The study identifies the role of the ubiquitin kinase PINK1 in inducing mitophagy through the recruitment of autophagy receptors. PINK1 phosphorylates ubiquitin to activate Parkin, which then forms ubiquitin chains on mitochondrial proteins, recruiting autophagy receptors such as NDP52 and Optineurin. These receptors, but not p62, are essential for PINK1/Parkin-mediated mitophagy. The study shows that PINK1 directly recruits NDP52 and Optineurin to mitochondria, independent of Parkin, to initiate mitophagy. Once recruited, these receptors recruit ULK1, DFCP1, and WIP1 to focal spots near mitochondria, functioning upstream of LC3. This supports a model where PINK1-generated phospho-ubiquitin serves as the autophagy signal on mitochondria, and Parkin amplifies this signal by generating more ubiquitin chains. The study also highlights the broader role of ubiquitin phosphorylation in autophagy pathways. The findings clarify the role of Parkin as an amplifier of the PINK1-generated mitophagy signal, phospho-ubiquitin, which engages autophagy receptors to recruit ULK1, DFCP1, WIP1, and LC3. The study demonstrates that PINK1 ubiquitin-kinase activity is sufficient to recruit autophagy receptors and upstream autophagy machinery to mitochondria to induce mitophagy. The results suggest that PINK1 generates a novel and essential signature (phospho-ubiquitin) on mitochondria to induce OPTN and NDP52 recruitment and mitophagy, while Parkin amplifies this signal by generating more ubiquitin chains on mitochondria, which are subsequently phosphorylated by PINK1. The study also reveals that NDP52 and OPTN recruit ULK1 to initiate mitophagy, and that ubiquitin phosphorylation, independent of Parkin, is sufficient to recruit ULK1 to mitochondria. The findings provide new insights into the mechanisms of mitophagy and the roles of autophagy receptors in this process.The study identifies the role of the ubiquitin kinase PINK1 in inducing mitophagy through the recruitment of autophagy receptors. PINK1 phosphorylates ubiquitin to activate Parkin, which then forms ubiquitin chains on mitochondrial proteins, recruiting autophagy receptors such as NDP52 and Optineurin. These receptors, but not p62, are essential for PINK1/Parkin-mediated mitophagy. The study shows that PINK1 directly recruits NDP52 and Optineurin to mitochondria, independent of Parkin, to initiate mitophagy. Once recruited, these receptors recruit ULK1, DFCP1, and WIP1 to focal spots near mitochondria, functioning upstream of LC3. This supports a model where PINK1-generated phospho-ubiquitin serves as the autophagy signal on mitochondria, and Parkin amplifies this signal by generating more ubiquitin chains. The study also highlights the broader role of ubiquitin phosphorylation in autophagy pathways. The findings clarify the role of Parkin as an amplifier of the PINK1-generated mitophagy signal, phospho-ubiquitin, which engages autophagy receptors to recruit ULK1, DFCP1, WIP1, and LC3. The study demonstrates that PINK1 ubiquitin-kinase activity is sufficient to recruit autophagy receptors and upstream autophagy machinery to mitochondria to induce mitophagy. The results suggest that PINK1 generates a novel and essential signature (phospho-ubiquitin) on mitochondria to induce OPTN and NDP52 recruitment and mitophagy, while Parkin amplifies this signal by generating more ubiquitin chains on mitochondria, which are subsequently phosphorylated by PINK1. The study also reveals that NDP52 and OPTN recruit ULK1 to initiate mitophagy, and that ubiquitin phosphorylation, independent of Parkin, is sufficient to recruit ULK1 to mitochondria. The findings provide new insights into the mechanisms of mitophagy and the roles of autophagy receptors in this process.