REGULATION OF THE CDC25 PROTEIN DURING THE CELL-CYCLE IN XENOPUS EXTRACTS
REGULATION OF THE CDC25 PROTEIN DURING THE CELL-CYCLE IN XENOPUS EXTRACTS
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DOI：
10.1016/0092-8674(92)90540-s
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发表时间：
1992-07-10
期刊：
影响因子：
64.5
通讯作者：
DUNPHY, WG
中科院分区：
文献类型：
--
作者：
KUMAGAI, A;DUNPHY, WG
cdc25 蛋白是一种高度特异性的酪氨酸磷酸酶，通过使 cdc2 蛋白激酶去磷酸化来触发有丝分裂。使用非洲爪蟾提取物，我们发现 cdc25 蛋白在整个分裂间期处于低水平活性。在接近有丝分裂开始时，cdc25 蛋白的磷酸酶活性显着升高，这与该蛋白在其 N 末端区域的广泛磷酸化相一致。 cdc25 的这种过度磷酸化形式的体外去磷酸化可将其磷酸酶活性降低至间期水平。此外，用冈田酸（一种加速进入有丝分裂的磷酸酶抑制剂）处理间期非洲爪蟾提取物，会引起 cdc25 的过早过度磷酸化并刺激其 cdc2 特异性酪氨酸磷酸酶活性。这些实验证明了cdc25调节系统的存在，该系统由磷酸化cdc25蛋白的假定调节结构域的刺激性激酶和抵消该激酶活性的抑制性丝氨酸/苏氨酸磷酸酶组成。
The cdc25 protein is a highly specific tyrosine phosphatase that triggers mitosis by dephosphorylating the cdc2 protein kinase. Using Xenopus extracts, we have found that the cdc25 protein is active at a low level throughout interphase. Near the onset of mitosis, the cdc25 protein undergoes a marked elevation in phosphatase activity that coincides with an extensive phosphorylation of the protein in its N-terminal region. In vitro dephosphorylation of this hyperphosphorylated form of cdc25 reduces its phosphatase activity back to the interphase level. Moreover, treatment of interphase Xenopus extracts with okadaic acid, a phosphatase inhibitor that accelerates the entry into mitosis, elicits both the premature hyperphosphorylation of cdc25 and the stimulation of its cdc2-specific tyrosine phosphatase activity. These experiments demonstrate the existence of a cdc25 regulatory system consisting of both a stimulatory kinase that phosphorylates a putative regulatory domain of the cdc25 protein and an inhibitory serine/threonine phosphatase that counteracts this kinase activity.