Estrogen Receptor Accessory Factors in Breast Cancer Cells
Abstract
The goal of this investigation was to identify proteins that associate with the ERa in a ligand- dependent manner and may therefore play a role in mediating the activity of the receptor. We have used the ligand binding domain of the ER (ERa-LBD) to capture proteins from mammalian cell extracts that associate with the ERa. One protein isolated by this technique is a kinase, able to bind and phosphorylate the ERa only in the presence of estrogen agonists such as estradiol. Using an array of chromatographic techniques and monitoring kinase activity, we have purified a stoichiometric complex of proteins to apparent homogeneity. Mass spectrometric sequencing has identified two of the protein components as Ca2+/calmodulin-dependent protein kinase II y and % (CamKII). Coimmunoprecipitation experiments show in vivo association of CamKII with ER upon stimulation of cells with estradiol and recent transfection experments suggest CamKll activity plays a role in transcriptional activation through the ERa. Additionally, site directed mutagenesis has defined the kinase binding site on the ER-LBD as a hydrophobic cleft previously implicated in recmitment of nuclear receptor coactivator proteins. Taken together, our data suggest that CamKII can serve as a novel modulator of ERa action. 1% MII%A%%D fl% %A%%%
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 01, 1998
- Accession Number
- ADA359619
Entities
People
- Geoffrey L Greene
Organizations
- University of Chicago