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. 2023 Jun 13;26(7):107121. doi: 10.1016/j.isci.2023.107121

Figure 2.

Figure 2

Members of the nitazene family are potent superagonists at MOR

(A) Chemical structures of N-desethyl isotonitazene, metonitazene, and morphine.

(B and C) G protein (GoA) dissociation (B) and β-arrestin2 recruitment (C) dose-response curves are shown, with efficacies reported as % DAMGO response. DAMGO (black), fentanyl (blue), morphine (purple), isotonitazene (red), N-desethyl isotonitazene (brown), and metonitazene (orange) were tested in both assays following incubation with the drug for 1 h; n ≥ 3 for all compounds.

(D) Dose-response curves from the GloSensor Gi/o-mediated cAMP inhibition assay are shown for isotonitazene (red), N-desethyl isotonitazene (brown), metonitazene (orange), morphine (purple), DAMGO (black), and fentanyl (blue), with data normalized to DAMGO and displayed as a percentage of DAMGO mediated cAMP inhibition; n ≥ 3 for all compounds.

(E) Radioligand binding derived affinity (pKi) values are shown for isotonitazene (red), N-desethyl isotonitazene (brown), metonitazene (orange), morphine (purple), DAMGO (black), and fentanyl (blue); n ≥ 3 for all compounds; displayed error bars represent mean and SEM.

(F) Hierarchical clustering heatmap and dendrograms for all tested compounds at the Gi/o/z subtypes G protein-dissociation BRET and GRK2-mediated β-arrestin recruitment BRET are shown. The data displayed are transduction coefficients log(Emax/EC50) calculated using control-normalized Emax and EC50. The color scale is set such that red indicates higher values, blue indicates lower values, and white indicates intermediate values relative to the minima and maxima of the data displayed. The top dendrogram shows the clustering of tested compounds across the assays performed, and the left dendrogram shows the clustering of values observed between each assay.

(G) Circular bar charts depicting the % DAMGO Emax values calculated from the Gi/o/z subtypes and GRK2 mediated β-arrestin recruitment BRET assays are shown for each compound. The black circle in the center of each graph indicates 100% Emax relative to DAMGO and is set as the baseline for the bars; bars projecting away from the center indicate values greater than 100%, while those projecting toward the center indicate values less than 100%. The color scale is set such that the red bar represents the global maxima of Emax values observed across all drugs at all shown assays, and blue represents the respective global minima.

Relates to Figure S2.