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. 1997 Jan 21;94(2):407–411. doi: 10.1073/pnas.94.2.407

Figure 4.

Figure 4

Both incorporation and extension of incorporated ribonucleotides by RT-F155V-H are slower than for deoxyribonucleotides. 5′ end radiolabeled 14-mer DNA primer was annealed to a 17-mer DNA template at a 1:1 ratio. (a) The primer was extended by RT-F155V-H using either 10 μM dTTP or rUTP as a substrate. At the indicated time points, an aliquot of the reaction was removed and analyzed by gel electrophoresis. (b) The primer was extended by RT-WT-H in the presence of 10 μM dTTP, 10 μM rUTP, or 200 μM rUTP. (c) The 14-mer primer was first extended by either 10 μM dTTP or 10 μM rUTP to completion. The extended 15-mer primers were then further extended by adding either 10 μM dATP or 10 μM rATP to the reaction. Markers were generated by extending *C14 with ddTTP (nt15) or dTTP plus ddATP (nt16). Products with ribonucleotides at the 3′ terminus migrated more slowly than those with deoxyribonucleotides at the terminus. The bands migrating at the position of nt17 (lanes 5–8 and 15–17) presumably resulted from untemplated extension of dATP at the last nucleotide of the template.