FIGURE 2.

Mechanical unbinding of single impβ-Ran pairs. Ran and impβ were immobilized onto AFM cantilevered tip and mica, respectively, through short polymer (PEG) linkers as described in Nevo et al. (2003). The tip was then repeatedly brought to and retracted from the surface, and the interaction force was measured by following the cantilever deflection, using the AFM setup. The trace shows a representative force-distance cycle recorded (at 5 Hz) for RanGDP-impβ in the presence of RanBP1. Unbinding is indicated by the sharp spike in the retraction curve; the parabolic delay antecedent the spike reflects the extension of the polymer linkers.