Fig. (4).

The Hall model [20] of allosteric function whereby the effect of the modulator on agonist-induced (A) or spontaneously formed active state receptor is affected by binding of the modulator (B). Shaded squares represent the respective species measured in functional and binding experiments. The fact that these species are different for the assay types leaves open the possibility that different responses to allosteric modulators may be observed in these two different assay formats.