Regulation of nucleocytoplasmic trafficking in plants

The timing and position of molecular components within the cell are clearly important in the context of signal transduction. One challenge in attaining correct cellular positioning is the nuclear envelope, which separates the cell into two fundamentally different compartments. Molecular passaging from one to the other is highly selective due to the required recognition by the nucleocytoplasmic transport machinery. It is becoming increasingly clear that a highly diverse set of mechanisms have developed to allow environmental (biotic and abiotic) and endogenous signals to alter the nucleocytoplasmic partitioning of key molecules. In many cases this occurs by adjusting the access of the regulated species to the canonical import/export machinery. Recent studies are uncovering the sophistication and complexity of the processes that use the canonical transport machinery in the service of a diversity of signaling pathways.

► Proper nucleocytoplasmic partitioning of core components is critical to signal transduction.
► We highlight novel and representative mechanisms that control import/export in diverse processes.
► Mechanisms include NLS/NES masking or exposure, piggybacking, proteolytic release and redox regulation.
► The molecular basis of temperature-regulated partitioning is an emerging new area.
► Hormone signaling relies on cytoplasmic retention by 14-3-3 proteins.