Figure 4.

Characterization of the binding of ΔIBB-importin α to Tpr and demonstration of different binding sites for ΔIBB-importin α and importin β on Tpr. Panel A: Increasing concentrations of ΔIBB-importin α were incubated with immobilized Tpr or C-Tpr and the bound ΔIBB-importin α was quantified as described in materials and methods. The data were analyzed as described in Fig. 1. Panel B: The binding of 60 nM importin β to Tpr pre-adsorbed to microtiter wells was analyzed in the absence of ΔIBB-importin α or in the presence of 60, 120, 300 and 600 nM ΔIBB-importin α, as indicated. Bound importin β and ΔIBB-importin α were quantified as described in Materials and Methods.