FIG. 6.

Antibodies to various ER epitopes can detect differences in conformation of the A2 and pS2 ERE-bound receptor. (A) Schematic representation of the epitopes for ER-specific antibodies used. (B) Partially purified, yeast-expressed ER (285 fmol) was incubated with A2 ERE-containing DNA fragments (odd-numbered lanes) or pS2 ERE-containing DNA fragments (even-numbered lanes). After a short incubation, antibodies (Ab) were added to the binding reactions as indicated and the complexes were fractionated on a nondenaturing acrylamide gel. The complexed DNA and free probe were visualized by autoradiography. (C) Partially purified, yeast-expressed ER (570 fmol) was incubated with pS2 ERE-containing DNA fragments. Samples were processed as for panel B.