Sequential dephosphorylation of p34(cdc2) on Thr-14 and Tyr-15 at the prophase/metaphase transition
Sequential dephosphorylation of p34(cdc2) on Thr-14 and Tyr-15 at the prophase/metaphase transition
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DOI：
10.1074/jbc.271.44.27847
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发表时间：
1996-11-01
影响因子：
4.8
通讯作者：
Meijer, L
中科院分区：
文献类型：
--
作者：
Borgne, A;Meijer, L
细胞周期的G（2）-M转换由p34（cdc 2）/细胞周期蛋白B激酶触发。在前期/中期转换期间，p34（cdc 2）的失活的Thr-14/Tyr-15磷酸化形式（T-P-Y-P）被cdc 25双特异性磷酸酶修饰为活性的Thr-14/Tyr-15去磷酸化形式（T-Y）。使用高度同步的海星卵母细胞作为细胞模型，我们表明体内和体外的去磷酸化分为两个步骤：Thr-14去磷酸化先于Tyr-15去磷酸化。通过蛋白磷酸酶2A体外处理T-P-Y-P可以获得瞬时中间形式（T-Y-P），其显示低但显著的激酶活性。这些结果提出了这样的可能性，即中间形式T-Y-P可能通过cdc 25磷酸酶的磷酸化/活化和wee 1激酶的磷酸化/失活参与p34（cdc 2）/细胞周期蛋白B复合物的自催化扩增。
The G(2)-M transition of the cell cycle is triggered by the p34(cdc2)/cyclin B kinase. During the prophase/metaphase transition, the inactive, Thr-14/Tyr-15 phosphorylated form of p34(cdc2) (T-P-Y-P) is modified to an active, Thr-14/Tyr-15 dephosphorylated form (T-Y) by the cdc25 dual-specificity phosphatase. Using highly synchronized starfish oocytes as a cellular model, we show that dephosphorylation in vivo and in vitro occurs in two steps: Thr-14 dephosphorylation precedes Tyr-15 dephosphorylation. The transient intermediate form (T-Y-P), which can be obtained in vitro by treatment of T-P-Y-P by protein phosphatase 2A, displays low but significant kinase activity. These results raise the possibility that the intermediate form T-Y-P may be involved in the autocatalytic amplification of the p34(cdc2)/cyclin B complex through phosphorylation/activation of the cdc25 phosphatase and phosphorylation/inactivation of the wee1 kinase.