A requirement for ER-derived COPII vesicles in phagophore initiation

A major unanswered question in the field of autophagy is how the double-membrane phagophore is formed. As this membrane expands, it engulfs proteins and organelles that are destined for degradation and then seals to form an autophagosome. A growing consensus in the field is that a subdomain of the ER initiates formation of the phagophore. We show that ER-derived COPII-coated vesicles, which bud from a specialized domain of the ER called the ER exit site (ERES), are a source of this membrane. This finding will now pave the way for a biochemical description of the early steps of phagophore initiation.