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Catalytic domain of the Serine/Threonine Kinases, Polo-like kinases STKs catalyze the transfer of the gamma-phosphoryl group from ATP to serine/threonine residues on protein substrates. PLKs play important roles in cell cycle progression and in DNA damage responses. They regulate mitotic entry, mitotic exit, and cytokinesis. In general PLKs contain an N-terminal catalytic kinase domain and a C-terminal regulatory polo box domain (PBD), which is comprised by two bipartite polo-box motifs (or polo boxes) and is involved in protein interactions. PLKs derive their names from homology to polo, a kinase first identified in Drosophila. There are five mammalian PLKs (PLK1-5) from distinct genes. There is good evidence that PLK1 may function as an oncogene while PLK2-5 have tumor suppressive properties. PLK1 functions as a positive regulator of mitosis, meiosis, and cytokinesis. PLK2 functions in G1 progression, S-phase arrest, and centriole duplication. PLK3 regulates angiogenesis and responses to DNA damage. PLK4 is required for late mitotic progression, cell survival, and embryonic development. PLK5 was first identified as a pseudogene containing a stop codon within the kinase domain, however, both murine and human genes encode expressed proteins. PLK5 functions in cell cycle arrest. |
Jiyao W et al.(2023). "The conserved domain database in 2023.",