HCG STRUCTURE-FUNCTION RELATIONSHIPS

该项目的长期目标包括阐明 的构象和结构-功能关系 胎盘来源的糖蛋白激素，人绒毛膜促性腺激素（hCG）， 描绘各种细胞内信号传导途径，以及 对hCG的相对未探索的细胞应答的表征。 一 工作模型已被开发为CG及其垂体衍生 对应物，促黄体生成激素（LH），结合了 化学和酶修饰，免疫作图，和 物理化学研究 为了实验性地测试这个模型， 定点诱变和示踪标记研究已经被设计成 阐明了异二聚体形成的亚基接触位点和氨基 受体结合和激活的酸性序列决定簇。 许多 研究强调了cAMP在促性腺激素介导的 细胞内信号，我们也有初步的证据， 包括肌醇-1，4，5三磷酸和可能的其他肌醇-- 含有磷脂;这种交替信号的假设将是 在转化的Leydig细胞中进行实验测试。 该项目还将 描绘了一些细胞反应促性腺激素和突变 proteins. 这些包括一个戏剧性的CG/LH介导的形态变化， 转化Leydig细胞（MA-10），我们认为这是由于细胞骨架 重组;一个拟议的CG/LH调节的细胞与重组的相互作用， 细胞外基质，包括调节剂，如分泌蛋白 酸性和富含半胱氨酸）;以及CG/LH对癌基因的调节 c-fos、c-jun和c-myc。 这个综合项目旨在 阐明调节异源二聚体形成的氨基酸序列决定簇 和受体识别/激活，细胞内信号传导途径 可能与cAMP不同，hCG的相对未开发的方面 功能

The long-range goals of this project include elucidation of the conformational and structure-function relationships of the placental-derived glycoprotein hormone, human chorionic gonadotropin (hCG), delineation of the various intracellular signaling pathways, and characterization of relatively unexplored cellular responses to hCG. A working model has been developed for CG and its pituitary-derived counterpart, luteinizing hormone (LH), that combines the results of chemical and enzymatic modifications, immunological mapping, and physicochemical studies. In order to experimentally test this model, site-directed mutagenesis and trace labeling studies have been designed to elucidate the subunit contact sites for heterodimer formation and the amino acid sequence determinants for receptor binding and activation. Numerous studies have emphasized the role of cAMP in gonadotropin-mediated intracellular signaling, and we also have tentative evidence for the involvement of inositol-1,4,5 trisphosphate and possibly other inositol-- containing phospholipids; this hypothesis of alternate signaling will be experimentally tested in transformed Leydig cells. This project will also delineate some of the cellular responses to gonadotropin and mutant proteins. These include a dramatic CG/LH-mediated morphological change in transformed Leydig cells (MA-10), which we propose is due to cytoskeletal reorganization; a proposed CG/LH-regulated interaction of cells with the extracellular matrix, involving such modulators as SPARC (Secreted Protein that is Acidic and Rich in Cysteine); and CG/LH regulation of the oncogenes c-fos, c-jun, and c-myc. This. comprehensive project is designed to elucidate amino acid sequence determinants regulating heterodimer formation and receptor recognition/activation, intracellular signaling pathways possibly distinct from cAMP, and relatively unexplored aspects of hCG function.