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Structural characterization of the trypsinized estrogen receptor
M Fritsch1, I Anderson, J Gorski
1Department of Biochemistry, University of Wisconsin-Madison 53706-1569.
Biochemistry
|December 21, 1993
Summary
Structural differences in rat uterine estrogen receptors (ERs) were studied. Ligand binding alters ER structure, affecting trypsin digestion patterns and oligomeric complex formation, indicating conformational changes upon activation.
Area of Science:
- Biochemistry
- Molecular Biology
- Endocrinology
Background:
- Estrogen receptors (ERs) regulate gene expression in target tissues.
- Understanding ER structural dynamics is crucial for hormone-dependent processes.
Purpose of the Study:
- To investigate structural differences between unoccupied and ligand-occupied rat uterine ERs.
- To elucidate how ligand binding affects ER conformation and stability.
Main Methods:
- Partial proteolysis using trypsin.
- Immunoblotting and affinity labeling with radioligands.
- Gel filtration chromatography to assess oligomeric states.
Main Results:
- Trypsin digestion of unoccupied ER yielded two fragments (28 kDa and 10 kDa).
- The 10 kDa fragment formed a large oligomeric complex, suggesting maintained tertiary structure.
- Ligand-occupied ERs showed altered trypsin sensitivity and different chromatographic profiles compared to unoccupied ERs.
Conclusions:
- Ligand binding induces significant conformational changes in rat uterine ERs.
- These changes affect protease sensitivity and the oligomeric state of the receptor.
- Structural alterations are key to ER function and regulation.