FIG. 6.

Critical regions required for YFP–SRC-1 recruitment. A03_1 cells were cotransfected with YFP-SRC780 (bottom row) and either CFP-LacER250–554 (A, top row), CFP-LacER534 (B, top row), or CFP-LacERV376D (C, top row). Cells were imaged before (left column) and after 20 min of 10 nM E2 (right column). CFP-LacER250–554 retains all of the critical residues required for agonist-induced YFP-SRC780 recruitment (A). Deletion of helix 12 (CFP-LacER534 [B]) prevents ligand-enhanced recruitment and eliminates most of the ligand-independent interactions. Mutation of the ER–SRC-1 interface (CFP-LacERV376D [C]) inhibits agonist-induced SRC-1 recruitment, but does not eliminate the ligand-independent interactions. The brighter signal is primarily due to contraction of the chromosomal region (Nye et al., submitted).