At the neuromuscular junction:

The nerve impulse is transmitted to the muscle across the neuromuscular synapse (also called the neuromuscular junction). The transmitter at the neuromuscular synapse is ACh. The ACh molecule binds to the postsynaptic ACh receptor, a complex of 5 proteins that constitute the postsynaptic ion channel. Binding of ACh by this receptor causes a conformational change in the receptor that leads to a local increase in the conductance of Na and K and other small ions. This produces a depolarization known as the endplate potential. The motor nerve endings secrete acetylcholine which activates nicotinic receptors of the muscle fiber membrane. Curare inhibits the nicotinic receptors and blocks neuromuscular transmission. The curariform drugs, derived from curare and termed nondepolarizing neuromuscular blockers, are the main examples; they do not alter the postsynaptic membrane potential. Ref: Ropper A.H., Samuels M.A. (2009). Chapter 45. Electrophysiologic and Laboratory Aids in the Diagnosis of Neuromuscular Disease. In A.H. Ropper, M.A. Samuels (Eds), Adams and Victor's Principles of Neurology, 9e.