Cell Cycle dependent changes in myosin 1 functions

肌凝蛋白在广泛的运动过程中起着核心作用。这些过程的多样性反映在我们细胞中发现的大量肌球蛋白马达上。目前，已鉴定出39种人肌球蛋白的编码基因，可分为12类。Dictyostelium disideum是一种高度运动的生物，可以依赖生长条件作为独立细胞存在或相互作用形成多细胞结构，相比之下，它的11种肌球蛋白补体要小得多，属于I(7)、II(1)、V(1)、VII(1)和XIV(1)。值得注意的是，盘基骨柱缺乏已知的从VI类和IX类向后移动的肌凝蛋白。因此，我们推测基于肌动蛋白的细胞外周向内转运是由一类肌凝蛋白介导的。我们将采用体内和体外的直接功能分析来证明1类肌球蛋白myosin- ic负责这种活性。此外，我们将使用蛋白质工程方法并比较单头和双头肌球蛋白V结构的功能行为，以阐明允许这种马达蛋白以明显的过程方式运输囊泡以对抗细胞内pN力的结构特征。

Myosins play a central role driving a wide range of motile processes. The diversity of these processes is reflected by the large number of myosin motors that are found in our cells. Currently, genes encoding 39 human myosins have been identified, which are classified in 12 distinct classes. Dictyostelium discoideum, a highly motile organism that can dependent on growth conditions exist as independent cells or interact to form multicellular structures, has in comparison a much smaller complement of 11 myosins belonging to classes I (7), II (1), V (1), VII (1), and XIV (1). Notably, Dictyostelium lacks known backwards moving myosins from class VI and IX. Therefore, we speculate that actin-based, inwards-directed transport from the cell periphery is mediated by a class I myosin. We will employ direct functional in vivo and in vitro assays to show that the class-l myosin myosin-IC is responsible for this activity. Additionally, we will use protein engineering approaches and compare the functional behavior of single and double-headed myosin V constructs, to elucidate the structural features that allow this motor protein to transport vesicles in an apparently processive fashion against pN forces inside the cell.