ERαK206A and K206G mutations lead to super-stimulation at AP-1 sites through the estrogen pathway. (A) Location of K206 at the base of the first zinc binding domain in the ERα DBD. (B) ERαK206A and ERα G400V.K206A ligand profiles in HeLa cells. The panel shows results of HeLa cell transfections in which activity of ERα, and ERα G400V with or without the K206A mutation, were assessed at the Coll73-Luc reporter (shown in schematic above), in the presence of a range of ligands. Note: ERα refers to the fully wild type human estrogen receptor (Fomerly pHEG0). All mutations in this manuscript are in this background unless performed in the human ERα that contains a G400V mutation in the ligand binding domain. This latter construct is designated ERαG400V (Formerly pHE0). "No ER" indicates cells transfected exactly as in all others in the experiment except that an empty expression vector (pSG5) is transfected instead of the same vector containing receptor cDNA, as indicated. Vehicle treatments (No H.) are represented by white bars, ICI by light grey bars, Ral by medium grey bars, Tam by dark grey bars and E2 by black bars. The figure represents a single representative experiment with standard deviations calculated from multiple wells. (C, D) ERα.K206A and ERα.K206G are both superactive at AP-1 sites, but not EREs. (C) The panel shows results from a transfection in which activities of ERα with and without the K206A/G mutations were assessed at an AP-1 site (Coll73-Luc reporter). (D) Results of a similar transfection in which activities of the same ERs were assessed at an ERE (ERE-Luc). The panel represents a single experiment with average results obtained from triplicate wells.