Acetylocholin

Acetylocholin is a neurotransmitter that plays a crucial role in the transmission of signals across the neuromuscular junction, which is the point of contact between a neuron and a muscle cell. It is synthesized from the amino acid choline and the coenzyme A (CoA) derivative acetyl-CoA in the cytoplasm of cholinergic neurons. The enzyme responsible for this synthesis is choline acetyltransferase (ChAT).

Once synthesized, acetylocholin is stored in synaptic vesicles within the presynaptic neuron. When an action potential reaches the axon terminal, it triggers the release of acetylocholin into the synaptic cleft. Acetylocholin then binds to nicotinic acetylcholine receptors on the muscle cell membrane, causing a depolarization of the muscle cell and the initiation of a muscle contraction.

After binding to the receptor, acetylocholin is rapidly degraded by the enzyme acetylcholinesterase (AChE) into choline and acetate. Choline is then recycled back into the neuron to be used for the synthesis of new acetylocholin molecules.

Acetylocholin is also involved in the transmission of signals in the central nervous system, where it acts on nicotinic and muscarinic receptors. Dysfunction of the acetylocholin system has been linked to various neurological and neuromuscular disorders, including myasthenia gravis, Alzheimer's disease, and Parkinson's disease.