Figure 4.

Stimulation of GTP hydrolysis by wild-type Ran but not E1-Ran, by full-length and carboxyl-terminal-deleted (c-del) RanGAP1 proteins. Recombinant wild-type Ran·[γ-³²P]GTP (∼1 μM) was incubated with GST-RanGAP1 (A, ∼0.01 μM, ○ or GST-c-del RanGAP1 (0.15 μM, ▪), GST-RanGAP1 (B, ∼0.01 μM) alone (▪) or GST-RanGAP1 (∼0.01 μM) plus GST-RanBP1 (0.5 μM, ○), and GST-c-del RanGAP1 (C, ∼0.15 μM) alone (▪) or GST-c-del RanGAP1 (∼0.15 μM) plus GST-RanBP1 (0.5 μM, ○). (D) E1-Ran·[γ-³²P]GTP (∼1 μM) was incubated with either GST (5.0 μM, ▪), GST-RanGAP1 (∼0.01 μM, ▴), or GST-c-del RanGAP1 (0.15 μM, ○). At the indicated times, the percentage of ³²P still bound to Ran was determined (see MATERIALS AND METHODS).