Fig. 6
From: The G2-to-M transition from a phosphatase perspective: a new vision of the meiotic division
At the top of the signalling pathway, the critical Arpp19 dephosphorylation at S109 by PP2A-B55δ. The G2 lock is achieved by high cAMP, high PKA activity and Arpp19 phosphorylation at S109. Arpp19 phosphorylation turns over due to PKA and PP2A-B55δ, with PP2A-B55δ being swamped by PKA. Upon PKA inhibition promoted by progesterone, Arpp19 is dephosphorylated at S109 by PP2A-B55δ and launches the signalling pathway that ends with Cdk1 activation. The targets of Arpp19 are still unknown. It could control the synthesis of new proteins required to activate Cdk1, such as Cyclin B1 or Mos