Function of Estrogen Receptor Tryosine Phosphorylation
Abstract
A biochemical analysis of a tyrosine 537 to phenylalanine mutation in the human estrogen receptor (hER) revealed no significant changes in DNA or hormone binding affinities compared to wild type receptor. However, the Y537F hER mutation resulted in altered hormone binding kinetics and a decreased receptor stability, as measured by a loss of hormone and DNA binding over time relative to wild type receptor. Phosphorylation of Y537 is not essential for hER function but Y537 is nevertheless a critical residue intricately involved with the conformation and ability of the hER to activate transcription. A phosphotyrosine peptide derived from the hER sequence surrounding Y537 and containing part of helix 12 in the ligand binding domain is capable of blocking specific hER-DNA binding in vitro . The phosphopeptide inhibition of DNA binding requires the phosphotyrosine and the amino acids carboxy terminal to it. Analysis of hER deletion fragments suggests the ligand binding domain is required for phosphopeptide inhibition. The phosphopeptide does not bind to or compete with the ligand binding site. The structural information of the ligand binding domain was exploited and a dimer-contact' oligopeptide was derived from the helical region of the wild type protein involved in receptor dimerization. This peptide, or I-box peptide, is capable of specifically precipitating the hER from cell extracts. Precipitation activity is correlated with the helical nature of the peptide: a peptide containing a secondary structure-disrupting proline residue has no effect on hER function.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 01, 1999
- Accession Number
- ADB257705
Entities
People
- Matthew R. Yudt
Organizations
- University of Rochester