Cysteine protease ATG4B (ATG4B)

Cysteine protease required for the cytoplasm to vacuole transport (Cvt) and autophagy. Cleaves the C-terminal amino acid of ATG8 family proteins MAP1LC3, GABARAPL1, GABARAPL2 and GABARAP, to show a C-terminal glycine.

Exposure of the glycine at the C- terminus is essential for ATG8 proteins conjugation into phosphatidylethanolamine (PE) and insertion to membranes, which is essential for autophagy. Has also an activity of delipidating receptor to the PE-conjugated forms.