Figure 1. Schematic illustration of the transgene expression system

Various promoters, the minimal promoter (TATA), the cytomegalovirus immediate-early enhancer/promoter (CMVP), and the RPE65 promoter (R65P) were used in the system. A: The luciferase reporter and chimeric transcriptional activator GAL4-VP16 were produced separately in DNA constructs, pLuc, and pGV series. pLuc, where luc is regulated by TATA, CMVP, or R65P, presents the promoter activity in transfected cells; pGV, where GAL4-VP16 is regulated by CMVP or R65P, is used for co-transfection with pLuc series, correspondingly. B: The reporter and GAL4-VP16 are expressed in single DNA constructs, pLuc-GV series. pLuc-GV includes two types of constructs, depending upon whether luc is controlled by TATA or R65P. The chimeric activator GAL4-VP16 regulated by CMVP or R65P is produced and subsequently provokes luc expression (thick arrow) by binding the 5x17-mer sequence located upstream of the 5' end of TATA or R65P.