Fig. 1. (A) Simplified representation of the NPC, showing approximate locations of nups within the pore. The disordered FG nups extend through the pore and collectively make up the permeability barrier. Reproduced with permission from Hoelz et al. (2011) ©Annual Reviews.1 (B and C) Show different proposed models for the nature of this barrier. (B) Has more freely fluctuating polymers, as in the virtual gate model, which would maintain a permeability barrier through entropic exclusion. (C) Is the selective phase model, where the polymers interact to form a highly crosslinked gel, forming an energetic barrier to transport. Reproduced from Hülsmann et al. (2012) with permission. Copyright ©Elsevier (2012).2 .
