Dimerization of mammalian progesterone receptors occurs in the absence of DNA and is related to the release of the 90-kDa heat shock protein

A. M. DeMarzo, C. A. Beck, S. A. Onate, D. P. Edwards

Research output: Contribution to journalArticlepeer-review

Abstract

In this study we have demonstrated that dimerization of mammalian progesterone receptors (PR) occurs in the absence of DNA. A specific immune coisolation assay was performed on extracts of T-47D human breast cancer cells with a monoclonal antibody specific for the full-length B form of progesterone receptor (PR-B). This resulted in coisolation of significant amounts of truncated form-A receptors (PR-A), indicating the presence of stable PR-A·PR-B dimers in solution. A positive correlation was observed between the ability of different receptor forms to oligomerize in solution and their ability to bind to specific DNA sequences. The ability to form stable PR-A·PR-B oligomers in the absence of DNA was also found to correlate with release of 90-kDa heat shock protein (hsp90) from the unactivated PR complex. These results support the hypothesis that dimerization in the absence of DNA is an important mechanism controlling receptor DNA-binding function and that hsp90 release may be a key step regulating dimerization. This suggests that hsp90 may function to repress DNA-binding activity indirectly by blocking receptor dimerization.

Original languageEnglish (US)
Pages (from-to)72-76
Number of pages5
JournalProceedings of the National Academy of Sciences of the United States of America
Volume88
Issue number1
DOIs
StatePublished - 1991
Externally publishedYes

Keywords

  • DNA-binding protein
  • dimers
  • progesterone response elements
  • steroid receptors

ASJC Scopus subject areas

  • General

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