STRUCTURE-FUNCTION OF PLASMA SEX STEROID-BINDING PROTEIN

我们建议继续进行长期研究， 血浆性类固醇结合蛋白的生物化学和生理学， 收缩压 该项目分为两个部分： 第一部分将包括描述化学物质的生物化学研究 类固醇结合位点的环境来解释类固醇如何与 蛋白质表面 我们将尝试确定氨基酸残基中的 通过亲和标记的人和兔SBP的类固醇结合位点， 并确定相邻的氨基酸序列。 由于人SBP结合 E2和T两者，而兔SBP仅结合T，比较应揭示 负责结合特异性的结构元件。 我们还将 对SBP晶体进行X射线衍射分析，并阐明 SBP的整个氨基酸序列，试图描述 类固醇结合蛋白的三维结构。 第二个目标是了解SBP在以下机制中的作用： 类固醇激素在生殖生物学中的作用。 我们将 测试一个新的假设，即SBP是性类固醇的特异性载体 穿过细胞膜 为此，我们将尝试鉴定SBP受体 通过将125 I-hSBP与MCF-7和HEC-50细胞孵育， 125 I-rSBP注入家兔体内， 电子生殖组织放射自显影检查 显微镜 我们还将在恒河猴中诱导长期SBP停药 猴体内注射抗SBP抗体F（ab）2片段，观察其对 月经周期和怀孕（分娩）。

We are proposing to continue our long term studies towards understanding the biochemistry and physiology of the plasma sex steroid-binding protein, SBP. The project is divided into two parts: The first will comprise biochemical studies describing the chemical environment of steroid-binding sites to explain how steroids are bound to protein surfaces. We will attempt to identify amino acid residues in the steroid binding sites of both human and rabbit SBP by affinity labeling, and to determine the adjacent amino acid sequence. Since human SBP binds both E2 and T whereas rabbit SBP only binds T, a comparison should reveal the structural elements responsible for binding specificity. We will also undertake an x-ray diffraction analysis on SBP crystals and elucidate the entire amino acid sequence of SBP in an attempt to describe the three-dimensional structure of a steroid-binding protein. The second objective is to understand the role of SBP in the mechanism of action of steroid hormones in relation to reproductive biology. We will test a new hypothesis implicating SBP as a specific carrier of sex steroids across membranes. To this end, we will attempt to identify a SBP receptor on the plasma membrane by incubating 125I-hSBP with MCF-7 and HEC-50 cells in culture, and by in vivo infusion of 125I-rSBP into rabbits followed by autoradiographic examination of reproductive tissues in the electron microscope. We will also induce a long-term SBP withdrawal in the rhesus monkey by infusing F(ab)2 fragments of SBP antibodies and study the effects on the menstrual cycle and pregnancy (parturition).