Fig. 2.

CaMKII directly phosphorylates Emi2 as a priming kinase to induce association of Plx1 with Emi2. (A) Ca²⁺ addition to CSF extract induces Plx1/Emi2 association. An MBP fusion of the Emi2 N terminus (or MBP alone) was incubated in CSF extract for five min with or without Ca²⁺ addition and with or without 281–309 peptide. Recombinant protein was purified on amylose resin, and associated Plx1 was detected by immunoblotting. (B) Emi2 binds the PBD of Plk1 after phosphorylation by CaMKII. Indicated MBP proteins were phosphorylated in vitro with CaMKII, Cdc2, or mock treatment, incubated with a GST fusion of the Plk1 PBD, and purified on amylose resin. Captured proteins were detected by Coomassie stain.