endosomal lumen acidification

Definition

Target type: biologicalprocess

Any process that reduces the pH of the endosomal lumen, measured by the concentration of the hydrogen ion. [GOC:jid]

Endosomal lumen acidification is a crucial process in eukaryotic cells, involving the lowering of pH within endosomes, membrane-bound compartments responsible for transporting and sorting internalized molecules. This acidification is driven by the activity of a proton pump, known as the vacuolar ATPase (V-ATPase). The V-ATPase is a multi-subunit complex that uses the energy from ATP hydrolysis to pump protons from the cytosol into the endosomal lumen. This proton pumping action creates an electrochemical gradient across the endosomal membrane, driving the movement of protons into the lumen and thus lowering the pH. The acidic environment within endosomes facilitates several important cellular functions: 1) Dissociation of receptor-ligand complexes. Many receptors bind to their ligands at neutral pH but release them at acidic pH, allowing for efficient cargo delivery. 2) Activation of enzymes involved in intracellular trafficking. Several hydrolytic enzymes, including proteases and lipases, are optimally active at acidic pH, enabling the degradation of internalized material. 3) Sorting of cargo. The acidic environment within endosomes influences the sorting of internalized molecules into different destinations, such as lysosomes or the trans-Golgi network. 4) Immune signaling. The acidification of phagosomes, specialized endosomes that engulf pathogens, plays a critical role in the activation of antimicrobial defense mechanisms. Overall, endosomal lumen acidification is an essential process for cellular homeostasis, enabling efficient intracellular trafficking, signaling, and degradation pathways.'
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Proteins (1)

Compounds (1)