MECHANISM OF ACTIVATION OF PLATELET GPIIB AND GPIIIA

血小板GPIB和GPIIIA的激活机制

• 批准号: 2910658
• 负责人: Jeffrey W Smith
• 金额: $ 39万
• 依托单位: SANFORD BURNHAM PREBYS MEDICAL DISCOVERY INSTITUTE
• 依托单位国家: 美国
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-05-01 至 2002-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2910658
• 关键词: SDS polyacrylamide gel electrophoresis; affinity chromatography; calpain; chemical association; chemical kinetics; conformation; cytoplasm; divalent cations; enzyme linked immunosorbent assay; epidermal growth factor; epitope mapping; fibrinogen receptors; high performance liquid chromatography; integrins; ligands; mass spectrometry; molecular site; peptide library; platelet activation; protein binding; protein purification; protein sequence; protein structure function; proteolysis; western blottings

The long term objective of this study is to understand the mechanism of activation of the platelet integrin GPIIb-IIIa. GPIIb-IIIa is key to platelet adhesion and aggregation. An understanding of its regulation is likely to be important for treating many cardiovascular diseases including myocardial infarction and stroke. GPIIb-IIIa exists on resting platelets in a dormant conformation unable to bind soluble fibrinogen. Upon platelet stimulation, IIb-IIIa becomes capable of binding fibrinogen and mediating platelet aggregation. Although activation of IIb-IIIa is key to platelet function, the mechanism its activation has not been solved. One hypothesis of the study is that proteolytic cleavage of the cytoplasmic domains of IIb-IIIa control the activation state of the integrin. This hypothesis will be tested by characterizing the structural differences in the cytoplasmic domain of two purified forms of IIb-IIIa which differ in activation state. A second goals of the study is to understand the structural basis of activation-dependent ligand binding to IIb-IIIa. Phage-display will be used to select ligands that bind preferentially to the dormant and active forms of the integrin. Results from this study are likely to provide a structure-activity series explaining activation-dependent ligand binding. A third aim of the study is to understand the kinetic aspects of integrin activation. Does activation result from an increase in ligand association rate or a decrease in ligand dissociation rate? These studies will be performed on whole platelets and with purified forms of dormant and active IIb-IIIa. A final goal is to understand how the divalent ion binding sites on IIb- IIIa influence the activation event. Binding studies will be performed between Ca2+ and purified conformers of dormant and active IIb-IIIa. Results from this analysis should determine which class of ion binding sites regulate activation of the integrin.

这项研究的长期目标是了解的机制