 Once in the cytoplasm, Ran-GTP is hydrolysed by RanGAP, forming Ran-GDP, and releasing the two importins for further activity.It is this hydrolysis of GTP that provides the energy for the cycle as a whole.In the nucleus, a GEF will charge Ran with a GTP molecule, which is then hydrolysed by a GAP in the cytoplasm, as stated above.