Affinage

GNB1

Guanine nucleotide-binding protein G(I)/G(S)/G(T) subunit beta-1 · UniProt P62873

Length
340 aa
Mass
37.4 kDa
Annotated
2026-06-10
40 papers in source corpus 12 papers cited in narrative 12 extracted findings
Cross-family judge vs UniProt: Affinage preferred faithfulness: 6/7 claims corpus-supported (86%)

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

GNB1 encodes the Gβ1 subunit of heterotrimeric G proteins, which obligatorily dimerizes with a Gγ subunit to form a Gβγ complex that couples to GPCRs and regulates downstream effectors; the integrity of this assembly is central to GNB1-associated neurodevelopmental disease (PMID:28087732, PMID:32918542). The Gβ1-Gγ interaction is conserved across eukaryotes, where Gβ stabilizes Gγ and both subunits maintain Gα at the plasma membrane (PMID:15701799). Disease-causing de novo missense mutations cluster at Gα-Gβγ and Gβγ-effector interfaces, and direct BRET/BiFC assays show that variants such as R52G, G64V, A92T, P94S, P96L, A106T, and D118G impair Gβ1-Gγ complex formation and GPCR coupling, while truncating and splice variants abolish Gγ dimerization and GPCR-mediated G protein activation, establishing both interface disruption and haploinsufficiency as mechanisms (PMID:27108799, PMID:28087732, PMID:32918542). A principal effector axis is the GIRK potassium channel: encephalopathy mutations exert subunit-specific, mutation-specific effects, with K78R producing gain-of-function and I80T/N and L95P producing loss-of-function GIRK regulation (PMID:34522861, PMID:40417225). The K78R gain-of-function increases GIRK activation in cortical neurons and is suppressed by ethosuximide in knock-in mice, linking GIRK hyperactivation to seizures (PMID:37275776), with absence seizures further driven through the thalamocortical circuit (PMID:36405774). Gβ1γ2 also associates with voltage-gated sodium channels and subtype-selectively inhibits Nav1.1 and Nav1.6, and K78R reduces sodium current and GABAergic transmission in parvalbumin interneurons (PMID:40482731). Beyond the nervous system, GNB1 signals through PI3K/Akt/mTOR and MAPK in leukemic cells (PMID:28650474), interacts with BAG2 to activate P38/MAPK in hepatocellular carcinoma (PMID:36718954), and supports adipocyte lipid droplet accumulation and lipid metabolism (PMID:40127054).

Mechanistic history

Synthesis pass · year-by-year structured walk · 11 steps
  1. 2016 Medium

    Established a structural hypothesis for how GNB1 mutations cause disease by mapping de novo variants onto Gα-Gβγ and Gβγ-effector interfaces.

    Evidence Whole-exome sequencing with structural mapping of mutation positions to known binding sites

    PMID:27108799

    Open questions at the time
    • No direct in vitro reconstitution of mutant effects in this study
    • Functional consequence inferred from structure rather than measured
    • Did not distinguish gain- from loss-of-function per variant
  2. 2017 High

    Provided direct functional evidence that specific missense variants impair Gβ1-Gγ assembly and GPCR coupling, converting the structural hypothesis into measured defects.

    Evidence BRET assays of Gβγ-Gα complex formation and D1R coupling across 10 missense variants

    PMID:28087732

    Open questions at the time
    • Did not assess effector-channel regulation
    • Negative variants (L30F, H91R, K337Q) lack mechanistic explanation
    • Limited to single GPCR readout
  3. 2017 Medium

    Linked GNB1 to oncogenic signaling by showing a somatic mutation activates PI3K/Akt/mTOR and MAPK independently of a driver fusion, conferring drug resistance.

    Evidence shRNA silencing of ETV6-ABL1 plus genomic/proteomic pathway profiling in leukemic cells

    PMID:28650474

    Open questions at the time
    • Single lab study
    • Direct effector of K78M-driven pathway activation not defined
    • No structural basis for gain-of-function established
  4. 2020 High

    Confirmed haploinsufficiency as a disease mechanism by demonstrating that truncating and splice variants fail to dimerize with Gγ and cannot activate G proteins.

    Evidence RNA-seq plus orthogonal BRET and BiFC assays of dimer formation and GPCR-induced activation

    PMID:32918542

    Open questions at the time
    • Downstream neuronal consequences not assessed
    • No in vivo model
    • Effector-level phenotype not measured
  5. 2021 High

    Identified GIRK channels as the key effector axis and showed encephalopathy mutations produce subunit-specific gain- or loss-of-function while sparing Gi/o coupling and CaV2.2.

    Evidence Heterologous electrophysiology, Gβγ-GIRK binding assays, expression analysis, and computational modeling of K78R/I80N/I80T

    PMID:34522861

    Open questions at the time
    • In vivo relevance not yet established
    • Mechanism of subunit selectivity incompletely defined
    • Limited to three variants
  6. 2022 Medium

    Defined the circuit-level basis of absence seizures, showing thalamocortical input regulates spike-wave discharges in Gnb1 mutant mice.

    Evidence In vivo recording with chemogenetic DREADD activation of thalamocortical neurons and EEG

    PMID:36405774

    Open questions at the time
    • Single lab study
    • Molecular link between GNB1 variant and circuit activity not fully resolved
    • Specific mutation context not detailed
  7. 2023 High

    Validated GIRK hyperactivation as an in vivo seizure mechanism and demonstrated pharmacological rescue, providing therapeutic rationale.

    Evidence K78R knock-in mice, MEA recordings, in vivo EEG, Xenopus oocyte electrophysiology, and ethosuximide intervention

    PMID:37275776

    Open questions at the time
    • Ethosuximide mechanism on GIRK GoF not fully defined
    • Generalizability to loss-of-function variants unknown
    • Long-term efficacy not addressed
  8. 2023 Medium

    Extended GNB1 oncogenic signaling by identifying BAG2 as a physical partner driving P38/MAPK-dependent hepatocellular carcinoma progression.

    Evidence Co-IP/LC-MS, P38 inhibitor intervention, and xenograft tumor model

    PMID:36718954

    Open questions at the time
    • Single lab study
    • Whether interaction is direct or complex-mediated unresolved
    • No reciprocal structural validation
  9. 2025 High

    Broadened the effector repertoire to voltage-gated sodium channels, showing Gβ1γ2 inhibits Nav1.1/Nav1.6 and K78R alters interneuron excitability and GABAergic transmission.

    Evidence Co-IP from mouse brain, heterologous electrophysiology, and cortical slice/dissociated interneuron recordings in Gnb1K78R/+ mice

    PMID:40482731

    Open questions at the time
    • Structural basis of Nav subtype selectivity unknown
    • Relative contribution of Nav vs GIRK effects to seizures unresolved
    • Direct binding interface not mapped
  10. 2025 Medium

    Demonstrated a distinct loss-of-function mechanism for L95P via protein destabilization rather than direct effector-interface disruption.

    Evidence Xenopus oocyte expression with RNA co-injection, electrophysiology, rigid-body docking, and thermodynamic calculations

    PMID:40417225

    Open questions at the time
    • Single mutation, single lab
    • Destabilization not confirmed by direct protein stability assays in vivo
    • No structural data beyond modeling
  11. 2025 Medium

    Revealed a non-neuronal metabolic role for GNB1 in adipocyte lipid storage and lipidome/proteome regulation.

    Evidence RNAi knockdown in human subcutaneous adipocytes with lipidomic and proteomic mass spectrometry

    PMID:40127054

    Open questions at the time
    • No rescue experiments
    • Single lab study
    • Signaling pathway linking GNB1 to lipid metabolism not defined

Open questions

Synthesis pass · forward-looking unresolved questions
  • How the spectrum of mutation-specific GIRK and Nav effects integrates into a unified predictive model of GNB1 encephalopathy phenotypes, and how GPCR/Gα coupling defects translate to specific circuit outcomes, remains unresolved.
  • No genotype-to-phenotype framework spanning gain- and loss-of-function variants
  • Structural mechanism of effector subtype selectivity unmapped
  • Relative weighting of GIRK, Nav, and GPCR-coupling contributions to seizures undefined

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0060089 molecular transducer activity 3 GO:0098772 molecular function regulator activity 3 GO:0005198 structural molecule activity 2
Localization
GO:0005829 cytosol 1 GO:0005886 plasma membrane 1
Pathway
R-HSA-112316 Neuronal System 4 R-HSA-162582 Signal Transduction 4 R-HSA-1430728 Metabolism 1
Partners
BAG2GIRKGNG1GNG2NAV1.1NAV1.6
Complex memberships
Gβγ heterodimerheterotrimeric G protein

Evidence

Reading pass · 12 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
2016 De novo missense mutations in GNB1 cluster in a sub-region affecting known Gα-Gβγ interaction interfaces and Gβγ-effector interaction sites, suggesting either constitutive Gβγ activation (when Gα binding is disrupted) or reduced effector interaction as disease mechanisms. Whole-exome sequencing with mapping of mutations to known structural binding sites; functional inference from known somatic gain-of-function mutations at overlapping residues American journal of human genetics Medium 27108799
2017 GNB1 missense mutations R52G, G64V, A92T, P94S, P96L, A106T, and D118G alter Gβ1 complex formation with Gγ and impair mutant Gβγ coupling to dopamine D1R receptors, as measured by BRET assays. Mutations L30F, H91R, and K337Q did not show altered functionality in these assays. BRET (bioluminescence resonance energy transfer) assays for Gβγ-Gα complex formation and GPCR coupling; functional testing of 10 missense variants Human molecular genetics High 28087732
2017 The GNB1 K89M mutation in ETV6-ABL1-positive leukemic cells activates PI3K/Akt/mTOR and MAPK signaling pathways independently of the ETV6-ABL1 oncogene, conferring resistance to tyrosine kinase inhibitors. shRNA-mediated silencing of ETV6-ABL1 in resistant cells; genomic and proteomic profiling; pathway activity measurement (PI3K/Akt/mTOR and MAPK) Oncogene Medium 28650474
2020 Loss-of-function GNB1 variants (a splice variant causing cryptic splice site usage and a truncating variant) fail to form dimers with Gγ subunit and are deficient in inducing GPCR-mediated G protein activation, establishing haploinsufficiency as a disease mechanism. RNA sequencing to confirm splice variant effect; BRET and BiFC (bimolecular fluorescence complementation) assays for Gβγ dimer formation and GPCR-induced G protein activation Molecular genetics & genomic medicine High 32918542
2021 GNB1 encephalopathy mutations K78R, I80N, and I80T do not alter Gi/o coupling or Gβγ regulation of CaV2.2, but profoundly affect Gβγ regulation of GIRK channels: K78R causes gain-of-function and I80T/N cause loss-of-function in a GIRK subunit-specific manner, with altered Gβ1 protein expression levels and Gβγ binding to cytosolic GIRK segments. Heterologous expression, electrophysiology, protein expression analysis, Gβγ binding assays to cytosolic GIRK segments; computational modeling iScience High 34522861
2023 The K78R GNB1 mutation causes gain-of-function (GoF) by increasing GIRK channel activation in cortical neurons and Xenopus oocytes; ethosuximide (ETX) suppresses this GoF effect and alleviates seizures in K78R knock-in mice, identifying GIRK channel hyperactivation as an epileptic mechanism in GNB1 encephalopathy. K78R knock-in mouse model; multi-electrode array recordings of cultured neurons; in vivo EEG; Xenopus oocyte electrophysiology; pharmacological inhibition with ETX Frontiers in cellular neuroscience High 37275776
2023 GNB1 physically interacts with BAG2 (co-immunoprecipitation followed by LC-MS), and this interaction activates the P38/MAPK signaling pathway to promote hepatocellular carcinoma cell proliferation, migration, invasion, and epithelial-to-mesenchymal transition. Co-immunoprecipitation followed by liquid chromatography-mass spectrometry; P38 inhibitor intervention; xenograft tumor model Cancer science Medium 36718954
2025 Gβ1γ2 complex associates with voltage-gated sodium channels (Navs) in mouse brain, and co-expression of Gβ1γ2 functionally inhibits Nav1.1 and Nav1.6 in heterologous cells in a subtype-selective manner. The K78R GNB1 mutation reduces spontaneous GABAergic transmission and decreases sodium current density in parvalbumin-expressing interneurons in cortical slices. Co-immunoprecipitation from mouse brain; heterologous expression electrophysiology; cortical slice electrophysiology in Gnb1K78R/+ mice; dissociated interneuron recordings Neurobiology of disease High 40482731
2025 The L95P GNB1 encephalopathy mutation reduces Gβ1 protein expression and, even when expression is restored, fails to effectively activate GIRK2 and GIRK1/2 channels in Xenopus oocytes; structural modeling indicates L95P primarily destabilizes the Gβ1 protein and the Gβ1-effector complex rather than disrupting the Gβγ-effector interface directly. Xenopus laevis oocyte heterologous expression with RNA co-injection; electrophysiology; rigid-body docking; thermodynamic calculations Frontiers in pharmacology Medium 40417225
2025 GNB1 knockdown in human subcutaneous adipocytes reduces lipid droplet accumulation and alters the lipidome (decreasing cholesterol esters, increasing phosphatidylcholines, phosphatidylinositols, and ceramides) and proteome (upregulating PLPP1 and CDH13, downregulating HSPA8), indicating a role for GNB1 in adipocyte lipid storage and metabolism. RNA interference knockdown; lipidomic analysis by mass spectrometry; proteomic analysis by mass spectrometry; digital PCR for knockdown confirmation PloS one Medium 40127054
2022 In Gnb1 mutant mice, thalamocortical (TC) neurons are activated prior to spike-wave discharge (SWD) onset and inhibited during SWD, while reticular thalamic (RT) neurons show the opposite pattern; chemogenetic activation of TC cells enhances SWD, demonstrating that sensory input regulates absence seizures through the thalamocortical pathway in GNB1 encephalopathy. In vivo recording in Gnb1 mutant mice; chemogenetic (DREADD) activation of thalamocortical neurons; EEG iScience Medium 36405774
2005 In Neurospora crassa, GNB-1 (Gβ) and GNG-1 (Gγ) physically associate in vivo (co-immunoprecipitation), GNB-1 is required for normal steady-state levels of GNG-1, and both subunits are required for maintaining Gα protein levels at the plasma membrane and for normal cAMP levels. Co-immunoprecipitation; genetic deletion analysis; plasma membrane fractionation; cAMP measurement Eukaryotic cell Medium 15701799

Source papers

Stage 0 corpus · 40 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2016 Germline De Novo Mutations in GNB1 Cause Severe Neurodevelopmental Disability, Hypotonia, and Seizures. American journal of human genetics 94 27108799
2005 The heterotrimeric G-protein subunits GNG-1 and GNB-1 form a Gbetagamma dimer required for normal female fertility, asexual development, and galpha protein levels in Neurospora crassa. Eukaryotic cell 64 15701799
2017 Novel GNB1 mutations disrupt assembly and function of G protein heterotrimers and cause global developmental delay in humans. Human molecular genetics 62 28087732
2018 Refining the phenotype associated with GNB1 mutations: Clinical data on 18 newly identified patients and review of the literature. American journal of medical genetics. Part A 54 30194818
2020 CircRNA circ_POLA2 promotes lung cancer cell stemness via regulating the miR-326/GNB1 axis. Environmental toxicology 53 32511866
1990 The gene for the beta-subunit of retinal transducin (Gnb-1) maps to distal mouse chromosome 4, and related sequences map to mouse chromosomes 5 and 8. Genomics 39 2328987
2016 Novel GNB1 missense mutation in a patient with generalized dystonia, hypotonia, and intellectual disability. Neurology. Genetics 37 27668284
2017 An activating mutation of GNB1 is associated with resistance to tyrosine kinase inhibitors in ETV6-ABL1-positive leukemia. Oncogene 28 28650474
2017 Novel GNB1 de novo mutation in a patient with neurodevelopmental disorder and cutaneous mastocytosis: Clinical report and literature review. European journal of medical genetics 28 29174093
2021 PAX8-AS1 knockdown facilitates cell growth and inactivates autophagy in osteoblasts via the miR-1252-5p/GNB1 axis in osteoporosis. Experimental & molecular medicine 23 34012023
2019 Phenotype-genotype correlations in patients with GNB1 gene variants, including the first three reported Japanese patients to exhibit spastic diplegia, dyskinetic quadriplegia, and infantile spasms. Brain & development 22 31735425
2020 CircRNA circ_POLA2 Promotes Cervical Squamous Cell Carcinoma Progression via Regulating miR-326/GNB1. Frontiers in oncology 20 32766125
2020 Haploinsufficiency as a disease mechanism in GNB1-associated neurodevelopmental disorder. Molecular genetics & genomic medicine 18 32918542
2023 GNB1 promotes hepatocellular carcinoma progression by targeting BAG2 to activate P38/MAPK signaling. Cancer science 15 36718954
2023 Epilepsy in a mouse model of GNB1 encephalopathy arises from altered potassium (GIRK) channel signaling and is alleviated by a GIRK inhibitor. Frontiers in cellular neuroscience 15 37275776
2021 Encephalopathy-causing mutations in Gβ1 (GNB1) alter regulation of neuronal GIRK channels. iScience 15 34522861
2021 Case Report: A Novel GNB1 Mutation Causes Global Developmental Delay With Intellectual Disability and Behavioral Disorders. Frontiers in neurology 12 34646230
2022 Sensory regulation of absence seizures in a mouse model of Gnb1 encephalopathy. iScience 10 36405774
2003 Comparative inter-strain sequence analysis of the putative regulatory region of murine psychostimulant-regulated gene GNB1 (G protein beta 1 subunit gene). DNA sequence : the journal of DNA sequencing and mapping 9 14631649
2006 A screen for mutations in the transducin gene GNB1 in patients with autosomal dominant retinitis pigmentosa. Molecular vision 7 17167406
2002 Isolation and sequencing of a putative promoter region of the murine G protein beta 1 subunit (GNB1) gene. DNA sequence : the journal of DNA sequencing and mapping 7 12180136
2023 Rod-cone dystrophy in an adult with GNB1-related disorder: An expansion of the phenotype and natural history. American journal of medical genetics. Part C, Seminars in medical genetics 6 37212526
2022 Dystonia with myoclonus and vertical supranuclear gaze palsy associated with a rare GNB1 variant. Parkinsonism & related disorders 6 36521323
2022 Cutaneous mastocytosis in a child with a de novo GNB1 mutation. Pediatric dermatology 4 35119134
2009 Phytoestrogens regulate mRNA and protein levels of guanine nucleotide-binding protein, beta-1 subunit (GNB1) in MCF-7 cells. Journal of cellular physiology 4 19170076
2024 GNB1 Encephalopathy: Clinical Case Report and Literature Review. Medicina (Kaunas, Lithuania) 3 38674235
2023 Atypical clinical course in two patients with GNB1 variants who developed acute encephalopathy. Brain & development 3 37453880
2024 GNB1 and obesity: Evidence for a correlation between haploinsufficiency and syndromic obesity. Clinical obesity 2 38596856
2024 The possible association of two novel heterozygous GNB1 variants with obesity and metabolic disorders. Hormones (Athens, Greece) 2 39581956
2012 Association of genetic variations in GNB1 with response to peginterferon plus ribavirin therapy for chronic hepatitis C in a Chinese population in Taiwan. BMC gastroenterology 2 23171003
2025 Integrative proteomic and lipidomic analysis of GNB1 and SCARB2 knockdown in human subcutaneous adipocytes. PloS one 1 40127054
2025 Structural and Functional Analysis of ASFV pI73R Reveals GNB1 Binding and Host Gene Modulation. International journal of molecular sciences 1 41465200
2024 GNB1-Related Rod-Cone Dystrophy: A Case Report. Case reports in ophthalmology 1 38500542
2024 Investigation of GNB1 derivative circular RNAs hsa_circ_0009361 and hsa_circ_0009362 expressions in colorectal cancer patients: potential new diagnostic factors. Gastroenterology and hepatology from bed to bench 1 38737931
2022 BCORL1 S878G, GNB1 G116S, SH2B3 A536T, and KMT2D S3708R tetramutation co-contribute to a pediatric acute myeloid leukemia: Case report and literature review. Frontiers in pediatrics 1 36324816
2026 Vitamin D3 prevents epileptic seizures by modulating the ras signalling pathway via Gnb1 and Casr in acute epilepsy mouse models. Epilepsy research 0 42150281
2025 Loss of expression and function of Gβγ by GNB1 encephalopathy-associated L95P mutation of the Gβ1 subunit. Frontiers in pharmacology 0 40417225
2025 Neuromodulation of voltage-gated sodium channels by Gβ1γ2 subunits: Implications for GNB1-linked encephalopathy. Neurobiology of disease 0 40482731
2024 KCNJ15 inhibits chemical-induced lung carcinogenesis and progression through GNB1 mediated Hippo pathway. Toxicology 0 39725264
2021 [Identification of a GNB1 gene variant in a child with autosomal dominant mental retardation 42]. Zhonghua yi xue yi chuan xue za zhi = Zhonghua yixue yichuanxue zazhi = Chinese journal of medical genetics 0 34096027

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