PLK2

Polo-like kinases (Plks) are a family of highly conserved silk/threonine protein kinases, including four family members, Plk1, Plk2, Plk3, and Plk4. Plks are widely found in eukaryotes and plays a key role in cell cycle regulation. Polo-like kinase 2 (P1k2, also known as a serine-inducible kinase, Snk) is a serine-threonine protein kinase that is induced by activity. PIk2 is called Polo-like kinase 2 because its C-terminus contains the polo box domain, which is a kinase domain and is a component of PIk2 interacting with its substrate. One of the proteins that bind to PIk2 is SPAR, a post-synaptic molecule, and a Rap/GAP (Rap GTPase activating protein). It contains the GAP domain and the Actin-binding domain, which binds to the post-synaptic backbone protein PSD95, allowing SPAR to enter the postsynaptic dense plaque.
Plk2 belongs to the G1 phase of Plks and controls cells to enter the S phase, similar in structure to other family members such as two highly conserved domains, the N-terminal silk/threonine protein kinase catalytically active domain and the C-terminal polo box, horse. The box and its flanking regions form a highly homologous C-terminal functional domain called the polo-box domain (PBD). PBD, as a single-mode phosphorylation serine-binding domain, inhibits the basal activity of the kinase domain in the absence of a binding substrate. PBD binds to a phosphorylated silk/threonine pedestal to open the kinase domain, and PBD binds to the pedestal to target the kinase to specific subcellular locations and their substrates, thereby regulating protein function.