FIG. 1.
ApG-primed transcription of 14-nt influenza virus vRNA model templates requires a RNA polymerase complex containing PB1, PB2, and PA. The results of in vitro transcription of a model 14-nt vRNA 3′ sequence in the presence of an equimolar concentration (2.5 μM) of a model 15-nt 5′ end sequence, evaluated using the [α-32P]GTP incorporation assay with different preparations of RNA polymerase prepared in parallel from the indicated plasmids (see Materials and Methods) and fractionated by 20% PAGE in 7 M urea, are shown. a, 14-nt product; b, 13-nt product (see text).