DYNAMICS OF CELLULAR FUNCTION OF PLANT VACUOLES.

液泡是植物细胞中最显眼的隔室之一。我们研究了植物液泡在功能和形态上的动态方面。液泡对细胞稳态起着至关重要的作用，包括代谢物的积累、蛋白质和无机离子的储存。液泡功能由初级和次级主动运输系统支持。我们将注意力集中在使液泡酸化并产生膜电位的液泡质子泵上。此外，Na^+/H^+反转运蛋白被表征为二级主动转运蛋白。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的中心液泡，并在发芽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中的机制，以及蛋白质储存液泡与中央液泡之间的转化机制。对酵母和植物细胞的液泡形成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、储存蛋白向液泡的胞内分选和细胞扩增等方面的生理意义。西村的研究小组发现，在种子中，密集的囊泡充当了从内质网到液泡储存蛋白质的运输囊泡的作用。在酵母系统中，已经确定了液泡形成的必要基因和蛋白质因子。Ohsumi的研究小组在酵母细胞中发现了自噬现象，并从细胞生物学和分子遗传学的角度分析了这一过程。在研究过程中，各成员之间进行了一些富有成效的合作工作。

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.