Fig. 4. Profile of volume fraction ϕ_r of pre-rRNA units in DFC layer.

The volume fraction of nascent pre-rRNA units is shown as a function of the position $r$ in the DFC layer ($r_{\mathrm{in}}<r<r_{\mathrm{ex}}$). The solid dark green line is derived by numerically calculating Supplementary Equations (S13), (S15), and (S16) for $\zeta =0.06$ with the condition that the volume fraction of solvent is zero and the occupancy of the terminal regions of pre-rRNAs by RBPs is unity. The values of other parameters are summarized in Table 1. The broken light green line is derived by using Supplementary Equation (S59) with ${\varphi }_{\mathrm{ex}}=0.0157$ and $r_{\mathrm{ex}}=1.98$ (which were derived from the numerical calculation to obtain the light green line). The volume fraction of freely diffusing RBPs is shown in the inset.