ИСТИНА

At-4/1 protein has been identified as an Arabidopsis thaliana polypeptide of unknown function capable of interaction with a plant virus movement protein involved in cell-to-cell transport of viral infection. At-4/1 protein has been shown to accumulate in the cytoplasm of plant cells in a polar fashion and to move through plasmodesmata to neghbouring cells. Here we report isolation of Nt-4/1 gene, the 4/1 gene from tobacco (Nicotiana tabacum), and subcelullar localization of the encoded protein as well as its structural properties. The Nt-4/1 protein fused to GFP, as it was previously described for At-4/1-GFP fusion protein, localizes in numerous small vesicular structures dispersed throughout the cytoplasm and, in addition, in the cell nucleus. Dynamic laser light scattering analysis revealed that the bacterially expressed Nt-4/1 protein can form dimers and trimers in vitro. Analysis of circular dichroism spectra of the Nt-4/1 protein demonstrated that it has a pronounced alpha-helical secondary structure. Using differential scanning calorimetry we revealed at least three calorimetric domains in the Nt-4/1 molecule.