Table A1. Summary of all parameters used in the present paper

α	Proportionality factor between effect (response) and active receptors in linear models (e.g., Clark equation, eq. 7; minimal two‐state model, eq. 16)
ε	Efficacy parameter for the present model (eq. 28)
γ	Gain (amplification) parameter for the present model (γ = Rtot/K γ, eq. 29 and 30)
k 1, k –1	Rate of forward reaction or backward reaction (law of mass action, eq. 1, 2)
K d	Equilibrium dissociation constant of the receptor binding; defined by eq. 2 for Langmuir‐Hill and Clark equations, eq. 12 for minimal two‐state model, and eq. 23 for present model)
K γ	Constant for the hyperbolic response function of the present model (eq. 27)
K i	Equilibrium dissociation constant for an inhibitor (Gaddum equation, eq. A2)
K obs	Apparent (observed) K for the effect (response), that is, EC50
K τ	Constant for the hyperbolic response function of the operational model (eq. 18)
n	Hill slope (see eq. 10)
Rtot	Total maximum number (concentration) of receptors in the system.
τ	Efficacy parameter in the minimal two‐state model, τ (mtsm) = [LR*]/[LR] (eq. 13) and in the mathematically equivalent operational model, τ (om) = [Rtot]/K τ (eq. 19)