Building the autophagosome: Molecular logic and membrane dynamics of autophagy

Autophagy is initiated by the formation of a double-membrane autophagosome which is fine-tuned by the involvement of multiple protein machineries, organelles, and membrane pools. Autophagosome formation proceeds through steps requiring membrane nucleation, membrane expansion, and vesicle closure, initiated and coordinated by the cohort of ATG (Autophagy) proteins and lipids, such as PI(3)P and PE. Recent studies provide insights into how different molecular machineries act and interact to enable this complex vesicular pathway. Here, we review the current understanding of the steps that lead to autophagosome formation from a molecular perspective and, in this context, discuss the role of protein–membrane crosstalk in moulding the phagophore structure.