Dynamic stability of the interphase nucleus in health and disease

Ongoing export of newly synthesized RNAs, as well as control of transcripti onal activity, involves dynamic nucleocytoplasmic transport of proteins. So me proteins that shuttle reside primarily in the nucleus while others are c oncentrated in the cytoplasm. Moreover, some proteins shuttle continuously, while others shuttle only once. A third group is stimulated to relocate ei ther into or out of the nucleus as a result of interruption of shuttling. I n addition to these protein-specific events, several physiological stimuli have global effects on nucleocytoplasmic transport. In related events, sele cted proteins move between distinct sites in the nucleoplasm, others enter and leave the nucleolus, and still others transit between the nuclear envel ope and cytoplasmic membranes. These multiple dynamic distributions provide numerous opportunities for precise communication between spatially distant sites in the cell. (C) 2000 Academic Press.