rSir3p assembles mononucleosomes and naked DNA into defined, high-molecular-weight complexes. 208–1 MN (lanes 3–11) and 208–1 DNA (lanes 15–23) were incubated at the indicated rSir3p, and samples were electrophoresed on a 1.0% agarose gel (1× TBE) as described in Materials and Methods. Lanes 2, 12, 14, and 24 contain mock-incubated (no rSir3p) 208–1 MN and 208–1 DNA controls. Lanes 1 and 13 contain 1 Kb+ DNA size markers (GIBCO/BRL). Arrowheads indicate the size of selected markers in base pairs.