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首页> 美国卫生研究院文献>The Journal of Biophysical and Biochemical Cytology >Role of nuclear glycogen synthase and cytoplasmic UDP glucose pyrophosphorylase in the biosynthesis of nuclear glycogen in HD33 Ehrlich-Lettre ascites tumor cells
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Role of nuclear glycogen synthase and cytoplasmic UDP glucose pyrophosphorylase in the biosynthesis of nuclear glycogen in HD33 Ehrlich-Lettre ascites tumor cells

机译：核糖原合酶和细胞质UDP葡萄糖焦磷酸化酶在HD33 Ehrlich-Lettre腹水肿瘤细胞中核糖原生物合成中的作用

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摘要

Biochemical and autoradiographic evidence show both glycogen synthesis and the presence of glycogen synthase (UDP glucose [UDPG]: glycogen 4- alpha-D-glucosyltransferase; EC 2.4.1.11) in isolated nuclei of Ehrlich- Lettre mouse ascites tumor cells of the mutant subline HD33. 5 d after tumor transplantation, glycogen (average 5-7 pg/cell) is stored mainly in the cell nuclei. The activity of glycogen synthase in isolated nuclei is 14.5 mU/mg protein. At least half of the total cellular glycogen synthase activity is present in the nuclei. The nuclear glycogen synthase activity exists almost exclusively in its b form. The Km value for (a + b) glycogen synthase is 1 x 10(-3) M UDPG, the activation constant is 5 x 10(-3) M glucose-6-phosphate (Glc-6-P). Light and electron microscopic autoradiographs of isolated nuclei incubated with UDP-[1-3H]glucose show the highest activity of glycogen synthesis not only in the periphery of glycogen deposits but also in interchromatin regions unrelated to detectable glycogen particles. Together with earlier findings on nuclear glycogen synthesis in intact HD33 ascites tumor cells (Zimmermann, H.-P., V. Granzow, and C. Granzow. 1976. J. Ultrastruct. Res. 54:115-123), the results of tests on isolated nuclei suggest a predominantly appositional mode of nuclear glycogen deposition, without participation of the nuclear membrane system. In intact cells, synthesis of UDPG for nuclear glycogen synthesis depends on the activity of the exclusively cytoplasmic UDPG pyrophosphorylase (UTP: alpha-D-glucose-1-phosphate uridylyltransferase; EC 2.7.7.9). However, we conclude that glycogen synthesis is not exclusively a cytoplasmic function and that the mammalian cell nucleus is capable of synthesizing glycogen.
机译：生化和放射自显影证据显示，糖原合成和糖原合酶（UDP葡萄糖[UDPG]：糖原4-α-D-葡萄糖基转移酶； EC 2.4.1.11）的存在均在突变的亚系的Ehrlich-Lettre小鼠腹水肿瘤细胞中HD33。肿瘤移植后5 d，糖原（平均5-7 pg /细胞）主要储存在细胞核中。分离的核中糖原合酶的活性为14.5 mU / mg蛋白。总细胞糖原合酶活性的至少一半存在于细胞核中。核糖原合酶活性几乎仅以b形式存在。 （a + b）糖原合酶的Km值是1 x 10（-3）M UDPG，激活常数是5 x 10（-3）M葡萄糖-6-磷酸（Glc-6-P）。用UDP- [1-3H]葡萄糖孵育的分离核的光学和电子显微镜放射自显影照片显示，不仅在糖原沉积物的外围，而且在与可检测糖原颗粒无关的染色质间区域，糖原合成的活性最高。再加上完整的HD33腹水肿瘤细胞中核糖原合成的早期发现（Zimmermann，H.-P.，V.Granzow和C.Granzow.1976年，J.Ultrastruct.Res.54：115-123），对孤立核的测试表明，核糖原沉积主要是并置模式，而没有核膜系统的参与。在完整细胞中，用于核糖原合成的UDPG的合成取决于胞质UDPG焦磷酸化酶（UTP：α-D-葡萄糖-1-磷酸尿嘧啶转移酶； EC 2.7.7.9）的活性。但是，我们得出的结论是，糖原合成不仅具有胞质功能，而且哺乳动物细胞核能够合成糖原。

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