| Property | Value |
|----------|-------|
| **Protein Name** | Nicotinic acetylcholine receptor subunit alpha-5 |
| **Gene** | [CHRNA5](/genes/chrna5) |
| **UniProt ID** | [P43680](https://www.uniprot.org/uniprot/P43680) |
| **PDB ID** | 5KLE, 6PV6 |
| **Molecular Weight** | ~53 kDa |
| **Subcellular Localization** | Plasma membrane (neuronal ligand-gated ion channel) |
| **Protein Family** | Cys-loop receptor family; Nicotinic acetylcholine receptor |
Nicotinic acetylcholine receptor subunit alpha-5 is a protein encoded by the CHRNA5 gene that chrna5-containing receptors have important physiological roles:. This page describes its structure, normal nervous system function, role in neurodegenerative disease, and potential as a therapeutic target.
CHRNA5 encodes the alpha-5 subunit of neuronal nicotinic acetylcholine receptors (nAChRs). This subunit has distinctive structural features:
- N-terminal extracellular domain: Contains the acetylcholine binding site; alpha-5 lacks key residues for high-affinity binding
- Cys-loop motif: Conserved feature of the Cys-loop receptor family
- Transmembrane domains (M1-M4): Form the ion channel pore
- Intracellular loop: Regulatory sequences for trafficking and modulation
CHRNA5 functions as a "accessory" subunit that modulates receptor function when incorporated into pentameric receptors with alpha/beta subunit composition (e.g., alpha-4/beta-2/alpha-5 or alpha-3/beta-4/alpha-5).
CHRNA5-containing receptors have important physiological roles:
- Enhanced agonist efficacy: Increases sensitivity to nicotine and acetylcholine
- Calcium permeability: Alters calcium signaling through the receptor
- Receptor trafficking: Influences assembly and surface expression
- Autonomic function: Modulates ganglionic transmission
- Reward pathways: Contributes to nicotine dependence mechanisms
CHRNA5 has strong connections to neurodegenerative diseases:
- Genetic association: CHRNA5 variants linked to AD risk and age of onset
- Cholinergic dysfunction: Altered expression in AD brains
- Nicotine neuroprotection: Alpha-5 containing receptors may mediate protective effects
- Amyloid interaction: Nicotine binding to alpha-5 receptors may affect Aβ aggregation
- PD risk gene: CHRNA5 polymorphisms associated with PD susceptibility
- Dopaminergic protection: Nicotinic signaling via alpha-5 receptors may protect dopaminergic neurons
- Smoking paradox: CHRNA5 variants explain some of the smoking-neuroprotection relationship
- Genetic determinant: CHRNA5 rs16969968 is one of the strongest predictors of nicotine dependence
- Gateway hypothesis: Links cholinergic signaling to substance use disorders
¶ Nicotinic Ligands
- Alpha-5 selective compounds: Under development for cognitive disorders
- Allosteric modulators: Target the unique properties of alpha-5 containing receptors
- Personalized medicine for nicotine dependence
- Neuroprotective drug development
- Cognitive enhancement strategies