Figure 2.
Upstream regulatory element in cyclin A exhibits temperature-sensitive transcriptional activity in ts13 cells. Deletion constructs of the cyclin A promoter cloned upstream of the luciferase gene were transfected into ts13 and ts13R3 cells as described in Materials and Methods. The transcriptional activity of each promoter at 33.5°C and 39.5°C was determined as a function of luciferase activity normalized for β-galactosidase activity. The ratios of activity detected at 33.5°C and 39.5°C are shown. The activity of each deletion construct relative to wild type (A-WT), given a value of 100%, in ts13 cells at 33.5°C is also shown. Indicated is the minimal cyclin A TSRE, which retains temperature-sensitive expression in ts13 but not in ts13R3 cells. The positions of potential protein binding sites including ATF are indicated. (N.D.) The experiment was not performed.