Figure 5.

Nuclease digestion of DNA/protein complexes reveals protection in the region corresponding to the β1 Inr. (A) DNase I footprinting identifies nucleotide interactions with putative transcription factors in the vicinity of the major transcription initiation site for the β1 gene [only the region of interest is displayed; lane 1, marker; lanes 2 and 3, BSA (60 μg); and lanes 4 and 5, nuclear extracts from neocortical cultures (60 μg)]. (B) Diagram depicts the Inr sequence with reference to protein binding sites and to promoter flanking sequence. The position of a hypersensitive site for nuclease digestion is marked *. Vertical bars indicate region in sequence corresponding to protected region in footprint. Mutations to wild type in M1, M2, and M3 are marked 1, 2, or 3 (cf. Fig. 6; see Materials and Methods for sequence).