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- FUNCTION: Plays a role in virion assembly. Autoregulates the synthesis of the viral early mRNA. Participates in the modulation of cellular gene expression preceeding viral DNA replication. This step involves binding to host key cell cycle regulators retinoblastoma protein RB1/pRb and TP53. Induces the disassembly of host E2F1 transcription factors from RB1, thus promoting transcriptional activation of E2F1-regulated S-phase genes. Inhibits host TP53 binding to DNA, abrogating the ability of TP53 to stimulate gene expression. Plays the role of a TFIID-associated factor (TAF) in transcription initiation for all three RNA polymerases, by stabilizing the TBP-TFIIA complex on promoters. Initiates viral DNA replication and unwinding via interactions with the viral origin of replication. The replication fork movement is facilitated by Large T antigen helicase activity. Activates the transcription of viral late mRNA, through host TBP and TFIIA stabilization. Interferes with histone deacetylation mediated by HDAC1, leading to activation of transcription (By similarity).
- SUBUNIT: Forms homohexamers in the presence of ATP. Interacts with host HDAC1. Interacts (via LXCXE domain) with host RB1; the interaction induces the aberrant dissociation of RB1-E2F1 complex thereby disrupting RB1's activity. Interacts (via LXCXE domain) with host pRB-related proteins RBL1 and RBL2. Interacts (via C-terminus) with host TOP1 and POLA1 allowing DNA replication. Interacts with host TP53, inhibiting TP53 binding to DNA. Interacts with host preinitiation complex components TBP, TFIIA and TFIID to regulate transcription initiation (By similarity).
- SUBCELLULAR LOCATION: Host nucleus (By similarity).
- ALTERNATIVE PRODUCTS:
2 named isoforms [FASTA] produced by alternative splicing.
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| Name | Small t antigen |
| Isoform ID | P15000-1 |
| This isoform is stored in UniProtKB/Swiss-Prot entry P15000. |
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- DOMAIN: The J domain is essential for multiple viral activities, including virion assembly, viral DNA replication, transformation and transcriptional activation (By similarity).
- DOMAIN: The LXCXE motif specifically binds to host pRB, RBL1, and RBL2 (By similarity).
- DOMAIN: The zinc finger region contributes to protein-protein interactions essential for the assembly of stable T-antigen hexamers at the origin of replication. The hexamers are required for subsequent alterations in the structure of origin DNA (By similarity).
- DOMAIN: The ATP binding/ATPase domain is required for proper hexamer assembly and helicase activity (By similarity).
- PTM: Phosphorylated on both serine and threonine residues. Small t antigen inhibits the dephosphorylation by the AC form of PP2A (By similarity).
- PTM: O-Glycosylated near the C-terminal region (By similarity).
- PTM: Acetylated by CBP in a TP53-dependent manner (By similarity).
- SIMILARITY: Contains 1 J domain.
- SIMILARITY: Contains 1 SF3 helicase domain.
- SIMILARITY: Contains 1 T-ag D1-type zinc finger.
- SIMILARITY: Contains 1 T-ag OBD DNA-binding domain.
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Copyrighted by the UniProt Consortium, see http://www.uniprot.org/terms.
Distributed under the Creative Commons Attribution-NoDerivs License.
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| Length: 691 AA [This is the length of the unprocessed precursor] |
Molecular weight: 80129 Da [This is the MW of the unprocessed precursor] |
CRC64: 2F26992D3C441A84 [This is a checksum on the sequence] |
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10 20 30 40 50 60
MDKVLNREES MELMDLLGLE RAAWGNLPLM RKAYLKKCKE FHPDKGGDED KMKRMNTLYK
70 80 90 100 110 120
KMEQDVKVAH QPDFGTWNSS EVPTYGTEEW ESWWSSFNEK WDEDLFCHED MFASDEEATA
130 140 150 160 170 180
DSQHSTPPKK KRKVEDPKDF PSDLHQFLSQ AVFSNRTLAC FAVYTTKEKA QILYKKLMEK
190 200 210 220 230 240
YSVTFISRHM CAGHNIIFFL TPHRHRVSAI NNFCQKLCTF SFLICKGVNK EYLLYSALTR
250 260 270 280 290 300
DPYHIIEESI QGGLKEHDFN PEEPEETKQV SWKLITEYAV ETKCEDVFLL LGMYLEFQYN
310 320 330 340 350 360
VEECKKCQKK DQPYHFKYHE KHFANAIIFA ESKNQKSICQ QAVDTVLAKK RVDTLHMTRE
370 380 390 400 410 420
EMLTERFNHI LDKMDLIFGA HGNAVLEQYM AGVAWLHCLL PKMDSVIFDF LHCVVFNVPK
430 440 450 460 470 480
RRYWLFKGPI DSGKTTLAAG LLDLCGGKAL NVNLPMERLT FELGVAIDQY MVVFEDVKGT
490 500 510 520 530 540
GAESKDLPSG HGINNLDSLR DYLDGSVKVN LEKKHLNKRT QIFPPGLVTM NEYPVPKTLQ
550 560 570 580 590 600
ARFVRQIDFR PKIYLRKSLQ NSEFLLEKRI LQSGMTLLLL LIWFRPVADF SKDIQSRIVE
610 620 630 640 650 660
WKERLDSEIS MYTFSRMKYN ICMGKCILDI TREEDSETED SGHGSSTESQ SQCSSQVSDT
670 680 690
SAPDSENPHS QELHLCKGFQ CFKRPKTPPP K
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P14999 in FASTA format |
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