Regulation of Myosin V Interaction with Cargo

细胞内隔室在精确的时间移动到它们正确的位置是一个基本的特性 所有细胞类型。例如，色素细胞、肠上皮细胞、淋巴细胞和神经元需要 特定的细胞器可以在适当的时间瞄准精确的位置。在每种情况下，肌球蛋白V分子 马达在细胞器运输中起关键作用。细胞器的长距离运动发生在微管上， 驱动蛋白和动力蛋白马达。值得注意的是，运输的后期步骤需要从驱动蛋白转移到肌球蛋白V 运动，然后在肌动蛋白上运动到终点。细胞器分离的调节 对它们的正确定位也至关重要。我们的总体目标是揭示 肌球蛋白V调节细胞组织。与高等真核生物中的特殊细胞类型相似， 酿酒酵母在精确的时间将细胞器定位到特定的位置。我们发现， 与细胞周期协调，酵母液泡的一部分被从母细胞定向到芽。 我们进一步发现，这种运动需要肌球蛋白V，Myo 2。此外，我们和其他人不- 涵盖了大多数酵母细胞内的运动只发生在肌动蛋白和需要肌球蛋白2。我们最近 进展提供了强有力的证据，假设酵母Myo 2的研究将告知我们的下， 哺乳动物肌球蛋白V马达的位置。我们鉴定了Rab GTP酶的保守结合位点， 外囊亚基Sec 15的独立位点。Rab GTP酶和外囊是保守的 分泌所需的蛋白质。Myo 2上的每个位点都是保守的，这强烈表明， 我们所了解的酵母Myo 2如何附着和脱离膜将直接适用于 人肌球蛋白Va、Vb和Vc。我们建议使用酵母系统来确定 控制肌球蛋白V的运输。我们的目标是：1）确定单个Myo 2接头的结合是否 蛋白质被其它Myo 2衔接蛋白增强或抑制。2)确定是否直接 Myo 2与Ypt 31/Ypt 32、Sec 4和Sec 15的相互作用所起的作用超出Myo 2与 分泌囊泡3)确定调节肌球蛋白V从货物中分离的机制。 相关性（参见说明）： 通过肌球蛋白V马达的细胞器的细胞内运输对于正常的细胞功能是至关重要的，并且动物 physiology.基于肌球蛋白V的转运缺陷导致选定的人类疾病，包括神经系统疾病， 紊乱我们的总体目标是确定机制，调节肌球蛋白V为基础的运输。

Movement of intracellular compartments to their correct locations at precise times is a fundamental property of all cell types. For example, pigment cells, intestinal epithelia, lymphocytes, and neurons, require that specific organelles be targeted to precise locations at the proper time. In each case, myosin V molecular motors play key roles in organelle transport. Long-range movement of organelles occurs on microtubules via kinesin and dynein motors. Notably, the late steps in transport require transfer from kinesin to a myosin V motor, followed by movement on actin to a terminal destination. Regulation of detachment of organelles from myosin V is also critical to their proper localization. Our overall goal is to uncover mechanisms whereby myosin V regulates cellular organization. Similar to specialized cell-types in higher eukaryotes, the yeast Saccharomyces cerevisiae targets organelles to specific locations at precise times. We discovered that in coordination with the cell-cycle, a portion of the yeast vacuole is targeted from the mother cell to the bud. We further discovered that this movement requires the myosin V, Myo2. Moreover, we and others dis- covered that most intracellular movement in yeast occurs solely on actin and requires Myo2. Our recent progress provides strong evidence for the hypothesis that studies of yeast Myo2 will inform our under- standing of mammalian myosin V motors. We identified a conserved binding site for Rab GTPases, and an independent site dedicated to the exocyst subunit Sec15. The Rab GTPases and exocyst are conserved proteins that are required for secretion. That each ofthe sites on Myo2 is conserved strongly suggests that what we learn about how yeast Myo2 attaches and detaches from membranes will be directly applicable to human myosin Va, Vb and Vc. We proposed to use the yeast system to determine the mechanisms that govern myosin V-based transport. Our aims are to: 1) Determine whether binding of individual Myo2 adaptor proteins are enhanced or inhibited by other Myo2 adaptor proteins. 2) Determine whether the direct interaction of Myo2 with Ypt31/Ypt32, Sec4 and Sec15 plays roles beyond the attachment of Myo2 to secretory vesicles. 3) Determine mechanisms that regulate the detachment of myosin V from cargoes. RELEVANCE (See instructions): Intracellular transport of organelles by myosin V motors is crucial to normal cellular function, and animal physiology. Defects in myosin V based transport cause selected human diseases including neurological disorders. Our overall goal is to determine the mechanisms that regulate myosin V-based transport.