Abstract
Macroautophagy/autophagy is an evolutionarily conserved degradation system with fundamental biological functions. The activation of the class III phosphatidylinositol 3-kinase (PtdIns3K) complexes and the subsequent production of phosphatidylinositol 3-phosphate (PtdIns3P) are pivotal to autophagy. Using a combination of structural biology, biochemistry, and biophysics, we revealed how the non-catalytic subunit BECN1 serves as a membrane-binding switch in the regulation of PtdIns3K complexes and autophagy.