7α,11β-Disubstituted estrogens: Probes for the shape of the ligand binding pocket in the estrogen receptor

To investigate whether the estrogen receptor accommodates 7α and 11β substituents on estradiol in two subsites or in a single subsite, we have prepared three sets of ligands bearing single (7α or 11β) or double (7α and 11β) substituents and measured their binding affinity. The different behavior of each set precludes a definitive choice, but supports a two subsite model with some limitations.