Catalytic domain of the Serine/Threonine Kinase, Plant B-type Cyclin-Dependent protein Kinase
STKs catalyze the transfer of the gamma-phosphoryl group from ATP to serine/threonine residues on protein substrates. The plant-specific B-type CDKs are expressed from the late S to the M phase of the cell cycle. They are characterized by the cyclin binding motif PPT[A/T]LRE. They play a role in controlling mitosis and integrating developmental pathways, such as stomata and leaf development. CdkB has been shown to associate with both cyclin B, which controls G2/M transition, and cyclin D, which acts as a mediator in linking extracellular signals to the cell cycle. CDKs belong to a large family of STKs that are regulated by their cognate cyclins. Together, they are involved in the control of cell-cycle progression, transcription, and neuronal function. The CdkB 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.