Subunits
To date, 17 nAChR subunits have been identified, which are divided into muscle-type and neuronal-type subunits. Of these 17 subunits, α2-α7, and β2-β4 have been cloned in humans, the remaining genes identified in chick and rat genomes.
The nAChR subunits have been divided into 4 subfamilies (I-IV) based on similarities in protein sequence. In addition, subfamily III has been further divided into 3 tribes.
| Neuronal-type | Muscle-type | ||||
| I | II | III | IV | ||
|---|---|---|---|---|---|
| α9, α10 | α7, α8 | 1 | 2 | 3 | α1, β1, δ, γ, ε |
| α2, α3, α4, α6 | β2, β4 | β3, α5 | |||
- Alpha genes: CHRNA1 (muscle), CHRNA2 (neuronal), CHRNA3, CHRNA4, CHRNA5, CHRNA6, CHRNA7, CHRNA8, CHRNA9, CHRNA10
- Beta genes: CHRNB1 (muscle), CHRNB2 (neuronal), CHRNB3, CHRNB4
- Other genes: CHRND (delta), CHRNE (epsilon), CHRNG (gamma)
Read more about this topic: Nicotinic Acetylcholine Receptor