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Structural highlights

Disease

[CHM2B_HUMAN] Defects in CHMP2B are the cause of frontotemporal dementia, chromosome 3-linked (FTD3) [MIM:600795]. FTD3 is characterized by an onset of dementia in the late 50's initially characterized by behavioral and personality changes including apathy, restlessness, disinhibition and hyperorality, progressing to stereotyped behaviors, non-fluent aphasia, mutism and dystonia, with a marked lack of insight. The brains of individuals with FTD3 have no distinctive neuropathological features. They show global cortical and central atrophy, but no beta-amyloid deposits.^[1] Defects in CHMP2B are the cause of amyotrophic lateral sclerosis type 17 (ALS17) [MIM:614696]. An adult-onset progressive neurodegenerative disorder with predominantly lower motor neuron involvement, manifest as muscle weakness and wasting of the upper and lower limbs, bulbar signs, and respiratory insufficiency.^{[2] [3]}

Function

[VPS4B_HUMAN] Involved in late steps of the endosomal multivesicular bodies (MVB) pathway. Recognizes membrane-associated ESCRT-III assemblies and catalyzes their disassembly, possibly in combination with membrane fission. Redistributes the ESCRT-III components to the cytoplasm for further rounds of MVB sorting. MVBs contain intraluminal vesicles (ILVs) that are generated by invagination and scission from the limiting membrane of the endosome and mostly are delivered to lysosomes enabling degradation of membrane proteins, such as stimulated growth factor receptors, lysosomal enzymes and lipids. In conjunction with the ESCRT machinery also appears to function in topologically equivalent membrane fission events, such as the terminal stages of cytokinesis and enveloped virus budding (HIV-1 and other lentiviruses).^{[4] [5] [6]} [CHM2B_HUMAN] Probable core component of the endosomal sorting required for transport complex III (ESCRT-III) which is involved in multivesicular bodies (MVBs) formation and sorting of endosomal cargo proteins into MVBs. MVBs contain intraluminal vesicles (ILVs) that are generated by invagination and scission from the limiting membrane of the endosome and mostly are delivered to lysosomes enabling degradation of membrane proteins, such as stimulated growth factor receptors, lysosomal enzymes and lipids. The MVB pathway appears to require the sequential function of ESCRT-O, -I,-II and -III complexes. ESCRT-III proteins mostly dissociate from the invaginating membrane before the ILV is released. The ESCRT machinery also functions in topologically equivalent membrane fission events, such as the terminal stages of cytokinesis and the budding of enveloped viruses (HIV-1 and other lentiviruses). ESCRT-III proteins are believed to mediate the necessary vesicle extrusion and/or membrane fission activities, possibly in conjunction with the AAA ATPase VPS4.

Evolutionary Conservation

Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf.

References

1. ↑ Skibinski G, Parkinson NJ, Brown JM, Chakrabarti L, Lloyd SL, Hummerich H, Nielsen JE, Hodges JR, Spillantini MG, Thusgaard T, Brandner S, Brun A, Rossor MN, Gade A, Johannsen P, Sorensen SA, Gydesen S, Fisher EM, Collinge J. Mutations in the endosomal ESCRTIII-complex subunit CHMP2B in frontotemporal dementia. Nat Genet. 2005 Aug;37(8):806-8. Epub 2005 Jul 24. PMID:16041373 doi:10.1038/ng1609
2. ↑ Parkinson N, Ince PG, Smith MO, Highley R, Skibinski G, Andersen PM, Morrison KE, Pall HS, Hardiman O, Collinge J, Shaw PJ, Fisher EM. ALS phenotypes with mutations in CHMP2B (charged multivesicular body protein 2B). Neurology. 2006 Sep 26;67(6):1074-7. Epub 2006 Jun 28. PMID:16807408 doi:10.1212/01.wnl.0000231510.89311.8b
3. ↑ Cox LE, Ferraiuolo L, Goodall EF, Heath PR, Higginbottom A, Mortiboys H, Hollinger HC, Hartley JA, Brockington A, Burness CE, Morrison KE, Wharton SB, Grierson AJ, Ince PG, Kirby J, Shaw PJ. Mutations in CHMP2B in lower motor neuron predominant amyotrophic lateral sclerosis (ALS). PLoS One. 2010 Mar 24;5(3):e9872. doi: 10.1371/journal.pone.0009872. PMID:20352044 doi:10.1371/journal.pone.0009872
4. ↑ Scheuring S, Rohricht RA, Schoning-Burkhardt B, Beyer A, Muller S, Abts HF, Kohrer K. Mammalian cells express two VPS4 proteins both of which are involved in intracellular protein trafficking. J Mol Biol. 2001 Sep 21;312(3):469-80. PMID:11563910 doi:10.1006/jmbi.2001.4917
5. ↑ von Schwedler UK, Stuchell M, Muller B, Ward DM, Chung HY, Morita E, Wang HE, Davis T, He GP, Cimbora DM, Scott A, Krausslich HG, Kaplan J, Morham SG, Sundquist WI. The protein network of HIV budding. Cell. 2003 Sep 19;114(6):701-13. PMID:14505570
6. ↑ Lata S, Schoehn G, Jain A, Pires R, Piehler J, Gottlinger HG, Weissenhorn W. Helical structures of ESCRT-III are disassembled by VPS4. Science. 2008 Sep 5;321(5894):1354-7. doi: 10.1126/science.1161070. Epub 2008 Aug, 7. PMID:18687924 doi:10.1126/science.1161070
7. ↑ Stuchell-Brereton MD, Skalicky JJ, Kieffer C, Karren MA, Ghaffarian S, Sundquist WI. ESCRT-III recognition by VPS4 ATPases. Nature. 2007 Oct 11;449(7163):740-4. PMID:17928862 doi:http://dx.doi.org/10.1038/nature06172