Abstract: The invention provides methods of determining the presence of a nuclear localization signal and/or the presence of a nuclear export signal in a protein of interest. The invention further provides chimeric nucleic acids and recombinant host cells for use in such methods. Additionally provided is a nucleic acid molecule encoding a modified LexA protein, wherein the modified LexA protein has no nuclear localization signal, as well as the modified LexA protein itself. In the nuclear import assay, if a protein of interest fused to a mLexA-Gal4AD hybrid contains a functional NLS, the fusion product will enter the yeast cell nucleus and activate the expression of reporter genes. In the nuclear export assay, if a protein of interest fused to a mLexA-SV40 NLS-Gal4AD hybrid contains a functional NES, the fusion product localized to the cell nucleus will exit into the cytoplasm, decreasing the reporter gene expression levels.

Abstract: The invention provides a nuclear targeting molecule having a nucleic acid sequence which encodes a nuclear localization signal of a VirE2 protein of Agrobacterium, the nuclear localization signal of the VirE2 protein having a mutation therein which renders the nuclear localization signal of the VirE2 protein capable of targeting deoxyribonucleic acid into the nucleus of an animal cell. The invention further provides a plasmid for targeting a DNA molecule into the nucleus of a host cell. The plasmid comprises the nuclear targeting molecule and a DNA molecule to be targeted to a nucleus. This plasmid of the subject invention can be introduced into various host cells, and the nuclear targeting molecule will target the DNA molecule to the nucleus of the host cell. Thus, the invention further provides a method of targeting a DNA molecule into the nucleus of a host cell.