The ULK complex initiates autophagosome formation at phosphatidylinositol synthase-enriched ER subdomains.

In our recent paper, we biochemically analyzed autophagosome-related membranes at the initiation stage of macroautophagy/autophagy using atg knockout (KO) cells and demonstrated that the ULK complex is recruited to 2 distinct membranes: the ER membrane and ATG9A-positive autophagosome precursors. We have also identified phosphatidylinositol synthase (PIS)-enriched ER subdomains as the initiation site of autophagosome formation. Based on these findings, we propose that the ULK complex, the PIS-enriched ER subdomain, and ATG9A vesicles together initiate autophagosome formation.