Figure 4

Comparison of sequences flanking RNA pol I promoter transcription initiation sites. Sequences adjacent to known RNA pol I promoter transcription initiation sites (nt -20 to + 10) from the indicated species were aligned with MDCK sequences flanking the transcription initiation site mapped by primer extension. The first base of the predominate RNA transcript of the indicated species is labeled +1. Conserved residues are indicated blue, red and green lettering. For all the indicated species, the -1 position is a T (red) and the +1 position a purine residue (green). The sequences from +2 to +9 (blue) are conserved in the indicated mammalian species. Based on the aligned sequences, the G residue (arrow) in the MDCK sequences was predicted to be the RNA pol I promoter transcription initiation site.