Autophagy protein 5 (ATG5) is a protein that, in humans, is encoded by the ATG5 gene located on chromosome 6. It is an E3 ubi autophagic cell death. ATG5 is a key protein involved in the extension of the phagophoric membrane in autophagic vesicles. It is activated by ATG7 and forms a complex with ATG12 and ATG16L1. This complex is necessary for LC3-I (microtubule-associated proteins 1A/1B light chain 3B) conjugation to PE (phosphatidylethanolamine) to form LC3-II (LC3-phosphatidylethanolamine conjugate). ATG5 can also act as a pro-apoptotic molecule targeted to the mitochondria. Under low levels of DNA damage, ATG5 can translocate to the nucleus and interact with survivin.
ATG5 is known to be regulated via various stress induced transcription factors and protein kinases.