Bouhoute A, Leclercq G
Laboratoire J.C. Heuson de Cancérologie Mammaire, Institut Jules Bordet, Brussels, Belgium.
Biochem Biophys Res Commun. 1996 Oct 23;227(3):651-7. doi: 10.1006/bbrc.1996.1564.
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.
我们之前证明了钙调蛋白（CaM）能够降低雌二醇（E2）与大鼠子宫雌激素受体（ER）的结合亲和力。我们现在表明，CaM会导致E2结合能力丧失，尤其是当ER分子对该激素表现出较低的结合亲和力时。通过蛋白质免疫印迹法和[125I]他莫昔芬氮丙啶共价标记，我们发现这种由CaM诱导的丧失与ER蛋白的消失无关。此外，我们能够证明CaM介导了仅表达其激素结合结构域（HBD，氨基酸282 - 595）的人重组ER的E2结合减少。因此，CaM可以在不涉及任何降解过程的情况下调节ER的HBD结构，这种构象变化不是由受体的其他结构域和/或天然ER异源复合物的成分介导的。
