Polo-like kinase

Polo-like Kinase

File:Polo-like kinase logo.png

Polo-like kinase logo

Polo-like kinase (PLK) is a family of serine/threonine protein kinases that play crucial roles in cell cycle regulation and various cellular processes. They are named after their homology to the Drosophila melanogaster protein called Polo, which is involved in regulating cell division in flies. In humans, there are four known members of the PLK family: PLK1, PLK2, PLK3, and PLK4.

Discovery and Structure

The first member of the PLK family, PLK1, was discovered in the late 1990s and has since been extensively studied. PLK1 is composed of multiple functional domains, including a kinase domain responsible for phosphorylation, a polo-box domain involved in substrate recognition, and a C-terminal domain that regulates protein-protein interactions.

Functions

PLKs are primarily known for their roles in cell cycle regulation, particularly in mitosis. They are involved in various processes such as centrosome maturation, spindle assembly, chromosome segregation, and cytokinesis. PLKs also play important roles in DNA damage response, DNA replication, and cell survival.

Regulation

The activity of PLKs is tightly regulated to ensure proper cell cycle progression. They are subject to multiple levels of regulation, including phosphorylation, protein-protein interactions, and subcellular localization. PLKs are activated by phosphorylation of specific residues within their activation loops, and their activity is further modulated by interactions with other proteins and localization to specific cellular structures.

Clinical Significance

Due to their critical roles in cell cycle regulation, PLKs have emerged as potential targets for cancer therapy. Overexpression of PLK1 has been observed in various types of cancer, and its inhibition has shown promising results in preclinical and clinical studies. Several PLK inhibitors are currently being developed and tested as anticancer drugs.

See Also

• Cell Cycle
• Protein Kinase
• Mitosis
• Cancer Therapy