Simulating PLCγ1’s effect on LAT cluster size and bond type. (A) The effect of PLCγ1 on LAT clustering is independent of LAT density ρ_LAT. Coarse-grained model simulating LAT clustering as a function of PLCγ1 concentration. In a wide range of LAT densities tested, PLCγ1 regulates LAT clustering in a nonmonotonic manner. LAT clusters are quantified by the number of LAT in each cluster (solid line) or the total number of molecules (LAT, Grb2, PLCγ1, or Sos1) in each cluster (dashed line, scaled down by a factor of 4 to fit in the same plot). Surface densities ρ_LAT are in units of σ⁻², where σ is the diameter of a particle, of the order of a few nanometers, and our experiments correspond roughly to ρLAT = 0.02σ⁻² (see Materials and methods and Simulation details). Shown are mean ± SEM. (B) Average coordination number for all four kinds of particles, as a function of ratio of PLCγ1:LAT, broken down to the contribution of each specific bond. Yellow-orange bars represent bonds involving PLCγ1, and blue bars, Grb2; a gray background represents bonds involving LAT, and a pink background, Sos1. Here, as throughout Fig. 6, ρ_LAT = 0.02 σ⁻². See Simulation details, section SI 3, for a complete analysis. Shown are mean ± SEM.