VP2_SV40
Domain
The D1 region of isoform VP2 and isoform VP3 is necessary and sufficient to direct the interaction with VP1.
The basic-rich C-terminal region of isoforms VP2 and VP3 is sufficient for DNA-binding and may cause compaction of the DNA.
The transmembrane region is only used when isoform VP2 and isoform VP3 form oligomers and integrate into the endoplasmic reticulum membrane.
Function
Isoform VP2
Structural protein that resides within the core of the capsid surrounded by 72 VP1 pentamers. Following virus endocytosis and trafficking to the endoplasmic reticulum, VP2 and VP3 form oligomers and integrate into the endoplasmic reticulum membrane. Heterooligomer VP2-VP3 may create a viroporin for transporting the viral genome across the endoplasmic reticulum membrane to the cytoplasm. Nuclear entry of the viral DNA involves the selective exposure and importin recognition of VP2 or VP3 nuclear localization signal (shared C-terminus). Plays a role in virion assembly within the nucleus in particular through a DNA-binding domain located in the C-terminal region. A N-terminal myristoylation suggests a scaffold function for virion assembly. The viral progenies exit the cells by lytic release. Isoform VP2 may repress SP1 activation of the SV40 early promoter, via specific protein-protein and protein-DNA interactions.
Isoform VP3
Structural protein that resides within the core of the capsid surrounded by 72 VP1 pentamers. Following virus entry, VP2 and VP3 form oligomers and integrate into the endoplasmic reticulum membrane. Heterooligomer VP2-VP3 may create a viroporin for transporting the viral genome across the endoplasmic reticulum membrane. Essential for focus formation and virus endoplasmic reticulum-to-cytosol membrane transport, required to recruit selective cellular components to the foci in the ER membrane. Nuclear entry of the viral DNA involves the selective exposure and importin recognition of VP2 or VP3 nuclear localization signal (shared C-terminus). Isoform VP3 represses SP1 activation of the SV40 early promoter, via specific protein-protein and protein-DNA interactions. SP1 additionally participates in recruiting VP3 to the SV40 minichromosome during SV40 assembly. Plays a role in virion assembly within the nucleus. May initiate host cell lysis when associated with VP4.
Isoform VP4
Viroporin inducing perforation of cellular membranes to trigger virus progeny release. Forms pores of 3 nm inner diameter. VP4 is expressed about 24 hours after the late structural proteins and is not incorporated into the mature virion.
Sequence Similarities
Belongs to the polyomaviruses capsid protein VP2 family.
Cellular localization
- Isoform VP2
- Virion
- Host nucleus
- Host endoplasmic reticulum
- Host endoplasmic reticulum membrane
- Following host cell entry, the virion enters into the endoplasmic reticulum through a calveolar-dependent pathway. Then, isoform VP2 integrates into the endoplasmic reticulum membrane and participates in the translocation of viral DNA to the nucleus. Shortly after synthesis, a nuclear localization signal directs isoform VP2 to the cell nucleus where virion assembly occurs.
- Isoform VP3
- Virion
- Host nucleus
- Host endoplasmic reticulum
- Host endoplasmic reticulum membrane
- Following host cell entry, the virion enters into the endoplasmic reticulum through a calveolar-dependent pathway. Then, isoform VP3 integrates into the endoplasmic reticulum membrane and participates in the translocation of viral DNA to the nucleus. Shortly after synthesis, a nuclear localization signal directs isoform VP3 to the cell nucleus where virion assembly occurs.
- Isoform VP4
- Host nucleus
Alternative names
Minor capsid protein VP2, Minor structural protein VP2