View source for 4imy


==The AFF4 scaffold binds human P-TEFb adjacent to HIV Tat==
<StructureSection load='4imy' size='340' side='right'caption='[[4imy]], [[Resolution|resolution]] 2.94&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[4imy]] is a 9 chain structure with sequence from [https://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=4IMY OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=4IMY 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]] 2.94&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=AMP:ADENOSINE+MONOPHOSPHATE'>AMP</scene>, <scene name='pdbligand=TPO:PHOSPHOTHREONINE'>TPO</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=4imy FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=4imy OCA], [https://pdbe.org/4imy PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=4imy RCSB], [https://www.ebi.ac.uk/pdbsum/4imy PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=4imy 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 ==
Human positive transcription elongation factor b (P-TEFb) phosphorylates RNA polymerase II and regulatory proteins to trigger elongation of many gene transcripts. The HIV-1 Tat protein selectively recruits P-TEFb as part of a super elongation complex (SEC) organized on a flexible AFF1 or AFF4 scaffold. To understand this specificity and determine if scaffold binding alters P-TEFb conformation, we determined the structure of a tripartite complex containing the recognition regions of P-TEFb and AFF4. AFF4 meanders over the surface of the P-TEFb cyclin T1 (CycT1) subunit but makes no stable contacts with the CDK9 kinase subunit. Interface mutations reduced CycT1 binding and AFF4-dependent transcription. AFF4 is positioned to make unexpected direct contacts with HIV Tat, and Tat enhances P-TEFb affinity for AFF4. These studies define the mechanism of scaffold recognition by P-TEFb and reveal an unanticipated intersubunit pocket on the AFF4 SEC that potentially represents a target for therapeutic intervention against HIV/AIDS. http://dx.doi.org/10.7554/eLife.00327.001.

The AFF4 scaffold binds human P-TEFb adjacent to HIV Tat.,Schulze-Gahmen U, Upton H, Birnberg A, Bao K, Chou S, Krogan NJ, Zhou Q, Alber T Elife. 2013;2:e00327. doi: 10.7554/eLife.00327. Epub 2013 Mar 5. PMID:23471103<ref>PMID:23471103</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
</div>
<div class="pdbe-citations 4imy" 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]]