Figure 4

Protein and DNA characterization of chromatin from HeLa cells with/without arsenic treatment. A) Chromatin-fractionation procedure. B) SDS–polyacrylamide gel analysis (SDS-PAGE) of chromatin architectural proteins (CAPs) and other chromatin proteins in salt fractions. Equal aliquots of fractions from successive extraction steps in a typical experiment were loaded onto a 4-12% polyacrylamide gel, which was electrophoresed and westernblotted for the various proteins. C) Ethidium bromide–stained agarose gel showing a typical MNase ladder of DNA purified from MNase-treated nuclei (MNase); followed by ladders of DNA purified from the nuclear supernatant (Supn); successive 80 mM, 150 mM, and 600 mM extractions; and the remaining pellet, as indicated in (A).