Ligand dissociation from estrogen receptor is mediated by receptor dimerization: Evidence from molecular dynamics simulations

Milton T. Sonoda, Leandro Martínez, Paul Webb, Munir S. Skaf, Igor Polikarpov

Research output: Contribution to journalArticlepeer-review

48 Scopus citations


Estrogen Receptor (ER) is an important target for pharmaceutical design. Like other ligand-dependent transcription factors, hormone binding regulates ER transcriptional activity. Nevertheless, the mechanisms by which ligands enter and leave ERs and other nuclear receptors remain poorly understood. Here, we report results of locally enhanced sampling molecular dynamics simulations to identify dissociation pathways of two ER ligands [the natural hormone 17β-estradiol (E2) and the selective ER modulator raloxifene (RAL)] from the human ERα ligand-binding domain in monomeric and dimeric forms. E 2 dissociation occurs via three different pathways in ER monomers. One resembles the mousetrap mechanism (Path I), involving repositioning of helix 12 (H12), others involve the separation of H8 and H11 (Path II), and a variant of this pathway at the bottom of the ligand-binding domain (Path II′). RAL leaves the receptor through Path I and a Path I variant in which the ligand leaves the receptor through the loop region between H11 and H12 (Path I′). Remarkably, ER dimerization strongly suppresses Paths II and II′ for E2 dissociation and modifies RAL escape routes. We propose that differences in ligand release pathways detected in the simulations for ER monomers and dimers provide an explanation for previously observed effects of ER quaternary state on ligand dissociation rates and suggest that dimerization may play an important, and hitherto unexpected, role in regulation of ligand dissociation rates throughout the nuclear receptor family.

Original languageEnglish (US)
Pages (from-to)1565-1578
Number of pages14
JournalMolecular Endocrinology
Issue number7
StatePublished - Jul 2008

ASJC Scopus subject areas

  • Molecular Biology
  • Endocrinology


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