Golgi lumen acidification

Definition

Target type: biologicalprocess

Any process that reduces the pH of the Golgi lumen, measured by the concentration of the hydrogen ion. [GOC:dph, PMID:23447592]

The Golgi lumen acidification is a crucial process for proper protein processing and sorting within the Golgi apparatus. It involves the creation and maintenance of a low pH environment within the Golgi cisternae, which is essential for several enzymatic activities.

The process begins with the active pumping of protons (H+) from the cytosol into the Golgi lumen by proton pumps. These pumps, primarily V-ATPases, use ATP hydrolysis to generate the electrochemical gradient that drives proton movement. The V-ATPases are multi-subunit complexes located on the Golgi membrane, and their activity is tightly regulated.

Once inside the lumen, the protons contribute to the acidification process. The pH gradient across the Golgi membrane is further maintained by the selective permeability of the membrane, which restricts the movement of other ions and molecules.

The low pH environment within the Golgi lumen plays a vital role in several enzymatic activities. For example, it facilitates the activation of glycosidases, which are enzymes involved in the modification of glycans on proteins. It also promotes the proper folding and assembly of certain proteins, as well as the formation of disulfide bonds.

The acidification process is also important for the sorting of proteins. Proteins destined for different cellular compartments are often tagged with specific sorting signals, and these signals are recognized by different receptors at the Golgi membrane. The pH gradient influences the binding affinity of these receptors, thereby contributing to the sorting process.

In summary, the acidification of the Golgi lumen is a critical process that involves the active pumping of protons into the lumen by V-ATPases. This process creates a low pH environment that is essential for various enzymatic activities, protein folding and assembly, and protein sorting. The proper functioning of the Golgi lumen acidification is crucial for maintaining cellular homeostasis and overall cell function.'
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