Figure 3.

DNase I footprinting of the minimal promoter region. A radiolabelled non-coding strand of the minimal Sau3AI–EagI promoter A element was DNase I digested as outlined in Materials and Methods. Titrations of recombinant human enzyme or total nuclear extract are as indicated. For Ap1 and Ap2 numbers refer to the amount added in footprinting units (f.p.u.) with nuclear extract in µg total protein/lane. Regions of protection that are of interest are as indicated, with multiple transcription start sites marked by asterisks. Lane pr., probe only; lanes Ap1, rhap1 protein; lanes Ap2, rhap2 protein; lanes HeLa, total HeLa nuclear extract; m, molecular weight markers.