Fig. 7.

Phosphorylation of B55 by Cdk1 is conserved in humans. a Cdk1–CyclinB1 phosphorylates human B55. Kinase assays using recombinant human Cdk1–Cyclin B1 and B55 were performed. A representative image of one of the experiments is depicted. b Alignment of the budding yeast Cdc55 and human B55. Red boxes mark the conserved T174 and S301 in Cdc55. c Model of the Net1 phosphorylation and Cdc14 release regulated by downregulation of the PP2A^Cdc55 via phosphorylation of the regulatory subunit Cdc55. During metaphase, futile cycles of Cdk1–Clb2 phosphorylation and PP2A^Cdc55 dephosphorylation maintain low levels of phosphorylated-Net1. During anaphase, Cdc55 phosphorylation promotes the inactivation of the phosphatase activity of the PP2A^Cdc55 (indicated as black dashed lines) and, as a consequence, Net1 phosphorylation is increased and Cdc14 is released from the nucleolus