DYNAMICS OF CELLULAR FUNCTION OF PLANT VACUOLES.

液泡是植物细胞内最明显的隔室中的液泡。我们从功能和形态上研究了植物液泡的动态变化。液泡具有许多对细胞稳态至关重要的功能，包括代谢产物、贮藏蛋白和无机离子的积累。液泡功能由初级和次级主动转运系统支持。我们把注意力集中在液泡质子泵上，它使液泡酸化并产生膜电位。此外，Na~+/H~+逆向转运蛋白也被认为是第二活性转运蛋白。液泡最重要的方面是它们在蛋白质储存中的作用。蛋白质储存液泡来源于成熟种子中的中心液泡，并在萌发种子中转化为中心液泡。我们分析了蛋白质积累到这些蛋白质储存液泡以及蛋白质储存液泡和中心液泡之间转换的机制。我们还对酵母和植物细胞的液泡形态发生机制和自噬功能的分子基础进行了研究。我们的研究揭示了液泡质子泵在离子积累、细胞内储存蛋白分选到液泡和细胞扩张中的生理意义。西村的研究小组发现了致密的小泡，这些小泡充当着从内质网到液泡的运输小泡，用于储存种子中的蛋白质。在酵母系统中，液泡形态发生所必需的基因和蛋白因子已被鉴定。OhSumi的团队在酵母细胞中发现了自噬，并在细胞生物学和分子遗传学的水平上分析了这一过程。在本次研究期间，各成员之间进行了一些卓有成效的合作工作。

Vacuole is one on the most conspicuous compartments within a plant cell. We have investigated dynamic aspect of plant vacuoles in function and morphology. The vacuole performs numerous functions vital to cellular homeostasis, including the accumulation of metabolites, storage proteins and inorganic ions. The vacuolar function is supported by the primary and secondary active transport systems. We focused our attention on the vacuolar proton pumps which acidify vacuoles and create a membrane potential. Also, Na^+/H^+antiporter has been characterized as the secondary active transporter. The most important aspect of vacuoles is their role in protein storage. The protein storage vacuoles are derived from central vacuoles in the maturating seeds and transformed to a central vacuole in the germinating seeds. We analyzed the mechanisms for the protein accumulation into these protein-storage vacuoles and for the transformation between the protein-storage vacuole and the central vacuole. And the mechanisms of vacuolar morphogenesis and the molecular basis of autophagic function have been investigated for yeast and plant cells.Our investigations revealed the physiological significance of vacuolar proton pumps in the ion accumulation, intracellular sorting of storage protein to vacuole and cell expansion. Nishimura's group found the dense vesicles that act as transport vesicles from ER to vacuoles for storage proteins in seeds. In yeast systems, the essential genes and protein factor for vacuole morphogenesis have been identified. Ohsumi's group found the autophagy in yeast cells and analyzed the process at levels of cell biology and molecular genetics. During this study, some fruitful, cooperative works among the members have been done.