FIG. 3.

Primer extension analysis designed to determine the 5′ ends of pause I RNA and the doublet RNA. Pause I RNA and the doublet RNA species from the gels shown in Fig. 2A were cut out and eluted, and their 5′ ends were determined by a primer extension approach. The oligonucleotide used in the primer extension reactions is complementary to nts +84 to +99 of the tna transcript. Dideoxy sequencing ladders were obtained with the same primer used for primer extension analysis. Lanes A and G are the Sequenase reaction lanes for dideoxyadenine and dideoxyguanidine, respectively.