Figure 3.
Transcriptional activity of chimeric cyclin A/c-fos promoters in ts13 cells. Promoter constructs were transiently transfected into ts13 and ts13R3 cells maintained at 33.5°C or 39.5°C. After 40–48 hr, the transcriptional activity of each promoter was determined and the ratio of activity detected at 33.5°C and 39.5°C shown. The relative activity of each promoter at 33.5°C is also given as a percentage of the activity detected for cyclin A (values shown in parentheses). A schematic diagram of the cyclin A, c-fos, and chimeric promoter upstream regulatory regions and core promoter elements are shown. The endpoints for the cyclin A core promoter are −41 to +5, and for the c-fos core promoter, −56 to +109. The position of the cyclin A TSRE, CCAAT-binding transcription factor site (CCAAT), serum response element (SRE), cAMP responsive element/activating transcription factor binding site (CRE/ATF), and GC-rich protein binding sites (GC box) are indicated. Not all known and potential protein binding sites are shown.