Summary of human AChR-binding constants. Left: Equilibrium constants. For all ACh-class agonists, resting- and active-state–binding energies are greater at the fetal α−γ site than at the adult α−ε and α−δ sites. Right: Rate constants. For all agonists, association to R is slower than diffusion (dashed line, 5 × 10⁹ M⁻¹s⁻¹) and greatest at α−γ. Dissociation rate constants are similar for all agonists and at all sites.