Autophagy, the process of bulk degradation of cellular proteins through an autophagosomic-lysosomal pathway is important for normal growth control and may be defective in tumor cells. It is involved in the preservation of cellular nutrients under starvation conditions as well as the normal turnover of cytosolic components. This process is negatively regulated by TOR (Target of rapamycin) through phosphorylation of autophagy protein ATG1. ATG101 is a recently discovered protein that stabilizes ATG13, another autophagy protein that forms a complex with the mammalian homologs of ATG1, ULK1 and ULK2, and with FIP200. This complex is a target of TOR phosphorylation under normal conditions, inhibition of TOR by rapamycin or leucine deprivation leads to dephosphorylation of ATG13, ULK1 and ULK2, which then leads to autophagy. ATG101 also interacts with ULK1 and is essential for autophagy.Synonyms: Autophagy-related protein 101, C12orf44, PP894, UPF0453 protein C12orf44