End-positioned nucleosomes containing mH2A161 migrate aberrantly in native gels when shifted by the Chd1 remodeler. (A) A representative nucleosome sliding experiment of end-positioned 0-N-33 nucleosomes that consisted of a mixture of major-type H2A nucleosomes (FAM-labeled) and either mH2A122 or mH2A161 nucleosomes (Cy5-labeled). A total of 100 nM nucleosome (50 nM each) was incubated with 20 nM Chd1 in a buffer containing 50 mM KCl, 5 mM MgCl2, 20 mM Tris.HCl (pH 7.5), 0.1 mM EDTA, 0.1 mg/ml BSA, 5 mM EDTA, 5% sucrose and 2 mM ATP. (B) A similar nucleosome sliding experiment as shown in (A), except using 0-N-80 end-positioned nucleosomes, and with sliding buffer containing 100 mM KCl. For all nucleosome sliding reactions, the same pattern of shifted nucleosomes migrating faster than the starting material was observed for mH2A161, whereas both major-type H2A and mH2A122 nucleosomes showed the expected slower migration indicative of nucleosome centering.