is a ubiquitin-like protein that is a constituent of the ATG8-conjugation system, one of two evolutionarily conserved phosphatidylethanolamine conjugation systems necessary for the formation of the autophagosome. The human ATG8 system includes seven ubiquitin-like light chain proteins (LCPs) that are homologs of yeast LC3: MAP1LC3A, -B, -C, GABARAP, GABARAPL1, -2, and -3. Pro-LCPs are cleaved by ATG4B to expose a C-terminal glycine residue, the cytosolic LCP-I form. The exposed C-terminus is conjugated to the head group amine of phosphatidylethanolamine (PE) through an amide bond by a sequence of ubiquitination-like reactions that involves an E1 (ATG7), an E2 (ATG3), and an E3 (a complex including ATG5, ATG12, and ATG16L). The PE-congugated form (LCP-II) is tightly associated with the autophagosomal membrane. The LCP-II forms can also be delipidated by the ATG4 proteases: most of the LCPs are delipidated and liberated from the membrane before autophagosomes fuse with lysosomes. Two isoforms of the human protein are produced by alternative splicing. Note: This description may include information from UniProtKB.
Protein type: Autophagy; Microtubule-binding; Ubiquitin-like modifier; Vesicle