Figure 4.

Spatial separation of Plk1 phosphorylation and activity. Proposed model for Plk1 activation during G2. Plk1 binds to its co-factor Bora and is subsequently activated at the centrosome on T210 by Aurora A. Activity of the T210-phosphorylated Plk1 is inhibited in the cytoplasm, possibly by Bora or by phosphatase activity directed at its substrates. T210-phosphorylated Plk1 then translocates to the nucleus where the inhibitory factors of Plk1 activity are absent and Plk1 starts phosphorylating its substrates. The contribution of nuclear Aurora A is currently unclear. Yellow and purple indicate high and low levels of Plk1 substrate phosphorylation, respectively. Red arrows indicate phosphorylation events. The “P” indicates phosphorylation of T210.