Autophagy-related protein 3 (IPR007135)

Short name: Autophagy-rel_prot_3

Overlapping homologous superfamilies


Domain relationships



Proteins in this entry belong to the Atg3 group of proteins and the Atg3 conjugation enzymes.

Autophagy is a degradative transport pathway that delivers cytosolic proteins to the lysosome (vacuole) [PMID: 11058089] and is induced by starvation [PMID: 9190802]. Cytosolic proteins appear inside the vacuole enclosed in autophagic vesicles. Autophagy significantly differs from other transport pathways by using double membrane layered transport intermediates, called autophagosomes [PMID: 11675007, PMID: 18472412]. The breakdown of vesicular transport intermediates is a unique feature of autophagy [PMID: 11058089]. Autophagy can also function in the elimination of invading bacteria and antigens [PMID: 18472412].

Atg3 is the E2 enzyme for the LC3 lipidation process [PMID: 18321988]. 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 [PMID: 18398292].

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 [PMID: 17227760]. 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.

Autophagocytosis is a starvation-induced process responsible for transport of cytoplasmic proteins to the vacuole. The cysteine residue within the HPC motif is the putative active-site residue for recognition of the Apg5 subunit of the autophagosome complex [PMID: 12482611].

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.