Identification of unoccupied but transformed nuclear estrogen receptor in cultured mouse leydig cell

  • Miyashita Y
  • Hirose T
  • Kouhara H
 et al. 
  • 2


    Mendeley users who have this article in their library.
  • 5


    Citations of this article.


The molecular forms of estrogen receptor (ER) in estrogen-responsive mouse Leydig cell line (B-l) have been examined in relation to their biological activity. ER was predominantly recovered in the nuclear fraction upon homogenization even after cells were precultured in the absence of E2and Phenol Red. This unoccupied nuclear ER (ERn) whose hormone binding ability was extremely thermostable could be extracted with 0.4 M KC1. This stability enabled us to determine hydrodynamic parameters in the ligand-free condition. The Stokes radius and sedimentation constant of this ERn in high salt condition were 5.5 nm and 6.0S, respectively, resulting in its molecular weight of 140,000. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of ER labeled with [3H]tamoxifen aziridine gave a single band of 65,000 Da, indicating that this ERn had a oligomer structure similar to that of transformed nuclear ER complexed with estrogen in the putative target cells. Therefore, we further examined the possibility that this ERn in B-l cells can activate estrogen-responsive genes without any aid from estrogen. Estrogen responsive element-thymidine kinase promoter-chloramphenicol acetyltransferase fusion gene (ERE-tk-CAT) was transfected into B-1 cells. CAT activity was enhanced only in cells stimulated with estrogen. It may be concluded from these results that transformed ERn can be formed in the absence of estrogen but that binding to estrogen may be required in order to exert its biological activity. © 1990.

Get free article suggestions today

Mendeley saves you time finding and organizing research

Sign up here
Already have an account ?Sign in

Find this document


  • Y. Miyashita

  • T. Hirose

  • H. Kouhara

  • S. Kishimoto

  • K. Matsumoto

  • B. Sato

Cite this document

Choose a citation style from the tabs below

Save time finding and organizing research with Mendeley

Sign up for free