FIG. 7.

hU3-55K directly interacts with 15.5K. A) ³⁵S-labeled hU3-55K was incubated with either GST-15.5K (0.25 or 25 pmol) in the absence (−) or presence (+) of U3 B/C motif RNA (U3BC) (lanes 3 to 6) or 25 pmol of GST (lane 2). Bound, radiolabeled proteins were purified using glutathione resin, resolved on a 12% polyacrylamide-SDS gel, and revealed by autoradiography. The amount of recombinant 15.5K used is indicated above each lane. Ten percent of the input material was used in the Input lane. GST 15.5K-WT, GST fused to wild-type 15.5K. B) ³⁵S-labeled hU3-55K was incubated with 25 pmol of either wild-type (WT) or mutant GST-15.5K (lanes 3 to 8) or GST (lane 2). Bound, radiolabeled proteins were purified using glutathione resin and resolved on a 12% polyacrylamide-SDS gel. Ten percent of the input material was used in the Input lane. The identity of the GST protein used is indicated above each lane.