FIG. 1.

5′-UTR of the HIV-1 promoter contains multiple high-affinity HMG I binding sites. To determine the location of potential HMG I binding sites, DNase I footprinting reactions were carried out as described in the text. Analysis of three segments within the 5′-UTR is shown. These include regions −105 to +1 (A), +56 to +128 (B), and +112 to +194 (C). The numbering is relative to the start site of transcription at +1. Solid boxes represent high-affinity binding sites, whereas shaded boxes illustrate the position of low-affinity HMG I binding sites. Since HMG I contains three distinct individual DNA-binding domains, each capable of producing a small footprint, the combination of these individual footprints has been described as a footprint region. (D) SDS–15% polyacrylamide gel showing 2 μg of recombinant HMG I.