Abstract
Stimulation of in vitro transcription by the upstream element (UE) of the adenovirus-2 major late promoter (Ad2MLP) involves a specific trans-acting factor present in a HeLa whole-cell extract. By following its transcriptional stimulatory activity and its DNase I footprint on the Ad2MLP-UE, we have purified this factor to greater than 10% purity and separated it from RNA polymerase B and the general transcription factors required for transcription from the Ad2MLP.