FIG. 2.

In vitro transcription of the very late p10 promoter. Plasmid pAcp10-CAT was used as template for in vitro transcription in nuclear extracts of the vertebrate cell lines HeLa and BHK and of uninfected (lanes u) or AcMNPV-infected S. frugiperda cells prepared at 20 h p.i. (lanes 20) and 40 h p.i. (lanes 40). Nuclear extracts of uninfected and AcMNPV-infected cells were prepared by the method of Gorski et al. (11). In vitro transcription with extracts of uninfected cells was performed in the presence of 6 mM Mg²⁺ and with extracts of infected cells in the presence of either 6 mM Mg²⁺ or 2.5 mM Mn²⁺; α-amanitin (2.5 μg/ml) was added to each reaction mixture. The extended products of 357 nt represent the very late p10 transcriptional start. Positions of DNA size markers (lane M) are shown on the right. ORF, open reading frame. The localization of the extended product and the corresponding start site are shown below.