The Classification and Basic Processes of Autophagy.

Autophagy is a general term for the process of the lysosomal degradation of intracellular components, a process occurring exclusively in eukaryotic cells. Based on the way that intracellular substrates are transported to lysosomes, autophagy in mammalian cells can be divided into three main types: macroautophagy, microautophagy, and chaperone-mediated autophagy (CMA). Each type has its unique molecular machinery and is tightly regulated by various cellular signals, helping cells adapt to a changing environment. Autophagy can also be divided into two categories based on cargo selectivity: selective autophagy and nonselective autophagy. Nonselective autophagy refers to the bulk transport of organelles or other cytoplasmic components to lysosomes, while selective autophagy refers to the degradation of a specific substrate. Autophagy plays an essential role in maintaining cellular homeostasis, and dysregulation of it may participate in the pathological process of many human diseases.