FIG. 8.

Ran-RanBP1 interaction. (A) Dissociation of the Ran-GDP-RanBP1 complex after adding excess Ran-GDP. Ran94-GDP-RanBP1 (6 μM) was mixed at a 1:1 ratio (vol/vol) with 250 μM RanBP1 in the stopped-flow apparatus. Fitting the curve to a single exponential yields a dissociation rate (k_off) of 0.06 s⁻¹. (B) Association of Ran-GDP and RanBP1. Ran94-GDP (1 μM final concentration) was mixed with increasing concentrations of RanBP1 in the stopped-flow apparatus. Kinetics were analyzed assuming pseudo-first-order conditions. The apparent rate constants were plotted against [RanBP1] to yield the results k_on = 0.08 μM⁻¹ s⁻¹ (slope) and k_off = 0.1 s⁻¹ (intercept). Measurements were performed and analyzed as described in Materials and Methods.