STRUCTURE-FUNCTION STUDIES OF GONADOTROPINS

人胎盘激素绒毛膜促性腺激素 与脑下垂体激素促黄体生成素、卵泡素 (FSH)和促甲状腺激素(TSH)构成一个糖蛋白家族 含有2个不同结构的二聚体的激素 亚基，阿尔法和贝塔。在一个动物物种中，阿尔法 亚基有相同的氨基酸序列；荷尔蒙是 以其独特的β亚基而闻名，这些亚基决定了 每种激素的生物特异性。每种激素都含有 不同的天冬酰胺连接的低聚糖。 利用DNA介导的转基因技术，我们将 研究不同的Beta亚基如何影响组装和 这些多亚单位复合体的加工。结合使用 我们将进行定点突变和基因融合实验 检查以下内容：(1)含氮碳水化合物的影响 关于组装、分泌和二硫键的形成。是吗？ 解释了细胞内行为的一些差异 我们已经看到的黄体生成素和绒毛膜促性腺激素β亚基的作用？(2) CGbeta亚基中的羧基末端序列。对于那些 含有两个天冬酰胺连接的糖单元的亚基，我们将 检查每个角色是否具有不同的功能角色 天冬酰胺碳水化合物组，以及(3)干扰效应 二硫键对黄体生成素和人绒毛膜促性腺激素代谢和分泌的影响 二聚体/亚单位。定点突变提供了最大的 构造结构功能图的直接方法 将翻译后修饰的依赖关系联系起来， 二硫键模式的生物活性、组装和分泌。

The human placental hormone chorionic gonadotropin (hCG) together with the pituitary hormones lutropin (LH), follitropin (FSH), and thyrotropin (TSH) constitute a family of glycoprotein hormones of dimeric structure containing 2 nonidentical subunits, alpha and beta. Within an animal species the alpha subunits have an identical amino acid sequence; the hormones are distinguished by their unique beta subunits, which determine the biologic specificity of each hormone. Each hormone contains different asparaginelinked oligosaccharides. Using the techniques of DNA mediated transfection we will examine how different beta subunits influence assembly and processing of these multisubunit complexes. In combination with site directed mutagenesis and gene fusion experiments we will examine the following: (1) the influence of Nlinked carbohydrate on assembly, secretion, and disulfide bond formation. Does it account for some of the differences in the intracellular behavior of LH and CG-beta subunits that we have seen? (2) the role of the carboxyterminal sequence in the CGbeta subunit. For those subunits bearing two asparaginelinked sugar units, we will examine if there are different functional roles for each asparagine carbohydrate group, and (3) the effects of disrupting disulfide bonds on the metabolism and secretion of LH and hCG dimers/subunits. Site directed mutagenesis provides the most direct approach toward constructing a structurefunction map relating the dependence of posttranslational modifications, bioactivity, assembly and secretion on disulfide bond patterns.