Affinage

VPS8

Vacuolar protein sorting-associated protein 8 homolog · UniProt Q8N3P4

Length
1428 aa
Mass
161.8 kDa
Annotated
2026-06-11
10 papers in source corpus 9 papers cited in narrative 9 extracted findings
Cross-family judge vs UniProt: Affinage preferred faithfulness: 7/7 claims corpus-supported (100%)

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

VPS8 is a subunit of the CORVET membrane-tethering complex that regulates endosomal trafficking by acting as a Rab5/Vps21 effector (PMID:19828734). In yeast, Vps8 is a membrane-associated protein required for accurate sorting of vacuolar hydrolases, functioning in retrieval of Golgi membrane proteins from the prevacuolar compartment, since its loss causes mislocalization and aberrant proteolysis of the CPY sorting receptor Vps10p (PMID:8864656). As the effector subunit of CORVET, Vps8 binds activated Vps21 and cooperates with Vps3, Vps16, and Vps33 to drive clustering of endosomal membranes (PMID:19828734). It engages distinct binding partners through separable regions: an N-terminal segment mediates membrane association and Vps21 binding, while a separate region mediates association with the HOPS/class C core, and loss of core binding more severely impairs endocytic cargo turnover and CPY sorting than loss of Vps21 binding (PMID:20173035, PMID:23840658). In metazoans, Vps8 assembles into a four-subunit miniCORVET (with Vps16A, Vps18, and Vps33A) that tethers early endosomes in Drosophila (PMID:27253064), and in human cells it localizes to Rab4/Rab11 recycling compartments to drive integrin recycling, controlling cell adhesion, spreading, focal adhesion formation, and migration (PMID:29476049). The relative abundance of Vps8 and the HOPS-specific subunit Vps41 governs the balance between the two complexes: Vps8 overexpression displaces Vps41 from late endosomes and inhibits HOPS-dependent late endosome maturation, autophagosome–lysosome fusion, and lysosome-related organelle formation (PMID:31194677). Vps21 further coordinates Vps8 with the PI3K Vps34 machinery on endosomes to support autophagy (PMID:36076954).

Mechanistic history

Synthesis pass · year-by-year structured walk · 9 steps
  1. 1996 Medium

    Established that Vps8 is required for fidelity of vacuolar protein sorting, framing it as a trafficking factor that retrieves Golgi membrane proteins from the prevacuolar compartment rather than a hydrolase itself.

    Evidence Genetic characterization of yeast vps8 mutants with subcellular fractionation and Western blotting for Vps10p localization and proteolysis

    PMID:8864656

    Open questions at the time
    • No molecular complex or direct binding partners identified
    • Mechanism of retrieval not defined
    • No Rab connection established
  2. 1998 Medium

    Genetic epistasis placed Pep5 at the site of Vps8 action, beginning to map the functional pathway around Vps8 in Golgi-to-prevacuolar transport.

    Evidence Genetic suppressor analysis of vps8/pep5 double mutants with hydrolase maturation and vacuolar morphology readouts in yeast

    PMID:9475722

    Open questions at the time
    • Physical interaction not tested
    • Did not define a discrete complex
    • Molecular nature of cooperation unresolved
  3. 2009 High

    Defined Vps8 as the effector subunit of the CORVET tethering complex and a Rab5/Vps21 partner, explaining how it physically links activated Rab to endosomal membrane clustering.

    Evidence In vivo late endosome biogenesis and clustering assays with protein interaction studies in yeast

    PMID:19828734

    Open questions at the time
    • Domain architecture of Vps21 versus core binding not yet mapped
    • Structural basis of tethering unknown
    • Metazoan relevance untested
  4. 2010 Medium

    Separated the membrane-binding, Vps21-binding, and HOPS-core-binding determinants of Vps8 and showed the core interaction is functionally dominant for cargo sorting.

    Evidence Two-hybrid analysis, immunoprecipitation, and deletion mapping with Ste6 turnover and CPY sorting readouts in yeast

    PMID:20173035

    Open questions at the time
    • Precise structural interfaces not resolved
    • Multiple membrane-binding regions not fully mapped
    • Single-lab two-hybrid evidence
  5. 2013 Medium

    Showed CORVET endosomal targeting depends on the N-terminal Rab-binding domains of Vps3 and Vps8 but that additional C-terminal binding sites exist, refining how the complex is recruited to membranes.

    Evidence N-terminal truncation mutagenesis with fractionation, microscopy, and sorting assays in yeast

    PMID:23840658

    Open questions at the time
    • C-terminal endosomal binding partners not identified
    • Quantitative contribution of each site unresolved
    • Structural model lacking
  6. 2016 High

    Extended Vps8 function to metazoans by identifying a four-subunit miniCORVET that tethers early endosomes in Drosophila despite the absence of a Vps3 homolog.

    Evidence Co-localization, reciprocal co-immunoprecipitation, and genetic loss-of-function with endosome morphology readout in Drosophila hemocytes and nephrocytes

    PMID:27253064

    Open questions at the time
    • Rab effector partner in flies not defined
    • Whether miniCORVET fully recapitulates yeast CORVET activity unclear
    • Tethering mechanism in vivo not reconstituted
  7. 2018 High

    Assigned a human cellular role to Vps8 in integrin recycling, linking endosomal trafficking to adhesion and migration phenotypes.

    Evidence siRNA depletion with co-localization (Rab4/Rab11), integrin trafficking, and adhesion/spreading/migration assays in mammalian cells

    PMID:29476049

    Open questions at the time
    • Direct Rab effector interactions in human cells not biochemically mapped
    • Cargo selectivity beyond integrins untested
    • Complex composition (CORVET vs CHEVI) at recycling endosomes not fully resolved
  8. 2019 High

    Demonstrated that Vps8 stoichiometry relative to Vps41 acts as a switch between CORVET and HOPS activities, explaining how Vps8 levels negatively regulate HOPS-dependent maturation and autophagy.

    Evidence Overexpression, microscopy of HOPS subunit localization, genetic epistasis, and autophagy/lysosomal biogenesis assays in Drosophila

    PMID:31194677

    Open questions at the time
    • Mechanism of competitive displacement at the core not structurally defined
    • Whether the same switch operates in mammals untested
    • Regulation of Vps8:Vps41 ratio in vivo unknown
  9. 2022 Medium

    Connected Vps8 to the PI3K Vps34 machinery via Vps21, showing Rab-dependent coordination of tethering with phosphoinositide signaling during autophagy.

    Evidence Co-localization, co-immunoprecipitation, and autophagy flux assays in vps21Δ yeast

    PMID:36076954

    Open questions at the time
    • Direct Vps8–Vps34 interaction versus Rab-bridged not distinguished
    • Single-lab study
    • Mechanistic order of recruitment events incomplete

Open questions

Synthesis pass · forward-looking unresolved questions
  • How the Vps8:Vps41 ratio is set and regulated in mammalian cells, and the structural basis by which Vps8 discriminates CORVET versus HOPS core assembly, remain unresolved.
  • No structure of mammalian CORVET/Vps8 interfaces
  • Regulators of complex stoichiometry unknown
  • Full cargo repertoire of Vps8-dependent trafficking undefined

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0060090 molecular adaptor activity 3
Localization
GO:0005768 endosome 3 GO:0005886 plasma membrane 1
Pathway
R-HSA-5653656 Vesicle-mediated transport 3 R-HSA-9612973 Autophagy 2
Partners
VPS16/VPS16AVPS18VPS21/RAB5VPS3VPS33/VPS33AVPS34VPS41
Complex memberships
CORVETHOPS core (class C)miniCORVET

Evidence

Reading pass · 9 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
1996 Yeast Vps8p is a membrane-associated hydrophilic protein of 135 kDa required for accurate sorting of vacuolar hydrolases CPY and proteinase A; in vps8 mutants the Golgi-localized CPY sorting receptor Vps10p mislocalizes to and is aberrantly proteolyzed in the vacuole, and several late-Golgi membrane proteins fail to be retained, indicating Vps8p functions in retrieval of Golgi membrane proteins from the prevacuolar compartment. Genetic characterization of vps8 mutants, subcellular fractionation, Western blotting for Vps10p localization and proteolysis European journal of cell biology Medium 8864656
1998 Genetic epistasis in yeast shows that the vps8-200 allele partially suppresses the vestigial vacuole phenotype of pep5 mutants, restoring near wild-type vacuolar hydrolase maturation and vacuolar morphology; this indicates Pep5p functions at the site of Vps8p action (Golgi-to-prevacuolar compartment transport) as well as more proximal to the vacuole. Genetic suppressor analysis (double-mutant phenotype characterization), vacuolar hydrolase maturation assays, vacuolar morphology assessment Genetics Medium 9475722
2009 Yeast Vps8 is the effector subunit of the CORVET tethering complex: it interacts and cooperates with activated Rab5 homolog Vps21 to induce clustering of late endosomal membranes; this clustering additionally requires Vps3, Vps16, and Vps33 but not other CORVET subunits, indicating CORVET subunits have distinct activities. In vivo late endosome biogenesis monitoring assay, protein interaction studies, fluorescence microscopy of endosomal clustering Molecular biology of the cell High 19828734
2010 Yeast Vps8 membrane association is independent of the class C/HOPS core complex and independent of Rab GTPase Vps21; multiple membrane-binding regions exist in Vps8, with one mapped to the N-terminal part. By two-hybrid analysis, Vps8 physically interacts with Vps21, and its interaction with the HOPS core complex was confirmed by immunoprecipitation. Deletions abolishing HOPS core binding strongly impair endocytic cargo (Ste6) turnover and CPY vacuolar sorting, while deletions abolishing Vps21 binding have only modest effects. Two-hybrid analysis, immunoprecipitation, deletion mapping, endocytic cargo turnover assays (Ste6, CPY sorting) Eukaryotic cell Medium 20173035
2013 The N-terminal domains of yeast Vps3 and Vps8 (which interact with Rab5/Vps21) are required for CORVET localization to endosomes and for endocytic protein sorting; dual truncation mislocalizes CORVET to the cytosol and impairs sorting but not complex assembly. Overexpression of Vps21 or a single truncated subunit can rescue endosomal localization, indicating CORVET has additional C-terminal binding sites for endosomes beyond its N-terminal β-propeller domains. N-terminal truncation mutagenesis, subcellular fractionation, fluorescence microscopy, protein sorting assays in yeast PloS one Medium 23840658
2016 Drosophila Vps8 localizes to early endosomes despite absence of a clear Vps3 homolog, and forms a 4-subunit miniCORVET complex with Vps16A, Dor/Vps18, and Car/Vps33A; loss of any of these subunits causes endosome fragmentation, establishing miniCORVET as an unconventional early endosomal tether in Drosophila. Fluorescence microscopy (co-localization), co-immunoprecipitation, genetic loss-of-function (endosome morphology readout) in Drosophila hemocytes and nephrocytes eLife High 27253064
2018 Human Vps3 and Vps8 localize to Rab4-positive recycling vesicles and co-localize with the CHEVI complex on Rab11-positive recycling endosomes; depletion of Vps3 or Vps8 delays delivery of internalised integrins to recycling endosomes and their return to the plasma membrane, causing defects in integrin-dependent cell adhesion, spreading, focal adhesion formation, and cell migration. siRNA depletion, fluorescence microscopy (co-localization with Rab4/Rab11 markers), integrin trafficking assays, cell adhesion/spreading/migration assays in mammalian cells Nature communications High 29476049
2019 Overexpression of Drosophila Vps8 abolishes late endosomal localization of HOPS-specific subunit Vps41/Lt and prevents HOPS assembly, thereby inhibiting HOPS-dependent trafficking routes including late endosome maturation, autophagosome-lysosome fusion, crinophagy, and lysosome-related organelle formation; this indicates Vps8 negatively regulates HOPS by outcompeting Vps41 when the Vps8:Vps41 ratio is altered. Overexpression studies, fluorescence microscopy (endosomal localization of HOPS subunits), genetic epistasis, autophagy and lysosomal biogenesis assays in Drosophila eLife High 31194677
2022 In yeast, Vps21 is required for colocalization and interaction of Vps8 with Vps34 on endosomes, and for subsequent Vps34-Atg21 interaction; loss of Vps21 disrupts localization of PI3K complex II subunits (Vps34, Vps38) from endosomes and partly disrupts PI3K complex I subunits (Vps34, Atg14) and Atg21 from the phagophore assembly site, delaying autophagy. Fluorescence colocalization microscopy, co-immunoprecipitation, autophagy flux assays in vps21Δ yeast International journal of molecular sciences Medium 36076954

Source papers

Stage 0 corpus · 10 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2009 The CORVET subunit Vps8 cooperates with the Rab5 homolog Vps21 to induce clustering of late endosomal compartments. Molecular biology of the cell 80 19828734
2016 MiniCORVET is a Vps8-containing early endosomal tether in Drosophila. eLife 52 27253064
2018 Vps3 and Vps8 control integrin trafficking from early to recycling endosomes and regulate integrin-dependent functions. Nature communications 41 29476049
1996 The VPS8 gene is required for localization and trafficking of the CPY sorting receptor in Saccharomyces cerevisiae. European journal of cell biology 26 8864656
2019 Vps8 overexpression inhibits HOPS-dependent trafficking routes by outcompeting Vps41/Lt. eLife 24 31194677
2013 The N-terminal domains of Vps3 and Vps8 are critical for localization and function of the CORVET tethering complex on endosomes. PloS one 19 23840658
2010 Mapping of Vps21 and HOPS binding sites in Vps8 and effect of binding site mutants on endocytic trafficking. Eukaryotic cell 16 20173035
2022 Vps21 Directs the PI3K-PI(3)P-Atg21-Atg16 Module to Phagophores via Vps8 for Autophagy. International journal of molecular sciences 11 36076954
1998 Genetic interaction with vps8-200 allows partial suppression of the vestigial vacuole phenotype caused by a pep5 mutation in Saccharomyces cerevisiae. Genetics 11 9475722
2025 ANKK1, ANKRD50, GRK5, PACSIN1 and VPS8 are novel candidate genes associated with late onset Parkinson's disease: Definition of a novel predictive protocol based on polygenic model of inheritance. Neurobiology of disease 0 40494419

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