The polyomavirus enhancer comprises multiple functional elements

The polyomavirus enhancer occupies 244 base pairs within noncoding sequences between the early and late transcription units. To define more precisely the DNA sequences that make up the enhancer, we cloned it together with the viral early promoter upstream of a reporter gene, isolated mutants bearing deletions introduced in vitro in the enhancer, and measured the capacity of the various mutant genomes to express the cat gene after transient …