Related Experiment Video
Updated: Jul 14, 2026

Biochemical Reconstitution of Steroid Receptor•Hsp90 Protein Complexes and Reactivation of Ligand Binding
Published on: September 21, 2011
Characterization and identification of a steroid receptor-binding protein, SRB-RGS
Mitsunori Ikeda1, Satoshi Inoue, Masami Muramatsu
1Department of Biochemistry, Kawasaki Medical School, Kurashiki, Okayama, Japan. ikeda@bcc.kawasaki-m.ac.jp
Abstract:
We cloned the cDNA of a novel steroid receptor-binding protein, SRB-RGS, which suppressed the estrogen receptor (ER)alpha-mediated and other promoter-driven transcriptional activities. This study revealed the interaction between the full-length SRB-RGS and full-length ERalpha or ERbeta by a coimmunoprecipitation assay. The full-length SRB-RGS and full-length ERalpha interacted in COS-7 cell by a mammalian two-hybrid system. The interaction between intrinsic SRB-RGS and ERs in the nuclear ER extract from the rat uteri was observed by the gel-shift assay. These results strongly suggested that SRB-RGS interacts with ERs bound to DNA (estrogen response element) in the nuclei of the cells. SRB-RGS suppressed very efficiently the ERalpha-, ERbeta-, and ERalpha+ERbeta-mediated transcriptional activities. Green fluorescence of enhanced green fluorescence protein (EGFP)-tagged SRB-RGS was localized both in the nucleus and in the cytoplasm. Intrinsic SRB-RGS was immunostained in the nucleus and the cytoplasm of HeLa cells. The putative SRB-RGS deduced from cDNA sequence was identified by the immunostaining and Western blotting by using the anti-SRB-RGS antibody. Overexpression of SRB-RGS induced the cell death in the HeLa cells. The nucleotide sequence of SRB-RGS cDNA that we cloned previously is identical with that of the newly isolated RGS3 cDNA. SRB-RGS could interact with ERs bound DNA in the nuclei of the cells and suppressed the ERs-mediated transcriptional activities.
Related Concept Videos
Transducer Mechanism: Nuclear Receptors
About 48 different soluble family members of nuclear receptors are identified that can be divided into two main classes:
Regulation of Nuclear Protein Sorting
The Two-State Receptor Model
The binding affinity of a drug determines its interaction with one...
Directing Proteins to the Rough Endoplasmic Reticulum
Internal Receptors
Types of Receptors: Internal Receptors
Similar to membrane-bound receptors, the binding of a ligand to the intracellular receptor of causes a conformational change in the...
