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Bromodomain-containing protein 4 - O60885 (BRD4_HUMAN)

 

Protein Feature View of PDB entries mapped to a UniProtKB sequence  

Number of PDB entries for O60885: 89
 
Function
Chromatin reader protein that recognizes and binds acetylated histones and plays a key role in transmission of epigenetic memory across cell divisions and transcription regulation. Remains associated with acetylated chromatin throughout the entire cell cycle and provides epigenetic memory for postmitotic G1 gene transcription by preserving acetylated chromatin status and maintaining high-order chromatin structure. During interphase, plays a key role in regulating the transcription of signal-inducible genes by associating with the P-TEFb complex and recruiting it to promoters: BRD4 is required to form the transcriptionally active P-TEFb complex by displacing negative regulators such as HEXIM1 and 7SKsnRNA complex from P-TEFb, thereby transforming it into an active form that can then phosphorylate the C-terminal domain (CTD) of RNA polymerase II. Promotes phosphorylation of 'Ser-2' of the C-terminal domain (CTD) of RNA polymerase II. According to a report, directly acts as an atypical protein kinase and mediates phosphorylation of 'Ser-2' of the C-terminal domain (CTD) of RNA polymerase II; these data however need additional evidences in vivo (PubMed:22509028). In addition to acetylated histones, also recognizes and binds acetylated RELA, leading to further recruitment of the P-TEFb complex and subsequent activation of NF-kappa-B. Also acts as a regulator of p53/TP53-mediated transcription: following phosphorylation by CK2, recruited to p53/TP53 specific target promoters. (data source: UniProt  )
Isoform B: Acts as a chromatin insulator in the DNA damage response pathway. Inhibits DNA damage response signaling by recruiting the condensin-2 complex to acetylated histones, leading to chromatin structure remodeling, insulating the region from DNA damage response by limiting spreading of histone H2AFX/H2A.x phosphorylation. (data source: UniProt  )
Subunit structure
Interacts with p53/TP53; the interaction is direct. Interacts (via CTD region) with CDK9 and CCNT1, acting as an associated component of P-TEFb complex. Interacts with RELA (when acetylated at 'Lys-310'). Interacts (via NET domain) with WHSC1L1, JMJD6, CHD4, GLTSCR1 and ATAD5. Isoform B: interacts with NCAPD3 and SMC2. Interacts with bovine papillomavirus type 1 regulatory protein E2 and human herpes virus-8 (HHV-8) protein LANA. These interactions may serve for the tethering of viral genomes to host mitotic chromosomes allowing successful partitioning of the viral genome during cell division. Interacts with Epstein-Barr virus (EBV) protein EBNA1; this interaction facilitates transcriptional activation by EBNA1. (data source: UniProt  )
Domain
The 2 bromo domains mediate specific binding to acetylated histones via Asn-140 and Asn-433, respectively (PubMed:20871596). The exact combination of modified histone tails required to recruit BRD4 to target genes is still unclear. The first bromo domain has high affinity for acetylated histone H4 tail, whereas the second bromo domain recognizes multiply acetylated marks in histone H3 (PubMed:22464331). A number of specific inhibitors bind competitively to acetyl-lysine-binding residues Asn-140 and Asn-433, promoting removal from acetylated histones. Many of these inhibitors are benzodiazepine derivatives (PubMed:22137933, PubMed:22136404, PubMed:23517011, PubMed:23530754). (data source: UniProt  )
UniProtKB:
Species: 
Gene names: Gene View for BRD4 HUNK1
Length:
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Data origin/color codes
The vertical color bar on the left side indicates data provenance.
Data in green originates from UniProtKB  
Data in yellow originates from Pfam  , by interacting with the HMMER3 web site  
Data in orange originates from the SCOP   (version 1.75) and SCOPe   (version 2.04) classifications.
Data in grey has been calculated using BioJava  . Protein disorder predictions are based on JRONN (Troshin, P. and Barton, G. J. unpublished), a Java implementation of RONN  
  • Red: potentially disorderd region
  • Blue: probably ordered region.
Hydropathy has been calculated using a sliding window of 15 residues and summing up scores from standard hydrophobicity tables.
  • Red: hydrophobic
  • Blue: hydrophilic.
Data in lilac represent the genomic exon structure projected onto the UniProt sequence.
Data in blue originates from PDB
  • Secstruc: Secondary structure projected from representative PDB entries onto the UniProt sequence.
Data in red indicates combined ranges of Homology Models from SBKB   and the Protein Model Portal  

The PDB to UniProt mapping is based on the data provided by the EBI SIFTS project. See also Velankar et al., Nucleic Acids Research 33, D262-265 (2005).