FIG 7.

hnRNP K competes with PTB for the FMDV IRES binding site. (A) The interaction between hnRNP K or PTB and the FMDV IRES assessed by RNA pulldown assays. Purified GST-hnRNP K or His-PTB as a recombinant protein was incubated with biotinylated FMDV IRES RNA. No RNA was used as a negative control. Then, streptavidin beads were used to capture the biotinylated RNA, and the complexes were analyzed by Western blotting using anti-GST and anti-His antibodies. (B) Increased amounts of hnRNP K decreased the interaction between PTB and the FMDV IRES, according to the results of the RNA pulldown assay. Various amounts (in micrograms) of GST-hnRNP K were added to compete with His-PTB for interaction with the biotinylated FMDV IRES RNA. Nonbiotinylated RNA was used as a negative control. The eluted proteins were subjected to SDS-PAGE (12%), and antibodies against GST and His were then used in the Western blot analysis.