Atg4B also known as APG4B, AUTL1 plays a crucial role in autophagy process, which is essential for cellular homeostasis and degradation of damaged organelles and proteins. This 393 amino acid protein is primarily located in cytoplasm and belongs to peptidase C54 family, functioning as a cysteine protease. Proper functioning of Atg4b is critical, as Atg4b regulates autophagic process, thereby influencing cellular responses to stress and maintaining cellular integrity. Additionally, Atg4B exists in multiple alternatively spliced isoforms, and Atg4B activity can be inhibited by N-ethylmaleimide, highlighting importance of post-translational modifications in regulatory mechanisms.