User:Alex Pennington/Sandbox 1

Nicotinic Acetylcholine ReceptorNicotinic Acetylcholine Receptor

The nicotinic acetylcholine receptor is a key protein in neuronal communication. This protein effectively converts neurotransmitter binding into a membrane depolarization event. The protein combines neurotransmitter binding sites, specifically acetylcholine, with a cationic ion channel, specifically sodium (Na).

FunctionFunction

PhysiologyPhysiology

The receptor is a cylidrically-shaped protein. It is embedded in the cell wall of post synaptic nerves at the skeletal neuromuscular junction. The receptor acts as a chemically controlled sodium (Na) channel also known as a ligand gated channel.

When in the presence of acetylcholine, the receptor undergoes a conformational change opening up the channel to an influx of sodium (Na) within the cell. When this happens the cell undergoes a depolarization event that triggers an action potential to propagate along the rest of the cell stimulating, for example, a muscle response.

The opening of these channels only lasts for a millisecond due to cholinesterase being present and breaking down acetylcholine attached to the receptor causing the receptor to close again. Introduction of cholinesterase inhibitors can cause a depolarization block. It works by creating a prolonged refractory period in the depolarization event promoted by the opening of the receptor channel.

LocationsLocations

•skeletal neuromuscular junctions

•sympathetic and parasympathetic nervous system

•autonomic ganglia

•central nervous system

Structural highlightsStructural highlights

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