FIGURE 1: Illustration of the role of the SIRT4-OPA1 axis in mitochondrial quality control, mitophagy inhibition, and accumulation of functionally impaired mitochondria linked to cellular aging. The depicted interaction partners of SIRT4, including components of the complexes I and V of the respiratory chain, have been identified by mass spectrometric analyses (unpublished results). L-OPA1, long form of the dynamin-related GTPase and mitochondrial fusion regulator optic atrophy 1; ROS, reactive oxygen species.