FIGURE 2.

Schematic of the U12-dependent P120 intron F diagramming the various spliced isoforms. (A) The indicated PCR primers flanking the splice sites anneal within the E6 and E7 exons surrounding intron F (the vector-specific RT primer is not indicated). The proper U12-dependent 5′ and 3′ splice sites are at positions 1 and 99, respectively. The correct U12-dependent branch site sequence is shaded, and the downstream cryptic U12-dependent branch site is underlined. The cryptic U2-dependent splice sites are at positions 13 and 93, and the cryptic U12-dependent 3′ splice site is at position 222. (B) Schematics of the three spliced isoforms observed by RT-PCR with indicated PCR product sizes after splicing.