an autophagy factor required for autophagosome formation. Target of the TOR kinase signaling pathway that regulates autophagy through the control of the phosphorylation status of ATG13 and ULK1, and the regulation of the ATG13-ULK1-RB1CC1 complex. Under starvation conditions, is localized to puncate structures primarily representing the isolation membrane; the isolation membrane sequesters a portion of the cytoplasm resulting in autophagosome formation. Phosphorylated by ULK1 and ULK2. Phosphorylation status depends on nutrient-rich conditions; dephosphorylated during starvation or following treatment with rapamycin. Part of a complex consisting of ATG13, ULK1 and RB1CC1. Interacts with ATG101. Interacts with ULK1 and -2 via C-terminus. Three isoforms of the human protein are produced by alternative splicing. Note: This description may include information from UniProtKB.