Figure 4.

Genomic footprinting over the MMTV promoter. (A Left) At low nucleosome density (glucose; Glu) there is a better access of GR to the HRE5 (marked by a triangle on the right) in response to ligand. The asterisks on the left mark two bands detected under all conditions, which do not correspond to guanines in the DNA sequence. Their identity is unknown. (Right) In the presence of NFI, at low nucleosome density, a cluster of guanines within the NFI site (triangle) is more protected before hormone treatment (lane 8) than after hormone induction (lane 7). The relevant guanine on HRE4 is marked by a triangle. (B) PhosphorImager quantitation of the protection over the NFI site and the HRE2, -3, and -4, derived from three experiments similar to that shown in A Right. The values were normalized for variations in loading using the strong band within the octamer distal site (OctD) at the bottom of the gel. The mean and standard deviation are shown.