FIG. 1.
RNA templates used in in vitro influenza virus transcription reactions. Vertical lines indicate the proposed base-paired region in the RNA fork model (3, 4). The U6 track, the proposed poly(A) site, is in bold. Nucleotides are numbered as primed numbers (3), starting from the 5′ end. The point mutations at positions 3′ and 4′ are indicated above those positions. (A) Sequence of 717-nt template. The sites for XhoI and BglII in plasmid pBXPCAT1 are indicated by arrows. The complements of the initiation and termination codons of the CAT gene are underlined and overlined, respectively. (B) Sequence of 49-mer template. The four residues in parentheses were absent in the deletion mutant.