[2] Plks are controlled at the level of protein synthesis and degradation, by the action of upstream kinases and phosphatases, and by localization to specific subcellular structures.
[5] This means that in the absence of a phosphorylated ligand, the PBD interacts with the catalytic domain thereby preventing substrate binding or kinase activation.
Occupancy of the PBD by an exogenous phosphopeptide ligand would then cause the release of the catalytic domain, which, together with phosphorylation on the T-loop, converts Plk to the active form.
[6] On exit from mitosis, Plks are proteolytically degraded through the ubiquitin-proteasome pathway after coming in contact with the ubiquitin-ligase Anaphase Promoting Complex (APC).
Plo1 (the Plk found in fission yeast) is part of a positive-feedback loop that controls the expression of genes that are required for cell division.
[13] Impairment of Plk function generally interferes with the normal onset of anaphase, indicating that Plks contribute to the control of APC activity.
[14] Cdc5 (Plk found in budding yeast) directly phosphorylates the meiotic cohesin and promotes its dissociation from the chromosome arms to allow for recombination but not from the centromeric region in meiosis I.
[17] Recent studies on the role of mammalian Plk1 in cytokinesis have also identified kinesin-related motor Mklp2 and dynein subcomponent NudC as potential substrates of Plk1 that interact with the PBD.
PLK1 has been found to phosphorylate the centralspindlin subunit CYK4 at the spindle midzone, thereby allowing the recruitment of the Rho guanine nucleotide-exchange factor (GEF) ECT2 to promote RhoA activation and thus actomyosin contraction of the ring.