Estrogen Receptor Alpha Ligand Binding Domain C381S, C417S, C530S in Complex with 4-hydroxytamoxifen

Experimental Data Snapshot

  • Resolution: 1.80 Å
  • R-Value Free: 0.242 
  • R-Value Work: 0.197 
  • R-Value Observed: 0.199 

wwPDB Validation   3D Report Full Report

Ligand Structure Quality Assessment 

This is version 1.3 of the entry. See complete history


Endoxifen, 4-Hydroxytamoxifen and an Estrogenic Derivative Modulate Estrogen Receptor Complex Mediated Apoptosis in Breast Cancer.

Maximov, P.Y.Abderrahman, B.Fanning, S.W.Sengupta, S.Fan, P.Curpan, R.F.Rincon, D.M.Q.Greenland, J.A.Rajan, S.S.Greene, G.L.Jordan, V.C.

(2018) Mol Pharmacol 94: 812-822

  • DOI: https://doi.org/10.1124/mol.117.111385
  • Primary Citation of Related Structures:  
    5T1Z, 5W9C, 5W9D, 6CBZ

  • PubMed Abstract: 

    Estrogen therapy was used to treat advanced breast cancer in postmenopausal women for decades until the introduction of tamoxifen. Resistance to long-term estrogen deprivation (LTED) with tamoxifen and aromatase inhibitors used as a treatment of breast cancer inevitably occurs, but unexpectedly low-dose estrogen can cause regression of breast cancer and increase disease-free survival in some patients. This therapeutic effect is attributed to estrogen-induced apoptosis in LTED breast cancer. Here, we describe modulation of the estrogen receptor (ER) liganded with antiestrogens (endoxifen and 4-hydroxytamoxifen) and an estrogenic triphenylethylene (TPE), ethoxytriphenylethylene (EtOXTPE), on estrogen-induced apoptosis in LTED breast cancer cells. Our results show that the angular TPE estrogen (EtOXTPE) is able to induce the ER-mediated apoptosis only at a later time compared with planar estradiol in these cells. Using real-time polymerase chain reaction, chromatin immunoprecipitation, western blotting, molecular modeling, and X-ray crystallography techniques, we report novel conformations of the ER complex with an angular estrogen EtOXTPE and endoxifen. We propose that alteration of the conformation of the ER complexes, with changes in coactivator binding, governs estrogen-induced apoptosis through the protein kinase regulated by RNA-like endoplasmic reticulum kinase sensor system to trigger an unfolded protein response.

  • Organizational Affiliation

    Department of Breast Medical Oncology, University of Texas MD Anderson Cancer Center, Houston, Texas (P.Y.M., B.A., P.F., D.M.Q.R., J.A.G., V.C.J.); The Ben May Department for Cancer Research, University of Chicago, Chicago, Illinois (S.W.F., S.S.R., G.L.G.); Department of Oncology, Lombardi Comprehensive Cancer Center, Washington, DC (S.S.); and Institute of Chemistry, Romanian Academy, Timisoara, Romania (R.F.C.).

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Estrogen receptor
A, B, C, D
249Homo sapiensMutation(s): 3 
UniProt & NIH Common Fund Data Resources
Find proteins for P03372 (Homo sapiens)
Explore P03372 
Go to UniProtKB:  P03372
PHAROS:  P03372
GTEx:  ENSG00000091831 
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP03372
Sequence Annotations
  • Reference Sequence
Small Molecules
Binding Affinity Annotations 
IDSourceBinding Affinity
OHT BindingDB:  5W9C Ki: min: 0.04, max: 5.7 (nM) from 5 assay(s)
IC50: min: 0.31, max: 40 (nM) from 11 assay(s)
EC50: min: 6, max: 16 (nM) from 3 assay(s)
Experimental Data & Validation

Experimental Data

  • Resolution: 1.80 Å
  • R-Value Free: 0.242 
  • R-Value Work: 0.197 
  • R-Value Observed: 0.199 
  • Space Group: P 32
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 58.308α = 90
b = 58.308β = 90
c = 276.947γ = 120
Software Package:
Software NamePurpose
HKL-3000data reduction
HKL-3000data scaling

Structure Validation

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Ligand Structure Quality Assessment 

Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2018-06-13
    Type: Initial release
  • Version 1.1: 2018-06-20
    Changes: Data collection, Database references
  • Version 1.2: 2018-07-04
    Changes: Data collection, Database references
  • Version 1.3: 2023-10-04
    Changes: Data collection, Database references, Refinement description