Ubiquitin-like-conjugating enzyme ATG3 (ATG3), also known as Apg3L and Apg3p, functions as a regulatory component of autophagosome biogenesis necessary for autophagy. ATG3 exhibits 98% aa sequence identity with both its mouse and rat orthologs. It is widely expressed and has highly levels in heart, skeletal muscle, kidney, liver and placenta. As an E2-like enzyme, involves in autophagy and mitochondrial homeostasis. ATG3 catalyzes the conjugation of ATG8-like proteins to PE which is essential for autophagy. ATG3 also can catalyze the conjugation of ATG12 to itself which palys a role in mitochondrial homeostasis but not in autophagy.