PCAF, active Peptide

PCAF, active (p300/CBP-associated factor, CREBBP-associated factor, CAF, P/CAF)

Cat. Num. AAA658593

• Purity: Purified; ~30% full length PCAF-GST
• Synonyms: PCAF; active; active (p300/CBP-associated factor; CREBBP-associated factor; CAF; P/CAF); active peptide

• Purity/Purification: Purified; ~30% full length PCAF-GST
• Form/Format: Supplied as a liquid 0.05M Tris-HCl, pH 8.0, 150mM sodium chloride, 25mM glutathione, 50% glycerol.

• Quality Control: HAT Assay: 500ng of PCAF was used to acetylate histones in vitro with tracer levels of [3H]AcetylCoA as the acetyl donor.
• Preparation and Storage: May be stored at 4 degree C for short-term only. For long-term storage, store at -20 degree C. Aliquots are stable for at least 6 months at -20 degree C. For maximum recovery of product, centrifuge the original vial after thawing and prior to removing the cap. Further dilutions can be made in assay buffer.

Related Product Information for PCAF, active peptide

A direct link exists between hyperacetylation of chromatin and transcriptional activation. Experiments have established that PCAF possesses intrinsic histone acetylase activity. PCAF primarily acetylates lysine 14 of H3. It acetylates lysine 8 of H4 less efficiently. PCAF also acetylates p53 in response to DNA damage. The distinct patterns of acetylation by PCAF may contribute to transcriptional regulation of important genes.

Product Categories/Family for PCAF, active peptide

Molecular Biology; MB-Transcription Factors

NCBI and Uniprot Product Information

• NCBI GI #: 135343
• Molecular Weight: ~79kD
• NCBI Official Full Name: Protein Tat

Uniprot Description

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. Other factors such as HTATSF1/Tat-SF1, SUPT5H/SPT5, and HTATIP2 are also important for Tat's function. Besides its effect on RNA Pol II processivity, Tat induces chromatin remodeling of proviral genes by recruiting the histone acetyltransferases (HATs) CREBBP, EP300 and PCAF to the chromatin. This also contributes to the increase in proviral transcription rate, especially when the provirus integrates in transcriptionally silent region of the host genome. To ensure maximal activation of the LTR, Tat mediates nuclear translocation of NF-kappa-B. In this purpose, it activates EIF2AK2/PKR which, in turns, may phosphorylate and target to degradation the inhibitor IkappaB-alpha which normally retains NF-kappa-B in the cytoplasm of unstimulated cells. Through its interaction with TBP, Tat may be involved in transcription initiation as well. Interacts with the cellular capping enzyme RNGTT to mediate co-transcriptional capping of viral mRNAs. Tat protein exerts as well a positive feedback on the translation of its cognate mRNA. Tat can reactivate a latently infected cell by penetrating in it and transactivating its LTR promoter. In the cytoplasm, Tat is thought to act as a translational activator of HIV-1 mRNAs ().