A GTPase Controlling Nuclear Trafficking: Running the Right Way or Walking RANdomly?  Deanna M Koepp, Pamela A Silver  Cell  Volume 87, Issue 1, Pages 1-4 (October 1996) DOI: 10.1016/S0092-8674(00)81315-X

Figure 1 Localization of Ran Effectors The compartmentalization of its regulators indicates that Ran moves between the cytoplasm and the nucleus. See text for details. Cell 1996 87, 1-4DOI: (10.1016/S0092-8674(00)81315-X)

Figure 2 Models for Nuclear Protein Import (A) Movement of the nuclear transport complex through a “gate” in the diffusion ratchet model. When Brownian motion places the transport complex inside the nucleus, Ran-GTP dissociates the complex, releasing importin α and the NLS substrate into the nuclear interior. (B) One dimensional diffusion of the nuclear transport complex (NTC) along cytoplasmic fibers that extend from the NPC could explain movement of the NTC to the pore. At the nuclear end of the fiber, translocation of the NTC into the nucleus occurs as a result of the dissociation of the NTC by Ran-GTP. (C) Alternatively, the NTC could move through the NPC using repeated rounds of GTP hydrolysis. Cell 1996 87, 1-4DOI: (10.1016/S0092-8674(00)81315-X)

Figure 3 Model for Transport Factor Cycling Nuclear transport factors cycle between the nucleus and the cytoplasm in order to promote multiple rounds of transport. See text for details. Cell 1996 87, 1-4DOI: (10.1016/S0092-8674(00)81315-X)