FIG. 7.

Cryptic splice donor sequence identified in the long terminal repeat of the ROSAcre gene trap virus. (a) ROSAcre has integrated 235 bp upstream of the transcription start of a known gene, Akr1a4. This insertion has trapped a novel transcript transcribed in the opposite orientation. (b) The transcript sequence obtained from 8A8 reveals a cryptic splice donor site in the U5 region of the provirus. The transcript is a readthrough of the genomic DNA-provirus junction. Splicing occurs between the cryptic splice donor (underlined) in the U5 region and the synthetic splice acceptor (underlined) cloned 5′ of the cre reporter. Green letters indicate the sequence spliced out of the transcript.