Polo-like kinase

Polo-like kinases (Plks) are important regulators of the cell cycle. Plks are involved in the formation of and the changes in the mitotic spindle and in the activation of CDK/cyclin complexes during M-phase of the cell cycle.Polo-like kinases (Plks) are a family of conserved serine/threonine kinases involved in the regulation of cell cycle progression through G2 and mitosis. Mammalian polo-like kinases include Plk1 (Xenopus Plx1), Plk2/Snk (Xenopus Plx2), Plk3/Prk/FnK (Xenopus Plx3) and Plk4/Sak. Most species have only one form of Plk; Drosophila (Polo), Schizosaccharomyces pombe (Plo1) and Saccharomyces cerevisiae (Cdc5). Polo-like kinases are involved in aspects of mitosis that include mitotic entry and exit and cytokinesis.

Structure
The catalytic domain of polo-like kinases is located in the N-terminus. The C-terminus of Plks contains one or two motifs known as polo boxes that help localize the kinase to specific mitotic structures during mitosis. These include the centrosomes in early M phase, the spindle midzone in early and late anaphase and the midbody during cytokinesis.

Cell Cycle Regulation
Plks mediate G2/M transitions, activation of cdc25 and mitotic processes including centrosome maturation, bipolar spindle formation, activation of the anaphase-promoting complex (APC), chromosome segregation, and actin ring formation (cytokinesis). Plk1 is involved in the regulation of key steps during cell division, DNA damage repair pathways, apoptosis, and the progression of the cell cycle. Plk3 is a multifunctional stress response protein that responses to signals induced by DNA damage and/or mitotic spindle disruption.

Substrates
Plk3 substrates include Chk2 and p53.

Described and named in 1993.