endosome to lysosome transport via multivesicular body sorting pathway

Definition

Target type: biologicalprocess

The directed movement of substances from endosomes to lysosomes by a pathway in which molecules are sorted into multivesicular bodies, which then fuse with the lysosome. [GOC:mah, PMID:12461556, PMID:16689637]

Endosome to lysosome transport via the multivesicular body (MVB) sorting pathway is a critical process for the degradation of cellular components, including proteins, lipids, and receptors. It involves the following steps:

1. **Cargo Sorting:** Internalized materials, including transmembrane proteins, lipids, and signaling molecules, are sorted in early endosomes. Proteins destined for degradation are often tagged with ubiquitin, a small protein that serves as a signal for sorting.

2. **MVB Formation:** The early endosome matures into a late endosome, characterized by the formation of intraluminal vesicles (ILVs) within its lumen. These ILVs are formed by inward budding of the endosome membrane. The ubiquitinated cargo proteins are specifically recognized and incorporated into these vesicles.

3. **ESCRT Machinery:** The formation of ILVs and their sorting of cargo relies on the ESCRT (Endosomal Sorting Complexes Required for Transport) machinery. This is a series of protein complexes that work in a sequential manner:
- ESCRT-0: Recognizes ubiquitinated cargo and initiates the budding process.
- ESCRT-I: Binds to ESCRT-0 and recruits ESCRT-II to the site of budding.
- ESCRT-II: Stabilizes the budding membrane.
- ESCRT-III: Forms a scaffold around the budding vesicle, promoting its scission from the endosome membrane.

4. **Fusion with Lysosomes:** The MVB, now containing the ILVs with degraded cargo, travels to and fuses with lysosomes. Lysosomes are acidic compartments containing hydrolytic enzymes that break down the cargo within the ILVs.

5. **Degradation:** The lysosomal enzymes degrade the cargo proteins, lipids, and other molecules. This degradation is essential for maintaining cellular homeostasis by removing damaged or unwanted components.

6. **Recycling:** While some materials are degraded, some are recycled back to the plasma membrane or other cellular compartments. This is a regulated process that allows for the efficient use of cellular resources.

Overall, the endosome to lysosome transport via the MVB sorting pathway is a complex and highly regulated process crucial for maintaining cell function and survival.'
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Proteins (1)

Compounds (6)