BD1

BD1 is the first bromodomain of BET proteins, whose two tandem bromodomains enable chromatin binding to facilitate transcription[1]. Mechanistically, BET proteins recognize acetylated histones and recruit transcription factors and P-TEFb to chromatin, promoting RNA polymerase II phosphorylation and transcription initiation and elongation[2]. In cancer and immunoinflammation models, steady-state gene expression primarily requires BD1, whereas inflammatory stimulus-induced rapid gene expression requires both BD1 and BD2[1]. Compared with BD2, BD1 therefore provides a stronger experimental handle for studying transcriptional maintenance and cancer-model responses, because BD1 inhibitors phenocopied pan-BET inhibitors in cancer models[1]. For research applications, JQ1 and I-BET established acetyl-lysine/bromodomain inhibition as chemical-probe strategies, while GSK789 and Olinone support domain-selective interrogation of BET-BD1 biology[3][4][5][6]. - BD1 supports steady-state transcription and chromatin engagement across BET protein research models. - BD1-selective inhibitors help separate cancer-model effects from BD2-linked inflammatory responses.