Regulation of cyclin-dependent kinases in Arabidopsis thaliana

In plants, different families of cyclin-dependent kinases (CDKs) and cyclin s have been identified, indicating that also in plants the progression thro ugh the cell cycle is regulated by CDKs. In all eukaryotes, CDKs exert thei r activity through well-controlled phosphorylations of specific substrates on serine/threonine residues. Such post-translational modifications are uni versal mechanisms in signal transduction pathways. They allow the organism to differentiate, regulate growth and/or adapt to environmental changes, th e latter being crucial for plants because of their sedentary life-style. Th is adaptation might explain the occurrence of a special CDK type with plant -specific features. This review focuses on the involvement of plant CDKs in different phases of the cell cycle in Arabidopsis thaliana and outlines th eir regulation by binding to other proteins, and by phosphorylation and dep hosphorylation.