ubiquitin-like (Ubl) domain found in autophagy-related ubiquitin-like protein
Autophagy is an essential intracellular process that targets large protein complexes, bacterial pathogens, and organelles for degradation. The autophagy-related ubiquitin-like proteins, such as Saccharomyces cerevisiae Atg8p, undergo a unique ubiquitin-like (Ubl) conjugation, a process essential for autophagosome formation. Ubiquitin is a protein modifier in eukaryotes that is involved in various cellular processes including transcriptional regulation, cell cycle control, and DNA repair. The ubiquitination process comprises a cascade of E1, E2 and E3 enzymes that results in a covalent bond between the C-terminus of ubiquitin and the epsilon-amino group of a substrate lysine. ATG8 family proteins undergo multistep modifications by the E1-like (ubiquitin activating) enzyme ATG7, and the E2-like (ubiquitin conjugating) enzyme ATG3. The mammalian ATG8 family is classified into three subfamilies: i) MAP1LC3 (microtubule associated protein 1 light chain 3) which includes MAP1LC3A, MAP1LC3B, MAP1LC3B2, and MAP1LC3C, ii) GABARAP (GABA type A receptor associated protein) which includes GABARAP, GABARAPL1, and GABARAPL3, and iii) GABARAPL2 (GABA type A receptor associated protein like 2), also known as GATE-16 (golgi-associated adenosine triphosphatase enhancer of 16 kDa).
Jiyao W et al.(2023). "The conserved domain database in 2023.",