Fig. 2. Interaction of SRP19 with nuclear transport receptors. Recombinant SRP19 and rpL23a, fused to two tandem z-tags (IgG-binding domain of protein A), were immobilized on IgG-sepharose and tested for binding of transport receptors from a HeLa cell extract. Where indicated, 10 µM RanQ69L[GTP] was added. RanQ69L is a GTPase-deficient Ran mutant that remains GTP-bound in the presence of cytoplasmic Ran GTPase-activating protein (RanGAP1) (Bischoff et al., 1994). After extensive washing, bound proteins were eluted, precipitated, and analyzed by SDS-PAGE, followed by immunoblotting with specific antibodies (top) or by Coomassie blue staining (bottom). Load in the bound fractions corresponds to 15x the starting material.
