Figure 3.
When incubated together PAP I incorporates all the nucleotides. Non-radioactive RNA of 260 nt was incubated with PAP and [α-32P]ATP for 40 min. The reaction was stopped by incubation at 70°C for 5 min and RNase A and RNase T1 (digesting at G, C and U but not A) were added for 1 h at 37°C following isolation of the RNA and analysis by denatured 12% PAGE and autoradiography (lane 2). In lane 3, non-radioactive CTP, GTP and UTP were added to the incubation with PAP I and the reaction proceeded as described for lane 2. The 260 nt radioactively labeled RNA is shown in lane 1 as a size marker. The polyadenylated RNA that was resistant to the ribonucleases and the digestion products produced when all nucleotides were used are indicated.