Nuclear import of DNA in digitonin-permeabilized cells

DNA can enter intact mammalian nuclei with varying degrees of efficiency in both transfected and microinjected cells, yet very little is known about the mechanism by which it crosses the nuclear membrane. Nucleocytoplasmic transport of fluorescently labeled DNA was studied using a digitonin-permeabilized cell system. DNA accumulated in the nucleus with a punctate staining pattern in over 80% of the permeabilized HeLa cells. Nuclear localization of the labeled DNA was energy dependent and occurred through the nuclear pore, but did not require the addition of soluble cytoplasmic protein factors necessary for protein import.