FIG. 1.
The HK97 NS1A protein does not bind the F2F3 fragment of CPSF30 and does not inhibit 3′-end processing of cellular pre-mRNAs. (A) GST pulldown assay. GST-F2F3 or GST was mixed with 35S-labeled NS1A protein of the indicated virus. (B) 3′-end processing assay. 293 cells (left panel) or quail embryo fibroblasts (right panel) were cotransfected with a pBC12 plasmid carrying a human β-globin gene and either an empty pcDNA3 plasmid (lane 1) or a pcDNA3 plasmid encoding the indicated NS1A protein. RNA was analyzed by RNase protection using a 270-nucleotide-long RNA probe spanning the 3′ cleavage site of the β-globin pre-mRNA. The protected RNA fragment corresponding to the uncleaved pre-mRNA is 210 nucleotides long, and the RNA fragment corresponding to the 3′-end-cleaved pre-mRNA is 160 nucleotides long. No residual probe containing 270 nucleotides was detected.