FIG. 6.

5′ boundary of the gene 21 promoter. Duplicate CAT assays were performed on extracts of uninfected cells that had been transfected with CAT reporter constructs containing either the entire 284-bp DNA segment separating ORF 20 and ORF 21 (p21), a 496-bp extension (p21Z), or various 5′ truncation mutations (p21A, p21B, p21C, and p21Δ) in the presence of the IE62 expression plasmid. The 5′ boundary of the gene 21 promoter was located to a region between nt 30585 (p21A) and nt 30626 (p21B). %CAT, average percent chloramphenicol acetylation; sd, standard deviation.