Fig. 3.
ERα enhances transcription through AP-1 by promoting transcription initiation. Templates containing no AP-1 sites or two AP-1 sites upstream of the adenovirus E4 promoter were assembled into chromatin and transcribed in the presence of ERα,E2, and Ral as indicated. Sarkosyl was added to 0.25% after the initiation of transcription by the addition of rNTPs to limit transcription to a single round. Note that transcription initiates primarily from the most 3′ start site of the AdE4 promoter in experiments in which Sarkosyl is added (21, 25).