
Fig. 10. A model for the action of Mog1-related proteins and RanBP1 on guanine
nucleotide exchange on Ran. When RanBP1 is present, Mog1 destabilises GDP
binding to Ran to form a transient, nucleotide-free complex. RanBP1 promotes
GTP loading by stabilising the GTP-conformation. RCC1 catalyses guanine
nucleotide exchange by increasing the rate at which equilibrium is acheived.
Thus, Mog1 and RanBP1 together alter the equilibrium of the reaction to favour
the formation of Ran-GTP.