STRUCTURE-FUNCTION OF PLASMA SEX STEROID-BINDING PROTEIN

我们建议继续我们的长期研究，以了解 血浆性类固醇结合蛋白的生化和生理学， SBP。该项目分为两部分： 第一项将包括描述这种化学物质的生物化学研究。 类固醇结合部位的环境来解释类固醇如何结合到 蛋白质表面。我们将尝试确定氨基酸残基在 亲和标记的人和兔SBP的类固醇结合部位 并确定相邻的氨基酸序列。由于人的SBP与 E_2和T都有，而兔SBP只与T结合，比较应该会发现 负责结合专一性的结构元素。我们还将 对SBP晶体进行了x射线衍射分析，并阐明了 SBP的全长氨基酸序列，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在高血压发病机制中的作用。 类固醇激素在生殖生物学中的作用。我们会 测试一种新的假说，即SBP是性类固醇的特定载体 穿过膜。为此，我们将尝试鉴定SBP受体 ~(125)I-hSBP与MCF-7和HEC-50细胞孵育在质膜上的研究 在培养和体内注射125I-RSBP后， 放射自显影检查生殖组织中的电子 显微镜。我们还将在恒河猴中诱导长期的SBP停药 猴SBP抗体F(Ab)2片段输注及效果研究 在月经周期和怀孕(分娩)方面。

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).