THE MECHANISM OF RU486 ANTAGONISM IS DEPENDENT ON THE CONFORMATION OF THE CARBOXY-TERMINAL TAIL OF THE HUMAN PROGESTERONE-RECEPTOR
THE MECHANISM OF RU486 ANTAGONISM IS DEPENDENT ON THE CONFORMATION OF THE CARBOXY-TERMINAL TAIL OF THE HUMAN PROGESTERONE-RECEPTOR
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DOI：
10.1016/0092-8674(92)90234-4
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发表时间：
1992-05-15
期刊：
影响因子：
64.5
通讯作者：
OMALLEY, BW
中科院分区：
文献类型：
--
作者：
VEGETO, E;ALLAN, GF;OMALLEY, BW
人孕激素受体B型（hPR-B）与特异性报告质粒一起在酿酒酵母中表达。为了理解拮抗剂配体活性的潜在机制，制备激素结合结构域（HBD）突变的hPR-B分子的文库。突变受体被鉴定为已经失去结合孕酮或R5020的能力;它仍然可以结合RU 486，并且令人惊讶的是，在这种“拮抗剂”和其他抗孕激素存在下完全激活转录。当在哺乳动物细胞中测定该受体突变体时，RU 486再次显示激动活性。序列分析表明，突变表型是由于羧基（C）端42个氨基酸的截短。我们得出结论，在极端的C-末端区域的氨基酸是必需的受体结合孕酮，而拮抗剂结合到一个网站位于更多的N-末端的HBD。我们的研究结果表明，极端的C-末端区域的受体含有抑制功能，沉默受体的反式激活在没有激动剂和拮抗剂的存在下。
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.