FIG. 4.
Determination of the distal transcriptional start site (P2dcuB) of dcuB by reverse-transcriptase-mediated primer extension. The reverse-transcriptase-mediated primer extension products were generated by using primers (P53, P129, P204, and P278) specific for the dcuB transcript (see Materials and Methods for details). Sequencing ladders (lanes A, C, G, and T) were generated by using the M13 universal primer and M13mp18 as the template. The relevant M13 nucleotide sequences (the underlined residues are those whose corresponding reaction products matched the size of the reverse transcription product) and the sizes of the primer extension products are shown.