FIG. 2.

DNase I footprinting defines regions of the coding strand that are involved in DBD binding. Increasing concentrations of purified DBD were incubated with A2 or pS2 ERE-containing DNA fragments which had been labeled on the coding strand. The binding reactions were subjected to limited DNase I digestion, and the cleaved DNA was fractionated on a denaturing acrylamide gel. The gel was dried and subjected to autoradiography. The positions and sequences of the A2 ERE and the pS2 ERE and DNase I-hypersensitive sites (∗) are indicated.