Abney T O, Melner M H
Steroids. 1979 Oct;34(4):413-27. doi: 10.1016/0039-128x(79)90103-x.
The properties and physical characteristics of a steroid binding component present in the immature (7 to 35 day) rat were investigated and found to be different from those of the 17 beta-estradiol receptor in the mature rat testis. These properties include a binding capacity of 483 fmol estradiol/mg protein, a Ka at equilibrium of 4.23 x 10(7)M-1, and broad steroid specificity as shown by interaction with several steroids; no binding was observed with diethylstilbestrol. The component, found in blood and several tissues including the testis, migrated as a 4.6S peak on sucrose gradients. This 4.6S component, which interacted with an anti-alphafetoprotein antiserum, decreased with age and was not detectable in the testis after day 21 or in the serum after day 25. These data suggest that this component is alphafetoprotein. Ontogenic appearance of the testicular cytoplasmic 17 beta-estradiol receptor in the developing rat was further elucidated. Sucrose gradient sedimentation analysis of cytosols revealed an 8S binding component that was first detectable at 23 days. Specific binding (fmol [3H]-estradiol/testis) was relatively low in neonates, rose to 59 fmol during the third week, and increased dramatically to 333 fmol at 7 weeks; binding rose only gradually after maturity. The receptor was tissue specific and steroid specificity studies demonstrated that only diethylstilbestrol and other estrogens were effective in competing with 17 beta-estradiol for binding sites. The Ka at equilibrium was determined as 3 x 10(10)M-1 and the binding sites were saturable in an in vitro system. The receptor did not interact with anti-alphafetoprotein antiserum as indicated by sucrose gradient studies. These data demonstrate the developmental appearance of the testicular cytoplasmic estradiol receptor in the immature rat.
对未成熟（7至35日龄）大鼠体内存在的一种类固醇结合成分的特性和物理特征进行了研究，发现其与成熟大鼠睾丸中的17β-雌二醇受体不同。这些特性包括结合能力为483 fmol雌二醇/毫克蛋白质，平衡时的Ka为4.23×10⁷M⁻¹，以及与多种类固醇相互作用所显示的广泛类固醇特异性；与己烯雌酚未观察到结合。该成分存在于血液和包括睾丸在内的多种组织中，在蔗糖梯度上以4.6S峰迁移。这种与抗甲胎蛋白抗血清相互作用的4.6S成分随年龄增长而减少，在21日龄后睾丸中无法检测到，在25日龄后血清中也无法检测到。这些数据表明该成分是甲胎蛋白。进一步阐明了发育中大鼠睾丸细胞质17β-雌二醇受体的个体发生情况。对细胞溶质进行蔗糖梯度沉降分析发现，一种8S结合成分在23日龄时首次可检测到。特异性结合（fmol [³H]-雌二醇/睾丸）在新生儿中相对较低，在第三周升至59 fmol，并在7周时急剧增加至333 fmol；成熟后结合仅逐渐上升。该受体具有组织特异性，类固醇特异性研究表明，只有己烯雌酚和其他雌激素能有效与17β-雌二醇竞争结合位点。平衡时的Ka测定为3×10¹⁰M⁻¹，且在体外系统中结合位点是可饱和的。蔗糖梯度研究表明，该受体不与抗甲胎蛋白抗血清相互作用。这些数据证明了未成熟大鼠睾丸细胞质雌二醇受体的发育情况。
