Figure 6: mTOR and AMPK regulation of macroautophagy. During nutrient rich conditions, mTOR remains active, phosphorylating ATG13, preventing its ability to form the large activating complex for autophagy (ATG13-FIP200-ULK1-ATG101). During periods of nutrient deprivation (amino acid deprivation, growth factor deprivation, and/or low-energy status), AMPK is activated and phosphorylates mTOR, preventing its ability to phosphorylate ATG13. This allows ATG13 to form the large activating complex, leading to the induction of autophagy. ATG: autophagy-related protein; P: phosphate; AMPK: adenosine monophosphate kinase; FIP200: focal adhesion kinase family-interacting protein of 200 kDa; ULK1: Unc-51-like kinase 1; mTOR: mammalian target of rapamycin.