Autophagy process is controlled by the Tor kinase activity.In nutrient-rich conditions, the phosphorylation activity of Tor inhibits autophagy;upon starvation the activity of Tor is reduced and dephosphorylation of its substrates results in autophagy induction.In the budding yeast Saccharomyces cerevisiae, the only key autophagy-related substrate of Tor appears to be Atg13, whose dephosphorylation is sufficient for autophagy induction, but the situations in other organisms are less clear.We use the fission yeast Schizosaccharomyces pombe to investigate the role of Atg1 3 in autophagy induction.We found that overexpressed Atg13 formed puncta in nutrient-rich conditions.Furthermore, Atg13 overexpression induced the puncta formation by a number of other Atg proteins under nutrient-rich conditions.Significant co-localization was observed between Atg13 puncta and the puncta formed by other Atg proteins, suggesting that Atg13 overexpression triggers a process similar to pre-autophagosomal structure (PAS)assembly during starvation-induced autophagy.We hypothesize that overexpressed Atg13 may saturate the capacity of Tor to phosphorylate it and Atg protein assembly results from the accumulation of unphosphorylated Atg13.Atg13 overexpression provides a simplified context to investigate the mechanisms of autophagy induction and PAS assembly.