Figure 4.

Free energy difference induced by inserting an attractive cargo into the NPC. Binding spots were distributed on the cargo’s surface following the uniform distribution. (A) The mean segment density of FG-Nups with different binding surface area S and interfacial energy γ. The cross-sectional distribution at the center of the pore (top) and the three-dimensional distribution (bottom) are shown. Visualized in the three-dimensional distribution are density values above a certain threshold. The cargo diameter d_cargo is 20 nm. The reference binding area $S^{\ast }$ is the surface area of a cargo whose diameter is 20 nm. (B) The relation between the cargo diameter d_cargo and the free energy difference accompanying the cargo insertion, $\text{Δ}\overline{F}={\overline{F}}_{\text{cargo}}$ − F_empty. The effect of the interfacial energy γ and the binding surface area S are shown. The dashed line indicates $\text{Δ}\overline{F}$ = k_BT. The schematics show how the binding spot distribution changes as we increase the binding area S. (C) The relation between the nuclear pore diameter D_pore and the critical diameter of the cargo $d_{\text{cargo}}^{\text{∗}}$, which signifies the maximal cargo size whose free energy difference is less than the thermal energy ($\text{Δ}\overline{F}$ < k_BT).