ID   VE4_HPV6A               Reviewed;          91 AA.
AC   Q84295;
DT   15-JUL-1998, integrated into UniProtKB/Swiss-Prot.
DT   18-JAN-2017, sequence version 2.
DT   23-FEB-2022, entry version 42.
DE   RecName: Full=Protein E4;
GN   Name=E4;
OS   Human papillomavirus type 6a.
OC   Viruses; Monodnaviria; Shotokuvirae; Cossaviricota; Papovaviricetes;
OC   Zurhausenvirales; Papillomaviridae; Firstpapillomavirinae;
OC   Alphapapillomavirus.
OX   NCBI_TaxID=37122;
OH   NCBI_TaxID=9606; Homo sapiens (Human).
RN   [1]
RP   NUCLEOTIDE SEQUENCE [GENOMIC DNA].
RX   PubMed=7778283; DOI=10.1006/viro.1995.1283;
RA   Hofmann K.J., Cook J.C., Joyce J.G., Brown D.R., Schultz L.D., George H.A.,
RA   Rosolowsky M., Fife K.H., Jansen K.U.;
RT   "Sequence determination of human papillomavirus type 6a and assembly of
RT   virus-like particles in Saccharomyces cerevisiae.";
RL   Virology 209:506-518(1995).
CC   -!- FUNCTION: Contributes to multiple aspects of the viral life cycle
CC       including viral genome amplification, suppression of suprabasal cell
CC       differentiation and egress of newly formed virions. Induces host cell
CC       cycle arrest at the G2 phase by associating with and preventing the
CC       nuclear entry of host CDK1/cyclin B1 complexes. Inhibits cellular DNA
CC       replication by preventing loading of host replication licensing
CC       proteins MCM2 and MCM7 onto chromatin. Within the cytoplasm, associates
CC       with host kinase SRPK1, a splicing factor regulator, and inhibits its
CC       activity. Therefore, E4 favors expression of late viral transcripts by
CC       inhibiting SRPK1-mediated phosphorylation of host serine-arginine (SR)
CC       proteins that have critical roles in mRNA metabolism. Late in the
CC       infectious cycle, E4 also acts to diminish the integrity of the
CC       keratinocyte by disrupting the keratin cytoskeleton and inducing
CC       apoptosis through alteration of mitochondrial function to facilitate
CC       egress of the newly formed virions. {ECO:0000250|UniProtKB:P06922}.
CC   -!- SUBUNIT: Assembles into oligomeric complexes. Interacts with host CDK1.
CC       Interacts with host SRPK1; this interaction may favor expression of
CC       late viral transcripts. Interacts with host cytokeratin components KRT8
CC       and KRT18. {ECO:0000250|UniProtKB:P06922}.
CC   -!- SUBCELLULAR LOCATION: Host cytoplasm {ECO:0000250|UniProtKB:P06922}.
CC       Host nucleus {ECO:0000250|UniProtKB:P06922}.
CC   -!- PTM: Phosphorylated by host ERK. The phosphorylation triggers a
CC       structural change that enhances keratin binding and protein stability.
CC       {ECO:0000250|UniProtKB:P06922}.
CC   -!- MISCELLANEOUS: The major E4 form is first synthesized as an E1^E4
CC       fusion protein from spliced E1^E4 transcripts, such that the first few
CC       amino acids of the E4 protein are derived from the N terminus of E1.
CC       {ECO:0000250|UniProtKB:P06922}.
CC   -!- SIMILARITY: Belongs to the papillomaviridae E4 protein family.
CC       {ECO:0000305}.
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DR   EMBL; L41216; AAA74215.1; ALT_SEQ; Genomic_DNA.
DR   SMR; Q84295; -.
DR   Proteomes; UP000007675; Genome.
DR   GO; GO:0030430; C:host cell cytoplasm; IEA:UniProtKB-SubCell.
DR   GO; GO:0042025; C:host cell nucleus; IEA:UniProtKB-SubCell.
DR   GO; GO:0039592; P:suppression by virus of G2/M transition of host mitotic cell cycle; IEA:UniProtKB-KW.
DR   InterPro; IPR003861; Papilloma_E4.
DR   Pfam; PF02711; Pap_E4; 1.
PE   3: Inferred from homology;
KW   Early protein; Host cytoplasm; Host G2/M cell cycle arrest by virus;
KW   Host nucleus; Host-virus interaction;
KW   Modulation of host cell cycle by virus; Phosphoprotein.
FT   CHAIN           1..91
FT                   /note="Protein E4"
FT                   /id="PRO_0000133259"
FT   REGION          16..51
FT                   /note="Disordered"
FT                   /evidence="ECO:0000256|SAM:MobiDB-lite"
FT   COMPBIAS        35..49
FT                   /note="Basic and acidic residues"
FT                   /evidence="ECO:0000256|SAM:MobiDB-lite"
SQ   SEQUENCE   91 AA;  10299 MW;  3E5962F89DE70227 CRC64;
     MADDSALHKK YPFLNLLHTP PHRPPPLCPQ APRKTQCKRR LENEHEESNS HLATPCVWPT
     LDPWTVETTT SSLTITTSTK EGTTVTVQLR L