Affinage

UNC79

Protein unc-79 homolog · UniProt Q9P2D8

Length
2635 aa
Mass
295.3 kDa
Annotated
2026-06-10
35 papers in source corpus 14 papers cited in narrative 14 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

UNC79 is a large cytosolic auxiliary subunit of the NALCN sodium leak channel complex that controls neuronal excitability underlying locomotion, circadian rhythm, sleep, and anesthetic sensitivity across nematodes, flies, and mammals (PMID:21040849, PMID:24223770, PMID:20714347). Within the assembled NALCN-FAM155A-UNC79-UNC80 quaternary complex, UNC79 partners with UNC80 to form a pillar-shaped heterodimer that docks onto the intracellular face of NALCN through tripartite contacts with the channel's cytoplasmic loops; two of these interfaces drive proper cell-surface localization, while a third relieves channel autoinhibition by extracting the auto-inhibitory CTD Interacting Helix from its binding site (PMID:35550517). UNC79 is bridged to NALCN through UNC80, and this UNC80 interaction is required for dendritic targeting of the complex (PMID:32620897). Functionally, UNC79 (with UNC80 and FAM155A) is needed to reconstitute a constitutively active, divalent-blocked monovalent cation current in heterologous systems (PMID:32494638) and confers the G protein-dependent sodium leak current that is activated by lowering extracellular Ca2+ (PMID:21040849). Beyond gating, UNC79 acts post-transcriptionally to stabilize NALCN/NA protein levels and localization, with channel subunits showing mutual interdependence for steady-state abundance without changes in transcript level (PMID:17350263, PMID:24223770, PMID:18336069). Heterozygous loss-of-function variants in UNC79 cause a neurodevelopmental syndrome, recapitulated by seizure phenotypes in flies and learning/memory deficits in heterozygous mice (PMID:37183800).

Mechanistic history

Synthesis pass · year-by-year structured walk · 11 steps
  1. 1987 Medium

    Established the first phenotypic handle on UNC79 by showing its mutation alters whole-animal anesthetic sensitivity, and placed it in a defined genetic pathway with UNC80 and the gap-junction gene unc-9.

    Evidence Anesthetic dose-response and suppressor epistasis in C. elegans

    PMID:3576211

    Open questions at the time
    • No molecular identity or biochemical activity defined
    • Link to an ion channel not yet established
  2. 2006 Medium

    Demonstrated that the mammalian UNC79 homolog is essential for a specific neural behavior, indicating a non-redundant physiological role in vivo.

    Evidence Gene-targeted knockout mice with adipsia behavioral phenotyping

    PMID:16807365

    Open questions at the time
    • Molecular mechanism of the behavioral defect not characterized
    • No connection to NALCN drawn in this study
  3. 2007 High

    Resolved how UNC79 regulates the channel by showing it controls NALCN/NA protein levels post-transcriptionally, placing it upstream of the channel in a conserved pathway.

    Evidence Genetic epistasis and protein-versus-mRNA quantification in Drosophila and C. elegans

    PMID:17350263

    Open questions at the time
    • Biochemical mechanism of protein stabilization unknown
    • Direct physical association with the channel not yet shown
  4. 2008 High

    Showed that UNC79 is required for proper axonal localization of the NALCN ortholog and for propagating neuronal activity to synapses, linking the protein to channel trafficking and function.

    Evidence In vivo calcium imaging and fluorescent localization in C. elegans loss-of-function mutants

    PMID:18336069 PMID:19074276

    Open questions at the time
    • Whether localization defect is direct or downstream of reduced channel abundance unclear
    • Molecular trafficking machinery not identified
  5. 2010 High

    Defined UNC79 as a bona fide complex member that confers extracellular Ca2+ sensitivity and G protein-dependent leak current, establishing its mechanistic contribution to channel gating.

    Evidence Knockout mouse hippocampal electrophysiology and Ca2+-sensitivity assays; positional cloning with ethanol/isoflurane pharmacology

    PMID:20714347 PMID:21040849

    Open questions at the time
    • Structural basis of the Ca2+ sensitivity not resolved
    • Identity of coupling G protein not defined
  6. 2013 High

    Demonstrated an interdependent post-transcriptional regulatory loop among UNC79, UNC80, and NA, and showed UNC79 has functions beyond promoting subunit expression, refining its role as more than a chaperone.

    Evidence Immunoprecipitation, protein/transcript quantification, and genetic rescue in Drosophila pacemaker neurons

    PMID:24223770

    Open questions at the time
    • Nature of the function not bypassed by increased NA protein undefined
    • Molecular basis of mutual stabilization unknown
  7. 2018 Medium

    Positioned the UNC79/NCA channel upstream of gap junctions in a sleep-regulation circuit, extending the pathway to a defined behavioral output.

    Evidence Genetic epistasis with egl-4 and innexin suppressors and arousal-threshold sleep assays in C. elegans

    PMID:30323068

    Open questions at the time
    • Cellular site of action within sleep circuitry not pinpointed
    • Direct molecular link to innexins not shown
  8. 2020 High

    Reconstituted the minimal functional channel and mapped the UNC80 domain required for UNC79 binding and dendritic targeting, distinguishing trafficking from current-carrying functions.

    Evidence Heterologous co-expression electrophysiology; reciprocal Co-IP, domain deletion, and localization imaging

    PMID:32494638 PMID:32620897

    Open questions at the time
    • Mechanism by which the UNC79-UNC80 interaction directs dendritic localization unresolved
    • Stoichiometry within native complex not defined here
  9. 2021 Medium

    Revealed spatially separable neuronal functions for UNC79, acting in mushroom body neurons for sleep and starvation resistance distinct from its pacemaker-neuron role in rhythmicity.

    Evidence Tissue-specific RNAi and rescue with behavioral assays in Drosophila

    PMID:34849820

    Open questions at the time
    • Whether distinct functions reflect different channel partners unclear
    • Molecular outputs in mushroom body neurons not defined
  10. 2022 High

    Provided the structural mechanism: UNC79 and UNC80 form a pillar-shaped heterodimer that tethers to NALCN and relieves autoinhibition, unifying trafficking and gating roles at atomic resolution.

    Evidence Cryo-EM of the mammalian NALCN-FAM155A-UNC79-UNC80 complex with functional validation of interfaces

    PMID:35550517

    Open questions at the time
    • Conformational dynamics during channel activation not captured
    • How extracellular Ca2+ sensing is transduced to the cytoplasmic UNC79-UNC80 module unresolved
  11. 2023 Medium

    Established UNC79 haploinsufficiency as causally linked to human neurodevelopmental pathology, connecting molecular function to disease.

    Evidence Human genetics with Drosophila seizure assays and heterozygous mouse learning/memory phenotyping

    PMID:37183800

    Open questions at the time
    • Human genetic association is associative; causality rests on model organisms
    • How partial loss of UNC79 alters NALCN function in human neurons not defined

Open questions

Synthesis pass · forward-looking unresolved questions
  • How extracellular Ca2+ and G protein signals are mechanistically transduced through the cytoplasmic UNC79-UNC80 module to gate NALCN, and how UNC79 selects among distinct neuronal functions, remain open.
  • No structure of the Ca2+-sensing or G protein-coupled state
  • Direct biochemical mechanism of post-transcriptional protein stabilization unknown

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0098772 molecular function regulator activity 3 GO:0060089 molecular transducer activity 2
Localization
GO:0005886 plasma membrane 3 GO:0005829 cytosol 2
Pathway
R-HSA-112316 Neuronal System 3 R-HSA-162582 Signal Transduction 1
Complex memberships
NALCN-FAM155A-UNC79-UNC80 channel complex

Evidence

Reading pass · 14 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
2022 Cryo-EM structure of the mammalian NALCN-FAM155A-UNC79-UNC80 quaternary complex shows that UNC79 and UNC80 form a large pillar-shaped heterodimer tethered to the intracellular side of NALCN through tripartite interactions with cytoplasmic loops of NALCN. Two of these interactions are essential for proper cell surface localization of NALCN, while a third relieves NALCN self-inhibition by pulling an auto-inhibitory CTD Interacting Helix (CIH) out of its binding site. Cryo-EM structure determination with functional validation Nature communications High 35550517
2010 UNC79 is a component of a NALCN channel complex in which UNC80 bridges NALCN to UNC79. This complex is required for a G protein-dependent Na+-leak current (I_L-Na) that is activated by lowering extracellular Ca2+. Neurons from unc79 knockout mice lack sensitivity of I_L-Na to changes in extracellular Ca2+, and the excitatory effect of reduced extracellular Ca2+ is absent. Knockout mouse electrophysiology (cultured hippocampal neurons), genetic analysis, Ca2+ sensitivity assay Neuron High 21040849
2020 UNC79 and UNC80 are bona fide subunits of the NALCN channel complex in mammals. The C-terminus of UNC80 contains a domain that interacts with UNC79 and is required for dendritic localization of the complex; UNC80 lacking this domain (as found in intellectual disability patients) still supports whole-cell NALCN currents but fails to localize to dendrites, implicating UNC79 interaction in dendritic membrane potential regulation. UNC80 knockout mice (neonatal lethal phenotype confirmed), domain-deletion constructs, Co-immunoprecipitation, subcellular localization imaging, whole-cell patch-clamp Nature communications High 32620897
2007 UNC-79 encodes a large cytosolic protein that controls NA (NALCN ortholog) protein levels by a post-transcriptional mechanism in both Drosophila and C. elegans. Biochemical studies show that loss of UNC-79 reduces NA protein without affecting transcript levels, placing UNC-79 upstream of the channel in a conserved pathway also involving the na/NALCN gene. Genetic epistasis (double mutants), biochemical assay of protein vs. mRNA levels, cross-species ortholog analysis Current biology : CB High 17350263
2013 In Drosophila, UNC79 and UNC80 are required for robust circadian locomotor rhythmicity in pacemaker neurons. Loss of unc79, unc80, or na leads to decreased expression of all three proteins with minimal effect on transcript levels, demonstrating an interdependent post-transcriptional regulatory relationship. Immunoprecipitation confirms that UNC79 and UNC80 form a complex with NA (NALCN ortholog) in the Drosophila brain. Functional requirements for UNC79 and UNC80 extend beyond merely promoting channel subunit expression, as increased NA protein cannot bypass the need for these subunits. Genetic loss-of-function alleles, tissue-specific RNAi and rescue, immunoprecipitation, protein and transcript quantification PloS one High 24223770
2008 In C. elegans, NCA-1 localization along axons and its function in propagating neuronal activity from cell bodies to synapses depend on UNC-79 and UNC-80. Loss of UNC-79 disrupts NCA-1 localization (enriched at nonsynaptic regions) and reduces synaptic calcium transients at neuromuscular junctions. In vivo calcium imaging, fluorescent protein localization, genetic loss-of-function analysis PLoS biology High 18336069
2010 Positional cloning of the mouse Lightweight (Lwt) mutation identifies it as a loss-of-function allele in the mouse UNC79 homolog. Lwt/Lwt homozygotes are perinatal lethal; heterozygotes are hypersensitive to acute ethanol and to the anesthetic isoflurane. Parallel C. elegans experiments confirm conserved hypersensitivity to ethanol in unc-79 mutants and in nca-1;nca-2 double mutants, placing UNC79 in the same pathway as NCA/NALCN channels. ENU forward mutagenesis, positional cloning, behavioral pharmacology (ethanol/isoflurane), genetic epistasis in C. elegans PLoS genetics High 20714347
2020 Robust functional expression of the NALCN channel complex in heterologous systems requires co-expression of UNC79, UNC80, and FAM155A. The resulting complex is constitutively active, conducts monovalent cations, and is blocked by physiological concentrations of extracellular divalent cations; it also shows voltage-dependent modulation. Heterologous expression (co-transfection), electrophysiology (whole-cell and single-channel recordings), pharmacological profiling Science advances High 32494638
2006 Targeted disruption of mouse KIAA1409 (UNC79 homolog) results in mice that lack the ability to drink (adipsia phenotype), establishing that UNC79 is essential for a specific neural behavior in mammals. Homozygous knockouts display this overt phenotypic defect. Gene-targeted knockout mice, behavioral phenotyping FASEB journal Medium 16807365
2008 In C. elegans, unc-79 and unc-80 mutants are defective in NCA ion channel stabilization and in transitioning between crawling and swimming locomotor rhythms, placing UNC-79 genetically upstream or in the same pathway as NCA channels for behavioral pattern generation. Genetic mutant analysis, in vivo calcium imaging, behavioral assays Proceedings of the National Academy of Sciences Medium 19074276
1987 Mutations in unc-79 confer hypersensitivity to halothane in C. elegans. The double mutant unc-79; unc-80 is slightly more sensitive than either single mutant, suggesting additive or partially redundant functions, and mutations in unc-9 suppress both unc-79 and unc-80 halothane hypersensitivity, placing these genes in a genetic pathway. Genetic mutant analysis, anesthetic dose-response (ED50 determination), epistasis with suppressor mutations Science Medium 3576211
2021 In Drosophila, UNC79 functions within mushroom body neurons (distinct from pacemaker neurons) to regulate sleep duration and starvation resistance, revealing a spatially separable role from its function in circadian rhythmicity in pacemaker neurons. Genetic knockdown (RNAi), tissue-specific rescue, sleep/behavioral assays, starvation resistance assays G3 (Bethesda, Md.) Medium 34849820
2023 Heterozygous loss-of-function variants in UNC79 in humans are associated with a neurodevelopmental syndrome. Drosophila with UNC79 knocked down display induced seizure-like phenotypes, and heterozygous loss-of-function mice show developmental delay in body weight and impaired learning and memory, establishing UNC79 haploinsufficiency as causally linked to neurological pathology. Human genetics, Drosophila RNAi seizure assay, heterozygous mouse KO behavioral testing (learning/memory, body weight) Genetics in medicine Medium 37183800
2018 Loss of UNC-79 in C. elegans robustly increases arousal thresholds during sleep bouts in L4-to-adult developmentally timed sleep, and this effect is suppressed by loss of EGL-4 or innexin proteins (UNC-7, UNC-9), placing UNC-79/NCA channels upstream of gap junctions in a sleep-regulation pathway. Genetic epistasis, behavioral sleep assays, arousal threshold measurement Genetics Medium 30323068

Source papers

Stage 0 corpus · 35 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2008 Genetic analysis of crawling and swimming locomotory patterns in C. elegans. Proceedings of the National Academy of Sciences of the United States of America 201 19074276
2010 Extracellular calcium controls background current and neuronal excitability via an UNC79-UNC80-NALCN cation channel complex. Neuron 163 21040849
2017 Exonic Mosaic Mutations Contribute Risk for Autism Spectrum Disorder. American journal of human genetics 146 28867142
2014 The sodium leak channel, NALCN, in health and disease. Frontiers in cellular neuroscience 131 24904279
2008 A putative cation channel, NCA-1, and a novel protein, UNC-80, transmit neuronal activity in C. elegans. PLoS biology 99 18336069
2007 A putative cation channel and its novel regulator: cross-species conservation of effects on general anesthesia. Current biology : CB 96 17350263
1990 Multiple sites of action of volatile anesthetics in Caenorhabditis elegans. Proceedings of the National Academy of Sciences of the United States of America 96 2326259
2010 A genomewide association study of nicotine and alcohol dependence in Australian and Dutch populations. Twin research and human genetics : the official journal of the International Society for Twin Studies 86 20158304
1987 Genetic analysis of halothane sensitivity in Caenorhabditis elegans. Science (New York, N.Y.) 72 3576211
2020 The NALCN channel complex is voltage sensitive and directly modulated by extracellular calcium. Science advances 55 32494638
1988 The effect of two genes on anesthetic response in the nematode Caenorhabditis elegans. Anesthesiology 46 2900611
2015 UNC80 mutation causes a syndrome of hypotonia, severe intellectual disability, dyskinesia and dysmorphism, similar to that caused by mutations in its interacting cation channel NALCN. Journal of medical genetics 42 26545877
2018 Genetic variants in components of the NALCN-UNC80-UNC79 ion channel complex cause a broad clinical phenotype (NALCN channelopathies). Human genetics 41 30167850
2010 Conserved role of unc-79 in ethanol responses in lightweight mutant mice. PLoS genetics 40 20714347
2015 Mutations in UNC80, Encoding Part of the UNC79-UNC80-NALCN Channel Complex, Cause Autosomal-Recessive Severe Infantile Encephalopathy. American journal of human genetics 38 26708753
2013 UNC79 and UNC80, putative auxiliary subunits of the NARROW ABDOMEN ion channel, are indispensable for robust circadian locomotor rhythms in Drosophila. PloS one 38 24223770
2023 New insights into the physiology and pathophysiology of the atypical sodium leak channel NALCN. Physiological reviews 33 37615954
2022 Structure and mechanism of NALCN-FAM155A-UNC79-UNC80 channel complex. Nature communications 26 35550517
2006 A gene-targeting approach for functional characterization of KIAA genes encoding extremely large proteins. FASEB journal : official publication of the Federation of American Societies for Experimental Biology 26 16807365
2012 NALCN: a regulator of pacemaker activity. Molecular neurobiology 23 22476981
2020 Intellectual disability-associated UNC80 mutations reveal inter-subunit interaction and dendritic function of the NALCN channel complex. Nature communications 22 32620897
2023 A new neurodevelopmental disorder linked to heterozygous variants in UNC79. Genetics in medicine : official journal of the American College of Medical Genetics 15 37183800
2018 Novel NALCN biallelic truncating mutations in siblings with IHPRF1 syndrome. Clinical genetics 13 29399786
2018 Gap Junctions and NCA Cation Channels Are Critical for Developmentally Timed Sleep and Arousal in Caenorhabditis elegans. Genetics 13 30323068
2017 Whole-Exome Sequencing-Based Mutational Profiling of Hepatitis B Virus-Related Early-Stage Hepatocellular Carcinoma. Gastroenterology research and practice 13 29333154
2011 Different genes influence toluene- and ethanol-induced locomotor impairment in C. elegans. Drug and alcohol dependence 11 21945072
2021 A screen for sleep and starvation resistance identifies a wake-promoting role for the auxiliary channel unc79. G3 (Bethesda, Md.) 8 34849820
2022 Differential modulation of C. elegans motor behavior by NALCN and two-pore domain potassium channels. PLoS genetics 7 35482723
2014 Food deprivation and nicotine correct akinesia and freezing in Na(+) -leak current channel (NALCN)-deficient strains of Caenorhabditis elegans. Genes, brain, and behavior 6 24995777
2023 Novel nonsense mutation in UNC80 in a Turkish patient further validates the sociable skill and severe gastrointestinal problems as part of disease spectrum. American journal of medical genetics. Part A 4 37067163
2023 Clinical features and molecular genetics associated with brain metastasis in suspected early-stage non-small cell lung cancer. Frontiers in oncology 3 37139160
2024 Analysis of the Association between Copy Number Variation and Ventricular Fibrillation in ST-Elevation Acute Myocardial Infarction. International journal of molecular sciences 1 38473795
2025 NALCN/Cch1 channelosome subunits originated in early eukaryotes. The Journal of general physiology 0 40910942
2025 Clinical Utility of Whole-Exome Sequencing in a Consanguineous Family with UNC80-related Neurodevelopmental Disorder: A Case Series and Review of the Literature. Cureus 0 41458659
2023 Canine Somatic Mutations from Whole-Exome Sequencing of B-Cell Lymphomas in Six Canine Breeds-A Preliminary Study. Animals : an open access journal from MDPI 0 37760246

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