Cholinergic Receptor Nicotinic Gamma Subunit (CHRNG) encodes the gamma (γ) subunit of the nicotinic [acetylcholine](/entities/acetylcholine) receptor (nAChR), a ligand-gated ion channel essential for neuromuscular junction (NMJ) formation and function. CHRNG is primarily expressed during embryonic development and is a critical component of the embryonic/muscle-type nAChR, which also includes alpha (α), beta (β), delta (δ), and epsilon (ε) subunits. While CHRNG expression diminishes after birth in skeletal muscle, research has revealed its presence in certain neuronal populations and emerging associations with neurodegenerative diseases including Alzheimer's disease (AD) and Parkinson's disease (PD).
Gene Information
Protein Structure and Function
Nicotinic Acetylcholine Receptor Architecture
The muscle-type nAChR is a pentameric assembly typically composed of two α subunits and one each of β, δ, and γ (embryonic) or ε (adult) subunits: (α1)₂β1δ1γ1/ε1. [@sine2012] [@ruegg1998]
Subunit Composition
α subunits (CHRNA1): Bind acetylcholine at two agonist sites
β subunit (CHRNB1): Structural and modulatory role
δ subunit (CHRND): Contributes to channel pore formation
γ subunit (CHRNG): Embryonic-specific, replaced by ε (CHRNE) in adults
Channel Properties
Ligand-gated: Opens upon acetylcholine binding
Non-selective cation channel: Permits Na⁺, K⁺, and Ca²⁺
Fast desensitization: Rapid transition to closed state
Reversible stoichiometry: 2 agonist binding sites per receptor
Developmental Expression
Embryonic Stage
CHRNG is the predominant γ subunit expressed during:
Muscle development: Critical for NMJ formation [@sine2012]
[Unknown, Ruegg, M.A. & Bixby, J.L. (1998). Agrin orchestrates synaptic differentiation at the vertebrate neuromuscular junction. Trends in Neurosciences, 21(1), 22-27 (1998)](https://pubmed.ncbi.nlm.nih.gov/9452866/)
[Hajós, M. et al., (2020). Nicotinic acetylcholine receptors in Alzheimer's disease: From pathophysiology to therapeutics. Neuropharmacology, 168, 107993 (2020)](https://doi.org/10.1016/j.neuropharm.2020.107993)
[Unknown, Quik, M. & Wonnacott, S. (2011). α6β2 and α4β2 nicotinic acetylcholine receptors as drug targets for Parkinson's disease. Movement Disorders, 26(10), 1765-1773 (2011)](https://pubmed.ncbi.nlm.nih.gov/21626558/)
[Michalova, S. et al., (2013). Congenital myasthenic syndromes due to mutations in CHRNA1, CHRNB1, CHRND, and RAPSN. Brain, 136(Pt 3), 944-956 (2013)](https://pubmed.ncbi.nlm.nih.gov/23404335/)