Regulation of Cytoplasmic Dynein Based Vesicle Transport

描述(申请人提供)：动力蛋白是一种多亚单位蛋白质复合体，与基于微管的马达(细胞质动力蛋白)一起工作，以支持一系列亚细胞运动功能。动力蛋白增强了运动的处理能力，并作为一种适配器蛋白，允许动力蛋白与膜和蛋白质货物结合。动力蛋白也可以独立于动力蛋白发挥作用，将蛋白质复合体和调节分子连接到微管上。动力蛋白甚至被证明与动力蛋白以外的其他运动相互作用。为了执行这些不同的功能，dynactin依赖于分布在其结构上的多个结合活动。马达结合使用分子的一部分，微管结合和加工性增强另一部分，货物结合又使用另一部分。Dynactin的结构完整性由其Dynamitin(P50)亚基维持，该亚基形成一座灵活的桥梁，将马达和微管结合亚基固定在货物结合结构域上。具体目标1侧重于了解Dynamitin与其他dynactin亚基及其自身的相互作用。具体目标2描述了清楚地定义动力蛋白/动力蛋白相互作用的分子和超微结构基础的实验。 细胞核是与动力蛋白和动力蛋白相互作用的众多细胞器之一。运动活动可以推动核移位，也可以推动有丝分裂开始时发生的核膜破裂。我们实验室的工作表明，dynactin使用位于货物结合结构域末端的亚基与细胞核结合。具体目标3的目的是阐明细胞周期调节的机制，并确定与动力蛋白结合的核膜成分。 我们最近发现，dynactin是信号转导分子的正常代谢和微管依赖的细胞质连接所必需的。与动力蛋白相关的是一对亚基p25和p27，它们与动力蛋白“核心”结构松散相关，p25和p27可能是可交换的亚基，允许不同的胞浆成分靶向动力蛋白和微管。在特定目标4中描述的实验中评估了p25/p27、dynactin核心和微管之间的动态相互作用。

DESCRIPTION (provided by applicant): Dynactin is a multisubunit protein complex that works in conjunction with the microtubule-based motor, cytoplasmic dynein, to support a range of subcellular motile functions. Dynactin enhances motor processivity and serves as an adaptor protein that allows dynein to bind membrane and protein cargoes. Dynactin can also function independently of dynein, to tether protein complexes and regulatory molecules to microtubules. Dynactin has even been shown to interact with motors other than dynein. To perform these diverse functions, dynactin relies on multiple binding activities that are distributed across its structure. Motor binding uses one part of the molecule, microtubule binding and processivity enhancement another, and cargo binding yet another. Dynactin's structural integrity is maintained by its dynamitin (p50) subunit, which forms a flexible bridge that anchors the motor and microtubule-binding subunit to the cargo-binding domain. Specific Aim 1 is focused on understanding dynamitin's interactions with other dynactin subunits and with itself. Specific Aim 2 describes experiments to clearly define the molecular and ultrastructural basis of the dynein/dynactin interaction. The nucleus is one of many organelles that interacts with dynactin and dynein. Motor activity can power nuclear translocation and also the nuclear envelope rupture that occurs at the onset of mitosis. Work from our lab suggests that dynactin binds nuclei using subunits that are located at the very end of the cargo-binding domain. The goal of Specific Aim 3 is to elucidate the mechanism of cell cycle regulation and identify components of the nuclear envelope that bind dynactin. We recently discovered that dynactin is required for the normal metabolism and microtubule-dependent cytoplasmic tethering of signal transduction molecules. The link to dynactin is a pair of subunits, p25 and p27, that are loosely associated with the dynactin "core" structure, p25 and p27 may be exchangeable subunits that allow different cytosolic components to be targeted to dynactin and microtubules. The dynamic interactions between p25/p27, the dynactin core and microtubules are evaluated in experiments described in Specific Aim 4.