Search Organism: All OrganismsArabidopsis thalianaBacillus subtilis 168Bos taurusCaenorhabditis elegansCanis familiarisDanio rerioDrosophila melanogasterEquus caballusEscherichia coli K12Gallus gallusHomo sapiensMacaca mulattaMus musculusNematostella vectensisOryza sativaPan troglodytesRattus norvegicusSaccharomyces cerevisiaeSchizosaccharomyces pombeStrongylocentrotus purpuratusTakifugu rubripesXenopus laevis home help / support contribute downloads mirrors about us EMBO J. Jul (1998); 17(13):3681-91 Transcription elongation factor P-TEFb mediates Tat activation of HIV-1 transcription at multiple stages. Zhou Q, Chen D, Pierstorff E, Luo K Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, CA 94720, USA. qzhou@uclink4.berkeley.edu Abstract: Tat stimulates human immunodeficiency virus type 1 (HIV-1) transcription elongation through recognition of the transactivation response (TAR) RNA stem-loop structure at the 5' end of nascent viral transcripts. Recently, a human transcription elongation factor P-TEFb, consisting of CDK9 kinase, cyclin T and other associated factors, has been shown to interact with Tat to restore Tat activation in HeLa nuclear extract depleted of P-TEFb. Here, we report the purification of a P-TEFb complex fraction containing epitope-tagged wild-type CDK9 or kinase-inactive CDK9 and five tightly associated polypeptides. Only wild-type P-TEFb complex with an active CDK9 kinase was able to hyperphosphorylate the C-terminal domain of RNA polymerase II and mediate Tat transactivation in P-TEFb-depleted HeLa nuclear extract. Tat also stimulated transcription elongation by recruitment of the P-TEFb complex to the HIV-1 promoter through a Tat-TAR interaction. A possible mechanism for P-TEFb to become associated with polymerase elongation complexes and function as a general elongation factor was demonstrated by an interaction of P-TEFb with double-stranded RNA molecules through an 87 kDa subunit. Finally, P-TEFb was found to interact with and phosphorylate Tat-SF1, a Tat cofactor required for Tat transactivation. Our data indicate that the various subunits of the human P-TEFb complex may play distinct roles at multiple stages to mediate Tat activation of HIV-1 transcription elongation. [PUBMED: 9649438] Copyright © 2009, Tyers Lab, The Samuel Lunenfeld Research Institute, Mount Sinai Hospital, All Rights Reserved. terms and conditions - privacy policy - Osprey Network Visualization System BioGRID: A General Repository for Interaction Datasets. Chris Stark, Bobby-Joe Breitkreutz, Teresa Reguly, Lorrie Boucher, Ashton Breitkreutz, Mike Tyers. Nucleic Acids Res. Jan 1;34:D535-9.