REGULATION OF NEUTROPHIL RECEPTOR/G PROTEIN INTERACTIONS

描述：化学诱导剂和生长因子之间的通讯 受体和下游Rho家族小GTP酶启动细胞事件 对白细胞和成纤维细胞的运动反应很重要。Dr。 Bokoch和他的同事们将研究一种这样的受体调节 途径，RAC/Cdc42介导的靶蛋白Pak的激活 (p21-激活的激酶)。拟议的研究针对的是生物 受体调节肌动蛋白细胞骨架的途径，并将 确定控制PAK活性的新机制。 在他们的第一个特定目标中，Pak通过的分子相互作用 调节肌动蛋白细胞骨架将在结构上和 在一个定义明确的成纤维细胞模型系统中进行机械处理。Pak中的域名 对细胞骨架调节的重要作用将使用组合来确定 分子和细胞方法。与之相互作用的靶蛋白 这些领域将被隔离和表征。 他们将把Pak对细胞骨架调节的研究扩展到 第二个目标，将评估一种新的Pak的GTPase非依赖性机制 监管。膜靶向激活PAK的分子基础 将会被调查。调查人员将审查这一事件的重要性 膜结合活化蛋白在轴突细胞骨架调节中的作用 以PC12电池为模型系统进行开发。美国政府的角色 还将探讨这一过程中与PAK结合的NCK适配子蛋白。 受体似乎通过与直接不同的机制控制PAK的活性 通过RAC或CDC42激活，包括调节去磷酸化 对PAK激活过程至关重要的反应。第三个目标将因此 专注于鉴定和纯化作用于 帕克。利用分子和生物化学手段，他们将探索这种机制。 其中磷酸酶控制PAK的活性，并将启动对 这种调节性磷酸酶与受体介导的PAK的相关性 激活。

DESCRIPTION: Communication between chemoattractant and growth factor receptors and downstream Rho family small GTPases initiates cellular events important for the motile responses of leukocytes and fibroblasts. Dr. Bokoch and his colleagues will investigate one such receptor-regulated pathway, the Rac/Cdc42-mediated activation of the target protein Pak (p21-activated kinase). The proposed studies address the biological pathways used by receptors to regulate the actin cytoskeleton, and will identify novel mechanisms by which Pak activity is controlled. In their first specific aim, the molecular interactions through which Pak regulates the actin cytoskeleton will be determined structurally and mechanistically in a well-defined fibroblast model system. Domains in Pak important for cytoskeletal regulation will be identified using a combination of molecular and cellular approaches. Target proteins which interact with these domains will be isolated and characterized. They will extend their studies of cytoskeletal regulation by Pak in the second aim, which will evaluate a novel GTPase-independent mechanism for Pak regulation. The molecular basis for Pak activation by membrane targeting will be investigated. The investigators will examine the significance of Pak activation by membrane association in cytoskeletal regulation of neurite development using the PC12 cell as a model system. The role of the Pak-binding Nck adapter protein in this process will also be probed. Receptors appear to control Pak activity by mechanisms distinct from direct activation via Rac or Cdc42 which include regulatory dephosphorylation reactions critical to the Pak activation process. The third aim will thus focus upon identification and purification of phosphatases that act upon Pak. Using molecular and biochemical means, they will probe the mechanisms by which phosphatases control Pak activity, and will initiate studies on the relevance of such regulatory phosphatases to receptor-mediated Pak activation.