Comparison of the nucleosome positions on the SNR6 gene locus. TFIIIC is omitted for the sake of clarity. Positions of the promoter elements are marked in panel A and described at the bottom of the figure. Numbers in bold and vertical arrows represent the MNase cut sites mapped by the indirect end-labeling technique in the upstream region. The rest of the numbers in panel B mark the positions of nucleosome boundaries mapped by Exo III footprinting. Nucleosomes are color coded, with their positions as given in Table 1. (A) Positions reported in vivo in the presence of TFIIIC . (B) All the in vitro positions in the absence of TFIIIC, as mapped in this study and summarized in Table 1. Positions 1, 2 and 7 are omitted for the sake of clarity. (C, D and E) show three possible registers (R1, R2 and R3) generated by the combinations of positions depicted in the panel (B) under three different conditions. Positions 5 and 6 are mutually exclusive. In vivo, 6 is occupied in repressed state (Panel D), while chromatin remodeler RSC shifts it to position 5 in active state (Panel E). Boundaries of position 12, which is selected after TFIIIC binding and chromatin remodeling in vivo are marked in bold.