Reversibly contractile nuclear matrix. Its isolation, structure, and composition.
Reversibly contractile nuclear matrix. Its isolation, structure, and composition.
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DOI：
10.1083/jcb.73.2.271
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发表时间：
1977-05
影响因子：
7.8
通讯作者：
Herlan, G
中科院分区：
文献类型：
--
作者：
Wunderlich, F;Herlan, G
我们从大核四膜虫中分离出一种可逆收缩的核骨架，当二价阳离子Ca和Mg（3：2）的总浓度降低至5 mM或增加至125 mM时，可逆收缩的“膨胀的”核基质。在收缩期间，膨胀基质的平均直径减小约24%;这对应于约55%的体积收缩。核基质的可逆收缩不依赖于ATP，也不能被水杨酸抑制。通过用Triton X-100处理并用DNase和RNase消化，然后用2 M NaCl提取，从大核中小心地除去89.7%的磷脂、99.6%的DNA、98.5%的RNA和74.8%的蛋白质，从而获得扩展的基质。电子显微镜检查显示，在扩展的基质中，残留的等效物的结构特征的大核：（a）残留的核包膜与核孔复合物;（B）残留的核仁在周边;（c）纤维状的内部网络。膨胀基质基本上由蛋白质（96.2%）和痕量DNA（0.8%）、RNA（0.5%）、磷脂（1.6%）和碳水化合物（0.9%）组成。最后一种，已通过气相色谱法测定，含有葡萄糖，甘露糖，和一个身份不明的糖的比例为1：5.4：5.7。膨胀基质的酸性氨基酸与碱性氨基酸的比率为1.55。十二烷基硫酸钠（SDS）凝胶电泳揭示了一个主要的蛋白质分子量为18,000，这显然是参与可逆的收缩过程。这种可逆收缩的扩展矩阵的机制仍有待阐明，但它不同于肌动蛋白-肌球蛋白收缩系统和收缩spasmoneme系统在vorticellids。
From Tetrahymena macronuclei we have isolated a reversibly contractile nucleo-skeleton, i.e., an "expanded" nuclear matrix which reversibly contracts when the total concentration of the bivalent cations, Ca and Mg (3:2), is decreased to 5 mM or increased to 125 mM. During contraction the average diameter of the expanded matrix becomes reduced by about 24%; this corresponds to a volume contraction of about 55%. The reversible contraction of the nuclear matrix does not depend on ATP and cannot be inhibited by salygran. The expanded matrix is obtained by removing carefully from the macronuclei 89.7% of the phospholipid, 99.6% of the DNA, 98.5% of the RNA, and 74.8% of the protein by treatment with Triton X-100 and digestion with DNase and RNase followed by an extraction with 2 M NaCl. Electron microscopy reveals, within the expanded matrix, residual equivalents to the structures characteristic for macronuclei: (a) a residual nuclear envelope with nuclear pore complexes; (b) residual nucleoli at the periphery; (c) a fibrillar internal network. The expanded matrix is essentially composed of proteins (96.2%) and traces of DNA (0.8%), RNA (0.5%), phospholipid (1.6%), and carbohydrates (0.9%). The last, which have been determined by gas chromatography, contain glucose, mannose, and an unidentified sugar in the ratio 1:5.4:5.7. The ratio of acidic to basic amino acids of the expanded matrix is 1.55. Sodium dodecyl sulfate (SDS) gel electrophoresis reveals a predominant protein with a mol wt of 18,000 which is apparently involved in the reversible contractile process. The mechanism of this reversible contraction of the expanded matrix remains to be elucidated, but it differs both from actin-myosin contraction systems and from the contractile spasmoneme system in vorticellids.