4ksl
From Proteopedia
Gumby/Fam105B in complex with linear di-ubiquitin
Structural highlights
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Function[UBC_HUMAN] Ubiquitin exists either covalently attached to another protein, or free (unanchored). When covalently bound, it is conjugated to target proteins via an isopeptide bond either as a monomer (monoubiquitin), a polymer linked via different Lys residues of the ubiquitin (polyubiquitin chains) or a linear polymer linked via the initiator Met of the ubiquitin (linear polyubiquitin chains). Polyubiquitin chains, when attached to a target protein, have different functions depending on the Lys residue of the ubiquitin that is linked: Lys-6-linked may be involved in DNA repair; Lys-11-linked is involved in ERAD (endoplasmic reticulum-associated degradation) and in cell-cycle regulation; Lys-29-linked is involved in lysosomal degradation; Lys-33-linked is involved in kinase modification; Lys-48-linked is involved in protein degradation via the proteasome; Lys-63-linked is involved in endocytosis, DNA-damage responses as well as in signaling processes leading to activation of the transcription factor NF-kappa-B. Linear polymer chains formed via attachment by the initiator Met lead to cell signaling. Ubiquitin is usually conjugated to Lys residues of target proteins, however, in rare cases, conjugation to Cys or Ser residues has been observed. When polyubiquitin is free (unanchored-polyubiquitin), it also has distinct roles, such as in activation of protein kinases, and in signaling.[1] [2] Publication Abstract from PubMedA complex interaction of signalling events, including the Wnt pathway, regulates sprouting of blood vessels from pre-existing vasculature during angiogenesis. Here we show that two distinct mutations in the (uro)chordate-specific gumby (also called Fam105b) gene cause an embryonic angiogenic phenotype in gumby mice. Gumby interacts with disheveled 2 (DVL2), is expressed in canonical Wnt-responsive endothelial cells and encodes an ovarian tumour domain class of deubiquitinase that specifically cleaves linear ubiquitin linkages. A crystal structure of gumby in complex with linear diubiquitin reveals how the identified mutations adversely affect substrate binding and catalytic function in line with the severity of their angiogenic phenotypes. Gumby interacts with HOIP (also called RNF31), a key component of the linear ubiquitin assembly complex, and decreases linear ubiquitination and activation of NF-kappaB-dependent transcription. This work provides support for the biological importance of linear (de)ubiquitination in angiogenesis, craniofacial and neural development and in modulating Wnt signalling. The linear ubiquitin-specific deubiquitinase gumby regulates angiogenesis.,Rivkin E, Almeida SM, Ceccarelli DF, Juang YC, MacLean TA, Srikumar T, Huang H, Dunham WH, Fukumura R, Xie G, Gondo Y, Raught B, Gingras AC, Sicheri F, Cordes SP Nature. 2013 Jun 20;498(7454):318-24. doi: 10.1038/nature12296. Epub 2013 May 24. PMID:23708998[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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