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首页> 美国卫生研究院文献>Biochemical Journal >Plant protein phosphatases. Subcellular distribution detection of protein phosphatase 2C and identification of protein phosphatase 2A as the major quinate dehydrogenase phosphatase.
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Plant protein phosphatases. Subcellular distribution detection of protein phosphatase 2C and identification of protein phosphatase 2A as the major quinate dehydrogenase phosphatase.

机译：植物蛋白磷酸酶。亚细胞分布蛋白磷酸酶2C的检测和蛋白磷酸酶2A的鉴定为主要奎宁酸脱氢酶磷酸酶。

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Protein phosphatases 1 and 2A (PP1 and PP2A) were identified in a variety of plant cells and found to be particulate or soluble depending on the species. In extracts prepared from oilseed-rape seeds these enzymes were associated with microsomes and more rapidly sedimenting fractions, whereas in wheat leaf extracts they were largely microsomal, the remainder being present in the soluble fraction. In pea leaf and carrot cell extracts PP1 and PP2A were almost entirely soluble. No PP1 or PP2A activity was associated with the membranes or stroma of chloroplasts in oilseed-rape seeds, pea leaves and wheat leaves. An Mg2(+)-dependent okadaic acid-insensitive protein phosphatase that resembles protein phosphatase 2C (PP2C) was detected in carrot cells, pea leaves and wheat leaves, but not in oilseed-rape seeds. In wheat leaf extracts PP2C was mostly present in the soluble fraction, a different location from PP1 or PP2A. The rapid inactivation of the cytosolic enzyme quinate dehydrogenase (QDH) in a fraction prepared from light-grown carrot cells was completely blocked by either okadaic acid or microcystin (two potent and specific inhibitors of PP1 and PP2A), whereas inhibitor 2 (a specific inhibitor of PP1) inhibited inactivation by only about 10%. Addition of the purified PP2A catalytic subunit from mammalian skeletal muscle increased the rate of QDH inactivation, whereas addition of mammalian PP1 did not. It is concluded that PP2A is the major enzyme responsible for dephosphorylating (inactivating) QDH in carrot cells. These observations indicate that okadaic acid and microcystin may be useful for identifying other plant processes that are controlled by phosphorylation/dephosphorylation mechanisms. Okadaic acid did not prevent the rapid inactivation of phosphoribulokinase or activation of glucose-6-phosphate dehydrogenase in a fraction prepared from light-grown pea leaves, and addition of the purified catalytic subunits of PP1 and PP2A did not accelerate either process. These observations, in conjunction with the absence of PP1 and PP2A activity in chloroplasts, suggest that these phosphatases are not involved in the regulation of chloroplast metabolism.
机译：蛋白质磷酸酶1和2A（PP1和PP2A）已在多种植物细胞中鉴定出来，并根据其种类呈颗粒状或可溶性。在从油菜籽种子制备的提取物中，这些酶与微粒体和更快的沉降部分相关，而在小麦叶提取物中，它们主要是微粒体，其余部分存在于可溶性部分中。在豌豆叶和胡萝卜细胞提取物中，PP1和PP2A几乎完全可溶。 PP1或PP2A活性与油菜籽，豌豆叶和小麦叶中的叶绿体膜或基质无关。 Mg2（+）依赖的冈田酸不敏感蛋白磷酸酶类似于蛋白磷酸酶2C（PP2C）在胡萝卜细胞，豌豆叶和小麦叶中检出，但在油菜籽中未检出。在小麦叶片提取物中，PP2C主要存在于可溶性部分中，与PP1或PP2A的位置不同。由轻度生长的胡萝卜细胞制备的馏分中的胞质酶奎宁酸脱氢酶（QDH）的快速失活被冈田酸或微囊藻毒素（PP1和PP2A的两种有效和特异性抑制剂）完全阻断，而抑制剂2（特异性抑制剂PP1）的灭活仅抑制约10％。从哺乳动物骨骼肌中加入纯化的PP2A催化亚基可增加QDH的失活速率，而哺乳动物PP1则没有。结论是PP2A是负责胡萝卜细胞QDH磷酸化（失活）的主要酶。这些观察结果表明，冈田酸和微囊藻毒素可用于鉴定受磷酸化/去磷酸化机制控制的其他植物过程。冈田酸不能阻止由浅色豌豆叶片制备的馏分中磷酸二氢激酶的快速失活或葡萄糖-6-磷酸脱氢酶的活化，并且添加纯的PP1和PP2A催化亚基不会加速任何一个过程。这些观察结果，再加上叶绿体中没有PP1和PP2A活性，表明这些磷酸酶不参与叶绿体代谢的调节。

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