The Nucleus's Revolving Door

Work done over the past 2 years shows that cells have evolved a highly complex system, involving an intricate division of labor among a host of different proteins that are structurally related, for transporting large molecules such as proteins and mRNAs into and out of the nucleus. Recent work also indicates that a small protein called Ran acts as the dispatcher, coordinating the direction of transport and linking the various nuclear transport pathways with critical events in the life and death of the cell. Because critical processes such as cell division and protein synthesis depend on molecules that have to be carried into or out of the nucleus at exactly the right time, these new findings are causing more and more researchers to take notice of the pivotal role nuclear transport plays in the life of the cell.