Lionne C, Buss F, Hodge T, Ihrke G, Kendrick-Jones J
Medical Research Centre, Laboratory of Molecular Biology, Structural Studies Division, Cambridge, UK.
Biochem Cell Biol. 2001;79(1):93-106.
Myosin V plays an important role in membrane trafficking events. Its implication in the transport of pigment granules in melanocytes and synaptic vesicles in neurons is now well established. However, less is known about its function(s) in other cell types. Finding a common function is complicated by the diversity of myosin V expression in different tissues and organisms and by its association with different subcellular compartments. Here we show that myosin V is present in a variety of cells. Within the same cell type under different physiological conditions, we observed two main cellular locations for myosin V that were dependent on the dynamics of the plasma membrane: in cells with highly dynamic membranes, myosin V was specifically concentrated at the leading edge in membrane ruffles, whereas in cells with less dynamic membranes, myosin V was enriched around the microtubule-organizing center. The presence of myosin V in the leading ruffling edge of the cell was induced by growth factor stimulation and was dependent on the presence of a functional motor domain. Moreover, myosin V localization at the microtubule-organizing center was dependent on the integrity of the microtubules. In polarized epithelial cells (WIF-B), where the microtubule-organizing region is close to the actin-rich apical surface, one single pool of myosin V, sensitive to the integrity of both microtubules and actin filaments, was observed.
肌球蛋白V在膜运输事件中起重要作用。目前已充分证实其在黑素细胞中色素颗粒运输以及神经元中突触小泡运输中的作用。然而，对于其在其他细胞类型中的功能了解较少。不同组织和生物体中肌球蛋白V表达的多样性以及它与不同亚细胞区室的关联，使得寻找其共同功能变得复杂。在此我们表明，肌球蛋白V存在于多种细胞中。在同一细胞类型的不同生理条件下，我们观察到肌球蛋白V有两个主要的细胞定位，这取决于质膜的动态变化：在具有高度动态膜的细胞中，肌球蛋白V特异性地集中在膜褶皱的前沿，而在膜动态性较低的细胞中，肌球蛋白V则富集在微管组织中心周围。细胞前沿褶皱边缘中肌球蛋白V的存在是由生长因子刺激诱导的，并且依赖于功能性运动结构域的存在。此外，肌球蛋白V在微管组织中心的定位取决于微管的完整性。在极化上皮细胞（WIF-B）中，微管组织区域靠近富含肌动蛋白的顶端表面，观察到单一的肌球蛋白V池，其对微管和肌动蛋白丝的完整性均敏感。
