Nicotinic acetylcholine receptor

Nicotinic acetylcholine receptor (nAChR) is a type of protein that responds to the neurotransmitter acetylcholine. nAChRs are found in many tissues throughout the body, particularly in the nervous system, where they play key roles in synaptic transmission.

Structure

nAChRs are composed of five subunits, arranged symmetrically around a central pore. Each subunit is made up of an extracellular domain, a transmembrane domain, and an intracellular domain. The extracellular domain contains the acetylcholine binding site, while the transmembrane domain forms the ion channel.

Function

nAChRs are ionotropic receptors, meaning they act as ion channels. When acetylcholine binds to the receptor, it causes the channel to open, allowing ions to flow across the cell membrane. This can trigger a variety of responses, depending on the type of cell and the specific ions involved.

In the nervous system, nAChRs are involved in transmitting signals between neurons. They are also found in muscle cells, where they play a crucial role in muscle contraction.

Clinical significance

nAChRs are the target of several drugs and toxins. For example, nicotine from tobacco binds to nAChRs, leading to the release of dopamine and other neurotransmitters. This is thought to be a major factor in the addictive properties of tobacco.

nAChRs are also implicated in a number of diseases, including Alzheimer's disease, Parkinson's disease, and myasthenia gravis. Research is ongoing to develop new drugs that can modulate the activity of nAChRs for therapeutic benefit.

See also

• Acetylcholine
• Neurotransmitter
• Ionotropic receptor
• Muscle contraction