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Journal Articles Journal of Biological Chemistry Year : 2002

Thr-161 phosphorylation of monomeric Cdc2

Abstract

Fully grown Xenopus oocyte is arrested at prophase I of meiosis. Re-entry into meiosis depends on the activation of MPF (M-phase promoting factor or cyclin B·Cdc2 complex), triggered by progesterone. The prophase-arrested oocyte contains a store of Cdc2. Most of the protein is present as a monomer whereas a minor fraction, called pre-MPF, is found to be associated with cyclin B. Activation of Cdc2 depends on two key events: cyclin binding and an activating phosphorylation on Thr-161 residue located in the T-loop. To get new insights into the regulation of Thr-161 phosphorylation of Cdc2, monomeric Cdc2 was isolated from prophase oocytes. Based on its activation upon cyclin addition and detection by an antibody directed specifically against Cdc2 phosphorylated on Thr-161, we show for the first time that the prophase oocyte contains a significant amount of monomeric Cdc2 phosphorylated on Thr-161. PP2C, a Mg2+-dependent phosphatase, negatively controls Thr-161 phosphorylation of Cdc2. The unexpected presence of a population of free Cdc2 already phosphorylated on Thr-161 could contribute to the generation of the Cdc2 kinase activity threshold required to initiate MPF amplification.
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Dates and versions

hal-02676747 , version 1 (31-05-2020)

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Veronique de Smedt, Robert Poulhe, Xavier Cayla, Frederic Dessauge, Anthi Karaiskou, et al.. Thr-161 phosphorylation of monomeric Cdc2. Journal of Biological Chemistry, 2002, 277 (32), pp.28592-28600. ⟨10.1074/jbc.M202742200⟩. ⟨hal-02676747⟩
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