ATG9 regulates autophagosome progression from the endoplasmic reticulum

The autophagosome, a cellular compartment involved in the turnover of macromolecules, contributes to nutrient homeostasis, stress resilience and defense. Although several proteins have been identified as contributing to autophagosome formation and function, the precise origins of the autophagosome have remained unclear. Using imaging, labeling and Arabidopsis mutants, Zhuang et al. show that the autophagosomal membrane is a clear outgrowth from an ER subdomain and that ATG9, a lipid-embedded protein, is essential for ER-derived autophagosome formation. Proc. Natl. Acad. Sci. USA 10.1073/pnas.1616299114