Figure 4. Competition binding assays demonstrate that PSC binds 2N templates preferentially over 1N templates but that binding to both templates is stable.

A. Competition assays in which competitor was added simultaneously with labeled substrates, as indicated. B. Competition assays in which competitor was added after a 15-minute pre-incubation with labeled substrate. PSC was used at 1nM and labeled nucleosomes at 0.5nM. Competitor was used up to 10nM.