Autophagosome Markers

The autophagosome is a spherical, double-membraned organelle which engulfs damaged organelles and other cytoplasmic contents for delivery to lysosomes as part of the macroautophagic intracellular degradation pathway. Activation of macroautophagy occurs upon nutrient deprivation, hypoxia and a variety of other cellular stresses. The stress-sensing mTOR kinase signalling hub is a central regulator of this pathway through inhibitory phosphorylation of ULK1, a protein complex consisting of ULK1, ATG13, ATG101, and ATG14. For example, upon nutrient depletion, mTOR-dependent ULK1 inhibition is suppressed, activating the ULK1 complex and prompting its recruitment to the phagophore assembly site (PAS). Phagophores are a cup-shaped, double-membraned precursor compartment to the mature autophagosome. This maturation is achieved through phagophore elongation, a ULK1-dependent process driving compartment expansion downstream of membrane-associated PI3K signalling.The elongated phagophore engulfs and sequesters cellular cargo before it is sealed to become an autophagosome. Two ubiquitin-like conjugation systems are central to phagophore maturation. One of these involves the microtubule-associated protein 1A/1B-light chain 3 (LC3) proteins, LC3A and LC3B. LC3A and LC3B promote phagophore elongation following their conjugation to phosphatidylethanolamine (PE) and subsequent localisation to the phagophore membrane. Lipidated LC3, known as LC3-II, is widely used as a marker for autophagosomes, allowing for their visualisation and quantification. Further, another marker, the adaptor protein p62, promotes selective autophagy through its interaction with LC3. As a result, p62 abundance on the autophagosome membrane serves as a proxy for autophagosome dynamics and cargo degradation. The process of macroautophagy is completed upon maturation of the autophagosome as it acquires lysosomal characteristics and initiates lysosomal fusion. Once this occurs, the cargo is exposed to lysosomal hydrolases which degrade proteins, lipids, nucleic acids, and other cellular components. Protein markers provide valuable insights into autophagosome dynamics, regulation, and interactions with other cellular components. We offer a range of antibodies against autophagosome markers including Apg12 antibodies, LC3B antibodies, LC3A antibodies, and RAB11A antibodies, that are validated across multiple applications and cover various host species, isotypes and conjugates.