Pull-down assays were performed in peptide binding buffer (PBB) [50mM Tris-HCl pH 8.0, 300mM NaCl, 0.1% NP-40 v/v] based on previously described protocols [23 (link), 24 (link)]. Biotinylated peptides (500 pmol) were immobilized on Streptavidin MagneSphere® Paramagnetic Particles (Promega) for 30 min at 25°C. Peptide sequences are provided in Supporting Information File 2 (Week 5). Particles were washed twice with 1 mL PBB, and particles were incubated with 40 pmol of GST protein in PBB + 0.5% bovine serum albumin (BSA; Sigma Aldrich) for 1 hr at 4°C. A small aliquot of the input protein solution was reserved for analysis by western blotting. After three washes with PBB, bound proteins were eluted by boiling for 5 min in 1× SDS Laemmli buffer. Samples were analyzed for the presence of the GST-tagged bromodomain using 10% SDS-PAGE and transferred (BioRad PROTEAN system) to PVDF membrane (BioRad). Membranes were dried and stored at 4°C for one week. Rehydrated membranes were then incubated in GST antibody (Sigma) for 1 hr at 25°C, washed three times with phosphate buffered saline (PBS) + 0.1% Tween-20 and incubated with HRP-conjugated secondary antibody. The western blotting protocol is detailed in Supporting Information File 2, Weeks 6 and 7.