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.

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