Abstract
In the nuclear pore complex (NPC), intrinsically disordered nuclear pore proteins (FG nups) form a selective barrier for transport into and out of the cell nucleus, in a way that remains poorly understood. The collective FG nup behaviour has long been conceptualized either as a polymer brush, dominated by entropic and excluded-volume (repulsive) interactions, or as a hydrogel, dominated by cohesive (attractive) interactions between FG nups. Here we compare mesoscale computational simulations with experimental data to demonstrate that FG nups are at the crossover point between these two regimes. Specifically, we find that repulsive and attractive interactions are balanced, resulting in morphologies and dynamics that are close to those of ideal polymer chains, where repulsion and attraction are absent. We demonstrate that this yields sufficient cohesion to seal the transport barrier, and yet maintains fast dynamics at the molecular scale, permitting the rapid FG nup rearrangements needed for transport events.
