RGD Reference Report - Characterization of bacterially expressed rat estrogen receptor beta ligand binding domain by mass spectrometry: structural comparison with estrogen receptor alpha. - Rat Genome Database

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Characterization of bacterially expressed rat estrogen receptor beta ligand binding domain by mass spectrometry: structural comparison with estrogen receptor alpha.

Authors: Witkowska, HE  Carlquist, M  Engstrom, O  Carlsson, B  Bonn, T  Gustafsson, JA  Shackleton, CH 
Citation: Witkowska HE, etal., Steroids. 1997 Aug-Sep;62(8-9):621-31.
RGD ID: 8694325
Pubmed: PMID:9292936   (View Abstract at PubMed)

Functional rat estrogen receptor beta ligand binding domain (rER beta LBD, aa 210-485) and human estrogen receptor alpha ligand binding domain (hER alpha LBD, aa 301-553) were expressed in Escherichia coli. Hormone binding assays revealed that both ER beta and ER alpha LBDs bound the natural ligand estradiol (E2) with similar affinity (Kd approximately 100 pM). Competitive binding experiments were carried out with ICI 164384, 4-hydroxytamoxifen, 16 alpha-bromo-estradiol, and genistein employing [3H]E2 as a tracer. No significant differences in responses of ER alpha and ER beta LBDs to ICI 164384 and 4-hydroxytamoxifen were observed, 16 alpha-Bromo-estradiol and genistein discriminated between the ER subtypes and acted as ER alpha and ER beta selective ligands, respectively. Final purification of recombinant proteins was achieved on an E2 affinity column, where they were subjected to in situ carboxymethylation. The partially carboxymethylated proteins actively bound E2. The carboxymethylated rER beta LBD had a molecular mass of 32251.6 Da, equivalent to the calculated mass with the addition of three carboxymethyl groups. No other proteins (of lower or higher molecular mass) were detected, so the LBD was considered structurally authentic and pure. By using a combination of intact protein mass spectrometric fragmentation and trypsin proteolysis (98% sequence coverage), it was established that rER beta cysteine-289 and -354 were not carboxymethylated on the affinity column, suggesting that they were shielded from alkylation in the E2-bound conformational state. Concurrent analysis of hER alpha LBD showed that under the same experimental conditions, the two equivalent ER alpha cysteines were not alkylated (alpha C381 and alpha C447). These data support close structural relationship between the E2-bound ER alpha LBD and ER beta LBD proteins.



Gene-Chemical Interaction Annotations    Click to see Annotation Detail View

  
Object SymbolSpeciesTermQualifierEvidenceWithNotesSourceOriginal Reference(s)
ESR2Humanafimoxifene affects bindingISOEsr2 (Rattus norvegicus)4-hydroxytamoxifen binds to Esr2 proteinRGD 
Esr2Ratafimoxifene affects bindingEXP 4-hydroxytamoxifen binds to Esr2 proteinRGD 
Esr2Mouseafimoxifene affects bindingISOEsr2 (Rattus norvegicus)4-hydroxytamoxifen binds to Esr2 proteinRGD 
ESR2Humanestradiol affects bindingISOEsr2 (Rattus norvegicus)Estradiol binds to Esr2 proteinRGD 
Esr2Ratestradiol affects bindingEXP Estradiol binds to Esr2 proteinRGD 
Esr2Mouseestradiol affects bindingISOEsr2 (Rattus norvegicus)Estradiol binds to Esr2 proteinRGD 
ESR2Humangenistein affects bindingISOEsr2 (Rattus norvegicus)Genistein binds to Esr2 proteinRGD 
Esr2Ratgenistein affects bindingEXP Genistein binds to Esr2 proteinRGD 
Esr2Mousegenistein affects bindingISOEsr2 (Rattus norvegicus)Genistein binds to Esr2 proteinRGD 

Gene Ontology Annotations    Click to see Annotation Detail View

Molecular Function

  
Object SymbolSpeciesTermQualifierEvidenceWithNotesSourceOriginal Reference(s)
Esr2Ratestradiol binding  IPIestradiol RGD 
Esr2Ratheterocyclic compound binding  IPIgenistein RGD 

Objects Annotated

Genes (Rattus norvegicus)
Esr2  (estrogen receptor 2)

Genes (Mus musculus)
Esr2  (estrogen receptor 2 (beta))

Genes (Homo sapiens)
ESR2  (estrogen receptor 2)


Additional Information