LC3B

By Christina Towers, PhD.

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.¹ LC3B is a subunit of the MAP1A and MAP1B microtubule-binding proteins and plays a central role in autophagosome membrane structure.

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.

LC3B, also known as microtubule-associated protein 1 light chain 3 beta (MAP1LC3B), is an autophagy gene that contributes appreciably to protein degradation. Autophagy is a highly synchronized and dynamic catabolic degradation activity that plays an essential role in cellular maintenance, development, antigen presentation and cell death.

Microtubule-associated protein light chain 3 (LC3) is considered one of the definitive markers of autophagy, and its use is widespread in labs throughout the world. Despite its popularity, there are several considerations when employing LC3 antibodies in immunoassays, Western blots in particular.

MAP1LC3 (shortened to LC3 in our antibody catalog) is one of four mammalian homologues of autophagy-related protein 8 (Atg8). It has been identified as a light chain subunit of the microtubule-associated proteins MAP1A/MAP1B. A modified form of LC3, LC3-II, has been identified as a marker for the autophagosomal membrane in mammals.

In rodents, MAP1LC3 (Microtubule-associated protein 1 light chain 3) is expressed in the renal visceral epithelial cells, or podocytes. LC3 antibody analysis has shown the protein accumulates in its membrane-bound form, LC3II, following conversion from LC3I.

We at Novus Biologicals have a broad antibody database covering the area of autophagy - over 1400 reagents in total. Autophagy is the bulk degradation of cytoplasmic components - literally, self-digestion of the cell. Double-membrane vesicles, called autophagosomes, carry unwanted cell components to the lysosomes within an inner autophagic membrane. They then fuse, liberating the autophagic body and its contents into the lumen of the vacuole for degradation. This is a complex process involving at least 16 proteins.