Multiple transcription terminators in E1a and E1b genes of adenovirus type 5

We located and characterized transcription terminators in the E1a and E1b genes by transferring the 3' fragments of the genes into the vector pSCAT10 [Sato et al., Mol. Cell. Biol. 6 (1986) 1032-1043] at a site located immediately downstream from the cat gene (coding for chloramphenicol acetyltransferase; CAT) and upstream from the simian virus 40 polyadenylation region. Multiple terminators were located downstream from the E1b gene, but not in the 3' region of the E1a gene. Fine analysis of these terminators by the CAT assay method and S1 nuclease mapping of in vivo transcripts indicated possible involvement of a G-rich sequence in transcription termination of the E1 region. These terminators were repeated tandemly and used by both the E1a and the E1b genes in a orientation-dependent manner.