FIG. 4.

hAR NTD physically interacts with SRC-1e and with the hAR LBD in COS cells. (A) COS cells were transfected with expression vectors for either GST alone or a fusion protein of GST with the hAR NTD, along with an expression vector for FLAG-tagged SRC-1e. After 24 h of incubation at 37°C, extracts were prepared and protein complexes bound to GST or GST-NTD were precipitated with glutathione Sepharose beads, immunoblotted, and stained with monoclonal anti-FLAG antibody. (B) COS cells were transfected and treated as described for panel A, except that GST fusion proteins of the DBD-LBD regions of the hAR and the mER were used. The cells were treated without hormone (lanes 1, 2, and 4) or with 100 nM of either R1881 (lane 3) or estradiol (lane 5) 24 h prior to the preparation of protein extracts and GST pull down. (C) COS cells were transfected and treated as for panel B, except that an expression vector for the hAR NTD was used instead of FLAG-tagged SRC-1e. The immunoblots were probed with a polyclonal anti-AR antiserum. +, present; −, absent.