There is a type of noncanonical autophagy, which is independent of ATG5 (autophagy related 5), also referred to as alternative autophagy. Both canonical and ATG5-independent alternative autophagy require the initiator ULK1 (unc-51 like kinase 1), but how ULK1 regulates these two types of autophagy differently remains unclear. A recent paper from Torii et al. demonstrates that phosphorylation of ULK1 at Ser746 by RIPK3 (receptor interacting serine/threonine kinase 3) is the key difference between these two types of autophagy; this phosphorylation is exclusively found during alternative autophagy.
Keywords: Alternative autophagy; Golgi; RIPK3; ULK1; phosphorylation.