Nicotinic Receptor

From Anvita Health Wiki

Contents 1 More Specific Terms 2 Function 3 Structure 4 Compartment 5 Expression 6 Pathology 7 More General Terms 8 Additional Terms 9 Internet Database 10 References

More Specific Terms

• nicotinic receptor alpha4-beta2

Function

• ionotropic nicotinic receptors mediate postsynaptic excitatory responses at the neuromuscular junction
• nicotinic receptors may also act presynaptically to modulate acetylcholine release in the periphery
• simultaneous binding of 2 molecules of acetylcholine is required for opening of the ion channel
• a conformational change that affects all subunits results in opening of the ion channel, permeable primarily to Na+ & secondarily Ca+2
• within the brain, nicotinic receptors function as ligand-gated ion channels linked to rapidly desensitizing Ca2+ influx, with variable permeability of Na+ relative to Ca+2
• role in modulation of release of several neurotransmitters ( glutamate, GABA & dopamine), mediating &/or modulating synaptic transmission & plasticity [4]
• nicotinic receptors are inhibited by neuromuscular blocking agents.

Structure

• skeletal muscle receptors consist of pentamers of (alpha)2-beta-gamma-delta
• in mature muscle endplates, the gamma subunit is replaced by an epsilon subunit, (alpha)2-beta-delta-epsilon
• in the mammalian CNS, nine different alpha subunits (2-10) & three different beta subunits (2-4) have been described
• it is assumed that most receptors are heteropentameric structures, with various combinations of alpha & beta subunits, but some receptors may form as homopentamers, notably alpha-7 ( CHRNA7)
• these alpha-7 homopentamers along with those containing alpha-4 & beta-2 subunits are the most abundant in brain.

Compartment

• cell junction, synapse,
• postsynaptic cell membrane, presynaptic cell membrane

Expression

• skeletal muscle, specifically at motor endplate
• within the brain, present on neurons & on glia.

Pathology

• role in neurodegeneration is suggested [4]

More General Terms

• ionotropic receptor
• cholinergic receptor
• Na+ channel
• multisubunit protein
• phosphoprotein

Additional Terms

• acetylcholine (Miochol, Pragmoline)
• acetylcholine (nicotinic) receptor antibody
• CNS cholinergic system
• myasthenia gravis

Internet Database

Prosite: [1]

References

1. Armstrong TINS 12(3) 117 1989
2. Kullberg et al Proc Natl Acad Sci U S A 1990 Mar;87(6):2067-71
3. Barnard EA. Receptor classes and the transmitter-gated ion channels. Trends Biochem Sci. 1992 Oct;17(10):368-74. Review. PMID: [2]
4. Fabian-Fine R, Skehel P, Errington ML, Davies HA, Sher E, Stewart MG, Fine A. Ultrastructural distribution of the alpha7 nicotinic acetylcholine receptor subunit in rat hippocampus. J Neurosci. 2001 Oct 15;21(20):7993-8003. PMID: [3]
5. The Pharmacological Basis of Therapeutics, 9th ed. Gilman et al, eds. Permagon Press/McGraw Hill, 1996 pg 178

nicotinic receptor (nicotinic acetylcholine receptor, nAChR)