Fig. 1

Diagram of the interactions between acetylcholine (A), NDNB (D), and the postsynaptic receptor (R). The complexes formed by binding of ACh and NDNB to AChR are represented by 3-letter symbols, where the first and last letters denote the first and second ligands occupying the sites 1 and 2, respectively. The state ARA* represents the activated AChR