The SWI/SNF-related, Matrix-associated, Actin-dependent Regulator of Chromatin (SMARC) proteins integrate into complexes that remodel chromatin. The SMARC family A (SMARCA) members SMARCA2 (also known as BRM) and SMARCA4 (BRG1) are helicases that contain structurally-related bromodomains for binding acetylated lysine residues on target proteins. The protein polybromo-1 (PB1, BRG1-associated factor) contains six bromodomains, but only the fifth (PB1(5)) shares the same structural signature as those of SMARCA2 and SMARCA4. PFI-3 is a probe that binds avidly to the structurally-similar SMARCA4 bromodomain and PB1(bromodomain 5) with Kd values of 89 and 48 nM, respectively. Evaluation of interactions of PFI-3 with different classes of bromodomains using thermal stability assay indicates that PFI-3 interacts selectively with bromodomains from SMARCA2 and SMARCA4 as well as the fifth domain of PB1. Similarly, PFI-1 does not interact with a panel of kinases. See the Structural Genomics Consortium (SGC) website for more information.
