The pseudokinase Mixed Lineage Kinase domain-like (MLKL) is an essential effector protein in the necroptotic cell death pathway downstream of the protein kinase Receptor Interacting Protein Kinase-3 (RIPK3).  RIPK3–mediated phosphorylation of the activation loop in MLKL trips a molecular switch to induce necroptotic cell death. The structure of mouse MLKL...