ER-phagy Cargo Receptor Antibody Sampler Kit #82484

The endoplasmic reticulum (ER) is a large multifaceted organelle that functions in protein folding and processing, calcium storage, and steroid and lipid biogenesis. It is composed of a heterogeneous and continuous network of flattened sacs, or sheets, and tubules that extend from the nuclear envelope to the plasma membrane. It can also be divided into rough ER and smooth peripheral ER; rough ER is predominantly within perinuclear sheets and decorated with ribosomes, and smooth peripheral ER is involved in metabolic activities such as lipid and steroid synthesis. Tubular ER extends throughout the cytoplasm and provides contact points for signaling to other organelles including providing lipids for phagophore formation needed for autophagy. The ER structure is regulated in a dynamic fashion to maintain homeostasis and adjust to cellular stress. Defects in this process may contribute to pathological conditions including metabolic and neurological disorders, cancer, and defense against infectious diseases.

ER-phagy is one of the key processes that regulates ER morphology and functions in the fragmentation and removal of ER segments. Accumulation of unfolded proteins or exposure to conditions such as metabolic or oxidative stress leads to compensatory ER stress programs that remodel the ER structure and activate signaling pathways to cope with those challenges. Activation of ER stress pathways, such as the unfolded protein response (UPR), increases ER membrane to help manage increased demand. Once the stress conditions subside, ER-phagy can eliminate unneeded ER fragments (reviewed in 1-3). Over the last several years, there have been advances in our understanding of ER-phagy. A significant advancement is the discovery of several ER-resident autophagy receptors, including FAM134B, CCPG1, ATL3, TEX264, SEC62, and RTN3L. These cargo receptors have distinct modes of regulation, expression patterns, and localization within the ER. Each of these proteins contains at least one LIR or GIM, which facilitates binding to LC3 or GABARAP family members on the autophagosome. These autophagy receptors contribute to ER-phagy at specific sites on the ER and in response to different stimuli, including nutrient deprivation, ER stress, and changes in calcium. Loss of these proteins is associated with damaged ER expansion, sustained activation of ER stress pathways, and pathophysiological regulation.