A,B Effects of EGF on ERα LBD mutants. COS-1 cells were transiently cotransfected with wtERα or C381A, E419A, E423A, H516A, E523A, N532A, D538A, D545N, H547A, H547D, and E542A/D545A, an estrogen responsive CAT reporter gene, and β-gal and treated for 24 hours with estradiol (1nM) or EGF (150ng/ml) in the presence and absence of the antiestrogen ICI-182,780 (500nM). The amount of CAT activity was measured, normalized to the amount of β-galactosidase activity, and expressed as the percent control. (mean±SD; three independent experiments). *, p < 0.05, **; p < 0.005; ***, p < 0.0005.
C. Proposed model of calcium activation of ERα. Model compares helices H3, H4, H5, H7, H10, H11, and H12 in inactive and active state bound to calcium.