Taking from the cytoplasm and giving to the pore: soluble transport factors in nuclear protein import.

The past year has seen the publication of a number of papers describing the identification of cytosolic factors involved in import of proteins to the nucleus. Although, at first glance, this gives the impression that the study of nuclear transport has become extremely complicated, these factors in fact form a relatively small group of proteins that have been given different names. Characterization of these proteins is improving understanding of the nuclear import process and provides a starting point for further investigation of the steps that occur at the nuclear pore complex.