Figure 5.

Substrate specificity of the ATP-dependent RNA unwinding activity. The reactions were incubated with ≈10 fmol of the corresponding duplex in the presence or absence of 200 μM ATP, as indicated. The position of the duplices and radiolabeled single-stranded RNA are indicated. The secondary structures of each substrate are represented schematically at the bottom. (a) RNA unwinding activity of 20S U5 snRNPs or isolated U5–200kD protein with U4/U6 RNA (Left) or the nonspliceosomal C4/MO Ia RNA (Right). The unwinding activity was investigated with 100 fmol U5 snRNPs or 1 pmol U5–200kD. (b) A 37-bp DNA duplex was incubated with ≈100 fmol 20S U5 snRNPs or 20 ng of hexameric large T antigen (denoted T-A.).