FIGURE 5.

RNA co-immunoprecipitation of a portion of the Bcl-x pre-mRNA using hnRNP K antibodies is dependent on the B1 region. The transcripts were incubated in HeLa nuclear extracts in splicing conditions and then on beads coupled with hnRNP K antibodies (Anti-hnRNP K) or preimmune serum (Serum). After five washes, the RNA was precipitated, migrated on an acrylamide gel, and quantified on a PhosphorImager. The left panel is a graph of the values of radioactivity measured. The right panel shows the relative levels of a tenth of the input RNA. The sequence of the point mutations that were tested is indicated in the bottom panel.