Figure 4

Tat binds to the ETS-18S region. Electro mobility shift assay (EMSA) using as the probe the region corresponding to the ETS-18S pre-rRNA, containing cleavage site 1 (probe IV in Fig. 3A). (A): nuclear extracts from control (WG), and transgenic (Tat-strain) strains were incubated, after heat shock treatment, with the ETS-18S probe. Lane 1, free probe. In lanes 2 and 3, the probe was incubated with 0.5 and 3 μg of nuclear extract from control strain. In lanes 4 and 5 the probe was incubated with 0.5 μg and 3 μg of nuclear extract from transgenic strain. Unspecific probe, was incubated (lane 7) or not (lane 6) with nuclear extract from transgenic strain. In lane 8 and 9 nuclear extracts were pre-incubated with the anti-Tat antibody and then with the probe. (B): Nuclear extracts from control (WG), lanes 2–3, and transgenic (Tat-strain) strains, lanes 4–5, were incubated, after heat shock treatment, with an unrelated structured probe (tRNA). Probe alone is shown in lane 1.