Figure 2.

(a) nAChRs share a similar overall structure to the ligand-gated chloride channels with individual subunits containing four trans-membrane domains (M1–M4) and a large extracellular N-terminal domain. The mature receptor (b) is a pentamer of either identical or non-identical subunits and gates a cation-selective channel following acetylcholine binding to the extracellular domain. Neonicotinoids such as imidacloprid activate the channel by binding to the same site. The only field-confirmed case of target site resistance to these compounds involves mutation (red circle) of arginine 81 to threonine (R81T) in Myzus persicae β1 subunit that causes repulsion of imidacloprid binding at the α/β subunit interface as shown in (c) (taken from Bass et al. (2015)).