Regulation of Cytoplasmic Dynein Based Vesicle Transport

描述（由申请人提供）：Dynactin是一种多亚基蛋白复合物，与基于微管的马达细胞质dynein一起工作，以支持一系列亚细胞运动功能。动力蛋白增强运动进程性，并作为一种接头蛋白，允许动力蛋白结合膜和蛋白质货物。动力蛋白也可以独立于动力蛋白起作用，将蛋白质复合物和调节分子拴在微管上。动力蛋白甚至被证明与动力蛋白以外的马达相互作用。为了执行这些不同的功能，dynactin依赖于分布在其结构中的多个绑定活动。马达结合使用分子的一部分，微管结合和加工能力增强另一部分，而货物结合又是另一部分。Dynactin的结构完整性是由它的dynamitin （p50）亚基维持的，它形成了一个灵活的桥，将马达和微管结合亚基锚定在货物结合结构域上。具体目标1侧重于了解动态蛋白与其他动态蛋白亚基以及自身的相互作用。具体目标2描述了明确定义动力蛋白/动力蛋白相互作用的分子和超微结构基础的实验。

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.