ID   ST_POVM3                Reviewed;         195 AA.
AC   P68834; P03078;
DT   21-JUL-1986, integrated into UniProtKB/Swiss-Prot.
DT   21-JUL-1986, sequence version 1.
DT   03-AUG-2022, entry version 72.
DE   RecName: Full=Small t antigen;
DE            Short=ST;
DE            Short=ST-AG;
OS   Murine polyomavirus (strain A3) (MPyV).
OC   Viruses; Monodnaviria; Shotokuvirae; Cossaviricota; Papovaviricetes;
OC   Sepolyvirales; Polyomaviridae; Alphapolyomavirus.
OX   NCBI_TaxID=157703;
OH   NCBI_TaxID=10090; Mus musculus (Mouse).
RN   [1]
RP   NUCLEOTIDE SEQUENCE [GENOMIC DNA].
RX   PubMed=225042; DOI=10.1016/0092-8674(79)90278-2;
RA   Friedmann T., Esty A., LaPorte P., Deininger P.L.;
RT   "The nucleotide sequence and genome organization of the polyoma early
RT   region: extensive nucleotide and amino acid homology with SV40.";
RL   Cell 17:715-724(1979).
CC   -!- FUNCTION: Promotes efficient viral genome replication by accelerating
CC       both G1 and S phase progression of the cell cycle. Inhibits host PP2A
CC       by binding to the A subunit, thereby displacing lower affinity
CC       regulatory B subunit. Inactivation of PP2A in turn results in the
CC       transactivation of cyclin A and cyclin D1 promoters. Late during the
CC       infection cycle, ST may induce dephosphorylation of host MTOR, leading
CC       to the inhibition of cap-dependent translation. May establish and
CC       maintain high levels of viral genomes during persistent infection in
CC       cell culture. {ECO:0000250|UniProtKB:P03081}.
CC   -!- SUBUNIT: Interacts with host PPP2R1A; the interaction inhibits PP2A
CC       activity. {ECO:0000250|UniProtKB:P03081}.
CC   -!- SUBCELLULAR LOCATION: Host cytoplasm. Host nucleus
CC       {ECO:0000250|UniProtKB:P03081}.
CC   -!- ALTERNATIVE PRODUCTS:
CC       Event=Alternative splicing; Named isoforms=3;
CC       Name=Small t antigen;
CC         IsoId=P68834-1; Sequence=Displayed;
CC       Name=Middle T antigen;
CC         IsoId=P0DOJ8-1, P03076-1;
CC         Sequence=External;
CC       Name=Large T antigen;
CC         IsoId=P0DOJ5-1, P03074-1;
CC         Sequence=External;
CC   -!- DOMAIN: The common region of ST and LT proteins comprises the J domain.
CC       This domain is essential for multiple viral activities, including
CC       virion assembly, viral DNA replication, transformation and
CC       transcriptional activation. This domain is also required for cyclin A-
CC       transactivating activity of ST. {ECO:0000250|UniProtKB:P03081}.
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DR   EMBL; J02289; AAA46874.1; -; Genomic_DNA.
DR   PIR; C03635; TVVPA.
DR   SMR; P68834; -.
DR   IntAct; P68834; 1.
DR   MINT; P68834; -.
DR   Proteomes; UP000006847; Genome.
DR   GO; GO:0030430; C:host cell cytoplasm; IEA:UniProtKB-SubCell.
DR   GO; GO:0042025; C:host cell nucleus; IEA:UniProtKB-SubCell.
DR   Gene3D; 1.10.287.110; -; 1.
DR   Gene3D; 1.20.120.1860; -; 1.
DR   InterPro; IPR001623; DnaJ_domain.
DR   InterPro; IPR036869; J_dom_sf.
DR   InterPro; IPR003354; Papo_T_antigen.
DR   InterPro; IPR036092; Papo_T_antigensf.
DR   Pfam; PF02380; Papo_T_antigen; 1.
DR   SMART; SM00271; DnaJ; 1.
DR   SUPFAM; SSF161240; SSF161240; 1.
DR   SUPFAM; SSF46565; SSF46565; 1.
PE   3: Inferred from homology;
KW   Acetylation; Alternative splicing; Early protein; Host cytoplasm;
KW   Host nucleus; Oncogene.
FT   CHAIN           1..195
FT                   /note="Small t antigen"
FT                   /id="PRO_0000115058"
FT   DOMAIN          12..75
FT                   /note="J"
FT   MOD_RES         1
FT                   /note="N-acetylmethionine; by host"
FT                   /evidence="ECO:0000250|UniProtKB:P03081"
SQ   SEQUENCE   195 AA;  22811 MW;  44EED6711E1AFEC3 CRC64;
     MDRVLSRADK ERLLELLKLP RQLWGDFGRM QQAYKQQSLL LHPDKGGSHA LMQELNSLWG
     TFKTEVYNLR MNLGGTGFQV RRLHADGWNL STKDTFGDRY YQRFCRMPLT CLVNVKYSSC
     SCILCLLRKQ HRELKDKCDA RCLVLGECFC LECYMQWFGT PTRDVLNLYA DFIASMPIDW
     LDLDVHSVYN PRLSP