Figure 2: Model parameters are obtained from poly-SUMO/poly-SIM dimerization experiments.

Plot of the dimer association constant, K_2v,⁶ vs. the valence, v. The module binding free energy, ϵ, is obtained from the slope of lnK_2v (blue line), while the intercept provides the reference concentration c₀. Clients (mono-, bi-, or trivalent SIM) have a lower binding affinity than scaffolds in the droplet phase, which we attribute to steric interactions between the network and the fluorescent labels. We account for this with a free energy offset, f_RFP, for clients in the dense phase (purple line).