title: Calmodulin decreases the estrogen binding capacity of the estrogen receptor.
abstract: We previously demonstrated the ability of calmodulin (CaM) to decrease the binding affinity of estradiol (E2) to the rat uterine estrogen receptor (ER). We show now that CaM induces a loss of E2 binding capacity especially when ER molecules exhibit a lower binding affinity for the hormone. By Western blotting and [125I]tamoxifen aziridine covalent labeling we found that this CaM-induced loss is not associated with a disappearance of the ER protein. In addition, we were able to demonstrate a CaM-mediated decrease in E2 binding of a human recombinant ER expressing solely its hormone binding domain (HBD, aa 282-595). Hence, CaM can modulate the structure of the HBD of the ER without any involvement of a degradative process, this conformational change is not mediated by other domains of the receptor and/or components of the native ER heterocomplex.
authors.affiliation: Laboratoire J.C. Heuson de Cancérologie Mammaire, Institut Jules Bordet, Brussels, Belgium.
authors.forename: A
authors.initials: A
authors.lastname: Bouhoute
authors.forename: G
authors.initials: G
authors.lastname: Leclercq
mesh_terms: D000818:Animals; D001665:Binding Sites; D002147:Calmodulin / Q000502:physiology*; D004958:Estradiol / Q000378:metabolism*; D006801:Humans; D011485:Protein Binding; D011487:Protein Conformation; D051381:Rats; D017208:Rats, Wistar; D011960:Receptors, Estrogen / Q000737:chemistry / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism
chemical_list: D002147:Calmodulin; D011960:Receptors, Estrogen; D011994:Recombinant Proteins; D004958:Estradiol