Pozueta-Romero J, Ardila F, Akazawa T
Research Institute for Biochemical Regulation, School of Agriculture, Nagoya University, Chikusa, Nagoya 464-01, Japan.
Plant Physiol. 1991 Dec;97(4):1565-72. doi: 10.1104/pp.97.4.1565.
In organello starch biosynthesis was studied using intact chloroplasts isolated from spinach leaves (Spinacia oleracea). Immunoblot analysis using a specific antiserum against the mitochondrial adenylate (ADP/ATP) translocator of Neurospora crassa shows the presence of an adenylate translocator protein in the chloroplast envelope membranes, similar to that existing in mitochondria and amyloplasts from cultured cells of sycamore (Acer pseudoplatanus). The double silicone oil layer-filtering centrifugation technique was employed to study the kinetic properties of adenylate transport in the purified chloroplasts; ATP, ADP, AMP, and most importantly ADP-Glc were shown to be recognized by the adenylate translocator. Similar to the situation with sycamore amyloplasts, only ATP and ADP-Glc uptake was inhibited by carboxyatractyloside, an inhibitor of the mitochondrial adenylate translocator. Evidence is presented to show that the ADP-Glc transported into the chloroplast stroma is utilized for starch synthesis catalyzed by starch synthase (ADP-Glc:1,4-alpha-d-glucan 4-alpha-d-glucosyltransferase). The high activity of sucrose synthase producing ADP-Glc observed in the extrachloroplastic fractions suggests that starch biosynthesis in chloroplasts may be coupled with the direct import of ADP-Glc from the cytosol.
利用从菠菜叶（菠菜）中分离出的完整叶绿体，对叶绿体中的淀粉生物合成进行了研究。使用针对粗糙脉孢菌线粒体腺苷酸（ADP/ATP）转运体的特异性抗血清进行免疫印迹分析，结果表明在叶绿体包膜膜中存在一种腺苷酸转运体蛋白，类似于在悬铃木（假挪威槭）培养细胞的线粒体和造粉体中存在的蛋白。采用双硅油层过滤离心技术研究纯化叶绿体中腺苷酸转运的动力学特性；结果表明，腺苷酸转运体能够识别ATP、ADP、AMP，最重要的是能够识别ADP - 葡萄糖。与悬铃木造粉体的情况类似，线粒体腺苷酸转运体的抑制剂羧基苍术苷仅抑制ATP和ADP - 葡萄糖的摄取。有证据表明，转运到叶绿体基质中的ADP - 葡萄糖被用于淀粉合酶（ADP - 葡萄糖：1,4 - α - d - 葡聚糖4 - α - d - 葡糖基转移酶）催化的淀粉合成。在叶绿体外部组分中观察到的产生ADP - 葡萄糖的蔗糖合酶的高活性表明，叶绿体中的淀粉生物合成可能与从细胞质中直接导入ADP - 葡萄糖有关。
