Terminates signal transduction at the neuromuscular junction by rapid hydrolysis of the acetylcholine released into the synaptic cleft. acetylcholine + H2O = acetate + choline + H(+) Interacts with PRIMA1. The interaction with PRIMA1 is required to anchor it to the basal lamina of cells and organize into tetramers (By similarity). Isoform H generates GPI-anchored dimers; disulfide linked. Isoform T generates multiple structures, ranging from monomers and dimers to collagen-tailed and hydrophobic-tailed forms, in which catalytic tetramers are associated with anchoring proteins that attach them to the basal lamina or to cell membranes. In the collagen-tailed forms, isoform T subunits are associated with a specific collagen, COLQ, which triggers the formation of isoform T tetramers, from monomers and dimers. Belongs to the type-B carboxylesterase/lipase family.