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. Author manuscript; available in PMC: 2014 Jul 1.
Published in final edited form as: Nat Commun. 2014;5:3318. doi: 10.1038/ncomms4318

Figure 7.

Figure 7

Schematic representation of the regulation of meiotic resumption by ARPP19 in Xenopus oocytes.

During oogenesis, the phosphorylation of ARPP19 by PKA at S109 is responsible for arresting oocyte in prophase I. In response to Pg, PKA activity is downregulated and, as a consequence, ARPP19 is partly dephosphorylated at S109. ARPP19 dephosphorylation at S109 is necessary to generate the threshold level of active Cdk1 by either facilitating ARPP19 phosphorylation at S67 or by controlling protein synthesis. Once a starter amount of active Cdk1 is formed, it initiates the MPF autoamplification loop. Gwl is activated under the control of Cdk1 and fully phosphorylates ARPP19 at S67, launching the MPF autoamplification independently of PKA activity and, thus, of ARPP19 phosphorylation at S109. At that time, meiotic M-phase entry becomes irreversible.