FIG. 3.

σ1s contains a novel NLS (¹⁵RSRRRLK²¹) that is necessary and sufficient for nuclear import. L929 cells were transiently transfected with GFP-PK (A), GFP-σ1s-PK (B), GFP-No NLS σ1s-PK (C), or σ1s NLS-GFP-PK (D) and analyzed via digital florescence microscopy. Removal of the σ1s NLS from GFP-σ1s-PK resulted in significant (*) (P < 0.001) loss of nuclear localization (E) while addition of the σ1s NLS resulted in significant translocation to the nucleus (F). σ1s amino acids ¹⁵RSRRRLK²¹ comprise a previously undiscovered NLS.