| Structural highlights
Disease
[CHM4B_HUMAN] Defects in CHMP4B are the cause of cataract posterior polar type 3 (CTPP3) [MIM:605387]. A subcapsular opacity, usually disk-shaped, located at the back of the lens. It can have a marked effect on visual acuity.[1]
Function
[PTN23_HUMAN] Plays a role in sorting of endocytic ubiquitinated cargos into multivesicular bodies (MVBs) via its interaction with the ESCRT-I complex (endosomal sorting complex required for transport I), and possibly also other ESCRT complexes. May act as a negative regulator of Ras-mediated mitogenic activity. Plays a role in ciliogenesis.[2] [3] [4] [CHM4B_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. When overexpressed, membrane-assembled circular arrays of CHMP4B filaments can promote or stabilize negative curvature and outward budding. Via its interaction with PDCD6IP involved in HIV-1 p6- and p9-dependent virus release.[5] [6] [7] [8] [9]
Publication Abstract from PubMed
SARA and endofin are endosomal adaptor proteins that drive Smad phosphorylation by ligand-activated transforming growth factor beta/bone morphogenetic protein (TGFbeta/BMP) receptors. We show in this study that SARA and endofin also recruit the tumor supressor HD-PTP, a master regulator of endosomal sorting and ESCRT-dependent receptor downregulation. High-affinity interactions occur between the SARA/endofin N termini, and the conserved hydrophobic region in the HD-PTP Bro1 domain that binds CHMP4/ESCRT-III. CHMP4 engagement is a universal feature of Bro1 proteins, but SARA/endofin binding is specific to HD-PTP. Crystallographic structures of HD-PTPBro1 in complex with SARA, endofin, and three CHMP4 isoforms revealed that all ligands bind similarly to the conserved site but, critically, only SARA/endofin interact at a neighboring pocket unique to HD-PTP. The structures, together with mutagenesis and binding analysis, explain the high affinity and specific binding of SARA/endofin, and why they compete so effectively with CHMP4. Our data invoke models for how endocytic regulation of TGFbeta/BMP signaling is controlled.
Structural Basis for Specific Interaction of TGFbeta Signaling Regulators SARA/Endofin with HD-PTP.,Gahloth D, Levy C, Walker L, Wunderley L, Mould AP, Taylor S, Woodman P, Tabernero L Structure. 2017 Jul 5;25(7):1011-1024.e4. doi: 10.1016/j.str.2017.05.005. Epub, 2017 Jun 8. PMID:28602823[10]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
See Also
References
- ↑ Shiels A, Bennett TM, Knopf HL, Yamada K, Yoshiura K, Niikawa N, Shim S, Hanson PI. CHMP4B, a novel gene for autosomal dominant cataracts linked to chromosome 20q. Am J Hum Genet. 2007 Sep;81(3):596-606. Epub 2007 Jul 27. PMID:17701905 doi:S0002-9297(07)61356-1
- ↑ Doyotte A, Mironov A, McKenzie E, Woodman P. The Bro1-related protein HD-PTP/PTPN23 is required for endosomal cargo sorting and multivesicular body morphogenesis. Proc Natl Acad Sci U S A. 2008 Apr 29;105(17):6308-13. doi:, 10.1073/pnas.0707601105. Epub 2008 Apr 23. PMID:18434552 doi:http://dx.doi.org/10.1073/pnas.0707601105
- ↑ Kim J, Lee JE, Heynen-Genel S, Suyama E, Ono K, Lee K, Ideker T, Aza-Blanc P, Gleeson JG. Functional genomic screen for modulators of ciliogenesis and cilium length. Nature. 2010 Apr 15;464(7291):1048-51. doi: 10.1038/nature08895. PMID:20393563 doi:10.1038/nature08895
- ↑ Stefani F, Zhang L, Taylor S, Donovan J, Rollinson S, Doyotte A, Brownhill K, Bennion J, Pickering-Brown S, Woodman P. UBAP1 is a component of an endosome-specific ESCRT-I complex that is essential for MVB sorting. Curr Biol. 2011 Jul 26;21(14):1245-50. doi: 10.1016/j.cub.2011.06.028. Epub 2011 , Jul 14. PMID:21757351 doi:http://dx.doi.org/10.1016/j.cub.2011.06.028
- ↑ Katoh K, Shibata H, Suzuki H, Nara A, Ishidoh K, Kominami E, Yoshimori T, Maki M. The ALG-2-interacting protein Alix associates with CHMP4b, a human homologue of yeast Snf7 that is involved in multivesicular body sorting. J Biol Chem. 2003 Oct 3;278(40):39104-13. Epub 2003 Jul 14. PMID:12860994 doi:10.1074/jbc.M301604200
- ↑ Strack B, Calistri A, Craig S, Popova E, Gottlinger HG. AIP1/ALIX is a binding partner for HIV-1 p6 and EIAV p9 functioning in virus budding. Cell. 2003 Sep 19;114(6):689-99. PMID:14505569
- ↑ 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
- ↑ Martin-Serrano J, Yarovoy A, Perez-Caballero D, Bieniasz PD. Divergent retroviral late-budding domains recruit vacuolar protein sorting factors by using alternative adaptor proteins. Proc Natl Acad Sci U S A. 2003 Oct 14;100(21):12414-9. Epub 2003 Sep 30. PMID:14519844 doi:10.1073/pnas.2133846100
- ↑ Hanson PI, Roth R, Lin Y, Heuser JE. Plasma membrane deformation by circular arrays of ESCRT-III protein filaments. J Cell Biol. 2008 Jan 28;180(2):389-402. Epub 2008 Jan 21. PMID:18209100 doi:jcb.200707031
- ↑ Gahloth D, Levy C, Walker L, Wunderley L, Mould AP, Taylor S, Woodman P, Tabernero L. Structural Basis for Specific Interaction of TGFbeta Signaling Regulators SARA/Endofin with HD-PTP. Structure. 2017 Jul 5;25(7):1011-1024.e4. doi: 10.1016/j.str.2017.05.005. Epub, 2017 Jun 8. PMID:28602823 doi:http://dx.doi.org/10.1016/j.str.2017.05.005
|
