secretion of lysosomal enzymes

Definition

Target type: biologicalprocess

The controlled release of lysosomal enzymes by a cell. [GOC:mah]

Lysosomal enzymes are synthesized in the endoplasmic reticulum (ER), where they undergo N-glycosylation, a process that involves the addition of oligosaccharide chains to asparagine residues. These newly synthesized enzymes then move to the Golgi apparatus, a series of flattened sacs that play a crucial role in protein sorting and modification. In the Golgi, the oligosaccharide chains on lysosomal enzymes are further modified through a series of enzymatic steps. One critical step involves the addition of mannose-6-phosphate (M6P) residues to the oligosaccharides. M6P serves as a molecular tag that directs lysosomal enzymes to their final destination. As lysosomal enzymes traverse the Golgi, they encounter specific receptors that recognize and bind to the M6P residues. These M6P receptors are also located in clathrin-coated pits, which are invaginations of the Golgi membrane. Once bound to the M6P receptors, lysosomal enzymes are packaged into clathrin-coated vesicles that bud off from the Golgi. These vesicles then transport the enzymes to late endosomes, which are acidic compartments within the cell. The acidic environment of the late endosomes triggers the dissociation of the lysosomal enzymes from the M6P receptors. The M6P receptors are recycled back to the Golgi, while the lysosomal enzymes are delivered to lysosomes, the primary degradative compartments of the cell. In addition to this M6P-dependent pathway, some lysosomal enzymes may be delivered to lysosomes through other pathways, such as the autophagy pathway. Autophagy involves the engulfment of cellular components, including damaged organelles, in double-membrane vesicles called autophagosomes. These autophagosomes then fuse with lysosomes, delivering their contents for degradation. The secretion of lysosomal enzymes is a tightly regulated process that ensures the proper targeting of these enzymes to lysosomes. Defects in this process can lead to lysosomal storage disorders, which result from the accumulation of undigested material in lysosomes. These disorders can affect various tissues and organs, leading to a range of clinical manifestations.'
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Proteins (1)

Compounds (1)