At the Center of Macroautophagy: Autophagosomes

Autophagosomes are double-membrane vesicles that are the hallmark of the intracellular catabolic process called macroautophagy. They are formed by the orchestrated interplay of the AuTophaGy-related (ATG) proteins. The cargo molecules sequestered by autophagosomes include long-lived proteins, protein complexes or aggregates, superfluous or excess organelles, and invading pathogens. Complete autophagosomes fuse with lysosomes delivering the sequestered material in the interior of these organelles where it is degraded by resident hydrolases. Autophagy represents a key survival mechanism because it clears the cytoplasm from unwanted and potentially toxic structures, but it can also represent an intracellular source of metabolites that is induced by cells to generate new macromolecules or energy in times of need.