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Catalytic domain of the Serine/Threonine Kinase, Polo-like kinase 4 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. There are five mammalian PLKs (PLK1-5) from distinct genes. PLK4, also called SAK or STK18, is structurally different from other PLKs in that it contains only one polo box that can form two adjacent polo boxes and a functional PDB by homodimerization. It is required for late mitotic progression, cell survival, and embryonic development. It localizes to centrosomes and is required for centriole duplication and chromosomal stability. Overexpression of PLK4 may be associated with colon tumors. The PLK4 subfamily is part of a larger superfamily that includes the catalytic domains of other STKs, protein tyrosine kinases, RIO kinases, aminoglycoside phosphotransferase, choline kinase, and phosphoinositide 3-kinase. |
Jiyao W et al.(2023). "The conserved domain database in 2023.",