Atg4B (ATG4 autophagy related 4 homolog B) is a cysteine protease required for autophagy, which cleaves the C-terminal part of either MAP1LC3, GABARAPL2 or GABARAP, allowing the liberation of form I. A subpopulation of form I is subsequently converted to a smaller form (form II). Form II, with a revealed C-terminal glycine, is considered to be the phosphatidylethanolamine (PE)-conjugated form, and has the capacity for the binding to autophagosomes [taken from the Universal Protein Resource (UniProt) www.uniprot.org/uniprot/ Q9Y4P1].
