Autophagy is an essential process that cells utilize to degrade and recycle damaged material and fuel metabolism, especially under stress. The process is evolutionarily conserved and complex, relying on over 20 key proteins. Induction of autophagy is mediated by the formation of the ULK and BECLIN complexes, the latter of which includes BH3-containing proteins and AMBRA1, resulting in the formation of a double membrane phagophore structure.
The process of autophagy, or lysosome-mediated degradation of damaged proteins and organelles in the cytosol, is a vital cellular process that acts as a quality control mechanism for proteins and organelles. The misregulation of autophagy can lead to an imbalance of cellular homeostasis and the subsequent development of disease. Therefore, the study of autophagy is at the forefront of neuroscience and cancer research, among others.
The human form of microtubule-associated protein light chain 3 (LC3) is expressed as 3 splice variants; LC3A, LC3B and LC3C (He et al., 2003). LC3B is a subunit of the MAP1A and MAP1B microtubule-binding proteins and plays a central role autophagosome membrane structure. This ubiquitin-like modifier is known to be involved in early stages of autophagosome formation and specifically with phagophore membrane elongation.
LC3B is subunit component of the LC3 autophagy biomarker associated with microtubule-associated proteins MAP1A and MAP1B and one of the best characterized markers to date. In resting state it is cytosolic, but upon activation, is lapidated and becomes embedded in the autophagosomal membrane.