Figure 1.

ATP-dependent RNA unwinding activity of MonoQ-purified mammalian 20S U5 snRNPs. The unwinding of a [³²P]-U4/U6 snRNA duplex (10 fmol) by 20S U5 snRNPs was assayed in the presence of ATP (lanes 2–5), without ATP (lane 7), or with the nonhydrolyzable analog γS-ATP (lane 8). Unwinding of the U4/U6 RNA duplex also was monitored with U5 snRNA (lane 9), 10S core U5 snRNPs (lane 10), and 12S U1 snRNPs (lane 6), in the presence of ATP. The concentrations of snRNPs or U5 snRNA used are indicated. The [³²P]-U4/U6 snRNA duplex in the absence of protein is shown in lane 1. The positions of duplex and single-stranded U4 RNA are indicated. Details concerning the analysis of RNA unwinding are described in Materials and Methods.