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X-ray structure of human ubiquitin Cd(II) adduct
Structural highlights
FunctionUBC_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] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedA structural investigation performed on adducts of human ubiquitin with group-12 metal ions reveals common preferential anchoring sites, the most populated one being His68; at higher metal ion concentration a second and a third site, close to the N-terminus of the protein, become populated and promote a polymorphic transition from orthorhombic to cubic form; Glu16 and Glu18, involved in the latter metal binding, undergo a remarkable displacement from their position in native ubiquitin; the aggregate stereochemistry appears to be driven by the clustering of deshielded backbone hydrogen-bond patches, and metal ions foster this process. Structural probing of Zn(ii), Cd(ii) and Hg(ii) binding to human ubiquitin.,Falini G, Fermani S, Tosi G, Arnesano F, Natile G Chem Commun (Camb). 2008 Dec 7;(45):5960-2. Epub 2008 Oct 9. PMID:19030552[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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