Maaroufi Y, Leclercq G
Laboratoire J. C. Heuson de Cancérologie Mammaire, Institut Jules Bordet, Brussels, Belgium.
J Steroid Biochem Mol Biol. 1994 Jan;48(1):155-63. doi: 10.1016/0960-0760(94)90262-3.
Regulatory properties of estrogen receptor (ER) result from the existence of functional domains within its primary structure. Thus, A/B and C domains which are rich in tyrosyl residues control gene expression while the E domain confers estrogen binding capacity. Hydroxylapatite (HAP) is known to adsorb ER. Scatchard plot analysis of [3H]estradiol binding patterns of HAP batches to which cytosolic ER had been adsorbed revealed that AB and/or C domains are mainly responsible for this property. Thus, treatment of these batches with the tyrosine reagent tetranitromethane (TNM) led to a dramatic release of adsorbed receptors. This did not occur with ER preparations devoid of exposed ABC domains obtained by selective immunoextraction with H-226 anti-ER monoclonal antibody prior to HAP assay. KC1 treatment (500 mM) of HAP batches also led to a release of bound receptors especially those devoid of exposed ABC domains. Such binding characteristics were also found with full length and truncated ERs produced in yeast: the full length receptor strongly interacted with HAP while the truncated receptor devoid of AB and C domains displayed only a weak adsorption. Additional investigation revealed that estradiol binding to cytosolic ER does not modify its reactivity towards TNM.
雌激素受体（ER）的调节特性源于其一级结构中功能域的存在。因此，富含酪氨酰残基的A/B和C结构域控制基因表达，而E结构域赋予雌激素结合能力。已知羟基磷灰石（HAP）可吸附ER。对吸附了胞质ER的HAP批次的[3H]雌二醇结合模式进行Scatchard作图分析表明，AB和/或C结构域主要负责这一特性。因此，用酪氨酸试剂四硝基甲烷（TNM）处理这些批次会导致吸附的受体大量释放。在用H-226抗ER单克隆抗体进行选择性免疫提取后获得的缺乏暴露ABC结构域的ER制剂中，在进行HAP分析之前，这种情况不会发生。对HAP批次进行KCl处理（500 mM）也会导致结合的受体释放，尤其是那些缺乏暴露ABC结构域的受体。在酵母中产生的全长和截短型ER中也发现了这种结合特性：全长受体与HAP强烈相互作用，而缺乏AB和C结构域的截短型受体仅表现出微弱的吸附。进一步的研究表明，雌二醇与胞质ER的结合不会改变其对TNM的反应性。
