Choline acetyltransferase

What is the synthetic pathway for acetylcholine?

Answer: The neurotransmitter molecule acetylcholine is synthesized by the enzyme choline acetyltransferase (ChAT).

choline acetyltransferase enzyme reaction

Acetylcholine (ACh) is one of most significant neurotransmitters in the brain. It is used for signaling between neurons. It also functions to send information from the nervous system to the muscles, as well as the internal organs.

Acetylcholine is produced by specific neurons that express the enzyme choline acetyltransferase (ChAT). This enzyme serves to move an acetyl- group from the molecule acetyl-CoA to the molecule choline. The chemical formula for an acetyl group is CH3CO-. The enzyme itself has two binding sites: The binding site for the choline molecule is inside the enzyme, while the binding site for acetyl-CoA is on the surface. A shift in conformation allows the molecules to come together, which forms the acetylcholine molecule.

Choline acetyltransferase is expressed most heavily in the terminal boutons, at the end of the axon. Here, ChAT serves to create more acetylcholine for packaging into synaptic vesicles for release.

The presence of choline acetyltransferase is a reliable marker for a cholinergic neuron. Staining for ChAT is very robust in a few brain regions, particularly in the basal nucleus of Meynert and the brain stem cholinergic centers such as the pedunculopontine tegmental nucleus (PPTg).

After acetylcholine is released, it is rapidly degraded by the enzyme acetylcholinesterase. From there, the degradation product choline is taken back into the presynaptic terminal by the membrane protein choline transporter.