ATG4A (Autophagy-related protein 4 homolog A) is a cysteine protease critical for autophagy, a conserved cellular degradation process. As a member of the ATG4 family (ATG4A-D), it specifically cleaves ATG8-family proteins (e.g., LC3. GABARAP) to expose a glycine residue essential for their conjugation to phosphatidylethanolamine on autophagosome membranes. This proteolytic activity, termed "priming," enables phagophore expansion and autophagosome formation. ATG4A also mediates "deconjugation" of lipidated ATG8 proteins during autophagosome maturation and cargo degradation.
Compared to its paralog ATG4B, ATG4A exhibits distinct substrate preferences, showing higher activity toward GABARAP subfamily proteins. Its expression varies across tissues, with implications in cancer progression. Studies link ATG4A dysregulation to tumors, where it may act as either an oncogene or tumor suppressor depending on context—e.g., promoting colorectal cancer metastasis while showing reduced expression in hepatocellular carcinoma.
ATG4A antibodies are vital tools for detecting protein expression, post-translational modifications, and subcellular localization in autophagy research. They enable applications like Western blotting, immunofluorescence, and immunohistochemistry, aiding studies on autophagy-related diseases (neurodegeneration, infection, cancer) and drug discovery. Validated antibodies help clarify ATG4A's role in maintaining proteostasis and its potential as a therapeutic target.