Esterase with broad substrate specificity. Contributes to the inactivation of the neurotransmitter acetylcholine. Can degrade neurotoxic organophosphate esters. an acylcholine + H2O = a carboxylate + choline + H(+) Inhibited by mercury. Inhibited by Tabun. Tabun forms a covalent adduct with Ser-226 that becomes irreversible upon aging. Homotetramer; disulfide-linked. Dimer of dimers. Detected in blood plasma (at protein level). Present in most cells except erythrocytes. N-glycosylated. No other PTM detected (PubMed:20946535). The major N-glycan structures are of the complex diantennary type with 1 and 2 N-acetylneuraminic acid molecules (Neu5Ac) making up approximately 33% and 47% of the total N-glycans, respectively. Only low amounts of fucosylated diantennary N-glycans are detected (approximately 2%). Triantennary N-glycans with or without fucose amount to approximately 13%, whereas 5% of the total N-glycans are of the oligomannosidic or hybrid type. The disease is caused by variants affecting the gene represented in this entry. Belongs to the type-B carboxylesterase/lipase family.