Progesterone enhances target gene transcription by receptor free of heat shock proteins hsp90, hsp56, and hsp70.

摘要: Steroid receptors regulate transcription of target genes in vivo and vitro a steroid hormone-dependent manner. Unoccupied progesterone receptor exists the low-salt homogenates cells as functionally inactive 8 to 10S complex with several nonreceptor components such two molecules 90-kDa heat shock protein (hsp90), 70-kDa (hsp70), 56-kDa (hsp56). Ligand-induced dissociation receptor-associated proteins hsp90 has been proposed mechanism activation. Nevertheless, it not established whether, beyond release proteins, steroidal ligand plays role modulating activity. To examine whether these from results constitutively active receptor, we isolated an unliganded form essentially free hsp90, hsp70, hsp56. Using recently developed hormone-responsive cell-free system, demonstrate for first time that is sufficient generate receptor. This purified still requires hormone high-affinity binding response element efficient transcriptional activation gene. When antiprogestin, Ru486, bound fails promote transcription. We propose cell, addition inhibitory distinct hormone-mediated event must precede gene