Abstract
Cytokinesis is the final critical step in the generation of two daughter cells that contain a full complement of genomic components and cytoplasmic organelles. Cytokinesis of plant cells occurs in phragmoplast, a cytokinetic machinery, that is mainly consist of bundles of microtubules (MTs) and microfilaments. The NACK-PQR pathway that includes kinesin-like protein NACK and the MAP kinase cascade is a key regulator for such cytokinesis. The pathway is activated after metaphase of M phase, induces dynamic instability of MTs and stimulates phragmoplast expansion (Sasabe et al., Genes & Dev., 2006). The activation is initiated by binding of NACK to NPK1 MAPKKK in the cascade. We here report that phosphorylation of NACK and NPK1 by CDK interferes binding of these two proteins before metaphase and that dephosphoraylation induces the binding and activates the pathway. CDK may be a major regulator that represses functions of factors controlling progressions of cytokinesis after metaphase.
