C19orf73, now officially named Autophagy-related protein 13, is a core regulatory factor in the initiation of cellular autophagy. As a key component of the ULK1/ATG1 complex, this protein plays a critical role in responding to signals such as nutrient deprivation and energy stress. When the mTORC1 pathway is inhibited, ATG13 forms a stable activation complex with proteins including ULK1 and FIP200, initiating autophagosome formation. Dysfunction of ATG13 is closely associated with various diseases: in neurodegenerative disorders, impaired autophagy leads to abnormal protein aggregation; in tumor development, autophagy exerts dual regulatory effects on cancer progression. The expression level and activity of ATG13 are finely regulated by phosphorylation modifications, making it a crucial molecular switch connecting upstream signals with downstream autophagy execution machinery. It has become an important target in both fundamental autophagy research and the development of therapies for related diseases.