T-DNA nuclear import is a central event in genetic transformation of plant cells 
by Agrobacterium. This event is thought to be mediated by two bacterial 
proteins, VirD2 and VirE2, which are associated with the transported T-DNA 
molecule. While VirD2 is imported into the nuclei of plant, animal and yeast 
cells, nuclear uptake of VirE2 occurs most efficiently in plant cells. To 
understand better the mechanism of VirE2 action, a cellular interactor of VirE2 
was identified and its encoding gene cloned from Arabidopsis. The identified 
plant protein, designated VIP1, specifically bound VirE2 and allowed its nuclear 
import in non-plant systems. In plants, VIP1 was required for VirE2 nuclear 
import and Agrobacterium tumorigenicity, participating in early stages of T-DNA 
expression.