Insect Ryanodine Receptor: Distinct but Coupled Insecticide Binding Sites for [<i>N</i>‑C<sup>3</sup>H<sub>3</sub>]Chlorantraniliprole, Flubendiamide, and [<sup>3</sup>H]Ryanodine

Radiolabeled anthranilic diamide insecticide [<i>N</i>-C<sup>3</sup>H<sub>3</sub>]­chlorantraniliprole was synthesized at high specific activity. It was compared with phthalic diamide insecticide flubendiamide and [<sup>3</sup>H]­ryanodine in radioligand binding studies with house fly muscle membranes to provide the first direct evidence with a native insect ryanodine receptor that the major anthranilic and phthalic diamide insecticides bind at different allosterically coupled sites, i.e., there are three distinct Ca<sup>2+</sup>-release channel targets for insecticide action.