Figure 3.

Disassembly pathways of the CRM1 nuclear export complex in the cytoplasm. Upon translocation across the nuclear pore complex, CRM1-cargo-RanGTP complex would encounter Ran-binding domains (RanBDs) of either freely diffusing RanBP1 as depicted in this figure RanBP2 that is a major component of the cytoplasmic fibril of the nuclear pore complex. RanBD rapidly dissociates cargo from CRM1 and RanGTP by an active displacement mechanism. RanGAP-mediated GTP hydrolysis terminates the disassembly reaction. Alternatively, the dis assembly reaction could proceed without using RanBDs, but RanBD-accelerated dissociation of cargo from CRM1 and RanGTP is much faster than the spontaneous dissociation of cargo, and so the disassembly pathway using RanBDs is most likely the major pathway of disassembly in the cytoplasm.