Acetylated histone-binding site, “WPF” shelf tryptophan (red), and a basic interaction site (blue) for (A) BRDT–BD1 (W50, K37, K41, and K45) and (B) BRD4–BD1 (W81, R68, K72, and K76). (C) Sequence similarity in each bromodomain of BRDT (left) and BRD4 (right) relative to BRD4–BD1. Percent similarities were relative to BRD4–BD1 calculated by the PDB sequence and structure alignment (PDB ID: 7L73 for BRDT–BD1 and 3UVW for BRD4–BD1).