FIG. 7.

Schematic representation of proteins associated with chromosomal telomeres and subtelomeric regions in vivo in a wild-type (A) or sir3 (B) strain. The physical presence of Rap1p at telomeres in vivo was first shown in reference 13 and confirmed herein. The presence of Sir2p, Sir3p, and Sir4p on subtelomeric nucleosomes is from references 30 and 75. The ovals labeled 2, 3, and 4 represent Sir2p, Sir3p, and Sir4p. Although one molecule of each telomere binding protein is indicated, nothing is known about the stoichiometry of telomere binding proteins except that there are 10 to 20 molecules of Rap1p per telomere (20, 87).