Role of the cytoskeleton in nucleocytoplasmic RNA and protein distributions.

Establishment and maintenance of correct partitioning of proteins and RNA molecules between nucleus and cytoplasm in a sine qua non of the viability of eukaryotic cells. Cytoskeletal elements play several roles in such partitioning: controlling the diffusion of proteins within the main cell compartments; presenting transportable macromolecular ligands to receptor sites within the pore complexes; maintaining the structure and dynamics of the pore complexes themselves. The solid-state transport machinery which moves mRNA molecules between particular sites in nucleus and cytoplasm is dependent on actin and other fibrils, and the migration of other major RNA types might show similar dependence. These various aspects of macromolecule partitioning illustrate one way in which the cytoskeleton is fundamental to the eukaryotic state.