FIGURE 10.

An illustration for the dependence of E% on D:A ratio and the local density parameter s. The shaded circle represents a donor-labeled reference disk. Solid circles marked A or D represent acceptor-labeled or donor-labeled ligand-receptor complexes, and unfilled circles represent unknown proteins or absence of protein. (A–B) Perfect cluster model, Eq. A3 with s = 1, and D:A = 0.5 (A) and D:A = 2 (B), respectively. (C–D) The fixed local density model, Eq. A3 with s = 1/2, and D:A = 0.5 (C), and D:A = 2 (D), respectively. E% decreases with increasing D:A ratio (left to right) and decreasing local density s (top to bottom), since fewer acceptors are available to the reference donor.