Nucleocytoplasmic transport

The nucleus and cytoplasm in eukaryotes are physically separated throughout interphase. The two compartments differ markedly in composition and function, but constant communication between them is a precondition for the survival of the cell; therefore molecular traffic across the nuclear envelope must be precisely choreographed. Modulation of this traffic might play a role in regulating some cellular activities. Indeed, the obvious sites of exchange, the nuclear pore-complexes, can adopt 'open' or 'closed' forms, and some transport-related activities are sensitive to endogenous nuclear envelope protein kinases that respond to hormonal and other signals. Moreover, nucleo-cytoplasmic transport processes change qualitatively and quantitatively during development, aging and carcinogenesis. A process that is fundamental to the eukaryotic state, and is likely to play a significant role in cell regulation, is inherently interesting; so it is not surprising that nucleo-cytoplasmic transport has been the subject of a good deal of research over the past few years. During the past decade, the application of molecular-biological and other techniques to the study of nucleocytoplasmic transport has led to advances in two particular areas: (1) the biochemistry of the pore-complex and of its interactions with transported macromolecules; and (2) identification of factors responsible for the accumulation of particular molecular species in one or other compartment.