Leysósím

Leysósóm, also known as lysosome in many languages, is a membrane-bound organelle present in many eukaryotic cells. It contains a suite of acid hydrolases capable of degrading proteins, nucleic acids, lipids, and carbohydrates. The lysosomal lumen maintains an acidic pH, typically about 4.5 to 5.0, which optimizes enzyme activity. By breaking down macromolecules, lysosomes play a central role in cellular digestion, nutrient recycling, and waste processing.

Structurally, a lysosome is enclosed by a single phospholipid membrane that protects the cytosol from the hydrolytic enzymes inside. The organelle harbors numerous enzymes, including proteases, nucleases, lipases, and glycosidases. Enzymes are delivered to lysosomes from the Golgi apparatus via mannose-6-phosphate targeting signals. The lysosomal membrane contains proton pumps (V-ATPases) to maintain acidity and transporters to move degradation products into the cytosol for reuse or excretion. Lysosomes can form through fusion of late endosomes with existing lysosomes, and they interact with autophagosomes during autophagy.

Functions of lysosomes extend beyond macromolecule digestion. They participate in autophagy, removing damaged organelles and proteins, and in endocytosis and phagocytosis, aiding immune defense and antigen processing. They also contribute to cellular signaling and homeostasis by regulating nutrient sensing and metabolic pathways.

Defects in lysosomal enzymes lead to lysosomal storage diseases, such as Tay–Sachs disease (beta-hexosaminidase A deficiency), Gaucher disease (glucocerebrosidase deficiency), Pompe disease (acid alpha-glucosidase deficiency), and Niemann-Pick disease (acid sphingomyelinase deficiency). Treatments include enzyme replacement therapies and supportive care, though clinical outcomes vary by disease. The lysosome was identified by Christian de Duve in 1955, a discovery that earned him the Nobel Prize in Physiology or Medicine in 1974.