Figure 1. Receptor protein complexes in macroautophagy. (A) A general model of the receptor protein complex. (B) The Cvt pathway (left) and mitophagy (right) in yeast with their respective cargos (prApe1 complex, mitochondrion), ligand (prApe1 propeptide), receptors (Atg19 and Atg32), scaffold (Atg11) and Atg8 family protein (Atg8). (C) Aggrephagy (left) and mitophagy (right) in mammalian cells and their receptor protein complexes. BNIP3L might act as a “mammalian Atg32” being integral to the mitochondrial outer membrane and interacting with LC3. SQSTM1 binds to ubiquitin (Ub) conjugated to aggregated proteins and mediates their interaction with the autophagic scaffold (WDFY3) and Atg8 family protein (LC3); SQSTM1 might play a similar role during pexophagy, mitophagy and xenophagy. Note that SQSTM1 might also directly recognize several ligands for aggrephagy and xenophagy in a Ub-independent manner (Table 1).