Extended Data Figure 4. Signalling properties of PZM21 at the opioid receptors.

Displayed are raw luminescence data from a G_i/o Glosensor assay. In agonist mode, agonists decrease luminescence while inverse agonists increase it by diminishing basal signalling. For each opioid receptor, a prototypical well-characterized agonist (black curves) and antagonist (red curves) were used to validate the assay. In antagonist mode, a competition reaction is performed with 50 nM agonist and an escalating amount of tested drug. Here, true antagonists increase the observed signal, consistent with their ability to compete with the agonist but not induce G_i signalling. Data are mean ± s.e.m. of non-normalized results (n =3 measurements).