Anti-phospho Brd4 (Ser492/Ser494) from rabbit, purified by affinity chromatography

Bromodomain-containing protein 4 (UniProt O60885; also known as MCAP, Mitotic chromosome-associated protein, Protein HUNK1) is encoded by the BRD4 (also known as HUNK1, MCAP) gene (Gene ID 23476) in human. Bromodomain-containing protein 4 is a BET (bromodomain and extra-terminal) protein family member that functions as a chromatin reader by binding acetylated lysines in histones. It plays a key role in transmission of epigenetic memory across cell divisions and transcription regulation. It remains associated with acetylated chromatin throughout the entire cell cycle and provides epigenetic memory for post-mitotic G1 gene transcription by preserving acetylated chromatin status and maintaining high-order chromatin structure. During interphase, it plays a key role in regulating the transcription of signal-inducible genes by associating with the P-TEFb complex and recruiting it to promoters. Bromodomain-containing protein 4 is required to form the transcriptionally active P-TEFb complex where it displaces negative regulators such as HEXIM1 and 7SKsnRNA complex from P-TEFb and transforms it into an active form that can then phosphorylate the C-terminal domain of RNA polymerase II. It promotes the phosphorylation of Ser2 of the C-terminal domain of RNA polymerase II. In addition to acetylated histones, Bromodomain-containing protein 4 also recognizes and binds acetylated RELA, leading to further recruitment of the P-TEFb complex and subsequent activation of NF-kappa-B. It is also reported to act as a regulator of p53/TP53-mediated transcription and following phosphorylation by casein kinase 2K2, it is recruited to p53/TP53 specific target promoters. BRD4 knockout in mice is shown to be lethal, while BRD4 function blockage by inhibitor JQ1 (Cat. No. 500586) treatment is reported to affect the transcription of critical synaptic proteins, resulting in memory deficits and decreased seizure susceptibility in mice.