Exploiting the DCAF16–SPIN4 interaction to identify DCAF16 ligands for PROTAC development

Traditional small molecule drugs often target protein activity directly, but challenges arise when proteins lack suitable functional sites. An alternative approach is targeted protein degradation (TPD), which directs proteins to cellular machinery for proteolytic degradation. Recent studies have identified additional E3 ligases suitable for TPD, expanding the potential of this approach. Among these, DCAF16 has shown promise in facilitating protein degradation through both PROTAC and molecular glue mechanisms. In this study, we developed a homogeneous time resolved fluorescence (HTRF) assay to discover new DCAF16 binders. Using an in-house electrophile library, we identified two diastereomeric compounds, with one engaging DCAF16 at cysteines C177-179 and another reducing its expression. We demonstrated that the compound covalently engaging DCAF16 can be transformed into a PROTAC capable of degrading FKBP12.