Autophagy Related Protein 4D (ATG4D)

Autophagy is the biologic process leading to intracellular destruction of endogenous proteins and removal of damaged organelles. ATG4D is a homolog of yeast Apg4, a cysteine protease involved in autophagy.The deduced 474-amino acid protein contains a putative active-site cysteine at position 134. ATG4D shares significant similarity with yeast Apg4, except for divergence at its N- and C-terminal ends. The absence of an N-terminal signal sequence suggests that ATG4D is a cytoplasmic enzyme. Northern blot analysis detected a 2.4-kb transcript that was highly expressed in skeletal muscle and more weakly expressed in testis. ATG4D was expressed in some tumor cell lines, but not in fetal tissues.