Schematic illustration of the ubiquitin-dependent and ubiquitin-independent pathways of mitophagy is shown. The ubiquitin-dependent mitophagy can be divided into PINK1/Parkin-dependent mitophagy (A) and PINK1-dependent mitophagy (B). (A) Once mitochondria are damaged, PINK1 will accumulate on the OMM (outer mitochondrial membrane) and activate it by phosphorylation. The activated PINK1 recruits and activates PARKIN by phosphorylation. Then, the activated PARKIN produces the polyubiquitin chains recognized by receptors (P62, OPTN, NDP52, TAX1BP1, and NBR1). These receptors will bind with the LC3 adaptor to engulf mitochondria to complete autophagy. (B) The activated PINK1 recruits ULK1, DFCP1, and WIPI1, which can be recognized by receptors (OPTN and NDP52) to induce PINK1-dependent mitophagy. (C) Some proteins, including NIX, BNIP3, FUNDC1, BCL2L13, FKBP8, and NLRX1, can directly recognize the LC3 adaptor and initiate the mitophagy process.