Frizzled6 agonist SAG1.3 is a small molecule SMO agonist that targets Frizzled6 (FZD6) as a partial agonist with limited subtype selectivity; Frizzled6 agonist SAG1.3 binds FZD6 and evokes a conformational change reminiscent of that seen in other agonist-bound GPCRs. In competition experiments, increasing concentrations of unlabeled SAG1.3 decreased BODIPY-cyclopamine (300 nM) binding to Nluc-FZD6 in a concentration-dependent manner (pKi=5.6). SAG1.3 mediates recruitment of mGsi proteins to FZD6 and induces conformational changes in FZD6, induces FZD6-dependent dissociation of heterotrimeric Gi and phosphorylation of ERK1/2, and modifies the interactions between FZD6 and DVL2.