P24109 (TAT_HV2CA) Reviewed, UniProtKB/Swiss-Prot
Last modified October 16, 2013. Version 69. History...
Names and origin
|Protein names||Recommended name:|
Transactivating regulatory protein
|Organism||Human immunodeficiency virus type 2 subtype A (isolate CAM2) (HIV-2) [Complete proteome]|
|Taxonomic identifier||11715 [NCBI]|
|Taxonomic lineage||Viruses › Retro-transcribing viruses › Retroviridae › Orthoretrovirinae › Lentivirus › Primate lentivirus group ›|
|Virus host||Homo sapiens (Human) [TaxID: 9606]|
|Sequence length||133 AA.|
|Protein existence||Inferred from homology|
General annotation (Comments)
Nuclear transcriptional activator of viral gene expression, that is essential for viral transcription from the LTR promoter and replication. Acts as a sequence-specific molecular adapter, directing components of the cellular transcription machinery to the viral RNA to promote processive transcription elongation by the RNA polymerase II (RNA pol II) complex, thereby increasing the level of full-length transcripts. In the absence of Tat, the RNA Pol II generates short or non-processive transcripts that terminate at approximately 60 bp from the initiation site. Tat associates with the CCNT1/cyclin-T1 component of the P-TEFb complex (CDK9 and CCNT1), which promotes RNA chain elongation. This binding increases Tat's affinity for a hairpin structure at the 5'-end of all nascent viral mRNAs referred to as the transactivation responsive RNA element (TAR RNA) and allows Tat/P-TEFb complex to bind cooperatively to TAR RNA. The CDK9 component of P-TEFb and other Tat-activated kinases hyperphosphorylate the C-terminus of RNA Pol II that becomes stabilized and much more processive By similarity.
Extracellular circulating Tat can be endocytosed by surrounding uninfected cells via the binding to several surface receptors. Endosomal low pH allows Tat to cross the endosome membrane to enter the cytosol and eventually further translocate into the nucleus, thereby inducing severe cell dysfunctions ranging from cell activation to cell death. Through By similarity.
Interacts with host CCNT1. Associates with the P-TEFb complex composed at least of Tat, P-TEFb (CDK9 and CCNT1), TAR RNA, RNA Pol II. Interacts with CCNT2; the resulting complex is unable to bind to TAR RNA By similarity.
The Arg-rich RNA-binding region binds the TAR RNA. This region also mediates the nuclear localization By similarity.
The phosphorylation by CDK9 does not seem to be important for transactivation function By similarity.
Belongs to the lentiviruses Tat family.
|Biological process||Host-virus interaction|
|Cellular component||Host nucleus|
|Coding sequence diversity||Alternative splicing|
|Technical term||Complete proteome|
|Gene Ontology (GO)|
|Biological_process||modulation by virus of host morphology or physiology|
Inferred from electronic annotation. Source: UniProtKB-KWtranscription, DNA-dependent
Inferred from electronic annotation. Source: UniProtKB-KW
|Cellular_component||host cell nucleolus|
Inferred from electronic annotation. Source: UniProtKB-SubCell
Inferred from electronic annotation. Source: UniProtKB-KWsequence-specific DNA binding transcription factor activity
Inferred from electronic annotation. Source: InterPro
|Complete GO annotation...|
|This entry describes 2 isoforms produced by alternative splicing. [Align] [Select]|
|Isoform Long (identifier: P24109-1) |
This isoform has been chosen as the 'canonical' sequence. All positional information in this entry refers to it. This is also the sequence that appears in the downloadable versions of the entry.
|Isoform Short (identifier: P24109-2) |
The sequence of this isoform differs from the canonical sequence as follows:
|Note: No experimental confirmation available. Expressed in the late stage of the infection cycle, when unspliced viral RNAs are exported to the cytoplasm by the viral Rev protein.|
Sequence annotation (Features)
|Feature key||Position(s)||Length||Description||Graphical view||Feature identifier|
|Chain||1 – 133||133||Protein Tat||PRO_0000085368|
|Region||53 – 69||17||Cysteine-rich By similarity|
|Region||70 – 80||11||Core By similarity|
|Motif||81 – 93||13||Nuclear localization signal, and RNA-binding (TAR) By similarity|
Amino acid modifications
|Modified residue||88||1||Phosphothreonine; by host CDK9 By similarity|
|Modified residue||97||1||Phosphoserine; by host CDK9 By similarity|
|Alternative sequence||103 – 133||31||Missing in isoform Short.||VSP_022438|
|||"Nucleotide sequence of a Guinea-Bissau-derived human immunodeficiency virus type 2 proviral clone (HIV-2CAM2)."|
Tristem M., Hill F., Karpas A.
J. Gen. Virol. 72:721-724(1991) [PubMed] [Europe PMC] [Abstract]
Cited for: NUCLEOTIDE SEQUENCE [GENOMIC DNA].
|||"Decoding Tat: the biology of HIV Tat posttranslational modifications."|
Hetzer C., Dormeyer W., Schnolzer M., Ott M.
Microbes Infect. 7:1364-1369(2005) [PubMed] [Europe PMC] [Abstract]
Cited for: REVIEW, ALTERNATIVE SPLICING.
|D00835 Genomic DNA. Translation: BAA00714.1.|
|PIR||TNLJCA. I38475. |
3D structure databases
Protocols and materials databases
Family and domain databases
|Gene3D||184.108.40.206. 1 hit. |
|InterPro||IPR001831. IV_Tat. |
|Pfam||PF00539. Tat. 1 hit. |
|PRINTS||PR00055. HIVTATDOMAIN. |
|Accession||Primary (citable) accession number: P24109|
|Entry status||Reviewed (UniProtKB/Swiss-Prot)|
|Annotation program||Viral Protein Annotation Program|
Index of protein domains and families