Molecular characterization of a carbon transporter in plastids from heterotrophic tissues:: The glucose 6-phosphate phosphate antiporter
Molecular characterization of a carbon transporter in plastids from heterotrophic tissues:: The glucose 6-phosphate phosphate antiporter
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DOI：
10.1105/tpc.10.1.105
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发表时间：
1998-01-01
期刊：
影响因子：
11.6
通讯作者：
Flügge, UI
中科院分区：
文献类型：
--
作者：
Kammerer, B;Fischer, K;Flügge, UI
非绿色组织的质体输入碳作为生物合成途径和能量的来源。在质体内，碳可用于淀粉的生物合成或作为氧化戊糖磷酸途径的底物，例如，我们已经使用玉米胚乳纯化质体葡萄糖6-磷酸/磷酸转运子（GPT），从玉米胚乳以及豌豆根和马铃薯块茎的组织中分离相应的cDNA，一级序列分析表明，这两个基因的GPT蛋白质具有高度的同源性，但相似性仅为38%。在一些实施方案中，所述蛋白质具有与磷酸丙糖/磷酸转运子（TPT）和磷酸烯醇丙酮酸/磷酸转运子（PPT）家族的成员相同的氨基酸。因此，GPT代表第三组质体磷酸盐反向转运蛋白。所有三类磷酸盐转运蛋白基因都表现出不同的表达模式。尽管TPT基因主要存在于进行光合碳代谢的组织中，并且PPT基因似乎普遍表达，但GPT基因的表达主要限于异养组织。在转化的酵母细胞中表达GPT的编码区，随后用纯化的蛋白质进行转运实验，证明GPT蛋白介导葡萄糖B-磷酸主要与无机磷酸和丙糖磷酸的1：1交换。因此，通过GPT输入的葡萄糖B-磷酸可用于淀粉生物合成，在此过程中释放无机磷酸，或作为氧化戊糖磷酸途径的底物，产生丙糖磷酸。
Plastids of nongreen tissues import carbon as a source of biosynthetic pathways and energy, Within plastids, carbon can be used in the biosynthesis of starch or as a substrate for the oxidative pentose phosphate pathway, for example, We have used maize endosperm to purify a plastidic glucose 6-phosphate/phosphate translocator (GPT), The corresponding cDNA was isolated from maize endosperm as well as from tissues of pea roots and potato tubers, Analysis of the primary sequences of the cDNAs revealed that the GPT proteins have a high degree of identity with each other but share only similar to 38% identical amino acids with members of both the triose phosphate/phosphate translocator (TPT) and the phosphoenolpyruvate/phosphate translocator (PPT) families. Thus, the GPTs represent a third group of plastidic phosphate antiporters. All three classes of phosphate translocator genes show differential patterns of expression. Whereas the TPT gene is predominantly present in tissues that perform photosynthetic carbon metabolism and the PPT gene appears to be ubiquitously expressed, the expression of the GPT gene is mainly restricted to heterotrophic tissues. Expression of the coding region of the GPT in transformed yeast cells and subsequent transport experiments with the purified protein demonstrated that the GPT protein mediates a 1:1 exchange of glucose B-phosphate mainly with inorganic phosphate and triose phosphates, Glucose B-phosphate imported via the GPT can thus be used either for starch biosynthesis, during which process inorganic phosphate is released, or as a substrate for the oxidative pentose phosphate pathway, yielding triose phosphates.