Gaubert C M, Carriero R, Shyamala G
Endocrinology. 1986 Apr;118(4):1504-12. doi: 10.1210/endo-118-4-1504.
The cytoplasmic estrogen receptors (ER) from mammary glands of estrogen-responsive nulliparous and estrogen-resistant lactating mice have been studied to delineate various relationships between the molecular properties of ER and estrogenic sensitivity. These studies indicate that there are essentially no differences in the hydrodynamic parameters of native ER isolated in hypotonic buffer; the ER from both tissues have a stokes radius of 80-85 A, sedimentation coefficient of 9-10S, and mol wt of 300,000-340,000. However, while 60-80% of the total ER in mammary glands of nulliparous mice, upon exposure to 400 mM KC1 is able to bind to DNA, under identical experimental conditions only approximately 20% of total ER from lactating mammary glands binds to DNA. Analyses of ER in buffers containing 400 mM KC1 reveal that the ER in lactating mammary glands have a larger mol wt (100,000-130,000) as compared to ER in mammary glands of nulliparous mice (70,000). The ER in lactating mammary glands also appear to be more acidic when analyzed by diethylaminoethyl cellulose chromatography. Experiments performed with mixed cytosol reveal that lactating mammary cytosol contains factors which can impede the ability of ER to bind to DNA subsequent to exposure to KC1. The possible significance of the observed differences in the properties of ER from estrogen-responsive and unresponsive mammary glands has been discussed.
为了阐明雌激素受体（ER）的分子特性与雌激素敏感性之间的各种关系，对雌激素反应性未生育小鼠和雌激素抵抗性泌乳小鼠乳腺中的细胞质雌激素受体进行了研究。这些研究表明，在低渗缓冲液中分离的天然ER的流体动力学参数基本没有差异；两种组织的ER的斯托克斯半径为80 - 85 Å，沉降系数为9 - 10S，分子量为300,000 - 340,000。然而，未生育小鼠乳腺中60 - 80%的总ER在暴露于400 mM KCl时能够与DNA结合，而在相同实验条件下，泌乳乳腺中的总ER只有约20%与DNA结合。对含有400 mM KCl的缓冲液中的ER进行分析发现，与未生育小鼠乳腺中的ER（70,000）相比，泌乳乳腺中的ER分子量更大（100,000 - 130,000）。通过二乙氨基乙基纤维素色谱分析，泌乳乳腺中的ER似乎也更具酸性。用混合细胞溶胶进行的实验表明，泌乳乳腺细胞溶胶中含有一些因子，这些因子在暴露于KCl后会阻碍ER与DNA结合的能力。已经讨论了在雌激素反应性和无反应性乳腺中观察到的ER特性差异的可能意义。
