磷（P）是每一株植物生長所需的十七大基本化學元素之一，包括為了植物根的形成和種子的發芽之用。磷在細胞成分中佔有很大的比例，包括細胞膜和胞器膜中的磷脂質，以及對於生理反應過程中，有高度調節性的磷酸蛋白。
植物胞器中，佔有最大體積的胞器是液泡，可以佔據細胞體積的90％。液泡儲存相當多的無機物與有機物，如礦物質、水、有毒化合物或被分解的代謝產物。
在液泡膜上，有兩種傳輸帶電荷的膜蛋白，其一為陽離子傳輸蛋白，包含鈣離子傳輸蛋白和鈉/鉀離子傳輸蛋白；其二為陰離子傳輸蛋白，主要為SPX-MFS傳輸蛋白家族，負責傳輸磷酸鹽。
在本研究中，標的蛋白（水稻SPX-MFS1）的分子量是78.7 kDa。經由MEMSAT-SVM分析，它具有十二個跨膜螺旋區。我們用酵母（BJ2168）異源表達系統做大量表現和純化高純度的SPX-MFS1蛋白。我們將依此分析OsSPX-MFS1，並試圖在未來能解出3維立體結構。

Phosphorus (P) is one of the seventeen essential elements for plant growth, including roots formation and seed germination. It is high importance for cellular components, such as phospholipids for membrane and phosphoproteins for regulation of enzymatic processes in the cell.
Plant vacuoles are the largest organelles occupying 90% volume of a plant cell. It have multiple functions including storage of small molecules such as minerals, water, toxic compounds and metabolites.
The charge transporters localized in the vacuolar membranes have two types: cation transporters, such as vacuolar Ca2+ transporters and vacuolar Na+/K+ transporters, and anion transporters, such as SPX-MFS families.
The molecular mass of Oryza sativa SPX-MFS1, is about 78.7 kDa. From the MEMSAT-SVM analysis, Oryza sativa SPX-MFS1 has twelve transmembrane helices. We would focus on overexpression of Oryza sativa SPX-MFS1 in the heterologous expression system using Saccharomyces cerevisiae (BJ2168) as a host and on the isolation of the yeast microsome containing this protein. We have obtained OsSPX-MFS1 and tried to analyze it for future in vitro research, like transport mechanism and 3-dimension structure determination.

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