Chain A: The Brzozowski model is Cartoons, colored Structure. Helices are numbered at their N-termini. Helix 12 is labelled "H12A"; EST is Spacefill, colored CPK.
Chain B: The Tanenbaum model is Backbone, colored blue. Helix 12 (magenta) is labelled "H12B" at its N-terminus.
(Residue numbering: Chain A is 300 less, and Chain B is 296 less than the standard ERa numbering.)
The numbered "Highlight" buttons above display details of the EST-binding region on the ER LBD. The following paragraphs briefly describe the displays.
1 a. ERa-EST complex. The principal interacting side chains on chain A are shown, colored CPK; chain colors as above. (Slab on)
H-bond distances are in Å.
1 b. Chains A and B: All of the EST-interacting residues are shown. Chain A residues are Sticks, colored CPK, and labeled; Chain B side chains are Sticks, colored blue. See Brzozowski (1997) Fig. 2a.
The following can be displayed separately:
Chain A, only; Sticks, colored CPK (Brzozowski).
Chain B, only; Sticks, colored CPK (Tanenbaum).
EST-interacting residues, only. Interacting residues are shown as Sticks, colored CPK. See Brzozowski (1997) Fig. 2c.
Note: the buttons in this group leave the "interacting residues" selected. Thus, any choice of display or color from the Chime menu can be used for additional highlighting.
The EST-binding sites of the two models are nearly identical. Helix 12 in the Tanenbaum model makes partial contacts with the same site, but on an adjacent subunit in the tetramer structure. Except for the striking difference in the orientation of helix 12, the main chain atoms of the two models superimpose with a rmsd = 0.5 Å.
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The estrogen receptor structures are described in Brzozowski, A. M., Pike, A. C., Dauter, Z., Hubbard, R. E., Bonn, T., Engstrom, O., Ohman, L., Greene, G. L., Gustafsson, J. A., Carlquist, M. (1997) "Molecular basis of agonism and antagonism in the oestrogen receptor". Nature 389:753. PubMed. [1ere.pdb; 3.1 Å; R = 0.22]
Tanenbaum, D. M., Wang, Y., Williams, S. P., Sigler, P. B. (1998) "Crystallographic comparison of the estrogen and progesterone receptor's ligand binding domains". Proc Natl Acad Sci U S A 95:5998. PubMed. [1a52.pdb; 2.8 Å; R = 0.22]
Structure alignments were done at the Combinatorial Extension Server.
Additional ER structures:
A. Estrogen Receptora ERa complexes with bound:
Estradiol (EST), an agonist.
Raloxifene (RAL), an antagonist.
Diethylstilbestrol (DES), an agonist & the NR Box II peptide.
Tamoxifen (OHT), an antagonist.
(Estradiol (EST), in an unusual tetrameric structure.)
B. Estrogen Receptorb ERb complexes with bound:
Genistein (GEN), a partial agonist.
Raloxifene (RAL), an antagonist.
C. Structural Alignments Pairwise superimposed comparisons:
ERa (EST) and ERb (GEN), ERa vs. ERb in agonist complexes.
ERa (RAL) and ERb (RAL), ERa vs. ERb in antagonist complexes.
ERa: DES and OHT, ERa: agonist vs. antagonist complex.
ERa: EST, Wild type ER vs. a triple mutant (Helix 12 in the antagonist conformation).
ERa: EST, The Brzozowski, et al. (1997) vs. Tanenbaum, et al. (1998) models.
"Helix 12 Gallery": ERa-EST vs. All five ER-antagonist (SERM) models.
D. DNA-Binding Domain:
ER-DBD Complex Base pair & backbone contacts.
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