Cysteine protease ATG4D (ATG4D)

Cysteine protease ATG4D: Cysteine protease required for the cytoplasm to vacuole transport (Cvt) and autophagy. Cleaves the C-terminal amino acid of ATG8 family proteins MAP1LC3 and GABARAPL2, to reveal a C-terminal glycine.

Exposure of the glycine in the C-terminus is vital 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.