Cholinesterase

acetylcholinesterase (Yt blood group)
Diagram of Pacific electric ray acetylcholinesterase. From PDB: 1EA5​.
Identifiers
Symbol	ACHE
Alt. symbols	YT
NCBI gene	43
HGNC	108
OMIM	100740
RefSeq	NM_015831
UniProt	P22303
Other data
EC number	3.1.1.7
Locus	Chr. 7 q22
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butyrylcholinesterase
Cartoon diagram of human butyrylcholinesterase. From PDB: 1P0I​.
Identifiers
Symbol	BCHE
Alt. symbols	CHE1, CHE2, E1
NCBI gene	590
HGNC	983
OMIM	177400
RefSeq	NM_000055
UniProt	P06276
Other data
EC number	3.1.1.8
Locus	Chr. 3 q26.1-26.2
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The enzyme cholinesterase (EC 3.1.1.8, choline esterase; systematic name acylcholine acylhydrolase) catalyses the hydrolysis of choline-based esters:

an acylcholine + H₂O = choline + a carboxylate

Several of these serve as neurotransmitters.^[1] Thus, it is either of two enzymes that catalyze the hydrolysis of these cholinergic neurotransmitters, such as breaking acetylcholine into choline and acetic acid.^[1] These reactions are necessary to allow a cholinergic neuron to return to its resting state after activation. For example, in muscle contraction, acetylcholine at a neuromuscular junction triggers a contraction; but for the muscle to relax afterward, rather than remaining locked in a tense state, the acetylcholine must be broken down by a choline esterase. The main type for that purpose is acetylcholinesterase (also called choline esterase I^[2] or erythrocyte cholinesterase); it is found mainly in chemical synapses and red blood cell membranes. The other type is butyrylcholinesterase (also called choline esterase II^[2] or plasma cholinesterase); it is found mainly in the blood plasma.