FIG. 1.

hPRA and hPRB repress SHR transcriptional activity by distinct mechanisms. HeLa cells were transiently transfected with 1.3 μg of 3XERE-TATA-LUC, 50 ng of pBKC-βgal, either 103 ng of pBKC-hPRA or 112 ng of pBKC-hPRB, and increasing concentrations of pRST7-ERα (100 ng, 600 ng, or 1,200 ng) or 100 ng of pBKC-TUP1 (CONTROL) plus 1,200 ng of pRST7-ERα. Variable amounts of pBSII-KS were used for a total of 3 μg of DNA. Transcriptional activity of the 3XERE-TATA-LUC reporter was measured 24 h after the addition of 10⁻⁸ M 17-β-estradiol alone or in the presence of increasing concentrations of R5020 (A) or RU486 (B). A control was done in the absence of ligands (not shown). The data are presented as percent activation where 100% represents a measure of 17-β-estradiol dependent transactivation by hER in the absence of hPRA or hPRB (n = 2). The average coefficient of variation at each point was <15%. NR, no progestins.