Much like trash collection helps rid your household of unwanted garbage, the cellular process of autophagy removes a cell's waste. During this process, unnecessary or problematic cellular components are degraded in organelles called lysosomes.
There are three types of autophagy – chaperone-mediated autophagy, microautophagy, and macroautophagy. In chaperone-mediated autophagy, the most selective of the three processes, a cytosolic molecular chaperone, heat shock cognate 70 kDa protein (Hsc70), recognizes the material to be degraded (which bears a specific amino acid tag) and transports it to the lysosomal membrane1. After binding to lysosome-associated membrane protein type 2A (LAMP-2A), the material is translocated to the interior of the lysosome where it is degraded by proteases. In microautophagy, cellular components destined for degradation are directly engulfed by invaginations of the lysosomal membrane2.
In macroautophagy, the pathway that the general term “autophagy” usually refers to, a portion of the cytoplasm is enclosed around a double-membrane, forming an organelle called an autophagosome. Its formation is regulated by autophagy-related (Atg) proteins that are recruited to the phagophore assembly site (PAS), where the autophagosome will eventually form2. The autophagosome travels to a lysosome, where the two organelles fuse, and the cytoplasmic contents are degraded by lysosomal hydrolases. Following degradation of macromolecules, basic cellular components such as amino acids are recycled to the cytoplasm through membrane permeases for reuse3.
At the simplest level, autophagy helps maintain cellular homeostasis by acting as a “quality control” system for cellular components2. It can also serve a cytoprotective function when upregulated in the face of environmental stressors such as a lack of nutrients or oxidative stress2. Though less well studied, a role for autophagy in a wide variety of processes, ranging from development to apoptosis to immune system antigen presentation, has also been reported3. Not surprisingly, abnormal autophagy has also been implicated in a number of diseases, including cancer, neurodegeneration, and infection1,4.
Contributed by Allison A. Curley, Ph.D.
Below is the current listing of Bethyl antibodies involved in autophagy research: