In vitro binding of CHD7 chromodomains to methylated H3K4. (A) Histone pulldown assays were performed using purified GST, GST-CHD7, and GST-CHD1 fusion proteins and purified histones (H) containing all possible covalent modifications. Bound proteins were analyzed by SDS-PAGE and Western blotting with the indicated antibodies. Lane 1 corresponds to input. (B, top) Peptide competition assay in which purified histones (H) were incubated with either H3K4me3 peptide (peptide K4) or H3K27me3 peptide (peptide K27) prior to incubating with indicated GST proteins. Pulldowns were performed with GST beads, and bound proteins were analyzed by SDS-PAGE and Western blotting with H3K4me3 antibody. Similar results were obtained with H3K4me1 and H3K4me2 peptides and antibodies (data not shown). Lanes 1–3 are input. A Coomassie-stained gel showing the purified GST proteins is shown on the bottom. The asterisk denotes a nonspecific band.
