Manual transfer of experimentally-verified manual GO annotation data to orthologs by curator judgment of sequence similarity
Gene Ontology annotation based on UniProtKB/Swiss-Prot keyword mapping
Gene Ontology annotation based on UniProtKB/Swiss-Prot Subcellular Location vocabulary mapping, accompanied by conservative changes to GO terms applied by UniProt
Automatic assignment of GO terms using logical inference, based on on inter-ontology links
Structural characterization and membrane binding properties of the matrix protein VP40 of Ebola virus.
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Cross-linking and electron microscopy show that C-terminally truncated VP40 self-associates into hexamers while the longer polypeptide is monomeric.
"As indicated by chemical cross-linking studies and electron microscopy, the larger polypeptide was present in a monomeric form, whereas the truncated one formed hexamers."
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The C-terminal part of VP40 is required for efficient association with membranes containing negatively charged lipids.
"Membrane association of truncated, hexameric VP40 was inefficient, indicating a membrane-recognition role for the C-terminal part."
Ebola virus VP40-induced particle formation and association with the lipid bilayer.
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VP40 expressed alone in mammalian cells induces membrane-bound particle formation, dependent on its conserved N-terminal PPxY motif.
"We found that VP40 is indeed able to induce particle formation when it is expressed in mammalian cells, and this process appeared to rely on a conserved N-terminal PPXY motif, as mutation or loss of this motif resulted in markedly reduced particle formation."
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Flotation gradient analysis demonstrates hydrophobic, salt-resistant association of VP40 with cellular membranes.
"Flotation gradient analysis indicated that VP40 binds to membranes in a hydrophobic manner, as NaCl at 1 M did not release the protein from the lipid bilayer."
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VP40 alone carries the information needed for particle formation.
"These findings demonstrate that VP40 alone possesses the information necessary to induce particle formation"
The matrix protein VP40 from Ebola virus octamerizes into pore-like structures with specific RNA binding properties.
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The X-ray structure shows VP40 N-terminal domains assembled into an octameric ring.
"Here we present the X-ray structure of octameric VP40 assembled through its N-terminal domain (NTD)."
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The octamer binds a specific RNA sequence and this RNA-bound form is present in infected cells.
"This strongly indicates, together with the RNA binding properties of full-length oligomeric VP40 in vitro, that octameric VP40 bound to a specific RNA sequence plays a role in the virus life cycle."
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The SDS-resistant octamer-RNA species was not detected in purified virus particles.
"However, no high molecular weight band corresponding to the SDS-resistant form detected in virus-infected cells could be detected, indicating that octameric VP40 might not be abundantly present in virus particles (Figure 5C)."
In vivo oligomerization and raft localization of Ebola virus protein VP40 during vesicular budding.
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VP40 oligomers are present in lipid rafts of mammalian cells, in VLPs and in authentic Ebola virus.
"Here, we demonstrate VP40 oligomers in lipid rafts of mammalian cells, virus-like particles, and in the authentic Ebola virus."
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VP40 actively recruits the ESCRT-I component TSG101 into lipid rafts.
"Furthermore, we demonstrate the active recruitment of TSG101 into lipid rafts by VP40."
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C-terminal mutagenesis coordinately disrupts oligomerisation at the plasma membrane, detergent-resistant membrane association and vesicular release.
"By mutagenesis, we identify several critical C-terminal sequences that regulate oligomerization at the plasma membrane, association with detergent-resistant membranes, and vesicular release of VP40, directly linking these phenomena."
A luciferase-based budding assay for Ebola virus.
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VP40 buds from mammalian cells as a VLP and is the major protein driving EBOV egress.
"The VP40 matrix protein of Ebola virus (EBOV) is capable of budding from mammalian cells as a virus-like particle (VLP) and is the major protein involved in virus egress."
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A budding-deficient VP40 mutant significantly reduces luciferase in the released VLP fraction, making luciferase a quantitative readout of VP40 budding.
"In contrast, when luciferase is co-expressed with a budding deficient mutant of VP40, luciferase levels in the VLP fraction decrease significantly."
Ebolavirus proteins suppress the effects of small interfering RNA by direct interaction with the mammalian RNA interference pathway.
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A screen of all EBOV proteins identified VP40, alongside VP30 and VP35, as an independent suppressor of RNA silencing.
"In addition to viral protein 35 (VP35), we found that VP30 and VP40 independently act as SRSs."
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The molecular mechanism was resolved for VP30 and VP35, not for VP40.
"Here, we present the molecular mechanisms of VP30 and VP35."
Characterization of filovirus protein-protein interactions in mammalian cells using bimolecular complementation.
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VP40-VP40 complexes localise predominantly to the plasma membrane while VP40-NP and NP-NP complexes are dispersed in the cytoplasm.
"We demonstrate that VP40-VP40 complexes localized predominantly at the plasma membrane, whereas VP40-NP and NP-NP complexes displayed a more dispersed pattern throughout the cytoplasm."
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VP40 self-association depends on the LPLGVA motif rather than on the PTAPPEY/PPPY late domains.
"the formation of EBOV or MARV VP40-VP40 complexes was dependent on the previously characterized LPLGVA and LPLGIM motifs of EBOV and MARV VP40 proteins, respectively, indicating that these motifs are important for VP40 oligomerization and subsequent budding"
The Ebola virus matrix protein penetrates into the plasma membrane: a key step in viral protein 40 (VP40) oligomerization and viral egress.
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Hydrophobic C-terminal residues Leu213, Ile293, Leu295 and Val298 are required for plasma membrane penetration, plasma membrane localisation, oligomerisation and particle egress.
"Mutagenesis of this hydrophobic region consisting of Leu 213 , Ile 293 , Leu 295 , and Val 298 demonstrated that membrane penetration is critical to plasma membrane localization, VP40 oligomerization, and viral particle egress."
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The paper's cellular readouts are plasma-membrane localisation scoring and VLP release, with no assay of viral or nucleocapsid movement within the cell.
"Release of VLPs was not detectable for L213A or L295A, whereas I293A and V298A had significantly reduced VLP release."
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Wild-type VP40 is predominantly at the plasma membrane with VLP extensions, while the hydrophobic mutants become diffusely cytosolic.
"WT EGFP-VP40 was predominantly localized to the PM with strong visual evidence of VLP extensions stemming from the PM"
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The cytoplasmic and premembrane pool of VP40 is predominantly monomeric and dimeric.
"the majority of VP40 in the cytoplasm or premembrane zone in the current and previous study ( 24 ) is monomeric or dimeric"
The Ebola virus matrix protein deeply penetrates the plasma membrane: an important step in viral egress.
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VP40 penetrates 8.1 angstrom into the hydrocarbon core of the plasma membrane bilayer.
"Experimental results indicate that VP40 penetrates 8.1 Å into the hydrocarbon core of the plasma membrane bilayer."
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VP40 itself deforms membranes, tubulating liposomes and vesiculating giant unilamellar vesicles, in a manner abolished by hydrophobic mutations.
"VP40 also induces substantial changes to membrane curvature as it tubulates liposomes and induces vesiculation into giant unilamellar vesicles, effects that are abrogated by hydrophobic mutations."
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The same hydrophobic residues are required for plasma membrane localisation and for VLP formation and release from cells.
"hydrophobic residues that penetrate deeply into the plasma membrane are essential for plasma membrane localization and virus-like particle formation and release from cells."
The Ebola Virus matrix protein, VP40, requires phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2) for extensive oligomerization at the plasma membrane and viral egress.
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VP40 alone forms VLPs that bud from the plasma membrane of live cells without other EBOV proteins.
"VP40 is the most abundant protein in EBOV virions and can form authentic looking virus like particles (VLPs) that bud from the plasma membrane of live cells in the absence of other EBOV proteins"
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PI(4,5)P2 is confined to the plasma membrane inner leaflet, making it a plasma-membrane-specific determinant of VP40 assembly.
"The subcellular location of PI(4,5)P2 is restricted to the plasma membrane inner leaflet (major)"
Ubiquitin Ligase WWP1 Interacts with Ebola Virus VP40 To Regulate Egress.
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WWP1 colocalises with VP40 at plasma-membrane budding sites in a WW-domain-dependent manner.
"results from confocal microscopy experiments demonstrated that WWP1 colocalizes with eVP40 at the site of budding at the plasma membrane in a WW-domain-dependent manner"
Ebola Virus VP40 Modulates Cell Cycle and Biogenesis of Extracellular Vesicles.
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Nuclear VP40 binds the cyclin D1 promoter and raises cyclin D1 levels, accelerating the cell cycle of producer cells.
"VP40 clones were accelerated in growth due to cyclin D1 upregulation, and nuclear VP40 was found bound to the cyclin D1 promoter."
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Dysregulated cell cycling is linked to altered extracellular vesicle biogenesis.
"Nuclear VP40 upregulates cyclin D1 levels, resulting in dysregulated cell cycle and EV biogenesis."
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VP40-containing extracellular vesicles induce apoptosis in recipient T cells and monocytes.
"VP40 EVs induced apoptosis in recipient T cells and monocytes."
Ubiquitin Ligase SMURF2 Interacts with Filovirus VP40 and Promotes Egress of VP40 VLPs.
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The multiple WW domains of SMURF2 interact with Ebola and Marburg VP40 in a PPxY-dependent manner.
"We go on to show by GST pulldown assays that the multiple WW domains of SMURF2 interact with eVP40 and mVP40 in a PPxY-dependent manner."
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SMURF2 knockdown inhibits VP40 VLP egress, so the interaction positively regulates budding.
"siRNA knockdown of endogenous SMURF2 led to inhibition of eVP40 VLP egress"
UniProtKB flat-file record for Zaire ebolavirus (Mayinga-76) VP40 (Q05128)
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VP40 is essential for particle assembly and budding and acts by engaging the viral ribonucleocapsid and host ESCRT components.
"Acts by interacting with viral ribonucleocapsid and host members of the ESCRT (endosomal sorting"
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VP40 exists as dimers, hexamers and octamers, with hexamers critical for budding and octamers assigned to genome replication and RNA binding.
"Octamers function in genome replication and RNA binding (PubMed:12919741)."
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VP40 has two overlapping late-budding domains, a PTAP/PSAP motif for TSG101 and a PPxY motif for NEDD4 and SMURF2.
"VP40 contains two overlapping L domains: a"
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The curated locations include host cytoplasm with experimental evidence.
"SUBCELLULAR LOCATION: Host cytoplasm {ECO:0000269|PubMed:21987757}."
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In the virion VP40 lines the inner side of the membrane, and it is the most abundant virion protein.
"MISCELLANEOUS: Most abundant protein in the virion."
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VP40 belongs to the filoviridae matrix protein VP40 family, which is the basis for the ISS transfers from Marburg VP40 (P35260).
"SIMILARITY: Belongs to the filoviridae matrix protein VP40 family."
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VP40 is ubiquitinated by host WWP1, which mediates efficient viral budding.
"Ubiquitinated by host WWP1. This modification mediates efficient"
Curation notes for Zaire ebolavirus VP40 (Q05128)
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Deep research was unavailable for this review and the GONUTS wiki was offline, so the CACAO rows were judged from the cached publications, UniProt and PubMed/PMC lookups.
"**Deep research was unavailable for this review.**"
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Three of the six CACAO rows pick a parent term where the cited paper's own assay supports the child, and one converts an egress phenotype into a transport process.
"**Wrong granularity (new-ish pattern, 3 of 6 rows).**"