FIGURE 6.

Binding of the Swap (A) and HEAT 9 loop (B) CRM1 variants to immobilized GST-PKI NES. Both wild type CRM1 (1–1071) and the CRM1-Swap variant bound to GST-PKI NES with a lower affinity than the tip deletion variant (1–1062). The addition of RanGTP significantly increased the affinity of wild type and CRM1-Swap for the NES. The HEAT 9 loop variant binds the NES with a higher affinity than wild type CRM1 in the absence of RanGTP, and the binding is comparable with that seen for the variant that combines the C-terminal helix tip deletion and HEAT 9 loop mutation. The variants all bound to the GST control with similar affinity (lower panel).