CDC2 H1 KINASE IS NEGATIVELY REGULATED BY A TYPE-2A PHOSPHATASE IN THE XENOPUS EARLY EMBRYONIC-CELL CYCLE - EVIDENCE FROM THE EFFECTS OF OKADAIC ACID
CDC2 H1 KINASE IS NEGATIVELY REGULATED BY A TYPE-2A PHOSPHATASE IN THE XENOPUS EARLY EMBRYONIC-CELL CYCLE - EVIDENCE FROM THE EFFECTS OF OKADAIC ACID
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DOI：
10.1002/j.1460-2075.1990.tb08159.x
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发表时间：
1990-03-01
期刊：
影响因子：
11.4
通讯作者：
KARSENTI, E
中科院分区：
文献类型：
--
作者：
FELIX, MA;COHEN, P;KARSENTI, E
在非洲爪哇胚胎中，细胞周期被缩写为间期和有丝分裂之间的快速变化。每个M期的开始是由cdc2激酶的周期性激活引起的，这是由一定水平的周期蛋白触发的，显然涉及p34cdc2的去磷酸化。我们已经从间期(间期提取液)和早期胚胎细胞周期第一次有丝分裂之前(前期提取液)采集的卵子制备了核糖体后上清液。在“间期提取液”中，cdc2激酶在室温下孵育后不会自发激活，而在“前期提取液”中，冈田酸对2A型磷酸酶的特异性抑制会诱导cdc2激酶激活。这需要亚阈值水平的细胞周期蛋白，并在提取物中存在颗粒因子。抑制物1和抑制物2抑制1型磷酸酶不会导致cdc2激酶的激活。这些结果表明，在细胞周期蛋白积聚的过程中，cdc2激酶的激活被一种2A型磷酸酶抑制。在“前期提取物”中，β-甘油磷酸和NaF抑制cdc2激酶的自发激活，但冈田酸、抑制物1和抑制物2或二价阳离子螯合不能抑制cdc2的自发激活。这表明，当细胞周期蛋白积累足够多时，cdc2激酶的激活涉及一种蛋白磷酸酶，它必须不同于1型和2A型磷酸酶，也不同于钙依赖型(2B型)和镁依赖型(2C型)磷酸酶。
In Xenopus embryos, the cell cycle is abbreviated to a rapid alteration between interphase and mitosis. The onset of each M phase is induced by the periodic activation of the the cdc2 kinase which is triggered by a threshold level of cyclins and apparently involves dephosphorylation of p34cdc2. We have prepared post-ribosomal supernatants from eggs sampled during interphase (interphase extracts) and just before the first mitosis of the early embryonic cell cycle (prophase extracts). In ''interphase extracts'', the cdc2 kinase never activates spontaneously upon incubation at room temperature whereas in ''prophase extracts'', specific inhibition of type 2A phosphatase by okadaic acid induces cdc2 kinase activation. This requires a subthreshold level of cyclin and the presence of a particulate factor in the extract. Inhibition of type 1 phosphatases by inhibitor 1 and inhibitor 2 never results in cdc2 kinase activation. These results demonstrate that during the period of cyclin accumulation, cdc2 kinase activation is inhibited by a type 2A phosphatase. In ''prophase extracts'', spontaneous activation of the cdc2 kinase is inhibited by .beta.-glycerophosphate and NaF, but not by okadaic acid, inhibitor 1 and inhibitor 2 or divalent cation chelation. This demonstrates that when enough cyclin has accumulated, cdc2 kinase activation involves a protein phosphatase which must be distinct from the type 1 and 2A phosphatases, and from the calcium-dependent (type 2B) and magnesium-dependent (type 2C) phosphatases.