Shchelkunova T A, Kassirova E G, Smirnov A N
Probl Endokrinol (Mosk). 1987 Nov-Dec;33(6):61-5.
The authors compared the properties of nonreceptor estrogen-binding protein (NREBP) of the ovaries of immature rats, specific estrogen-binding protein (SEBP) of the liver and alpha-fetoprotein (alpha-FP) of the rat blood serum. It was shown that all 3 proteins with moderate affinity bound 3H-estradiol (Ka approximately 10(8)M-1) and were characterized by a high rate of interaction with ligand (K+1 approximately 10(6)M-1c-1) and dissociation of hormone-protein complexes (K-1 approximately 10(-2)c-1). NREBP and alpha-FP manifested a very close hormonal specificity of affinity differing from SEBP specificity: both proteins bound intensively estrone and estradiol, to a lesser degree, estriol, and did not bind androgens and hexestrol. Stokes' radii of the molecules of 3 proteins were 4.4 and 2.5 nm, respectively. Rabbit antiserum to alpha-FP suppressed the hormone-binding activity of blood alpha-FP and ovarian NREBP but not liver SEBP. With growth of animals a study of the time course of the levels of ovarian NREBP and blood alpha-FP has shown that the presence of NREBP in the ovarian cytosol does not probably result from blood proteins mechanical contamination of the sample in homogenization. It has been assumed that intracellular alpha-FP or its close analog may be involved in the regulation of ovarian endocrine function, reversibly binding estrogens.
作者比较了未成熟大鼠卵巢的非受体雌激素结合蛋白（NREBP）、肝脏的特异性雌激素结合蛋白（SEBP）和大鼠血清甲胎蛋白（α-FP）的特性。结果表明，这三种蛋白均以中等亲和力结合³H-雌二醇（Ka约为10⁸M⁻¹），其特点是与配体的相互作用速率高（K₊₁约为10⁶M⁻¹c⁻¹）以及激素-蛋白复合物的解离速率高（K₋₁约为10⁻²c⁻¹）。NREBP和α-FP表现出非常相似的亲和力激素特异性，与SEBP的特异性不同：这两种蛋白都能强烈结合雌酮和雌二醇，对雌三醇的结合程度较低，且不结合雄激素和己烷雌酚。这三种蛋白分子的斯托克斯半径分别为4.4和2.5纳米。抗α-FP兔抗血清可抑制血液α-FP和卵巢NREBP的激素结合活性，但不能抑制肝脏SEBP的活性。随着动物的生长，对卵巢NREBP和血液α-FP水平的时间进程研究表明，卵巢胞质溶胶中NREBP的存在可能并非来自匀浆过程中样品受到血液蛋白的机械污染。据推测，细胞内α-FP或其紧密类似物可能参与卵巢内分泌功能的调节，可逆地结合雌激素。
