Terminates signal transduction at the neuromuscular junction by rapid hydrolysis of the acetylcholine released into the synaptic cleft. acetylcholine + H2O = acetate + choline + H(+) Homotetramer; composed of disulfide-linked homodimers. Interacts with PRIMA1. The interaction with PRIMA1 is required to anchor it to the basal lamina of cells and organize into tetramers (By similarity). Synapses usually contain asymmetric molecules of cholinesterase, with a collagen-like part disulfide-bonded to the catalytic part. A different, globular type of cholinesterase occurs on the outer surfaces of cell membranes, including those of erythrocytes. This is the catalytic subunit of an asymmetric or soluble form of ACHE. Belongs to the type-B carboxylesterase/lipase family.