TASHET of the HIV core promoter binds nuclear complexes distinct from those binding the canonical Adenovirus major late promoter (AdMLP). (A) Radiolabelled oligonucleotides corresponding to the HIV core promoter were incubated with HeLa nuclear extracts and the resulting complexes were separated on a native polyacrylamide gel. Bound complexes were analyzed by phosphorimaging. The binding reactions were challenged by the addition of a 200 fold molar excess of unlabelled HIV wt promoter (lane 2), or AdMLP (lane 3). Pre-initiation complexes of HIV (PICH) and other HIV core promoter-binding cellular factors are labelled at the left. n.s. indicates a non-specific complex. The free probe is shown with an arrow at the bottom of the gel. (B) As in A except that radiolabelled AdMLP was the probe. Specific complexes are indicated with arrows in both panels.