the pore lumen, while channel closure is achieved by lipid occlusion when inhibitors (mefloquine, arachidonic acid) competitively displace N-terminal helices from their pore-lining configuration (PMID:36906653, PMID:39455592). Channel conductance is potentiated by Ca²⁺/calmodulin binding at the C-terminal tail (W277/V284 anchors) and by CaMKII phosphorylation of overlapping cytoplasmic domains, while CaMKII phosphorylation simultaneously weakens ZO-1 scaffold interactions to remodel electrical synapse architecture; LNX1/LNX2 E3 ubiquitin ligases ubiquitinate Cx36 to drive gap junction plaque internalization (PMID:27917108, PMID:19095792, PMID:19418635, PMID:30295974). In beta-cells, Cx36-dependent coupling propagates hyperpolarizing currents to coordinate insulin secretion, with transcription controlled by Beta2/NeuroD1 (activator) and NRSF/REST (repressor), while in the retina, layer-specific Cx36 gap junctions differentially set visual detection thresholds and regulate emmetropization (PMID:17395748, PMID:22729650, PMID:14565956, PMID:41623460, PMID:34083742).

Mechanistic history

Synthesis pass · year-by-year structured walk · 16 steps
  1. 1998 High

    The identity of a neuron-specific connexin was unknown; cloning of Cx36 from mammalian brain established GJD2 as the first connexin expressed preferentially in neurons rather than glia, defining a new molecular basis for neuronal electrical synapses.

    Evidence Degenerate RT-PCR cloning, in situ hybridization with neurotoxin lesion validation in rat brain

    PMID:9753189

    Open questions at the time
    • Functional channel properties not yet determined
    • No loss-of-function data
  2. 2000 High

    Whether Cx36 operated outside the CNS was unclear; detection of Cx36 selectively in pancreatic beta-cells established a second major physiological context and linked gap junctions to insulin secretion biology.

    Evidence In situ hybridization, immunolabeling, FACS-purified beta- vs. non-beta-cell fractions in rodent islets

    PMID:10905480

    Open questions at the time
    • Functional consequence for insulin secretion not yet demonstrated
    • Human beta-cell expression not confirmed at this point
  3. 2001 High

    Whether neuronal and glial gap junctions share connexins was debated; ultrastructural FRIL demonstrated that Cx36 is exclusively neuronal, with no overlap with astrocytic (Cx43/Cx30/Cx26) or oligodendrocytic (Cx32) connexins.

    Evidence Freeze-fracture replica immunogold labeling of >4000 gap junctions in adult rat CNS

    PMID:12064610

    Open questions at the time
    • Regional variation in co-expression with other neuronal connexins (e.g. Cx45) not fully resolved
  4. 2003 High

    How Cx36 expression is restricted to neurons and beta-cells was unknown; identification of NRSF/REST as a transcriptional repressor acting via an NRSE element in the GJD2 promoter explained tissue specificity—cells lacking NRSF (neurons, beta-cells) express Cx36.

    Evidence Luciferase reporter assays, NRSF viral gain-of-function in beta-cell lines, NRSE mutagenesis, HDAC inhibitor treatment

    PMID:14565956

    Open questions at the time
    • Other transcription factors (beyond NRSF) controlling Cx36 not yet identified
    • Chromatin-level regulation not mapped
  5. 2004 High

    Whether Cx36 was functionally required for beta-cell secretion (versus a bystander) was unresolved; lentiviral rescue of Cx36 (but not E-cadherin) in Cx36-depleted MIN6 cells demonstrated specific and non-redundant control of insulin secretion by Cx36 gap junctions.

    Evidence Stable antisense transfection, lentiviral rescue, insulin secretion assays with multiple secretagogues

    PMID:15023528

    Open questions at the time
    • In vivo relevance in whole-animal glucose homeostasis not yet tested
  6. 2007 High

    The biophysical mechanism by which Cx36 controls beta-cell excitability was unclear; electrophysiology in Cx36 KO pancreatic slices showed that Cx36 propagates hyperpolarizing currents from inactive cells, dampening excitability across the islet, and that Cx36 channels are strongly cation-selective.

    Evidence Patch-clamp electrophysiology in pancreatic slices from Cx36-/-, +/-, +/+ mice; tracer permeability with multiple charged dyes

    PMID:17395748 PMID:17828386

    Open questions at the time
    • Structural basis for cation selectivity not yet determined
    • Molecular identity of permeant species in vivo unknown
  7. 2008 High

    How Cx36 coupling strength is dynamically regulated was unknown; discovery that CaMKII directly binds and phosphorylates Cx36 at cytoplasmic domains analogous to the CaMKII–NR2B interaction established a Ca²⁺-dependent plasticity mechanism for electrical synapses.

    Evidence In vitro CaMKII binding and phosphorylation assays with Cx36 cytoplasmic peptides, immunofluorescence colocalization in inferior olive

    PMID:19095792

    Open questions at the time
    • Phosphorylation sites not mapped to specific residues at this stage
    • In vivo consequence of phosphorylation on coupling not demonstrated
  8. 2009 High

    How Cx36 is anchored at gap junction plaques was unresolved; identification of ZO-2 and ZO-3 as PDZ1-domain partners binding the C-terminal SAYV motif established a scaffold complex at Cx36 electrical synapses.

    Evidence Reciprocal co-immunoprecipitation, in vitro PDZ pull-down, C-terminal truncation mutagenesis in HeLa and betaTC-3 cells

    PMID:19418635

    Open questions at the time
    • Whether ZO-1 also binds Cx36 directly not confirmed until later studies
    • Functional consequence of scaffold disruption on coupling not tested
  9. 2012 High

    The developmental transcriptional activator of Cx36 in beta-cells was unknown; Beta2/NeuroD1 was shown to bind E-boxes in the GJD2 promoter and transactivate it, establishing Cx36 as a direct transcriptional target during prenatal beta-cell differentiation.

    Evidence Reporter gene assays with GJD2 promoter fragments, E-box binding assays, lentiviral NeuroD1 expression, developmental immunolabeling

    PMID:22729650

    Open questions at the time
    • Whether NeuroD1 also controls Cx36 in neurons not tested
    • Epigenetic regulation of the GJD2 locus not addressed
  10. 2016 High

    How Ca²⁺ directly modulates Cx36 channels was structurally undefined; NMR resolution of the CaM–Cx36 C-terminal complex revealed Ca²⁺-loaded CaM binds at W277/V284 in a compact conformation and activates Cx36 channels, unlike its inhibitory role on other connexins.

    Evidence NMR solution structure, Ca²⁺-dependent binding assays, electrophysiological channel activation measurements

    PMID:27917108

    Open questions at the time
    • Full-length Cx36–CaM complex structure not available
    • Whether CaM and CaMKII binding are mutually exclusive in situ remains unclear
  11. 2018 High

    How Cx36 gap junctions are turned over was unknown; LNX1/LNX2 E3 ubiquitin ligases were identified as direct interactors that ubiquitinate Cx36 and drive gap junction plaque internalization, establishing ubiquitin-dependent degradation as a removal mechanism.

    Evidence Co-IP, PDZ pull-down, cotransfection of ligase-active vs. ligase-dead LNX isoforms, LNX null mice

    PMID:30295974

    Open questions at the time
    • Specific ubiquitination sites on Cx36 not mapped
    • Whether LNX acts at all Cx36-expressing tissues not tested
  12. 2023 High

    The structural basis for Cx36 gating and cation selectivity was unknown; cryo-EM structures at 2.2–3.6 Å revealed that channel opening requires an α-to-π-helix transition in TM1 that positions N-terminal helices into a negatively charged pore, while closure involves lipid occlusion of the channel.

    Evidence Cryo-electron microscopy of human Cx36 gap junction channels in open and closed conformations

    PMID:36906653

    Open questions at the time
    • Dynamics of lipid entry/exit not resolved
    • No structures with CaM or CaMKII-phosphorylated Cx36
  13. 2024 High

    How pharmacological inhibitors block Cx36 was structurally undefined; cryo-EM structures with mefloquine, arachidonic acid, and hexanol showed all three bind a common N-terminal helix pocket, shifting it from a pore-lining to a flexible state that permits lipid occlusion, unifying the inhibition mechanism.

    Evidence Cryo-EM structures of inhibitor-bound Cx36 with conformational state analysis

    PMID:39455592

    Open questions at the time
    • No activator-bound structures available
    • Whether this mechanism extends to in vivo neuromodulatory inhibition is untested
  14. 2024 High

    How Cx36 traffics from ER to plasma membrane was poorly understood; identification of the C-terminal valine as a COPII/Sec24 ER-export signal and the SAYV PDZ motif as a Grasp55-mediated Golgi retention signal established opposing regulatory checkpoints in the early secretory pathway.

    Evidence BioID proximity labeling, siRNA knockdown, co-immunoprecipitation, confocal ER/Golgi localization in HEK293T cells

    PMID:39395036

    Open questions at the time
    • Whether these trafficking signals are regulated by phosphorylation in vivo is unknown
    • Post-Golgi trafficking steps not mapped
  15. 2025 High

    Whether Cx36 gap junctions serve identical functions across retinal layers was unclear; layer-specific knockout showed that outer retinal Cx36 lowers visual thresholds (increases sensitivity) while inner retinal Cx36 maintains thresholds, revealing opposing functional roles of the same connexin in different circuit contexts.

    Evidence Transgenic mice with retinal layer-specific Cx36 knockout, operant behavioral assay, psychophysical modeling

    PMID:41623460

    Open questions at the time
    • Circuit-level mechanism by which inner vs. outer Cx36 differentially set thresholds not fully resolved
    • Contribution of Cx36 phosphorylation state in each layer not tested
  16. 2025 High

    The relative contribution of Cx36 gap junctions versus paracrine signaling to delta-beta cell coordination in islets was debated; selective delta-cell Cx36 KO and vesicle-release blockade demonstrated that paracrine signals (Urocortin 3) dominate, with Cx36 providing a secondary coordination mechanism.

    Evidence GCaMP6s Ca²⁺ imaging, delta-cell-specific Cx36 knockout, Rho-GTPase inhibitor to block vesicle release

    PMID:40956879

    Open questions at the time
    • Whether Cx36 coupling between delta and beta cells is physiologically regulated remains unclear
    • Direct measurement of delta-beta electrical coupling not performed

Open questions

Synthesis pass · forward-looking unresolved questions
  • Key unresolved questions include: (1) the full-length structure of Cx36 in complex with CaM or in a CaMKII-phosphorylated state; (2) how post-Golgi trafficking delivers Cx36 to specific synaptic sites; (3) the identity and roles of most proteins in the Cx36 electrical synapse proteome identified by proximity labeling; and (4) whether Cx36 dysfunction directly causes human Mendelian disease.
  • No CaM-bound or phospho-Cx36 cryo-EM structure
  • Post-Golgi trafficking pathway undefined
  • Most BioID-identified interactors lack functional validation
  • No causative human mutations in GJD2 linked to Mendelian disease with direct evidence

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0005215 transporter activity 6 GO:0098631 cell adhesion mediator activity 3
Localization
GO:0005886 plasma membrane 5 GO:0005783 endoplasmic reticulum 1 GO:0005794 Golgi apparatus 1 GO:0005829 cytosol 1
Pathway
R-HSA-112316 Neuronal System 6 R-HSA-1500931 Cell-Cell communication 6 R-HSA-162582 Signal Transduction 6 R-HSA-382551 Transport of small molecules 3 R-HSA-9609507 Protein localization 1
Partners
CALM1CAMK2BGORASP2LNX1LNX2TJP1TJP2TJP3
Complex memberships
Cx36 homotypic gap junction channel (dodecameric)

Evidence

Reading pass · 41 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
1998 Cx36 (encoded by GJD2) was cloned as a new connexin family member of 321 amino acids, and in situ hybridization showed it is expressed predominantly in mammalian neurons (inferior olive, olfactory bulb, hippocampus, brainstem nuclei, retinal ganglion cell and inner nuclear layers), making it the first connexin shown to be expressed preferentially in neurons rather than glia. Degenerate RT-PCR cloning, genomic library isolation, in situ hybridization, neurotoxin lesion experiments The European journal of neuroscience High 9753189
1999 The human GJD2 gene was cloned and localized to chromosome 15q14; its coding sequence is 98% identical at the protein level to mouse/rat Cx36, and the gene structure (single intron 71 bp after the translation initiation site) is conserved across species, confirming it is the human ortholog of rodent Cx36. Gene cloning, sequencing, fluorescence in situ hybridization (FISH), radioactive in situ hybridization Journal of neuroscience research High 10462698
2000 Cx36 is selectively expressed by insulin-producing beta-cells in the central region of pancreatic islets, with little or no expression in other endocrine cell types (alpha, delta cells), establishing beta-cell-specific gap junctional coupling via Cx36. In situ hybridization, immunolabeling with affinity-purified antibodies, FACS-purified beta- vs. non-beta-cell fractions Diabetes High 10905480
2001 Freeze-fracture replica immunogold labeling (FRIL) demonstrated that Cx36 is exclusively localized to neuronal gap junctions in adult rat CNS, whereas Cx26, Cx30, and Cx43 are restricted to astrocytes and Cx32 to oligodendrocytes, establishing separate and non-overlapping connexin-defined pathways for neuronal versus glial gap junctional communication. Freeze-fracture replica immunogold labeling (FRIL), confocal immunocytochemistry Cell communication & adhesion High 12064610
2001 Global ischemia induced a selective increase in Cx36 protein (without corresponding mRNA increase) in parvalbumin-positive inhibitory interneurons of CA1 hippocampus before neuronal death, suggesting post-translational regulation of Cx36 and a role for Cx36 gap junctions in the survival of GABAergic interneurons. Western blot, Northern blot, in situ hybridization, double immunofluorescence, Cx32 knockout mouse model The Journal of neuroscience Medium 11567043
2002 N-terminal domain mutagenesis of Cx36 identified a structural element necessary for normal subcellular localization; site-directed mutagenesis of putative phosphorylation motifs did not alter localization, indicating that phosphorylation/dephosphorylation is not the major regulatory step in Cx36 protein transport. Cx36-EGFP formed functional gap junction plaques with electrical properties indistinguishable from native Cx36. Cx36-EGFP transfection in neuroblastoma cell lines and primary hippocampal neurons, mutagenesis, electrophysiology Journal of neuroscience research Medium 12210839
2003 The neuron-restrictive silencer factor (NRSF/REST) acts as a transcriptional repressor of the GJD2 (Cx36) gene via a conserved neuron-restrictive silencer element (NRSE) in the promoter; ectopic NRSF expression in beta-cell lines markedly reduced Cx36 mRNA and protein, and mutation of the NRSE relieved repression, explaining why Cx36 is expressed specifically in neurons and beta-cells (which lack NRSF). Luciferase reporter assays, viral gene transfer of NRSF into beta-cell lines, NRSE mutagenesis, trichostatin A (HDAC inhibitor) treatment The Journal of biological chemistry High 14565956
2003 Cx36-dependent gap junction coupling controls cytosolic Ca2+ handling in populations of insulin-producing cells; loss of Cx36 expression altered Ca2+ transients, identifying a molecular link between Cx36 and the stimulus-secretion pathway for insulin secretion. Antisense Cx36 transfection in MIN6 cells, Ca2+ imaging, insulin secretion assays Cell communication & adhesion Medium 14681053
2004 Mefloquine potently and selectively blocks Cx36 gap junction channels (IC50 ~300 nM) and Cx50 channels (IC50 ~1.1 µM) while only affecting Cx43, Cx32, and Cx26 at 10–100-fold higher concentrations; mefloquine (25 µM) blocked gap junctional coupling between neocortical interneurons in brain slices with minimal nonspecific effects on synaptic potentials or intrinsic properties. Whole-cell patch clamp in transfected N2A cells, acute neocortical brain slices, pharmacological dose-response Proceedings of the National Academy of Sciences of the United States of America High 15297615
2004 Cx36, but not E-cadherin, is specifically required for normal insulin secretion in MIN6 beta-cells; lentivirus-mediated restoration of Cx36 (but not E-cadherin) rescued insulin secretory defects in Cx36 antisense-transfected clones, demonstrating that Cx36 gap junction function specifically controls beta-cell secretion. Stable antisense transfection, lentiviral transduction, insulin secretion assays Experimental cell research High 15023528
2004 A lacZ reporter driven by the Cx36 locus revealed expression in GABAergic neurons of cerebellar nuclei, non-GABAergic neurons of the inferior olive, mitral cells of the olfactory bulb, parvalbumin-positive cells of cerebral cortex, retinal layers, insulin-producing beta-cells of the pancreas, and the adrenal medulla, establishing the full tissue distribution of Cx36 in adult mice. Beta-galactosidase reporter gene expression in Cx36(+/del[LacZ]) transgenic mice, histochemistry The Journal of comparative neurology High 15116387
2005 Human and mouse microglia express Cx36 mRNA and protein, and Cx36 gap junctions form between microglia and neurons in co-culture, providing electrophysiological coupling below 30 pS consistent with Cx36 channel properties; this establishes a direct physical channel of communication between microglia and neurons via Cx36. RT-PCR, Western blot, immunofluorescence, electrophysiology (coupling measurements), Lucifer yellow dye coupling Journal of neuroscience research Medium 16211561
2006 FRIL ultrastructural analysis confirmed that Cx36 (and less abundantly Cx45) is present at neuronal gap junctions specifically at 'mixed' glutamatergic/electrical synapses between mitral/tufted cell dendrites in the olfactory bulb; Cx36 was absent from olfactory receptor neuron axons, and genomic analysis revealed multiple miRNA binding sites in the 3'-UTR of Cx36 consistent with post-transcriptional regulation. Freeze-fracture replica immunogold labeling (FRIL), confocal immunofluorescence, genomic miRNA binding site analysis Journal of neurocytology High 16841170
2007 Cx36 gap junctional coupling electrically hyperpolarizes beta-cells by propagating the membrane potential of adjacent inactive cells; in Cx36 knockout mice with blocked KATP channels, beta-cells rapidly depolarized and showed continuous electrical activity rather than the hyperpolarized state seen in coupled cells. Loss of Cx36 also increased Ca2+ channel density and altered the kinetics of insulin secretion in response to glucose changes. Electrophysiology in pancreatic slices from Cx36-/-, Cx36+/-, and Cx36+/+ mice; Ca2+ channel recordings; comparison with NMRI mice Diabetes High 17395748
2007 Cx36 channels in beta-cells preferentially permit exchange of cationic molecules (cations and positively charged tracers) over anionic molecules, demonstrating strong cation selectivity; glibenclamide stimulation increased coupling for all permeant molecules, while coupling extent varied depending on molecular charge. Microinjection of tracers differing in size and charge into islet cells of Cx36 knockout, transgenic, and wild-type mice; MIN6 cell coupling assays Diabetologia High 17828386
2008 CaMKII directly binds to two juxtamembrane cytoplasmic domains of Cx36 and phosphorylates Cx36 in vitro; both binding domains resemble the pseudosubstrate and pseudotarget sites of CaMKII and show phosphorylation-dependent interaction and autonomous CaMKII activation, analogous to CaMKII interaction with the NR2B subunit of NMDA receptors. CaMKII and Cx36 were significantly co-localized in the inferior olive. 35S-labeled CaMKII binding assay to Cx36 cytoplasmic domains, in vitro phosphorylation assay, colocalization by immunofluorescence in inferior olive Proceedings of the National Academy of Sciences of the United States of America High 19095792
2008 Human beta-cells express Cx36 protein at the membrane in lipid raft domains where it forms functional gap junctions that preferentially exchange cationic molecules; Cx36 mRNA levels correlate with insulin gene expression in both control and type 2 diabetic islets, establishing Cx36 as the native coupling protein of human beta-cells that contributes to gene expression regulation. Immunostaining, lipid raft fractionation, dye coupling assays, correlation analysis of Cx36 and insulin mRNA in human islets from T2D and control donors Human molecular genetics High 19000992
2009 Cx36 directly interacts with the PDZ1 domain of ZO-2 and ZO-3 via its C-terminal SAYV PDZ-binding motif; co-IP from Cx36-transfected HeLa cells and betaTC-3 cells confirmed co-immunoprecipitation, and in vitro pull-down with truncated Cx36 lacking SAYV abolished binding, establishing ZO-2 and ZO-3 as scaffold partners at Cx36-containing gap junctions. Co-immunoprecipitation, in vitro PDZ domain pull-down assay, C-terminal peptide competition, truncation mutagenesis Neurochemistry international High 19418635
2012 The transcription factor Beta2/NeuroD1 binds to three E-boxes in a 2-kbp fragment of the GJD2 promoter and, together with its cofactor E47, transactivates the promoter; this establishes Cx36 as a direct transcriptional target of Beta2/NeuroD1 during prenatal beta-cell differentiation, and Cx36 protein is selectively expressed by beta-cells throughout prenatal pancreas development. Reporter gene assay with GJD2 promoter fragments, ChIP-like binding assays, lentiviral expression of Beta2/NeuroD1, mouse pancreas developmental staging by immunolabeling The Journal of membrane biology High 22729650
2012 Cx36 gap junction channels exhibit ~10-fold higher single-channel permeability (Pγ) for cationic dyes vs. anionic dyes of similar mass; Pγ for anionic dye Alexa-350 was 358-fold lower than Cx43, 138-fold lower than Cx40, confirming that Cx36 is one of the most cation-selective connexins, consistent with its role in K+-mediated electrical coupling. Dual whole-cell voltage clamp combined with dual-mode fluorescence imaging of single gap junction channels in HeLa cells stably expressing Cx36-EGFP The Journal of membrane biology High 22752717
2012 Intercellular synchronization of Ca2+ oscillations in MIN6 cells is a reliable measure of Cx36-dependent coupling; cells with reduced Cx36 show decreased Ca2+ synchrony, glibenclamide promotes Cx36 coupling and increases synchrony, and quinine inhibits it. Drug screens using this assay identified compounds affecting Cx36 distribution and insulin content. Semi-automatic fluorimetric Ca2+ imaging in MIN6 cell populations, pharmacological modulation of Cx36 PloS one Medium 22848521
2014 Genetic knockout of Cx36 in mice expressing ATP-insensitive KATP channels (neonatal diabetes model) restored near-normal glucose-stimulated Ca2+ activity and insulin secretion, and prevented hyperglycemia; demonstrating that Cx36-mediated coupling propagates the hyperpolarizing effect of overactive KATP channels across beta-cells, and that reducing coupling can compensate for this defect. Double-transgenic mouse model (Cx36 KO × ATP-insensitive KATP), glucose homeostasis measurements, islet Ca2+ imaging, insulin secretion assays Diabetes High 24458355
2015 Phosphorylation of Cx36 at Ser293 is significantly elevated in AII amacrine cells of rd10 and rd1 retinal degeneration mouse models compared to wildtype, using a phospho-specific antibody; this elevated phosphorylation state is associated with increased gap junction coupling that underlies aberrant spontaneous hyperactivity in degenerating retina. Immunofluorescence with phospho-Ser293 specific antibody in rd10 and rd1 mouse retinas vs. wildtype Frontiers in cellular neuroscience Medium 26483638
2016 Calmodulin (CaM) binds to the carboxy-terminus of Cx36 in a calcium-dependent manner at a site overlapping the CaMKII binding site; NMR solution structure reveals CaM binds Cx36 in its characteristic compact state with major hydrophobic contacts at W277 (anchor position 1) and V284 (position 8); Ca2+-loaded CaM activates Cx36 channels, unlike its effect on other connexins. NMR spectroscopy, Ca2+-dependent binding assays, electrophysiology of Cx36 channel activity after CaM application Frontiers in molecular neuroscience High 27917108
2016 A synonymous SNP (rs3743123, S196S) in GJD2 alters gap junction plaque formation and cell coupling in HeLa cells transfected with the variant cDNA compared to wildtype; transgenic mice expressing the variant under insulin promoter showed postnatal reduction of islet Cx36 levels and beta-cell survival, causing hyperglycemia, demonstrating functional consequences of this silent polymorphism. Transfection of HeLa cells, transgenic mouse lines with insulin promoter-driven variant vs. WT Cx36, immunostaining, glucose measurements PloS one Medium 26959991
2017 CaMKII-β and CaMKII-δ co-localize specifically with Cx36-containing gap junctions in the mouse retina; in the outer retina only CaMKII-β co-localizes with Cx36, while in the inner retina both CaMKII-β and -δ co-localize with Cx36, suggesting isoform-specific regulation of electrical synapses in different retinal layers. Confocal microscopy with double-labeling for Cx36 and four CaMKII isoforms in mouse retina Frontiers in molecular neuroscience Medium 29311815
2018 E3 ubiquitin ligases LNX1 and LNX2 co-localize with Cx36-containing gap junctions in adult mouse brain, co-immunoprecipitate with Cx36, and LNX PDZ2 domain pulls down Cx36; cotransfection of E3 ligase-competent LNX isoforms with Cx36 caused loss of Cx36 gap junction plaques between cells, whereas ligase-inactive isoforms did not, establishing LNX-mediated ubiquitination as a mechanism for Cx36 internalization. Immunofluorescence colocalization, co-immunoprecipitation, PDZ pull-down, cotransfection of wild-type vs. ligase-dead LNX isoforms, LNX null mice The European journal of neuroscience High 30295974
2018 Three unique cysteine residues (C264 in TM4, C92 and C87 in TM2) form a specific docking pocket in Cx36 accessible only to short-chain n-alcohols and isoflurane (which stimulate Cx36 GJ conductance) but not to inhibitory compounds; cysteine substitution mutations at these sites reversed the stimulatory effect of hexanol and isoflurane to inhibitory, suggesting that stimulation involves reshuffling of inter-subunit disulfide bonds (C264-C92) to intra-subunit bonds (C264-C87). Structural modeling/docking, site-directed mutagenesis of cysteines, dual whole-cell patch-clamp in HeLa and N2A cells Bioscience reports Medium 29298877
2020 A Cx36-GCaMP fusion biosensor formed functional gap junctions with PKA-regulated Neurobiotin coupling; local Ca2+ increases around Cx36 gap junctions were resolved in response to Ca2+ ionophore and glutamate application; glutamate potentiated Cx36-GCaMP coupling in HeLa cells via endogenous NMDA/kainate-type glutamate receptors and a Ca2+/CaMKII-dependent mechanism, demonstrating that glutamate receptor activation locally regulates Cx36 coupling strength through Ca2+ and CaMKII. Cx36-GCaMP fusion protein, tracer coupling assay, Ca2+ imaging, pharmacological CaMKII inhibition, RNA-seq confirmation of glutamate receptor expression eNeuro Medium 32179580
2021 Depletion of zebrafish gjd2a (Cx35.5, ortholog of mammalian GJD2) caused hyperopia and electrophysiological changes in the retina, while depletion of gjd2b (Cx35.1) caused nuclear cataract that triggered axial elongation; establishing that GJD2 orthologs regulate ocular biometry and refractive status through retinal and lenticular mechanisms. Zebrafish gjd2 morpholino/CRISPR knockouts, ocular biometry, electroretinography, immunohistochemistry, scRNA sequencing Communications biology High 34083742
2021 Cx36 expression in zebrafish ortholog GJD2 and retinal gap junctions (particularly in the IPL) regulate emmetropization; form-deprivation decreased total Cx36 and phosphorylated Cx36 (P-Cx36) and the P-Cx36/Cx36 ratio in the IPL, while pharmacological uncoupling with 18-β-GA induced myopia and reduced Cx36 and P-Cx36 in both IPL and OPL, implicating Cx36 phosphorylation state as a functional readout in refractive development. Form-deprivation and lens-induced myopia in guinea pigs, subconjunctival injection of gap junction uncoupler 18-β-GA, quantitative immunofluorescence of Cx36 and P-Cx36, neurobiotin cut-loading Investigative ophthalmology & visual science Medium 34283211
2021 CaM and CaMKII binding to Cx36 are both calcium-dependent, with overlapping binding sites on the Cx36 C-terminus; CaM can engage Cx36 outside the gap junction plaque. The review synthesizes evidence that these Ca2+-dependent interactions constitute a core regulatory mechanism for Cx36 electrical synapse plasticity: Ca2+ elevation leads to CaM binding, which activates CaMKII, which phosphorylates Cx36 to modulate coupling strength. Review synthesizing binding assays, NMR structure, electrophysiology, and phosphorylation data from multiple studies International journal of molecular sciences Medium 33922931
2023 Cryo-EM structures of human Cx36 gap junction channel at 2.2–3.6 Å resolution revealed a dynamic equilibrium between closed and open states: in the closed state, channel pores are obstructed by lipids with N-terminal helices (NTHs) excluded from the pore; in the open state, pore-lining NTHs create a more acidic pore than Cx26 or Cx46/50, explaining Cx36's strong cation selectivity. Channel opening involves an α-to-π-helix transition in TM1 that weakens protomer-protomer interactions. Cryo-electron microscopy at 2.2–3.6 Å resolution, structural analysis of open and closed states Nature communications High 36906653
2024 Cryo-EM structures of human Cx36 in complex with inhibitors (mefloquine, arachidonic acid, 1-hexanol) showed that all three competitively bind a pocket at the N-terminal helices (NTH), inducing a conformational shift from the pore-lining NTH (PLN) state to a flexible NTH (FN) state that allows lipids to obstruct the channel pore, revealing the molecular mechanism of Cx36 channel inhibition. Cryo-electron microscopy structures with inhibitor-bound Cx36, structural comparison of PLN vs. FN conformational states Nature communications High 39455592
2024 The C-terminal tip of Cx36 mediates two distinct interactions in the early secretory pathway: the terminal valine acts as an ER export signal recruiting COPII cargo receptors Sec24A/B/C at ER exit sites, while the PDZ-binding motif SAYV mediates interaction with Golgi-stacking protein Grasp55 to stabilize Cx36 in the Golgi. Sec24 promotes ER exit, while Grasp55 retains Cx36 in the Golgi, establishing opposing regulatory roles in Cx36 trafficking. HEK293T expression system, siRNA knockdown, BioID proximity labeling screens, co-immunoprecipitation, confocal microscopy of ER vs. Golgi localization, overexpression studies Cellular and molecular life sciences High 39395036
2025 Hemichannel permeability assays showed that Cx36 hemichannels selectively allow ATP release but not glutamate or lactate; mutational analysis of N-terminus charge and N-terminus–TM2 interactions (informed by differential selectivity between Cx46 and Cx50) identified these structural elements as key determinants of permselectivity, showing that molecular size alone cannot explain connexin hemichannel selectivity. Co-expression of genetically encoded fluorescent sensors for ATP, glutamate, and lactate with connexins in cells; N-terminus mutagenesis; pharmacological stimulation bioRxiv (preprint)preprint Medium bio_10.1101_2025.03.12.642803
2025 Electrostatic interactions (ESIs) at the second extracellular (E2) loop interface are required for Cx36 gap junction formation: at least three ESI residue pairs per E2-E2 interface must be intact for functional GJ conductance. These unique ESIs also ensure Cx36 docking specificity to itself, preventing heterotypic GJ formation with other brain connexins (Cx26, Cx30, Cx31.3, Cx32, Cx43, Cx45, Cx47). Computational electrostatic calculations, systematic missense mutagenesis of E2 interface residues, dual patch-clamp in HEK293 cell pairs bioRxiv (preprint)preprint Medium bio_10.1101_2025.10.25.684567
2025 ZO-1 interacts with Cx36 via PDZ1 domain binding to the Cx36 PDZ-binding motif (SAYV), and this interaction is inherently weak; molecular dynamics simulations and binding assays identified a single substitution at position 319 and acidic residues adjacent to the PBM that evolutionarily weaken this interaction. CaMKII-mediated phosphorylation of Cx36 reduces ZO-1 binding, suggesting that ZO-1 unbinding is a necessary event during potentiation of electrical synapses. Gaussian accelerated molecular dynamics, binding affinity assays, site-directed mutagenesis at PBM and adjacent residues, CaMKII phosphorylation assays bioRxiv (preprint)preprint Medium bio_10.1101_2025.10.27.684941
2025 Cx36 gap junctions in the outer retina lower visual thresholds (i.e., increase sensitivity) under dim light, while inner retinal Cx36 gap junctions are required for maintaining thresholds; complete Cx36 KO increased visual thresholds 16.5-fold relative to controls, and outer retina-specific Cx36 removal lowered thresholds 2.6-fold, demonstrating layer-specific and opposing roles of Cx36 in setting visual detection thresholds via the rod OFF-pathway. Transgenic mice with retinal layer-specific Cx36 knockout, operant behavioral assay, psychophysical modeling iScience High 41623460
2025 In pancreatic islets, delta cell activation precedes beta cell Ca2+ oscillations at high glucose, and selective Cx36 knockout in delta cells confirmed that low-density Cx36 gap junctions contribute to delta-beta cell coordination; however, blockade of vesicle release (paracrine signaling) eliminated coupling between most delta and beta cells, demonstrating that beta-delta coordination is primarily driven by paracrine signals (Urocortin 3) with secondary contribution from Cx36 gap junctions. GCaMP6s Ca2+ imaging of hundreds of cells simultaneously, selective delta-cell Cx36 knockout, Rho-GTPase inhibitor ML-141 to block vesicle release Proceedings of the National Academy of Sciences of the United States of America High 40956879
2024 In vivo BioID proximity labeling using Cx36-EGFP in AII amacrine cells identified more than 50 new proteins associated with Cx36 electrical synapses in mouse retina, including scaffold proteins, adhesion molecules, and cytoskeletal regulators; ZO-1 and ZO-2 were confirmed, and Sipa1l3 was identified as a new electrical synapse scaffold that interacts with ZO-1, ZO-2, and Cx36. In vivo BioID proximity labeling (GFP-nanobody-TurboID in mice; Cx35b-TurboID transgenic zebrafish), mass spectrometry, immunofluorescence, binding interaction assays bioRxiv (preprint)preprint Medium bio_10.1101_2024.11.26.625481

Source papers

Stage 0 corpus · 93 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2002 Generation and initial analysis of more than 15,000 full-length human and mouse cDNA sequences. Proceedings of the National Academy of Sciences of the United States of America 1479 12477932
2011 Phylogenetic-based propagation of functional annotations within the Gene Ontology consortium. Briefings in bioinformatics 656 21873635
2004 The status, quality, and expansion of the NIH full-length cDNA project: the Mammalian Gene Collection (MGC). Genome research 438 15489334
2013 Genome-wide meta-analyses of multiancestry cohorts identify multiple new susceptibility loci for refractive error and myopia. Nature genetics 387 23396134
1998 Cloning of a new gap junction gene (Cx36) highly expressed in mammalian brain neurons. The European journal of neuroscience 377 9753189
2004 Potent block of Cx36 and Cx50 gap junction channels by mefloquine. Proceedings of the National Academy of Sciences of the United States of America 271 15297615
2000 Expression of Cx36 in mammalian neurons. Brain research. Brain research reviews 216 10751658
2001 Identification of cells expressing Cx43, Cx30, Cx26, Cx32 and Cx36 in gap junctions of rat brain and spinal cord. Cell communication & adhesion 179 12064610
2010 A genome-wide association study identifies a susceptibility locus for refractive errors and myopia at 15q14. Nature genetics 174 20835239
2007 Cx36-mediated coupling reduces beta-cell heterogeneity, confines the stimulating glucose concentration range, and affects insulin release kinetics. Diabetes 140 17395748
2013 Nine loci for ocular axial length identified through genome-wide association studies, including shared loci with refractive error. American journal of human genetics 136 24144296
2000 Cx36 preferentially connects beta-cells within pancreatic islets. Diabetes 136 10905480
2001 Global ischemia-induced increases in the gap junctional proteins connexin 32 (Cx32) and Cx36 in hippocampus and enhanced vulnerability of Cx32 knock-out mice. The Journal of neuroscience : the official journal of the Society for Neuroscience 119 11567043
2004 Expression pattern of lacZ reporter gene representing connexin36 in transgenic mice. The Journal of comparative neurology 104 15116387
2008 The neuronal connexin36 interacts with and is phosphorylated by CaMKII in a way similar to CaMKII interaction with glutamate receptors. Proceedings of the National Academy of Sciences of the United States of America 99 19095792
2008 Cx36 makes channels coupling human pancreatic beta-cells, and correlates with insulin expression. Human molecular genetics 98 19000992
2020 Systematic mapping of genetic interactions for de novo fatty acid synthesis identifies C12orf49 as a regulator of lipid metabolism. Nature metabolism 92 32694731
1999 Structure, chromosomal localization, and brain expression of human Cx36 gene. Journal of neuroscience research 90 10462698
2005 Human and mouse microglia express connexin36, and functional gap junctions are formed between rodent microglia and neurons. Journal of neuroscience research 85 16211561
2006 Ultrastructural localization of connexins (Cx36, Cx43, Cx45), glutamate receptors and aquaporin-4 in rodent olfactory mucosa, olfactory nerve and olfactory bulb. Journal of neurocytology 76 16841170
2012 Impaired β-cell-β-cell coupling mediated by Cx36 gap junctions in prediabetic mice. American journal of physiology. Endocrinology and metabolism 61 22569071
2004 Association of the connexin36 gene with juvenile myoclonic epilepsy. Journal of medical genetics 60 15235036
2003 Critical role of the transcriptional repressor neuron-restrictive silencer factor in the specific control of connexin36 in insulin-producing cell lines. The Journal of biological chemistry 59 14565956
2007 Beta cells preferentially exchange cationic molecules via connexin 36 gap junction channels. Diabetologia 53 17828386
2013 The quest for juvenile myoclonic epilepsy genes. Epilepsy & behavior : E&B 48 23756480
2000 Cx36 is dynamically expressed during early development of mouse brain and nervous system. Neuroreport 46 11117498
2004 Differentiating the effects of Cx36 and E-cadherin for proper insulin secretion of MIN6 cells. Experimental cell research 42 15023528
2002 Evidence for a role of the N-terminal domain in subcellular localization of the neuronal connexin36 (Cx36). Journal of neuroscience research 42 12210839
2002 Mutations in the calcium-binding motifs of CDH23 and the 35delG mutation in GJB2 cause hearing loss in one family. Human genetics 40 12522556
2006 Confirmatory evidence for an association of the connexin-36 gene with juvenile myoclonic epilepsy. Epilepsy research 37 16876983
2014 Genome-wide meta-analysis of myopia and hyperopia provides evidence for replication of 11 loci. PloS one 36 25233373
2010 Expression of connexin genes in the human retina. BMC ophthalmology 36 20979653
2009 Direct association of connexin36 with zonula occludens-2 and zonula occludens-3. Neurochemistry international 36 19418635
2022 Quantitative fragmentomics allow affinity mapping of interactomes. Nature communications 33 36115835
2023 Cryo-EM structures of human Cx36/GJD2 neuronal gap junction channel. Nature communications 31 36906653
2017 Differential Distribution of Retinal Ca2+/Calmodulin-Dependent Kinase II (CaMKII) Isoforms Indicates CaMKII-β and -δ as Specific Elements of Electrical Synapses Made of Connexin36 (Cx36). Frontiers in molecular neuroscience 26 29311815
2008 Zebrafish early cardiac connexin, Cx36.7/Ecx, regulates myofibril orientation and heart morphogenesis by establishing Nkx2.5 expression. Proceedings of the National Academy of Sciences of the United States of America 26 18337497
2015 Characterization of connexin36 gap junctions in the human outer retina. Brain structure & function 25 26173976
2014 Genome-wide association study of maternal and inherited effects on left-sided cardiac malformations. Human molecular genetics 25 25138779
2021 Loss of Gap Junction Delta-2 (GJD2) gene orthologs leads to refractive error in zebrafish. Communications biology 24 34083742
2016 Structural and Functional Consequences of Connexin 36 (Cx36) Interaction with Calmodulin. Frontiers in molecular neuroscience 24 27917108
2010 Visual responses in the lateral geniculate evoked by Cx36-independent rod pathways. Vision research 21 20709095
2023 Sequential genome-wide CRISPR-Cas9 screens identify genes regulating cell-surface expression of tetraspanins. Cell reports 20 36724073
2014 Decreasing cx36 gap junction coupling compensates for overactive KATP channels to restore insulin secretion and prevent hyperglycemia in a mouse model of neonatal diabetes. Diabetes 20 24458355
2012 Neurons and β-cells of the pancreas express connexin36, forming gap junction channels that exhibit strong cationic selectivity. The Journal of membrane biology 20 22752717
2017 A GJA9 frameshift variant is associated with polyneuropathy in Leonberger dogs. BMC genomics 19 28841859
2012 Connexin36 (Cx36) expression and protein detection in the mouse carotid body and myenteric plexus. Acta histochemica 18 22897942
2019 Rod Photoreceptors Signal Fast Changes in Daylight Levels Using a Cx36-Independent Retinal Pathway in Mouse. The Journal of neuroscience : the official journal of the Society for Neuroscience 17 31776212
2018 E3 ubiquitin ligases LNX1 and LNX2 localize at neuronal gap junctions formed by connexin36 in rodent brain and molecularly interact with connexin36. The European journal of neuroscience 17 30295974
2017 Cx36, Cx43 and Cx45 in mouse and rat cerebellar cortex: species-specific expression, compensation in Cx36 null mice and co-localization in neurons vs. glia. The European journal of neuroscience 17 28561933
2016 A Variant of GJD2, Encoding for Connexin 36, Alters the Function of Insulin Producing β-Cells. PloS one 17 26959991
2015 Increased phosphorylation of Cx36 gap junctions in the AII amacrine cells of RD retina. Frontiers in cellular neuroscience 17 26483638
2003 Cx36 involvement in insulin secretion: characteristics and mechanism. Cell communication & adhesion 17 14681053
2001 Cx36 and the function of endocrine pancreas. Cell communication & adhesion 17 12064624
2012 The intercellular synchronization of Ca2+ oscillations evaluates Cx36-dependent coupling. PloS one 15 22848521
2018 Neuroprotective effects of leonurine against oxygen-glucose deprivation by targeting Cx36/CaMKII in PC12 cells. PloS one 14 30016355
2015 Association between Ocular Axial Length-Related Genes and High Myopia in a Han Chinese Population. Ophthalmologica. Journal international d'ophtalmologie. International journal of ophthalmology. Zeitschrift fur Augenheilkunde 14 26485405
2013 Evaluating the association between pathological myopia and SNPs in RASGRF1. ACTC1 and GJD2 genes at chromosome 15q14 and 15q25 in a Chinese population. Ophthalmic genetics 14 23834555
2018 Cx36 in the mouse hippocampus during and after pilocarpine-induced status epilepticus. Epilepsy research 13 29476948
2012 Cx36 is a target of Beta2/NeuroD1, which associates with prenatal differentiation of insulin-producing β cells. The Journal of membrane biology 12 22729650
2010 Role of Cx36 gap junction modulation in general anaesthetic anticonvulsant action. European journal of pharmacology 12 20599911
2022 The Role of GJD2(Cx36) in Refractive Error Development. Investigative ophthalmology & visual science 11 35262731
2019 Decreased expression of gap junction delta-2 (GJD2) messenger RNA and connexin 36 protein in form-deprivation myopia of guinea pigs. Chinese medical journal 11 31283648
2017 A potential role for neuronal connexin 36 in the pathogenesis of amyotrophic lateral sclerosis. Neuroscience letters 11 29246791
2016 The role of Cx36 and Cx43 in 4-aminopyridine-induced rhythmic activity in the spinal nociceptive dorsal horn: an electrophysiological study in vitro. Physiological reports 11 27462070
2021 Phenotypic Consequences of the GJD2 Risk Genotype in Myopia Development. Investigative ophthalmology & visual science 10 34406332
2018 Heritability of myopia and its relation with GDJ2 and RASGRF1 genes in Lithuania. BMC ophthalmology 10 29793445
2020 Localized Calcium Signaling and the Control of Coupling at Cx36 Gap Junctions. eNeuro 9 32179580
2017 The inhibitor of connexin Cx36 channels, mefloquine, inhibits voltage-dependent Ca2+ channels and insulin secretion. Molecular and cellular endocrinology 9 29208420
2002 Mutational analysis of the connexin 36 gene (CX36) and exclusion of the coding sequence as a candidate region for catatonic schizophrenia in a large pedigree. Schizophrenia research 9 12363395
2021 The Roles of Calmodulin and CaMKII in Cx36 Plasticity. International journal of molecular sciences 8 33922931
2016 Expression of connexin 26 and connexin 43 is reduced in Hirschsprung's disease. The Journal of surgical research 8 27916369
2021 The Role of Retinal Connexins Cx36 and Horizontal Cell Coupling in Emmetropization in Guinea Pigs. Investigative ophthalmology & visual science 7 34283211
2018 Molecular basis for potentiation of Cx36 gap junction channel conductance by n-alcohols and general anesthetics. Bioscience reports 6 29298877
2017 Dynamic Expression of CX36 Protein in Kainic Acid Kindling induced Epilepsy. Translational neuroscience 6 28729916
2021 Extensive GJD2 Expression in the Song Motor Pathway Reveals the Extent of Electrical Synapses in the Songbird Brain. Biology 5 34827092
2022 Astragaloside IV ameliorates cerebral ischemia-reperfusion injury via upregulation of PKA and Cx36. Neuroreport 4 36126263
2020 Cadmium versus Lanthanum Effects on Spontaneous Electrical Activity and Expression of Connexin Isoforms Cx26, Cx36, and Cx45 in the Human Fetal Cortex. Cerebral cortex (New York, N.Y. : 1991) 4 31408166
2025 Heterogeneity in the coordination of delta cells with beta cells is driven by both paracrine signals and low-density Cx36 gap junctions. Proceedings of the National Academy of Sciences of the United States of America 3 40956879
2020 Altered Expression of GJD2 Messenger RNA and the Coded Protein Connexin 36 in Negative Lens-induced Myopia of Guinea Pigs. Optometry and vision science : official publication of the American Academy of Optometry 3 33278187
2019 Gap junctions and expression of Cx36, Cx43 and Cx45 in the posterodorsal medial amygdala of adult rats. Histology and histopathology 3 31495909
2022 Early decrease in Cx36 is associated with increased cell adhesion molecules (CAMs) junctional content in mouse pancreatic islets after short-term high-fat diet feeding. Annals of anatomy = Anatomischer Anzeiger : official organ of the Anatomische Gesellschaft 2 35114378
2015 Cx36 expression in the AII-mediated rod pathway is activity dependent in the developing rabbit retina. Developmental neurobiology 2 26084632
2024 Trafficking of Connexin36 (Cx36) in the early secretory pathway. bioRxiv : the preprint server for biology 1 38585986
2024 Characterizing ER Retention Defects of PDZ Binding Deficient Cx36 Mutants Using Confocal Microscopy. Bio-protocol 1 39100594
2024 Regulation of Cx36 trafficking through the early secretory pathway by COPII cargo receptors and Grasp55. Cellular and molecular life sciences : CMLS 1 39395036
2024 Mefloquine-induced conformational shift in Cx36 N-terminal helix leading to channel closure mediated by lipid bilayer. Nature communications 1 39455592
2022 Association of CX36 Protein Encoding Gene GJD2 with Refractive Errors. Genes 1 35885949
2025 (-) - (11R, 12S)-mefloquine ameliorates neuropathic pain by modulating Cx36-ER stress interaction in the pain-related central nervous system in rats. Life sciences 0 39828229
2025 Whole exome sequencing identified mutations of forkhead box I 1 (FOXI1), keratin 6 C (KRT6C) and gap junction protein delta 2 (GJD2) in a low-grade oncocytic tumor of the kidney: a case report. Diagnostic pathology 0 39980061
2025 Retinal Cx36 gap junctions in the inner and outer plexiform layers differentially control visual thresholds. iScience 0 41623460
2024 Upregulation of the long noncoding RNA GJA9-MYCBP and PVT1 is a potential diagnostic biomarker for acute lymphoblastic leukemia. Cancer reports (Hoboken, N.J.) 0 38994720
2015 Characterization of the zebrafish cx36.7 gene promoter: Its regulation of cardiac-specific expression and skeletal muscle-specific repression. Gene 0 26692140