The mechanism of RU486 antagonism is dependent on the conformation of the carboxy-terminal tail of the human progesterone receptor.
Journal Article
The human progesterone receptor form B (hPR-B) was expressed in Saccharomyces cerevisiae together with a specific reporter plasmid. To understand the mechanism underlying antagonist ligand activity, libraries of hormone binding domain (HBD)-mutated hPR-B molecules were prepared. A mutant receptor was identified that had lost the ability to bind either progesterone or R5020; it could still bind RU486 and, surprisingly, fully activated transcription in the presence of this "antagonist" and other antiprogestins. When this receptor mutant was assayed in mammalian cells, RU486 again demonstrated agonistic activity. Sequence analysis indicated that the mutant phenotype was due to truncation of the carboxy (C)-terminal 42 aa. We conclude that amino acids in the extreme C-terminal region are required for the receptor to bind progesterone, while antagonists bind to a site located more N-terminal of the HBD. Our results suggest that the extreme C-terminal region of the receptor contains an inhibitory function that silences receptor transactivation in the absence of agonist and in the presence of antagonist.
Full Text
Duke Authors
Cited Authors
- Vegeto, E; Allan, GF; Schrader, WT; Tsai, MJ; McDonnell, DP; O'Malley, BW
Published Date
- May 15, 1992
Published In
Volume / Issue
- 69 / 4
Start / End Page
- 703 - 713
PubMed ID
- 1586949
Pubmed Central ID
- 1586949
International Standard Serial Number (ISSN)
- 0092-8674
Digital Object Identifier (DOI)
- 10.1016/0092-8674(92)90234-4
Language
- eng
Conference Location
- United States