Phosphoprotein phosphatase 1 (PP1) is a component of the isolated sea urchin mitotic apparatus.
Phosphoprotein phosphatase 1 (PP1) is a component of the isolated sea urchin mitotic apparatus.
复制标题
磷蛋白磷酸酶 1 (PP1) 是分离的海胆有丝分裂器的组成部分。
DOI：
10.1002/cm.970290311
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发表时间：
1994
影响因子：
--
通讯作者：
Silver,RB
中科院分区：
文献类型：
--
作者：
Johnston,JA;Sloboda,RD;Silver,RB
分离的有丝分裂器官的一个相对分子质量为62,000(P62)的蛋白质组分是钙/钙调蛋白依赖的蛋白激酶的底物，体外p62的磷酸化与微管的解体直接相关。体内实验已经确定受精后p62的磷酸化增加；磷酸盐的最大掺入出现在后期中期/后期早期，之后下降。因为p62的水平在整个细胞周期中是恒定的[Johnston and Sloboda，1992：J.Cell Biol.119：843-54]，所以在后期开始后观察到p62磷酸化的降低很可能是由于磷酸酶的作用。通过使用标准的体外磷酸化实验检测保持放射性标记的磷酸化p62的相对量随时间的变化，观察分离的有丝分裂器中能够去磷酸化p62的磷酸蛋白磷酸酶的活性。为了研究p62磷酸酶的特性，在体外用冈田酸和花盏花素A抑制p62的去磷酸化。在体外实验中，发现特定浓度的冈田酸(50-500 nM)和盏花素A(10-100 nM)能有效地抑制p62的去磷酸化。较低浓度的两种抑制剂对p62去磷酸化的影响都可以忽略不计。这些数据表明，使用这里描述的程序从海胆胚胎中分离出与有丝分裂器相关的磷酸蛋白磷酸酶1型活性。这些发现的含义与我们对有丝分裂和胞质分裂调控的理解有关。©1994 Wiley-Liss，Inc.
A protein component of isolated mitotic apparatus having a relative molecular mass of 62,000 (p62) is a substrate of a calcium/calmodulin dependent protein kinase, and the phosphorylation of p62 in vitro correlates directly with microtubule disassembly. In vivo experiments have determined the phosphorylation of p62 increases after fertilization; maximum incorporation of phosphate occurs during late metaphase/early anaphase and decreases thereafter. Because the level of p62 is constant throughout the cell cycle [Johnston and Sloboda, 1992:J. Cell Biol.119:843–54] the decrease in phosphorylation of p62 observed after anaphase onset is most likely due to the action of a phosphatase. By examination of the relative amount of phosphorylated p62 which remained radiolabeled as a function of time using a standard in vitro phosphorylation assay, the activity of a phosphoprotein phosphatase capable of dephosphorylating p62 in the isolated mitotic apparatus was observed. To characterize the p62 phosphatase, okadaic acid and calyculin A were used to inhibit the dephosphorylation of p62 in vitro. It was found that specific concentrations of okadaic acid (50–500 nM) and of calyculin A (10–100 nM) were effective at inhibiting the dephosphorylation of p62 in vitro. Lower concentrations of either inhibitor had a negligible effect on dephosphorylation of p62. These data indicate the presence of phosphoprotein phosphatase type 1 activity associated with mitotic apparatus isolated from sea urchin embryos using the procedures described here. The implications of these findings relative to our understanding of the regulation of mitosis and cytokinesis are discussed. © 1994 Wiley‐Liss, Inc.