text: Rhee and Pugh introduce ChIP-exo by performing analyses on a small collection of transcription factors: Reb1, Gal4, Phd1, Rap1 in yeast and CTCF in human. Reb1 sites were often found in clusters and these clusters had ~10-fold higher occupancy than expected. Secondary sites in clusters were found ~40 bp from a primary binding site. Binding motifs of Gal4 showed a strong preference for three of the four nucleotides, suggesting a negative interaction between Gal4 and the excluded nucleotide. Phd1 recognizes three different motifs which explains previous reports of the ambiguity of Phd1's binding motif. Rap1 was found to recognize four motifs. 
  Ribosomal protein genes bound by this protein had a tendency to use a particular motif with a stronger consensus sequence. Other genes often used clusters of weaker consensus motifs, possibly to achieve a similar occupancy. Binding motifs of CTCF employed four "modules". Half of the bound CTCF sites used modules 1 and 2, while the rest used some combination of the four. It is believed that CTCF uses its zinc fingers to recognize different combinations of these modules.
  Rhee and Pugh analyzed pre-initiation complex (PIC) structure and organization in Saccharomyces genomes. Using ChIP-exo, they were able to, among other discoveries, precisely identify TATA-like features in promoters reported to be TATA-less.