Nuclear import of proteins: putative import factors and development of in vitro import systems in higher plants

Nuclear import of proteins is a highly regulated, multi-step process in vertebrate and yeast cells. It is mediated by a variety of soluble factors and requires energy that is provided, at least partially, by the action of the small GTPase Ran. Recent efforts have led to the establishment of the first plant in vitro protein import systems. The data obtained indicate that the nuclear import machinery is highly conserved, but it appears that there are features that are unique to higher plants.