Fig. 1. Dimerization of BRD4 constructs containing BID upon CK2 phosphorylation.

a Summary of the BRD4 constructs used in the study. A schematic representation of full-length BRD4 (long isoform A) and known regions is reported. b Coomassie-stained SDS-PAGE gel showing the purity of the recombinantly produced BRD4 constructs 1-530, 1-579, 1-722. c Elution profiles of analytical size-exclusion chromatography (SEC) performed with 20 µM of the indicated constructs in the presence of 250 mM NaCl or 1 M NaCl. Std: Gel filtration standards (Bio-Rad) analysed in the corresponding low or high salt running buffer. d Elution profiles of the indicated constructs analysed by SEC-MALS. Samples are labeled as follows: black line indicates purified from bacteria, blue line indicates purified from insect cells, orange line indicates phosphorylated in vitro using CK2, dotted grey line in panels c, and d indicate protein molecular weight standards. The dotted line at each peak, colored as above, indicates the measured MW. The dotted horizontal grey lines in panel d represent the theoretical MW of the monomer or dimer of BRD4^1–530, BRD4^1–579, BRD4^1–722, calculated from the primary sequence.