Target type: cellularcomponent
The volume enclosed by the outermost membrane of a multivesicular body. [GOC:pde, PMID:21183070]
The multivesicular body (MVB) lumen is a unique cellular compartment that serves as a central hub for the sorting and degradation of various cellular components. It is a dynamic structure enclosed by a limiting membrane and characterized by the presence of numerous intraluminal vesicles (ILVs) that bud from the limiting membrane. These ILVs are enriched with various cargo molecules, including proteins, lipids, and nucleic acids, destined for degradation or trafficking to other cellular locations.
The MVB lumen is a highly acidic environment, with a pH typically ranging from 5.0 to 6.0. This acidity is maintained by the activity of proton pumps, which actively transport protons from the cytosol into the lumen. The acidic pH is essential for the optimal function of various enzymes and sorting factors that reside within the MVB lumen, facilitating the degradation and processing of cargo molecules.
The luminal environment is also characterized by the presence of specific protein complexes that facilitate the sorting and packaging of cargo into ILVs. These complexes include ESCRT (endosomal sorting complexes required for transport) proteins, which recognize specific sorting signals on cargo molecules and mediate their inclusion into the ILVs. Other proteins, such as ubiquitin ligases, are also present in the MVB lumen and contribute to the sorting process by tagging cargo molecules with ubiquitin moieties, a signal for their internalization into ILVs.
The MVB lumen is a dynamic and multifaceted compartment that plays a crucial role in cellular homeostasis by regulating the degradation of various cellular components, including misfolded proteins, signaling receptors, and intracellular pathogens. It also contributes to the generation of exosomes, small membrane-bound vesicles that are released from cells and mediate intercellular communication.'
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| Protein | Definition | Taxonomy |
|---|---|---|
| Pepsin A-5 | A pepsin A-5 that is encoded in the genome of human. [PRO:DNx, UniProtKB:P0DJD9] | Homo sapiens (human) |
| Pro-cathepsin H | A cathepsin H that is encoded in the genome of human. [PRO:DNx, UniProtKB:P09668] | Homo sapiens (human) |
| Pepsin A-5 | A pepsin A-5 that is encoded in the genome of human. [PRO:DNx, UniProtKB:P0DJD9] | Homo sapiens (human) |
| Pro-cathepsin H | A cathepsin H that is encoded in the genome of human. [PRO:DNx, UniProtKB:P09668] | Homo sapiens (human) |
| Compound | Definition | Classes | Roles |
|---|---|---|---|
| leupeptin | aldehyde; tripeptide | bacterial metabolite; calpain inhibitor; cathepsin B inhibitor; EC 3.4.21.4 (trypsin) inhibitor; serine protease inhibitor | |
| e 64 | E 64: cysteine protease inhibitor of microbial origin, which inhibits cathepsin B (EC 3.4.22.1) and cathepsin L (EC 3.4.22.-) | dicarboxylic acid monoamide; epoxy monocarboxylic acid; guanidines; L-leucine derivative; zwitterion | antimalarial; antiparasitic agent; protease inhibitor |
| pepstatin | pepstatin: inhibits the aspartic protease endothiapepsin | pentapeptide; secondary carboxamide | bacterial metabolite; EC 3.4.23.* (aspartic endopeptidase) inhibitor |
| ca 074 | |||
| odanacatib | odanacatib: a selective inhibitor of cathepsin K for the treatment of post-menopausal osteoporosis; structure in first source | ||
| calpain inhibitor iii | calpain inhibitor III: potential anticataract drug | ||
| gallinamide a | gallinamide A: antimalarial peptide from marine cyanobacteria | ||
| 6-(3,5-difluoroanilino)-9-ethyl-2-purinecarbonitrile | 6-aminopurines | ||
| 9-(3,5-difluorophenyl)-6-(ethylamino)-2-purinecarbonitrile | imidazoles | ||
| grassystatin a | grassystatin A: isolated from a cyanobacterium, identified as Lyngbya cf.; structure in first source | ||
| tipranavir | tipranavir : A pyridine-2-sulfonamide substituted at C-5 by a trifluoromethyl group and at the sulfonamide nitrogen by a dihydropyrone-containing m-tolyl substituent. It is an HIV-1 protease inhibitor. tipranavir: inhibits HIV-1 protease | sulfonamide | antiviral drug; HIV protease inhibitor |