ID   TAT_SIVGB               Reviewed;         115 AA.
AC   P22384;
DT   01-AUG-1991, integrated into UniProtKB/Swiss-Prot.
DT   01-AUG-1991, sequence version 1.
DT   23-FEB-2022, entry version 93.
DE   RecName: Full=Protein Tat;
DE   AltName: Full=Transactivating regulatory protein;
GN   Name=tat;
OS   Simian immunodeficiency virus (isolate GB1) (SIV-mnd) (Simian
OS   immunodeficiency virus mandrill).
OC   Viruses; Riboviria; Pararnavirae; Artverviricota; Revtraviricetes;
OC   Ortervirales; Retroviridae; Orthoretrovirinae; Lentivirus.
OX   NCBI_TaxID=11732;
OH   NCBI_TaxID=9527; Cercopithecidae (Old World monkeys).
RN   [1]
RP   NUCLEOTIDE SEQUENCE [GENOMIC RNA].
RX   PubMed=2797181; DOI=10.1038/341539a0;
RA   Tsujimoto H., Hasegawa A., Maki N., Fukasawa M., Miura T., Speidel S.,
RA   Cooper R.W., Moriyama E.N., Gojobori T., Hayami M.;
RT   "Sequence of a novel simian immunodeficiency virus from a wild-caught
RT   African mandrill.";
RL   Nature 341:539-541(1989).
RN   [2]
RP   MUTAGENESIS OF CYS-37, AND INTERACTION WITH HUMAN CCNT1.
RX   PubMed=10364329; DOI=10.1128/jvi.73.7.5777-5786.1999;
RA   Bieniasz P.D., Grdina T.A., Bogerd H.P., Cullen B.R.;
RT   "Analysis of the effect of natural sequence variation in Tat and in cyclin
RT   T on the formation and RNA binding properties of Tat-cyclin T complexes.";
RL   J. Virol. 73:5777-5786(1999).
CC   -!- FUNCTION: Nuclear transcriptional activator of viral gene expression,
CC       that is essential for viral transcription from the LTR promoter and
CC       replication. Acts as a sequence-specific molecular adapter, directing
CC       components of the cellular transcription machinery to the viral RNA to
CC       promote processive transcription elongation by the RNA polymerase II
CC       (RNA pol II) complex, thereby increasing the level of full-length
CC       transcripts. In the absence of Tat, the RNA Pol II generates short or
CC       non-processive transcripts that terminate at approximately 60 bp from
CC       the initiation site. Tat associates with the CCNT1/cyclin-T1 component
CC       of the P-TEFb complex (CDK9 and CCNT1), which promotes RNA chain
CC       elongation. This binding increases Tat's affinity for a hairpin
CC       structure at the 5'-end of all nascent viral mRNAs referred to as the
CC       transactivation responsive RNA element (TAR RNA) and allows Tat/P-TEFb
CC       complex to bind cooperatively to TAR RNA. The CDK9 component of P-TEFb
CC       and other Tat-activated kinases hyperphosphorylate the C-terminus of
CC       RNA Pol II that becomes stabilized and much more processive (By
CC       similarity). {ECO:0000250}.
CC   -!- FUNCTION: Extracellular circulating Tat can be endocytosed by
CC       surrounding uninfected cells via the binding to several surface
CC       receptors. Endosomal low pH allows Tat to cross the endosome membrane
CC       to enter the cytosol and eventually further translocate into the
CC       nucleus, thereby inducing severe cell dysfunctions ranging from cell
CC       activation to cell death. Through (By similarity). {ECO:0000250}.
CC   -!- SUBUNIT: Interacts with host CCNT1. Associates with the P-TEFb complex
CC       composed at least of Tat, P-TEFb (CDK9 and CCNT1), TAR RNA, RNA Pol II.
CC       Interacts with CCNT2; the resulting complex is unable to bind to TAR
CC       RNA (By similarity). {ECO:0000250}.
CC   -!- SUBCELLULAR LOCATION: Host nucleus, host nucleolus {ECO:0000250}.
CC   -!- SIMILARITY: Belongs to the lentiviruses Tat family. {ECO:0000305}.
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DR   EMBL; M27470; AAB49572.1; -; Genomic_RNA.
DR   GO; GO:0044196; C:host cell nucleolus; IEA:UniProtKB-SubCell.
DR   GO; GO:0003723; F:RNA binding; IEA:UniProtKB-KW.
DR   GO; GO:0001070; F:RNA-binding transcription regulator activity; IEA:InterPro.
DR   GO; GO:0050434; P:positive regulation of viral transcription; IEA:InterPro.
DR   Gene3D; 4.10.20.10; -; 1.
DR   InterPro; IPR001831; IV_Tat.
DR   InterPro; IPR036963; Tat_dom_sf.
DR   Pfam; PF00539; Tat; 1.
PE   1: Evidence at protein level;
KW   Activator; Host nucleus; Host-virus interaction; RNA-binding;
KW   Transcription; Transcription regulation.
FT   CHAIN           1..115
FT                   /note="Protein Tat"
FT                   /id="PRO_0000085381"
FT   REGION          37..53
FT                   /note="Cysteine-rich"
FT                   /evidence="ECO:0000250"
FT   REGION          54..64
FT                   /note="Core"
FT                   /evidence="ECO:0000250"
FT   MOTIF           65..73
FT                   /note="Nuclear localization signal, and RNA-binding (TAR)"
FT                   /evidence="ECO:0000255"
FT   MUTAGEN         37
FT                   /note="C->S: Loss of binding to cyclin T."
FT                   /evidence="ECO:0000269|PubMed:10364329"
SQ   SEQUENCE   115 AA;  13248 MW;  AF220B634A585FFD CRC64;
     MEPSGKEDHN CPPQDSGQEE IDYKQLLEEY YQPLQACENK CWCKKCCFHC MLCFQKKGLG
     IRYHVYRKRV PGTNKKIPGS GEEAIRRAID LSFHRTASRT YTANGQTTEK KKATA