Fig. 6.
Simulated stimuli (a and b) and agonist concentration-response curves (c) for the condition of a transducer slope factor greater than 1 (m = 1.8). The stimuli were generated using eq. 30 under Appendix with the concentration of guanine nucleotide set to a high value (X = 1.0 mM). The stimulus was then used as input to the operational model (eq. 1) to yield the response as a function of the agonist concentration. The affinity constants of the agonists (A–G) for the inactive state of the receptor were the same (Ka = 105 M−1). Those for the active state (Kb) were 3 × 1010, 3 × 109, 3 × 108, 108, 3 × 107, 107, and 3 × 106, respectively, as indicated by the Kb/Ka ratios in a and b. The other parameters were the same as those given in the legend to Fig. 3 except that the value of the transducer slope factor in the operational model (m) was 1.8. The basal response caused by constitutive receptor activity was only 0.011% for this simulation.