View source for 4ogr


==crystal structure of P-TEFb complex with AFF4 and Tat==
<StructureSection load='4ogr' size='340' side='right'caption='[[4ogr]], [[Resolution|resolution]] 3.00&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[4ogr]] is a 12 chain structure with sequence from [https://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens] and [https://en.wikipedia.org/wiki/Human_immunodeficiency_virus_type_1_(HXB3_ISOLATE) Human immunodeficiency virus type 1 (HXB3 ISOLATE)]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=4OGR OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=4OGR FirstGlance]. <br>
</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">X-ray diffraction, [[Resolution|Resolution]] 3&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=ACE:ACETYL+GROUP'>ACE</scene>, <scene name='pdbligand=ADN:ADENOSINE'>ADN</scene>, <scene name='pdbligand=TPO:PHOSPHOTHREONINE'>TPO</scene>, <scene name='pdbligand=ZN:ZINC+ION'>ZN</scene></td></tr>
<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=4ogr FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=4ogr OCA], [https://pdbe.org/4ogr PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=4ogr RCSB], [https://www.ebi.ac.uk/pdbsum/4ogr PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=4ogr ProSAT]</span></td></tr>
</table>
== Disease ==
[https://www.uniprot.org/uniprot/CDK9_HUMAN CDK9_HUMAN] Note=Chronic activation of CDK9 causes cardiac myocyte enlargement leading to cardiac hypertrophy, and confers predisposition to heart failure.
== Function ==
[https://www.uniprot.org/uniprot/CDK9_HUMAN CDK9_HUMAN] Protein kinase involved in the regulation of transcription. Member of the cyclin-dependent kinase pair (CDK9/cyclin-T) complex, also called positive transcription elongation factor b (P-TEFb), which facilitates the transition from abortive to productive elongation by phosphorylating the CTD (C-terminal domain) of the large subunit of RNA polymerase II (RNAP II) POLR2A, SUPT5H and RDBP. This complex is inactive when in the 7SK snRNP complex form. Phosphorylates EP300, MYOD1, RPB1/POLR2A and AR, and the negative elongation factors DSIF and NELF. Regulates cytokine inducible transcription networks by facilitating promoter recognition of target transcription factors (e.g. TNF-inducible RELA/p65 activation and IL-6-inducible STAT3 signaling). Promotes RNA synthesis in genetic programs for cell growth, differentiation and viral pathogenesis. P-TEFb is also involved in cotranscriptional histone modification, mRNA processing and mRNA export. Modulates a complex network of chromatin modifications including histone H2B monoubiquitination (H2Bub1), H3 lysine 4 trimethylation (H3K4me3) and H3K36me3; integrates phosphorylation during transcription with chromatin modifications to control co-transcriptional histone mRNA processing. The CDK9/cyclin-K complex has also a kinase activity towards CTD of RNAP II and can substitute for CDK9/cyclin-T P-TEFb in vitro. Replication stress response protein; the CDK9/cyclin-K complex is required for genome integrity maintenance, by promoting cell cycle recovery from replication arrest and limiting single-stranded DNA amount in response to replication stress, thus reducing the breakdown of stalled replication forks and avoiding DNA damage. In addition, probable function in DNA repair of isoform 2 via interaction with KU70/XRCC6. Promotes cardiac myocyte enlargement. RPB1/POLR2A phosphorylation on 'Ser-2' in CTD activates transcription. AR phosphorylation modulates AR transcription factor promoter selectivity and cell growth. DSIF and NELF phosphorylation promotes transcription by inhibiting their negative effect. The phosphorylation of MYOD1 enhances its transcriptional activity and thus promotes muscle differentiation.<ref>PMID:9857195</ref> <ref>PMID:10393184</ref> <ref>PMID:10574912</ref> <ref>PMID:10912001</ref> <ref>PMID:10757782</ref> <ref>PMID:11145967</ref> <ref>PMID:11112772</ref> <ref>PMID:11575923</ref> <ref>PMID:11884399</ref> <ref>PMID:11809800</ref> <ref>PMID:12037670</ref> <ref>PMID:15564463</ref> <ref>PMID:14701750</ref> <ref>PMID:17956865</ref> <ref>PMID:18362169</ref> <ref>PMID:19844166</ref> <ref>PMID:19575011</ref> <ref>PMID:20493174</ref> <ref>PMID:20930849</ref> <ref>PMID:20081228</ref> <ref>PMID:20980437</ref> <ref>PMID:21127351</ref> 
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
Superelongation complexes (SECs) are essential for transcription elongation of many human genes, including the integrated HIV-1 genome. At the HIV-1 promoter, the viral Tat protein binds simultaneously to the nascent TAR RNA and the CycT1 subunit of the P-TEFb kinase in a SEC. To understand the preferential recruitment of SECs by Tat and TAR, we determined the crystal structure of a quaternary complex containing Tat, P-TEFb, and the SEC scaffold, AFF4. Tat and AFF4 fold on the surface of CycT1 and interact directly. Interface mutations in the AFF4 homolog AFF1 reduced Tat-AFF1 affinity in vivo and Tat-dependent transcription from the HIV promoter. AFF4 binding in the presence of Tat partially orders the CycT1 Tat-TAR recognition motif and increases the affinity of Tat-P-TEFb for TAR 30-fold. These studies indicate that AFF4 acts as a two-step filter to increase the selectivity of Tat and TAR for SECs over P-TEFb alone.DOI: http://dx.doi.org/10.7554/eLife.02375.001.

AFF4 binding to Tat-P-TEFb indirectly stimulates TAR recognition of super elongation complexes at the HIV promoter.,Schulze-Gahmen U, Lu H, Zhou Q, Alber T Elife. 2014 Apr 24;3:e02375. doi: 10.7554/eLife.02375. PMID:24843025<ref>PMID:24843025</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
</div>
<div class="pdbe-citations 4ogr" style="background-color:#fffaf0;"></div>

==See Also==
*[[Cyclin 3D structures|Cyclin 3D structures]]
*[[Cyclin-dependent kinase 3D structures|Cyclin-dependent kinase 3D structures]]
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Homo sapiens]]
[[Category: Large Structures]]
[[Category: Alber T]]
[[Category: Schulze-Gahmen U]]