InterPro domain: IPR007135

Atg3 is the E2 enzyme for the LC3 lipidation process [ 1 ]. It is essential for autophagocytosis. The super protein complex, the Atg16L complex, consists of multiple Atg12-Atg5 conjugates. Atg16L has an E3-like role in the LC3 lipidation reaction. The activated intermediate, LC3-Atg3 (E2), is recruited to the site where the lipidation takes place [ 2 ].

Atg3 catalyses the conjugation of Atg8 and phosphatidylethanolamine (PE). Atg3 has an alpha/beta-fold, and its core region is topologically similar to canonical E2 enzymes. Atg3 has two regions inserted in the core region and another with a long alpha-helical structure that protrudes from the core region as far as 30 A [ 3 ]. It interacts with atg8 through an intermediate thioester bond between Cys-288 and the C-terminal Gly of atg8. It also interacts with the C-terminal region of the E1-like atg7 enzyme.

This entry represents a group of ubiquitin-like-conjugating enzymes, including Atg3 and Atg10.

Atg10 acts as an E2-like enzyme that catalyzes the conjugation of ATG12 to ATG5 [ 4 ].

1. The Atg16L complex specifies the site of LC3 lipidation for membrane biogenesis in autophagy. Mol. Biol. Cell 19, 2092-100
2. The Ubi brothers reunited. Autophagy 4, 540-1
3. The crystal structure of Atg3, an autophagy-related ubiquitin carrier protein (E2) enzyme that mediates Atg8 lipidation. J. Biol. Chem. 282, 8036-43
4. An Atg10-like E2 enzyme is essential for cell cycle progression but not autophagy in Schizosaccharomyces pombe. Cell Cycle 12, 271-7