FIG. 4.

Identification of the region in RTA that is required for transcription activation. The RTA deletions illustrated in Fig. 3A were introduced into pCR3.1-ORF50. The RTA mutants (designated RtaΔ4, RtaΔ5, etc.) were examined for the ability to activate the ori-Lyt RRE-containing promoter as well as the K8 delayed-early promoter by use of luciferase reporters. The reporter plasmids containing a firefly luciferase gene under control of the ori-Lyt promoter or the K8 delayed-early promoter were introduced into BJAB cells by electroporation or into 293 cells by calcium phosphate precipitation. Renilla luciferase plasmid was included in each transfection as an internal control. At 48 h posttransfection, dual luciferase assays were performed with the lysates of transfected cells. Relative luciferase activities were calculated by dividing the normalized firefly luciferase activity of each reporter by that of pGL3 plasmid in pCR3.1-transfected cells.