Acetylcholine receptors
| acetylcholine receptor | ||||||
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| Aliases | cholinergic receptorAChRACh receptorCholinoceptor | |||||
| External IDs | GeneCards: [1] | |||||
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| Species | Human | Mouse | ||||
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| Location (UCSC) | n/a | n/a | ||||
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An acetylcholine receptor (abbreviated AChR) is an integral membrane protein that responds to the binding of acetylcholine, a neurotransmitter.
Like other transmembrane receptors, acetylcholine receptors are classified according to their "pharmacology," or according to their relative affinities and sensitivities to different molecules. Although all acetylcholine receptors, by definition, respond to acetylcholine, they respond to other molecules as well.
Nicotinic and muscarinic are two main kinds of "cholinergic" receptors.
Molecular biology has shown that the nicotinic and muscarinic receptors belong to distinct protein superfamilies.
Nicotinic receptors are of two types: Nm and Nn. Nm is located in the neuromuscular junction which causes the contraction of skeletal muscles by way of end-plate potential (EPPs). Nn causes depolarization in autonomic ganglia resulting in post ganglionic impulse. Nicotinic receptors cause the release of catecholamine from the adrenal medulla, and also site specific excitation or inhibition in brain. Both Nm and Nn are Na+ and Ca++ channel linked but Nn is also linked with an extra K+ channel.
The nAChRs are ligand-gated ion channels, and, like other members of the "cys-loop" ligand-gated ion channel superfamily, are composed of five protein subunits symmetrically arranged like staves around a barrel. The subunit composition is highly variable across different tissues. Each subunit contains four regions which span the membrane and consist of approximately 20 amino acids. Region II which sits closest to the pore lumen, forms the pore lining.
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Wikipedia