Figure 4.

Identification of a monopartite NLS present in SF3b¹⁵⁵. (Left) A schematic description of the analyzed constructs is shown. In SF3b¹⁵⁵-ΔNLS, the putative bipartite NLS (KRKRR(x)₁₃KK; amino acid residues 196–216) has been deleted, whereas in mutant SF3b¹⁵⁵-N²¹⁴N²¹⁵, the second basic cluster was modified by replacing the lysine residues with asparagine. In the fusion protein construct PK-NLS, amino acid residues 196–200 (first basic cluster) of protein SF3b¹⁵⁵ were fused in-frame to the cytoplasmic protein pyruvate kinase. (Right) The intracellular distribution of the corresponding proteins expressed in MCF-7 cells upon transient transfection was detected with the anti-myc antibody. Phase contrast (A, C, and E) and corresponding immunofluorescence micrographs (B, D, and F) are shown. Scale bar is 10 μm.