Figure 8.

Time-dependence of receptor occupancy during the diffusion of irreversible ligands into the box synapse. This simulation used the parameters from Table 1, except that ${\ell }_{-}$ is set to 0 so that bound ligands do not dissociate. Fig. S6 shows the corresponding graphs for free ligands. (A) Unliganded (R) and liganded (RC) receptors as a function of time. The right hand axis indicates the fraction of liganded receptors. (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. The dashed lines indicate the fraction of liganded receptors for the synapse as a whole. Thus, when the overall receptor occupancy is 0.9, segments 5 and 6 have a receptor occupancy of 0.49 but receptors in the other segments are essentially fully occupied.