FIG. 5.
PTB and CstF64 compete for the same pre-mRNA binding sites in a UV cross-linking competition assay. (α-pA) 0, 10, 50, 100, or 250 ng of rPTB was added to a CstF purified protein fraction. Following UV cross-linking, labeled proteins were fractionated by SDS-polyacrylamide gel electrophoresis. As described above, PTB and CstF64 compete for binding to α-globin pA pre-mRNA. (β-pA) 0, 10, 50, 100, 250, or 500 ng of rPTB was added to a CstF purified protein fraction as for α-pA. Again, PTB and CstF64 compete for binding to the β-globin pA pre-mRNA.