A RAPID ONE-STEP METHOD TO PURIFY BACULOVIRUS-EXPRESSED HUMAN ESTROGEN-RECEPTOR TO BE USED IN THE ANALYSIS OF THE OXYTOCIN PROMOTER

We have produced a truncated form of the human estrogen receptor (hER) as a fusion protein with glutathione S-transferase (GST) in Spodopter a frugiperda (Sf) cells using the baculovirus expression vector (BEV) system. The protein is correctly produced and can be purified from cru de whole-cell extracts by a single-step, batch-wise affinity-purificat ion procedure. We show that this GST-hER fusion protein binds at its D NA-binding site specifically and in a hormone-inducible manner. Furthe rmore, we used the purified hER to analyze the complex estrogen respon se element (ERE) in the promoter of the oxytocin-encoding gene.