Phosphorylation of Cdc20 is required for its inhibition by the spindle checkpoint
Phosphorylation of Cdc20 is required for its inhibition by the spindle checkpoint
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DOI：
10.1038/ncb1022
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发表时间：
2003-08-01
影响因子：
21.3
通讯作者：
Chen, RH
中科院分区：
文献类型：
--
作者：
Chung, EN;Chen, RH
纺锤体检查点延迟后期，直到所有染色体都正确地附着在纺锤体微管上。当纺锤体检查点在独立的动点被激活时，检查点蛋白BubR1、Bub3和MAD2结合并抑制后期促进复合体(APC)的激活剂CDc20。在这里，我们发现非洲爪哇Cdc20在有丝分裂过程中在Ser50、Thr、Thr 68和Thr 79处被磷酸化，而丝裂原激活蛋白激酶(MAPK)参与了Thr或Thr 68处的磷酸化。缺乏磷酸化的CDC20突变体能够激活莱维氏X.laevis卵提取液中的APC。然而，其中四个磷酸化位点中的任何一个被改变为Ala或Val的Cdc20突变体由于与纺锤体检查点蛋白的亲和力降低而未能响应纺锤体检查点信号。这项研究表明，纺锤体检查点通过抑制完全磷酸化的CDC20来阻止后期。我们的结果对纺锤体检查点沉默机制也有一定的意义。
The spindle checkpoint delays anaphase until all chromosomes are properly attached to spindle microtubules. When the spindle checkpoint is activated at unattached kinetochores, the checkpoint proteins BubR1, Bub3 and Mad2 bind and inhibit Cdc20, an activator of the anaphase-promoting complex (APC). Here, we show that Xenopus laevis Cdc20 is phosphorylated at Ser 50, Thr 64, Thr 68 and Thr 79 during mitosis and that mitogen-activated protein kinase (MAPK) contributes to the phosphorylation at Thr 64 or Thr 68. Cdc20 mutants that are phosphorylation-deficient are able to activate the APC in X. laevis egg extracts. However, Cdc20 mutants in which any of the four phosphorylation sites were altered to Ala or Val failed to respond to the spindle checkpoint signal, owing to their reduced affinity for the spindle checkpoint proteins. This study demonstrates that the spindle checkpoint stops anaphase by inhibiting fully-phosphorylated Cdc20. Our results also have implications for the spindle checkpoint silencing mechanism.