Polo, greatwall, and protein phosphatase PP2A Jostle for pole position

In the majority of cases, Plk1's PBD binds to a phosphorylated motif in which the phosphorylation site matches the MPF consensus sequence. [...]Polo must usually wait for targets to be phosphorylated by MPF before it can impose its authority [4]. Rim15, the budding yeast Greatwall kinase, phosphorylates yeast Endosulfine (and human Ensa and Arpp19) at the equivalent site to the Xenopus kinase, and yeast phospho-Endos subsequently binds components of a ribosome-associated protein complex to control mRNA stability [15]. [...]it is plausible that phospho-Endos/Arrp19 may yet be found to target molecules other than PP2A in cell cycle control in other systems. [...]the introduction of Scant into Xenopus Greatwall increases its interphase activity and promotes premature commitment to mitosis [19].