Figure 2.

Time dependence of receptor occupancy during the onset phase of buffered diffusion. The standard parameters (Table 1) were used in this simulation. Ligands bind to a single site on each of the 2 × 10⁴ receptors. The ligand concentration external to the synapse was clamped at 15 × L_eq so that at equilibrium, only 6.25% of the receptors were unliganded. The simulation was run using a time step of 0.25 μs; traces show points at 1 ms intervals. Fig. S1 shows the corresponding graphs for free ligands. (A) Unliganded (R) and liganded (RC) receptors as a function of time. (B) Unliganded (R) receptors as a function of time within the different segments of the box synapse. Segments 1 and 10 are nearest to the clamped surface.