Structure and Function of Platelet Glycoprotein lb-IX-V Complex

血小板糖蛋白 lb-IX-V 复合物的结构和功能

• 批准号: 7017839
• 负责人: Renhao Li
• 金额: $ 32.04万
• 依托单位: UNIVERSITY OF TEXAS HLTH SCI CTR HOUSTON
• 依托单位国家: 美国
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-02-01 至 2009-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7017839
• 关键词: CHO cells; binding sites; biological signal transduction; cell membrane; clinical research; disulfide bond; extracellular; glycoproteins; human subject; mass spectrometry; molecular assembly /self assembly; platelet aggregation; protein isoforms; protein protein interaction; protein structure; protein structure function; proteomics; recombinant proteins; stoichiometry

DESCRIPTION (provided by applicant): Platelet glycoprotein (GP) Ib-IX-V complex mediates initial platelet adhesion to the injured vessel wall and transduces signals to induce platelet activation and aggregation. Malfunction of this multi-subunit receptor complex leads to severe bleeding and can contribute to many cardiovascular diseases. Despite decades of intensive study, regulation of the complex function is not clear, nor is the process by which the platelet activating signal is mediated by the complex. We hypothesize that inter-subunit interactions are important to the functions and regulation of the complex. Since the 3-dimensional organization of the complex is unknown and inter-subunit interactions are largely unexplored, as a necessary prelude to test our hypothesis this project seeks to identify and characterize the inter-subunit interactions in the GP Ib-IX-V complex. In Specific Aim 1, we propose to test the hypothesis that the transmembrane domains play vital roles in inter-subunit associations and thus are important for expression and assembly of the GP Ib-IX-V complex. The studies are based on our observation that replacing the transmembrane domain of GP Ibalpha or lbbeta subunit with an unrelated sequence decreases significantly the complex expression level. Structural and functional roles of specific residues in the transmembrane domains, including polar residues and membrane-proximal disulfide forming cysteine residues, will be defined. The molecular basis for the subunit stoichiometry in the GP Ib-IXV complex will also be elucidated. In Specific Aim 2, we will define the interfacial regions and residues among the extracellular domains of the complex and explore their contribution to complex assembly and function. The studies are based on our observations that first, the extracellular domains of GP Ibbeta and IX subunits associate and stabilize each other, and second, glycocalicin, the soluble extracellular domain of GP Ibalpha, binds directly to the recombinant extracellular domain of GP IX. Overall, careful dissection of individual interactions in the isolated proteins, in the transfected mammalian cells and in the platelets will enable us to develop tools and reagents that specifically perturb the inter-subunit interaction of interest and will pave the way for studies of the likely structural changes in the GP Ib-IX-V complex in response to ligand binding or intracellular regulatory signals. This project will also provide a stepping stone for studies on the interaction of the GP Ib-IX-V complex with other receptors and may lead to novel therapeutic strategies to combat various complex-related hematological disorders and diseases. Relevance to public health: The glycoprotein Ib-IX-V complex in the platelet helps the blood to clot properly. Malfunction of this complex leads to severe bleeding and can contribute to many cardiovascular diseases. This project seeks to understand the structure of the Ib-IX-V complex and to learn how it functions

描述（由申请人提供）：血小板糖蛋白（GP）IB-IX-V复合物介导了最初的血小板粘附到受伤的血管壁上，并传递信号以诱导血小板激活和聚集。这种多工资受体复合物的故障导致严重的出血，并可能导致许多心血管疾病。尽管进行了数十年的深入研究，但复杂功能的调节尚不清楚，血小板激活信号的过程也不是由复合物介导的。我们假设亚基间相互作用对于复合物的功能和调节很重要。由于该复合物的三维组织是未知的，并且基本上没有探索生成间的相互作用，这是检验我们的假设的必要前奏，该项目旨在识别和表征GP IB-IX-V复合物中的亚基间相互作用。在特定的目标1中，我们建议检验以下假设：跨膜结构域在亚基间关联中起着至关重要的作用，因此对于GP IB-IX-V复合物的表达和组装很重要。这些研究基于我们的观察结果，即以无关序列取代GP Ibalpha或LBBETA亚基的跨膜结构域可显着降低复数表达水平。将定义特定残基在跨膜结构域中的结构和功能作用，包括极性残基和膜二硫化物形成半胱氨酸残基。 GP IB-IXV复合物中亚基化学计量的分子基础也将得到阐明。在特定的目标2中，我们将定义配合物的细胞外域之间的界面区域和残基，并探索它们对复杂组装和功能的贡献。这些研究基于我们的观察结果，即GP IBBETA和IX亚基的细胞外结构域相关并稳定稳定，其次，GP iBalpha的可溶细胞外域糖蛋白直接与GP IX的重组外胞外结构域结合。总体而言，在分离的蛋白质，转染的哺乳动物细胞和血小板中仔细解剖各个相互作用将使我们能够开发工具和试剂，这些工具和试剂专门扰乱了利益的增益间相互作用，并将为GP IB-IX-V复合物中可能结构性变化的研究铺平道路，以响应ligandix-ix-ix-ix-v络合物的结合或静脉内构成的调节。该项目还将为研究GP IB-IX-V复合物与其他受体的相互作用的研究提供垫脚石，并可能导致新型的治疗策略来对抗各种复杂的复杂血液学疾病和疾病。与公共卫生有关：血小板中的糖蛋白IB-IX-V复合物有助于血液正确地凝结。这种复合物的故障导致严重的出血，并可能导致许多心血管疾病。该项目旨在了解IB-IX-V复合物的结构，并了解其运作方式