Mitochondrial membrane potential regulates PINK1 import and proteolytic destabilization by PARL. PINK1, a mitochondrial kinase involved in Parkinson's disease, is regulated by the mitochondrial protease PARL. PARL mediates PINK1 cleavage dependent on mitochondrial membrane potential. In the absence of PARL, PINK1 is stabilized, while mitochondrial membrane potential loss leads to PINK1 accumulation on the outer mitochondrial membrane, where it recruits Parkin. PARL-mediated proteolysis generates a 52-kD PINK1 fragment, which is subsequently degraded by the proteasome. PINK1's localization and stability are regulated by mitochondrial membrane potential, with PARL playing a key role in its proteolytic processing. Mutations in PINK1's transmembrane domain affect its cleavage and localization. The study shows that PARL is essential for PINK1 processing and that PINK1's stability and function are regulated by mitochondrial membrane potential. The findings suggest that PARL facilitates the rapid degradation of PINK1 in the mitochondrial inner membrane, which is crucial for mitochondrial quality control. The results also highlight the importance of mitochondrial membrane potential in regulating PINK1's localization and function, and provide insights into the mechanisms underlying PINK1 and Parkin-mediated mitophagy.Mitochondrial membrane potential regulates PINK1 import and proteolytic destabilization by PARL. PINK1, a mitochondrial kinase involved in Parkinson's disease, is regulated by the mitochondrial protease PARL. PARL mediates PINK1 cleavage dependent on mitochondrial membrane potential. In the absence of PARL, PINK1 is stabilized, while mitochondrial membrane potential loss leads to PINK1 accumulation on the outer mitochondrial membrane, where it recruits Parkin. PARL-mediated proteolysis generates a 52-kD PINK1 fragment, which is subsequently degraded by the proteasome. PINK1's localization and stability are regulated by mitochondrial membrane potential, with PARL playing a key role in its proteolytic processing. Mutations in PINK1's transmembrane domain affect its cleavage and localization. The study shows that PARL is essential for PINK1 processing and that PINK1's stability and function are regulated by mitochondrial membrane potential. The findings suggest that PARL facilitates the rapid degradation of PINK1 in the mitochondrial inner membrane, which is crucial for mitochondrial quality control. The results also highlight the importance of mitochondrial membrane potential in regulating PINK1's localization and function, and provide insights into the mechanisms underlying PINK1 and Parkin-mediated mitophagy.