Schematic illustration for the Drp1-Zip1 interaction-dependent mitochondrial quality surveillance during the mitochondrial fission. Mitochondrial morphology continuously changed by the fusion-fission cycle. (1) Upon stimuli, Drp1 moves to the mitochondria, and interacts with the mitochondrial Zip1 to induce the focal MMP reduction. (2) Drp1 cuts the mitochondria through their oligomerization. (3) Healthy piece of mitochondria recovers their MMP and stays in the fusion-fission cycle, but the damaged mitochondria fail to recover and are subsequently removed by the mitophagy.