Choline is a chemical with chemical formula

(CH₃)₃N⁺CH₂CH₂OH.

The neurotransmitter acetylcholine is converted into choline and acetic acid by the enzymes acetylcholinesterase. This happens typically in the juncture between a motor nerve cell and a muscle cell. Pseudocholinesterase, the other major form of cholinesterase, is also capable of breaking down acetylcholine.

Acetylcholine is synthesized from choline and acetate, a reaction catalyzed by the enzymes acetyl coenzyme A and choline acetyltransferase.