Affinage

RAB3GAP1

Rab3 GTPase-activating protein catalytic subunit · UniProt Q15042

Length
981 aa
Mass
110.5 kDa
Annotated
2026-06-10
33 papers in source corpus 12 papers cited in narrative 12 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

RAB3GAP1 encodes the catalytic (GTPase-activating) subunit of the heterodimeric RAB3GAP complex, which pairs with the non-catalytic subunit RAB3GAP2 to inactivate Rab3-GTP and thereby control calcium-regulated exocytic release of neurotransmitters and hormones (PMID:15696165, PMID:16532399). Genetic and electrophysiological studies establish that this GAP activity governs vesicle release at a late step: in Drosophila, Rab3-GAP relieves a Rab3-dependent brake on synaptic homeostasis (PMID:21338884), and in mammalian secretory systems the complex supports exocytosis of cargoes including Claudin-1 during epidermal barrier formation (PMID:23685254) and Myocilin in ocular cells under FOXC1 transcriptional control (PMID:28575017). The exocytic function is spatially gated by palmitoylation: the Golgi S-acyltransferase zDHHC9 modifies RAB3GAP1 on multiple cysteine residues, and although palmitoylation-deficient mutants retain bulk GAP activity, they fail to support exocytosis, indicating that lipidation targets RAB3GAP1 to specific membrane domains to confer spatiotemporal control over the Rab3 cycle and ANP release from cardiomyocytes (PMID:37325411, PMID:39953729). Beyond Rab3, the complex acts as a GEF-activating module for Rab18, promoting autolysosome maturation through GTP-Rab18 binding to Beclin1/Atg6 within Vps34 Complex I, a role independent of Rab3 itself (PMID:25495476, PMID:32248620). RAB3GAP1 additionally localizes to ER and Golgi, binds VAP-B via an FFAT-like motif to influence nuclear envelope formation, and interacts with DOCK7 and TMF1 to support neurite outgrowth and ER-Golgi trafficking (PMID:25612670, PMID:37385458). Loss-of-function mutations in RAB3GAP1 cause Warburg Micro syndrome, with patient and fetal tissue showing impaired autophagy, disrupted cortical neurogenesis, and bilateral cataracts (PMID:15696165, PMID:41413608).

Mechanistic history

Synthesis pass · year-by-year structured walk · 12 steps
  1. 2005 High

    Establishing that RAB3GAP1 is the catalytic GAP subunit regulating Rab3-mediated exocytosis answered what gene underlies a defined neurodevelopmental disorder and tied its molecular activity to secretion.

    Evidence Homozygous inactivating mutations in 12 families with Warburg Micro syndrome

    PMID:15696165

    Open questions at the time
    • Did not define how loss of GAP activity produces the brain malformation phenotype
    • No structural characterization of the catalytic site
  2. 2006 High

    Identifying RAB3GAP2 as the non-catalytic partner answered the question of complex composition, defining RAB3GAP as an obligate heterodimer.

    Evidence Missense mutation in RAB3GAP2 and embryonic mRNA expression of both subunits in zebrafish

    PMID:16532399

    Open questions at the time
    • Stoichiometry and assembly mechanism of the heterodimer not resolved
    • Distinct contributions of each subunit not separated
  3. 2011 High

    Genetic epistasis at the Drosophila NMJ resolved where in the release cycle Rab3-GAP acts, showing it relieves a Rab3-imposed brake on synaptic homeostasis at a late stage of vesicle release.

    Evidence Electrophysiological genetic screen with Rab3-GAP/Rab3 epistasis at the Drosophila NMJ

    PMID:21338884

    Open questions at the time
    • Molecular identity of the late-step effectors downstream of Rab3 not defined
    • Mammalian relevance of the homeostasis role untested
  4. 2013 Medium

    Demonstrating that Rab3Gap1 is required for Claudin-1 delivery to the plasma membrane extended its exocytic role beyond neurons to epithelial barrier formation.

    Evidence siRNA knockdown and rescue in rat epidermal keratinocytes with Claudin-1 localization readout

    PMID:23685254

    Open questions at the time
    • Whether Rab3 or another Rab mediates Claudin-1 trafficking not established
    • Single-lab finding without reciprocal validation
  5. 2014 Medium

    Discovery of a Rab3-independent autophagy function established a second pathway requiring RAB3GAP1 GAP activity, broadening the complex beyond classical exocytosis.

    Evidence C. elegans genetics plus human fibroblast siRNA, ATG5 puncta and lipid-droplet colocalization, FEZ1/FEZ2 epistasis

    PMID:25495476

    Open questions at the time
    • The GTPase substrate driving autophagy modulation not yet identified at this stage
    • Mechanism of reciprocal regulation with FEZ1/FEZ2 unclear
  6. 2014 Medium

    Mapping a direct VAP-B interaction via an FFAT-like motif placed RAB3GAP1 at the ER and linked it to nuclear envelope formation through ERGIC.

    Evidence Direct binding assay, FFAT-motif point mutagenesis, co-IP and overexpression

    PMID:25612670

    Open questions at the time
    • Functional role of the VAP-B interaction in normal physiology not established
    • Single-lab biochemistry
  7. 2017 Medium

    Identifying FOXC1 as a transcriptional activator of RAB3GAP1/2 connected the complex to regulated Myocilin secretion in ocular cells, situating it within a developmental gene-regulatory program.

    Evidence FOXC1 manipulation with RAB3GAP1/2 expression and MYOC secretion readouts

    PMID:28575017

    Open questions at the time
    • Direct vs indirect transcriptional regulation not distinguished
    • Relevance to neuronal RAB3GAP1 regulation unknown
  8. 2020 Medium

    Defining the Rab3GAP-Rab18 module acting on Vps34 Complex I via Beclin1 explained mechanistically how the complex promotes autolysosome maturation independent of Rab3.

    Evidence Drosophila Rab3GAP2 mutant, co-IP of GTP-Rab18 with Atg6/Beclin1, colocalization with Vps34 subunits, Atg14/UVRAG epistasis

    PMID:32248620

    Open questions at the time
    • Whether RAB3GAP1 acts as Rab18 GEF directly or through RAB3GAP2 not separated
    • Single-lab, largely model-organism evidence
  9. 2023 Medium

    Showing that zDHHC9 palmitoylates Rab3gap1 to spatially segregate it from Rab3a revealed a post-translational mechanism that gates its GAP activity and exocytic output.

    Evidence Palmitoylation assay, zDHHC9 manipulation, Rab3a-GTP and ANP secretion measurements in cardiomyocytes

    PMID:37325411

    Open questions at the time
    • The specific membrane domains targeted not fully mapped at this stage
    • Generality beyond cardiomyocytes untested
  10. 2023 Medium

    Localizing RAB3GAP1 to ER/Golgi and identifying DOCK7 and TMF1 as partners connected its trafficking role to neurite outgrowth and to neurodevelopmental pathology.

    Evidence Mass spectrometry, co-IP, colocalization and siRNA knockdown in human stem cell-derived neurons

    PMID:37385458

    Open questions at the time
    • Whether DOCK7/TMF1 interactions are GAP-activity dependent unclear
    • Causal hierarchy among trafficking defects and stress-pathway activation not resolved
  11. 2025 Medium

    Mapping specific palmitoylated cysteines and showing a 5CS mutant retains GAP activity but cannot drive exocytosis dissociated catalysis from membrane targeting, establishing palmitoylation as the spatial determinant of the Rab3 cycle.

    Evidence Site-directed cysteine mutagenesis with in vitro GAP assay, Rab3a-GTP and ANP secretion readouts in cardiomyocytes

    PMID:39953729

    Open questions at the time
    • The precise membrane microdomain destination of palmitoylated RAB3GAP1 not visualized
    • Single-lab cardiomyocyte system
  12. 2025 Medium

    Demonstrating impaired autophagy, disrupted cortical neurogenesis, and lens autophagy defects in patient and fetal tissue connected RAB3GAP1 loss to the cellular basis of Warburg Micro syndrome features.

    Evidence IHC, western blotting and EM on human fetal/infant brain tissue and patient-derived fibroblasts

    PMID:41413608

    Open questions at the time
    • Whether autophagy failure is the primary driver of neurogenesis defects or a parallel consequence not resolved
    • Causal chain from GAP loss to progenitor depletion not mechanistically dissected

Open questions

Synthesis pass · forward-looking unresolved questions
  • How RAB3GAP1's distinct activities — Rab3 GAP, Rab18 GEF-activation, and ER/Golgi trafficking partner — are coordinated within a single cell and which is rate-limiting for Warburg Micro syndrome pathology remains open.
  • No structural model integrating catalytic and membrane-targeting functions
  • Relative contribution of exocytic vs autophagic defects to neurodevelopmental disease unquantified
  • Whether palmitoylation gating operates outside cardiomyocytes unknown

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0098772 molecular function regulator activity 4 GO:0140096 catalytic activity, acting on a protein 2
Localization
GO:0005783 endoplasmic reticulum 2 GO:0005886 plasma membrane 2 GO:0005794 Golgi apparatus 1 GO:0005811 lipid droplet 1
Pathway
R-HSA-5653656 Vesicle-mediated transport 3 R-HSA-9612973 Autophagy 3 R-HSA-112316 Neuronal System 2 R-HSA-1266738 Developmental Biology 2
Partners
DOCK7RAB18RAB3GAP2TMF1VAPBZDHHC9
Complex memberships
RAB3GAP complex (RAB3GAP1/RAB3GAP2)

Evidence

Reading pass · 12 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
2005 RAB3GAP1 encodes the catalytic subunit of RAB3 GTPase activating protein (RAB3GAP), a heterodimeric complex that regulates calcium-mediated exocytic release of neurotransmitters and hormones via the Rab3 pathway; inactivating mutations in RAB3GAP1 cause Warburg Micro syndrome. Identification of homozygous inactivating mutations in 12 families; genetic loss-of-function with defined clinical phenotype Nature genetics High 15696165
2006 RAB3GAP is a heterodimeric protein consisting of a catalytic subunit (RAB3GAP1) and a non-catalytic subunit (RAB3GAP2); mutations in either subunit disrupt complex function and cause related neurodevelopmental disorders. Identification of homozygous missense mutation in RAB3GAP2 causing abnormal splicing; mRNA expression studies in zebrafish embryos for both subunits American journal of human genetics High 16532399
2011 Drosophila Rab3-GAP is necessary for both the induction and expression of synaptic homeostasis at the NMJ, acting at a late stage of vesicle release by relieving an opposing influence on homeostasis catalyzed by Rab3 (independent of NMJ anatomy changes). Electrophysiology-based genetic screen; loss-of-function mutant analysis at Drosophila NMJ with epistasis between Rab3-GAP and Rab3 Neuron High 21338884
2013 RAB3GAP1 mediates exocytosis of Claudin-1 to the plasma membrane, which is required for tight junction formation and epidermal barrier acquisition; siRNA knockdown of Rab3Gap1 prevents plasma membrane Claudin-1 expression and barrier formation, and re-expression rescues this defect. siRNA knockdown in rat epidermal keratinocytes; rescue experiments; co-localization of Rab3Gap1 cell surface expression with Claudin-1 membrane localization during mouse epidermal development Developmental biology Medium 23685254
2014 VAP-B directly binds to RAB3GAP1 (catalytic subunit of RAB3GAP) through an FFAT-like motif on RAB3GAP1 at the ER; VAP-B binds RAB3GAP1 even within the RAB3GAP1/2 heterodimer. Mutation of the FFAT-like motif reduces VAP-B binding but increases binding to ERGIC-53. Overexpression of RAB3GAP1 affects nuclear envelope formation more potently than the FFAT-like motif mutant, implicating this interaction in nuclear envelope formation via ERGIC. Direct binding assay; single amino acid substitution of FFAT-like motif; co-immunoprecipitation; overexpression studies The Kobe journal of medical sciences Medium 25612670
2014 RAB3GAP1 and RAB3GAP2 modulate autophagosomal biogenesis and affect autophagy at basal and rapamycin-induced conditions; their autophagy modulatory activity depends on the GTPase-activating activity of RAB3GAP1 but is independent of the RAB GTPase RAB3. RAB3GAP1/2 colocalize with Atg8 family members at lipid droplets and reciprocally regulate autophagy relative to FEZ1/FEZ2. C. elegans genetics and human primary fibroblasts; siRNA knockdown; ATG5 puncta analysis; colocalization; epistasis with FEZ1/FEZ2 Autophagy Medium 25495476
2017 Transcription factor FOXC1 positively regulates RAB3GAP1 and RAB3GAP2 expression; FOXC1 regulation of RAB3GAP1 and RAB3GAP2 affects secretion of Myocilin (MYOC), linking RAB3GAP1 to extracellular trafficking/exocytosis in ocular cells. Biochemical and molecular techniques; manipulation of FOXC1 levels; measurement of RAB3GAP1/2 expression and MYOC secretion PloS one Medium 28575017
2020 The Rab3GAP-Rab18 module (comprising Rab3GAP1/2 complex acting as GEF for Rab18) promotes autolysosome maturation through interaction with Vps34 Complex I; GTP-bound Rab18 binds to Atg6/Beclin1 (a permanent subunit of Vps34 complexes). Loss of Rab3GAP2 in Drosophila leads to perturbed autolysosome morphology, destabilization of Rab7-positive compartments, and perturbation of lysosomal biosynthetic transport. Drosophila Rab3GAP2 mutant model; co-immunoprecipitation of GTP-Rab18 with Atg6/Beclin1; colocalization of Rab3GAP2 and Rab18 with Vps34 Complex I subunits; epistasis with Atg14/UVRAG overexpression The FEBS journal Medium 32248620
2023 The Golgi S-acyltransferase zDHHC9 palmitoylates Rab3gap1, resulting in spatial segregation of Rab3gap1 from Rab3a, elevation of Rab3a-GTP levels, formation of Rab3a-positive peripheral vesicles, and impairment of exocytosis that limits atrial natriuretic peptide (ANP) release from cardiomyocytes. Biochemical palmitoylation assay; zDHHC9 manipulation; measurement of Rab3a-GTP levels; ANP secretion assay; subcellular localization imaging in cardiomyocytes JACC. Basic to translational science Medium 37325411
2025 Palmitoylation of Rab3gap1 on multiple cysteine residues (Cys-509, 510, 521, 522, and 678) by zDHHC9 is required for Rab3gap1-mediated exocytosis and ANP release in cardiomyocytes; a palmitoylation-deficient Rab3gap15CS mutant maintains total cellular GAP activity and reduces Rab3a-GTP levels similarly to wild-type, but is incapable of promoting exocytosis and ANP release, indicating palmitoylation targets Rab3gap1 to specific intracellular membrane domains for spatiotemporal control of the Rab3 cycle. Site-directed mutagenesis of cysteine residues; palmitoylation assay; GTPase activity assay; Rab3a-GTP measurement; ANP secretion assay in cardiomyocytes Biophysical journal Medium 39953729
2023 RAB3GAP1 is localized to ER and Golgi compartments in neurons; its downregulation reduces neurite outgrowth and complexity in human stem cell-derived neurons. RAB3GAP1 physically interacts with axon elongation factor DOCK7 and ER-to-Golgi trafficking modulator TMF1; loss of RAB3GAP1 disrupts the sub-cellular localization of TMF1 and DOCK7 across Golgi and ER compartments, and activates stress response pathways (ATF6, MAPK, PI3-AKT). Mass spectrometry; co-immunoprecipitation; colocalization analysis; siRNA knockdown in human stem cell-derived neurons; subcellular fractionation Neurobiology of disease Medium 37385458
2025 Loss of RAB3GAP1 in human fetal brain tissue and patient-derived fibroblasts impairs autophagy (confirmed by immunocytochemistry, western blotting, and electron microscopy), disrupts cortical development (reduced SOX2-positive progenitors, disorganized radial glia, increased caspase-3, fewer DCX- and CTIP2-positive neurons), and causes bilateral cataracts associated with autophagy disruption in the fetal lens. Histology and immunohistochemistry on fetal brain and infant brain tissue; western blotting; electron microscopy; immunocytochemistry in patient-derived skin fibroblasts Acta neuropathologica communications Medium 41413608

Source papers

Stage 0 corpus · 33 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2005 Mutations of the catalytic subunit of RAB3GAP cause Warburg Micro syndrome. Nature genetics 177 15696165
2013 Mutation spectrum in RAB3GAP1, RAB3GAP2, and RAB18 and genotype-phenotype correlations in warburg micro syndrome and Martsolf syndrome. Human mutation 110 23420520
2006 Mutation in Rab3 GTPase-activating protein (RAB3GAP) noncatalytic subunit in a kindred with Martsolf syndrome. American journal of human genetics 88 16532399
2011 Rab3-GAP controls the progression of synaptic homeostasis at a late stage of vesicle release. Neuron 83 21338884
2014 RAB3GAP1 and RAB3GAP2 modulate basal and rapamycin-induced autophagy. Autophagy 75 25495476
2010 New RAB3GAP1 mutations in patients with Warburg Micro Syndrome from different ethnic backgrounds and a possible founder effect in the Danish. European journal of human genetics : EJHG 50 20512159
2013 Replication and meta-analysis of candidate loci identified variation at RAB3GAP1 associated with keratoconus. Investigative ophthalmology & visual science 27 23833071
2015 A RAB3GAP1 SINE Insertion in Alaskan Huskies with Polyneuropathy, Ocular Abnormalities, and Neuronal Vacuolation (POANV) Resembling Human Warburg Micro Syndrome 1 (WARBM1). G3 (Bethesda, Md.) 25 26596647
2023 zDHHC9 Regulates Cardiomyocyte Rab3a Activity and Atrial Natriuretic Peptide Secretion Through Palmitoylation of Rab3gap1. JACC. Basic to translational science 23 37325411
2012 RAB3GAP1, RAB3GAP2 and RAB18: disease genes in Micro and Martsolf syndromes. Biochemical Society transactions 23 23176487
2020 The Warburg Micro Syndrome-associated Rab3GAP-Rab18 module promotes autolysosome maturation through the Vps34 Complex I. The FEBS journal 20 32248620
2015 A mutation in the Warburg syndrome gene, RAB3GAP1, causes a similar syndrome with polyneuropathy and neuronal vacuolation in Black Russian Terrier dogs. Neurobiology of disease 16 26607784
2014 VAP-B binds to Rab3GAP1 at the ER: its implication in nuclear envelope formation through the ER-Golgi intermediate compartment. The Kobe journal of medical sciences 14 25612670
2016 A Homozygous RAB3GAP1:c.743delC Mutation in Rottweilers with Neuronal Vacuolation and Spinocerebellar Degeneration. Journal of veterinary internal medicine 12 26968732
2015 Novel RAB3GAP1 compound heterozygous mutations in Japanese siblings with Warburg Micro syndrome. Brain & development 12 26421802
2013 Rab3Gap1 mediates exocytosis of Claudin-1 and tight junction formation during epidermal barrier acquisition. Developmental biology 10 23685254
2017 FOXC1 modulates MYOC secretion through regulation of the exocytic proteins RAB3GAP1, RAB3GAP2 and SNAP25. PloS one 9 28575017
2025 Rab3gap1 palmitoylation cycling modulates cardiomyocyte exocytosis and atrial natriuretic peptide release. Biophysical journal 8 39953729
2019 Revealing the functions of novel mutations in RAB3GAP1 in Martsolf and Warburg micro syndromes. American journal of medical genetics. Part A 8 30730599
2020 Novel mutation in the RAB3GAP1 gene, the first diagnosed Warburg Micro syndrome case in Syria. Oxford medical case reports 6 32477580
2021 Novel manifestations of Warburg micro syndrome type 1 caused by a new splicing variant of RAB3GAP1: a case report. BMC neurology 5 33910511
2017 Novel RAB3GAP1 Mutations Causing Warburg Micro Syndrome in Two Italian Sisters. Journal of pediatric neurosciences 5 29675078
2014 Large homozygous RAB3GAP1 gene microdeletion causes Warburg micro syndrome 1. Orphanet journal of rare diseases 5 25332050
2022 Novel RAB3GAP1 Mutation in the First Tunisian Family With Warburg Micro Syndrome. Journal of clinical neurology (Seoul, Korea) 4 35196747
2015 RECURRENT RAB3GAP1 MUTATIONS IN THE TURKISH POPULATION. Genetic counseling (Geneva, Switzerland) 4 26852512
2021 Global effects of RAB3GAP1 dysexpression on the proteome of mouse cortical neurons. Amino acids 3 34363538
2023 The Warburg micro syndrome protein RAB3GAP1 modulates neuronal morphogenesis and interacts with axon elongation end ER-Golgi trafficking factors. Neurobiology of disease 1 37385458
2023 First Clinical Report of Two RAB3GAP1 Pathogenic Variant in Warburg Micro Syndrome. Journal of pediatric genetics 1 37575647
2021 A novel mutation in RAB3GAP1 gene in Chinese patient causing the Warburg micro syndrome: A case report. Medicine 1 33466118
2025 Biallelic null RAB3GAP1 variants impair cortical development and autophagy in Warburg Micro syndrome: evidence from fetal brain tissue and patient fibroblasts. Acta neuropathologica communications 0 41413608
2023 Novel, homozygous RAB3GAP1 c.2606 + 1G>A, p.Glu830ValfsTer9 variant and chromosome 3q29 duplication in a Turkish individual with Warburg micro syndrome. Clinical dysmorphology 0 36876345
2023 Exome sequencing identifies a novel pathogenic variant in RAB3GAP1 causing Warburg Micro syndrome in a Pakistani family. International journal of developmental neuroscience : the official journal of the International Society for Developmental Neuroscience 0 37186309
2020 [Analysis of a case of Warburg micro syndrome type 1 due to variant of RAB3GAP1 gene]. Zhonghua yi xue yi chuan xue za zhi = Zhonghua yixue yichuanxue zazhi = Chinese journal of medical genetics 0 33306828

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