Autophagy is a major catabolic pathway, which involves the sequestration of superfluous or dysfunctional cellular components into autophagosomes and their delivery to lysosomes for degradation.The formation of autophagosomes depends on a concerted action of canonical and autophagy-specific membrane trafficking and remodeling pathways.A highly conserved set of autophagy related (Atg)-proteins is hierarchically recruited to the phagophore assembly site to coordinate the biogenesis of autophagosomes.Their specific contribution remained,however, unclear.We use a powerful combination of in vitro reconstitution techniques and in vivo studies to reveal how Atg-proteins drive the initiation and expansion of the cup-shaped autophagic precursor membrane, called phagophore.We reconstituted a critical step in autophagy, which is thought to control phagophore-initiation, from purified components on model membranes in vitro.I will present our recent results that cover the molecular mechanism by which autophagy is initiated.