FIG. 3.

Interference footprinting performed with oligo tel1, which contains telomeric sequences at the 3′ and 5′ ends. (A) Interference footprinting was performed with oligo tel1, whose sequence is shown at the bottom of the figure, using the procedure described in Materials and Methods. The telomeric repeats in the oligo tel1 sequence are indicated with boldface letters. The concentrations of the reagents used for these assays, DMS (panel I), formic acid (panel II), and KMnO₄ (panel III), are indicated. Pr, unincorporated ³²P-labeled dATP. (B) Quantitative analysis of the data shown in A was performed as described in Materials and Methods. The histograms present data obtained in the analysis of one lane from each interference assay and of a corresponding control lane, namely the 0.3% DMS, 2.5% formic acid, and 0.1 mM KMnO₄ lanes. The relative interference values are shown as bars. For calculations of the interference resulting from modification of T4 or T5, the molecules modified at T4 and T5 were assumed to be equally labeled (see Results).