Autophagy is a highly conserved catabolic pathway which maintains cellular homeostasis and cell survival under conditions of stress or disease. Upon autophagy induction, a unique double-membraned structure, called a phagophore, forms and expands into a cup shape to engulf cytosolic material. This phagophore membrane expands and closes to form an autophagosome. Fusion of the autophagosome with the lysosome completes the process allowing for degradation and recycling of the captured content. Critical, essential machinery initiating and driving these membrane-mediated steps are the ATG (Autophagy related) proteins. We have been studying a cohort of these ATG proteins in mammalian cells to understand how they function after acute induction of autophagy. We use molecular cell biology approaches to understand the signals, location and protein-protein networks required for functional activation of the ATG proteins and membrane formation. Our work and progress on advancing the current knowledge of the function of the ATG proteins, in particular ATG9A, and WIPIs will be discussed.