Cytoplasmic Linker Protein-Associating Protein at the Nexus of Hormone Signaling, Microtubule Organization, and the Transition From Division to Differentiation in Primary Roots.

The transition from cell division to differentiation in primary roots is dependent on precise gradients of phytohormones, including auxin, cytokinins and brassinosteroids. The reorganization of microtubules also plays a key role in determining whether a cell will enter another round of mitosis or begin to rapidly elongate as the first step in terminal differentiation. In the last few years, progress has been made to establish connections between signaling pathways at distinct locations within the root.

The Microtubule-Associated Protein CLASP Sustains Cell Proliferation through a Brassinosteroid Signaling Negative Feedback Loop.

The capacity for sustained cell division within the plant meristem is a critical determinant of organ structure and performance. This capacity is diminished in mutants lacking the microtubule-associated protein CLASP and when brassinosteroid signaling is increased. Here, we discovered that CLASP is both targeted by and promotes activity of the brassinosteroid pathway in Arabidopsis root apical meristems.

The ARM Domain of ARMADILLO-REPEAT KINESIN 1 is Not Required for Microtubule Catastrophe But Can Negatively Regulate NIMA-RELATED KINASE 6 in Arabidopsis thaliana.

Microtubules are dynamic filaments, the assembly and disassembly of which are under precise control of various associated proteins, including motor proteins and regulatory enzymes. In Arabidopsis thaliana, two such proteins are the ARMADILLO-REPEAT KINESIN 1 (ARK1), which promotes microtubule disassembly, and the NIMA-RELATED KINASE 6 (NEK6), which has a role in organizing microtubule arrays. Previous yeast two-hybrid and in vitro pull-down assays determined that NEK6 can interact with ARK1 through the latter protein's Armadillo-repeat (ARM) cargo domain.