Fig. 2. Transcriptional activity of purified Put3p. Yeast in vitro transcription reactions contained, where indicated, either Put3+AH (200 nM) or Put3p (15 nM) and were supplemented with compounds at the concentrations indicated (in mM). Transcription products from the template shown above the figure were analysed by primer extension. The positions of the E4 extension products (indicated by the asterisk) and the primer are indicated, and the sizes of the primer and extension products (in numbers of nucleotides) are shown.