This gradient arises from the exclusive nuclear localization of RanGEFs , proteins that exchange GDP to GTP on Ran molecules .
The import cycle is powered by the nucleo - cytoplasmic RanGTP gradient .
This gradient arises from the exclusive nuclear localization of RanGEFs , proteins that exchange GDP to GTP on RanGTP molecules .
The import cycle is powered by the nucleo - cytoplasmic RanGTP gradient .