A0A1C9KCZ1 · A0A1C9KCZ1_9REOV
- ProteinOuter capsid protein VP4
- StatusUniProtKB unreviewed (TrEMBL)
- Organism
- Amino acids776 (go to sequence)
- Protein existenceInferred from homology
- Annotation score4/5
Function
function
Outer capsid protein VP4: Spike-forming protein that mediates virion attachment to the host epithelial cell receptors and plays a major role in cell penetration, determination of host range restriction and virulence. Rotavirus attachment and entry into the host cell probably involves multiple sequential contacts between the outer capsid proteins VP4 and VP7, and the cell receptors. It is subsequently lost, together with VP7, following virus entry into the host cell. Following entry into the host cell, low intracellular or intravesicular Ca2+ concentration probably causes the calcium-stabilized VP7 trimers to dissociate from the virion. This step is probably necessary for the membrane-disrupting entry step and the release of VP4, which is locked onto the virion by VP7. During the virus exit from the host cell, VP4 seems to be required to target the newly formed virions to the host cell lipid rafts.
Outer capsid protein VP5*: Forms the spike 'foot' and 'body' and acts as a membrane permeabilization protein that mediates release of viral particles from endosomal compartments into the cytoplasm. During entry, the part of VP5* that protrudes from the virus folds back on itself and reorganizes from a local dimer to a trimer. This reorganization may be linked to membrane penetration by exposing VP5* hydrophobic region. In integrin-dependent strains, VP5* targets the integrin heterodimer ITGA2/ITGB1 for cell attachment.
Outer capsid protein VP8*: Forms the head of the spikes and mediates the recognition of specific host cell surface glycans. It is the viral hemagglutinin and an important target of neutralizing antibodies. In sialic acid-dependent strains, VP8* binds to host cell sialic acid, most probably a ganglioside, providing the initial contact. In some other strains, VP8* mediates the attachment to histo-blood group antigens (HBGAs) for viral entry.
Miscellaneous
In group A rotaviruses, VP4 defines the P serotype.
Some rotavirus strains are neuraminidase-sensitive and require sialic acid to attach to the cell surface. Some rotavirus strains are integrin-dependent. Some rotavirus strains depend on ganglioside for their entry into the host cell. Hsp70 also seems to be involved in the entry of some strains.
Features
Showing features for site.
Type | ID | Position(s) | Description | ||
---|---|---|---|---|---|
Site | 231-232 | Cleavage | |||
Site | 241-242 | Cleavage | |||
Site | 247-248 | Cleavage; associated with enhancement of infectivity | |||
GO annotations
Aspect | Term | |
---|---|---|
Cellular Component | host cell endoplasmic reticulum-Golgi intermediate compartment | |
Cellular Component | host cell plasma membrane | |
Cellular Component | host cell rough endoplasmic reticulum | |
Cellular Component | host cytoskeleton | |
Cellular Component | membrane | |
Cellular Component | viral outer capsid | |
Biological Process | permeabilization of host organelle membrane involved in viral entry into host cell | |
Biological Process | virion attachment to host cell |
Keywords
- Molecular function
- Biological process
Names & Taxonomy
Protein names
- Recommended nameOuter capsid protein VP4
- Alternative names
- Cleaved into 2 chains
Organism names
- Organism
- Strain
- Taxonomic lineageViruses > Riboviria > Orthornavirae > Duplornaviricota > Resentoviricetes > Reovirales > Sedoreoviridae > Rotavirus
Accessions
- Primary accessionA0A1C9KCZ1
Proteomes
Subcellular Location
UniProt Annotation
GO Annotation
Outer capsid protein VP5*
Note: Outer capsid protein.
Outer capsid protein VP8*
Note: Outer capsid protein.
Outer capsid protein VP4
Note: The outer layer contains 180 copies of VP4, grouped as 60 dimers. Immature double-layered particles assembled in the cytoplasm bud across the membrane of the endoplasmic reticulum, acquiring during this process a transient lipid membrane that is modified with the ER resident viral glycoproteins NSP4 and VP7; these enveloped particles also contain VP4. As the particles move towards the interior of the ER cisternae, the transient lipid membrane and the non-structural protein NSP4 are lost, while the virus surface proteins VP4 and VP7 rearrange to form the outermost virus protein layer, yielding mature infectious triple-layered particles. VP4 also seems to associate with lipid rafts of the host cell membrane probably for the exit of the virus from the infected cell by an alternate pathway.
Keywords
- Cellular component
PTM/Processing
Features
Showing features for chain, disulfide bond.
Type | ID | Position(s) | Description | ||
---|---|---|---|---|---|
Chain | PRO_5029074075 | 1-231 | Outer capsid protein VP8* | ||
Chain | PRO_5023465852 | 1-776 | Outer capsid protein VP4 | ||
Chain | PRO_5029074074 | 248-776 | Outer capsid protein VP5* | ||
Disulfide bond | 318↔380 | ||||
Post-translational modification
Outer capsid protein VP4: Proteolytic cleavage by trypsin results in activation of VP4 functions and greatly increases infectivity. The penetration into the host cell is dependent on trypsin treatment of VP4. It produces two peptides, VP5* and VP8* that remain associated with the virion. Cleavage of VP4 by trypsin probably occurs in vivo in the lumen of the intestine prior to infection of enterocytes. Trypsin seems to be incorporated into the three-layered viral particles but remains inactive as long as the viral outer capsid is intact and would only be activated upon the solubilization of the latter.
Keywords
- PTM
Interaction
Subunit
Outer capsid protein VP4: Homotrimer. VP4 adopts a dimeric appearance above the capsid surface, while forming a trimeric base anchored inside the capsid layer. Only hints of the third molecule are observed above the capsid surface. It probably performs a series of molecular rearrangements during viral entry. Prior to trypsin cleavage, it is flexible. The priming trypsin cleavage triggers its rearrangement into rigid spikes with approximate two-fold symmetry of their protruding parts. After an unknown second triggering event, cleaved VP4 may undergo another rearrangement, in which two VP5* subunits fold back on themselves and join a third subunit to form a tightly associated trimer, shaped like a folded umbrella. Outer capsid protein VP4: Interacts with VP6. Outer capsid protein VP4: Interacts with VP7. Outer capsid protein VP5*: Homotrimer. The trimer is coiled-coil stabilized by its C-terminus, however, its N-terminus, known as antigen domain or 'body', seems to be flexible allowing it to self-associate either as a dimer or a trimer.
Structure
Family & Domains
Features
Showing features for domain, region, motif, coiled coil.
Type | ID | Position(s) | Description | ||
---|---|---|---|---|---|
Domain | 65-224 | Haemagglutinin outer capsid protein VP4 concanavalin-like | |||
Region | 65-224 | Spike head | |||
Region | 248-479 | Spike body and stalk (antigen domain) | |||
Domain | 250-474 | Rotavirus VP4 membrane interaction | |||
Motif | 308-310 | DGE motif; interaction with ITGA2/ITGB1 heterodimer | |||
Region | 389-409 | Hydrophobic; possible role in virus entry into host cell | |||
Motif | 448-450 | YGL motif; interaction with ITGA4 | |||
Coiled coil | 484-511 | ||||
Domain | 485-776 | Rotavirus VP4 helical | |||
Region | 510-776 | Spike foot | |||
Domain
Outer capsid protein VP4: The VP4 spike is divided into a foot, a stalk and body, and a head.
Sequence similarities
Belongs to the rotavirus VP4 family.
Keywords
- Domain
Family and domain databases
Sequence
- Sequence statusComplete
- Length776
- Mass (Da)86,994
- Last updated2016-11-30 v1
- ChecksumF6AC66E15734F42B
Sequence databases
Nucleotide Sequence | Protein Sequence | Molecule Type | Status | |
---|---|---|---|---|
KU508383 EMBL· GenBank· DDBJ | AOP32352.1 EMBL· GenBank· DDBJ | Genomic RNA |