ROLE OF PROTEIN PHOSPHATASES IN BLOOD PLATELET FUNCTION

血小板在伤口愈合和炎症过程中的作用已被证实。 已经很好地建立了。 在执行这些功能时，血小板经历 大量的生化和形态变化 分子 然而，控制血小板反应性的机制是 不太了解。 因此，为什么血小板不能正常发挥功能， 某些疾病状态仍然是一个悬而未决的问题。 认为是 刺激反应偶联中的重要反应， 许多人已经研究了血小板蛋白的磷酸化， 包括我们的实验室;但具体的参与 调节血小板反应的磷酸化反应仍然存在 不清楚 本申请的广泛的长期目标是 了解这些反应在血小板中的作用。 磷酸化 蛋白质的状态反映了蛋白激酶和 磷酸酶活性 因此，有几条道路可以追求， 解决这个问题。 本研究计划的目标是 描述血小板磷酸酶的基本性质及其作用。 建议的研究将集中在蛋白质丝氨酸/苏氨酸 磷酸酶，PP 1，主要集中注意力在：（一） 这种酶的理化性质，其中包括了解 其结构、亚细胞定位和底物特异性 利用外源磷蛋白。(ii)识别哪个 对血小板激动剂作出反应而发生的生化事件取决于 PP 1活性。 这些研究将利用冈田酸， PP 1的渗透性抑制剂，试图定义细胞内 PP 1需要正常进行的途径。 （三）尝试 将鉴定内源性血小板磷蛋白 PP 1的底物。 表征PPl敏感性磷酸化可以 帮助鉴定调节血小板反应性的蛋白质。

The role of platelets in wound healing and inflammation processes has been well established. In performing these functions, platelets undergo massive biochemical and morphological changes. The molecular mechanism(s), however, by which platelet reactivity is controlled is poorly understood. Thus, why platelets fail to function normally in certain disease states remains an open question. Recognized as being important reactions in stimulusresponse coupling, the role of phosphorylation of platelet proteins has been studied by many laboratories including ours; but the involvement of specific phosphorylation reactions in regulating platelet responses remains unclear. The broad long-term objective of this application is to understand the role of these reactions in platelets. The phosphorylation status of proteins reflects a balance between protein kinase and phosphatase activities. Thus, there are several paths one can pursue to address this problem. The objectives of this research program are to characterize basic properties of platelet phosphatases and their roles. The proposed studies will concentrate on the protein serine/threonine phosphatase, PP1, focussing attention primarily on: (i) The physiochemical properties of this enzyme, which includes an understanding of its structure, subcellular localization, and substrate specificity making use of exogenous phosphoproteins. (ii) Identifying which of the biochemical event that occur in response to a platelet agonist depends on PP1 activity. These studies will make use of okadaic acid, a membrane permeable inhibitor of PP1, in attempt to define the intracellular pathway that requires PP1 to proceed normally. Finally, (iii) attempts will be made to identify the platelet phosphoproteins that are endogenous substrates for PP1. Characterizing PPl-sensitive phosphorylations may help identify proteins that regulated platelet reactivity.