View source for 8ic9


==Lys48-linked K48C-diubiquitin==
<StructureSection load='8ic9' size='340' side='right'caption='[[8ic9]], [[Resolution|resolution]] 1.25&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[8ic9]] is a 4 chain structure with sequence from [https://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=8IC9 OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=8IC9 FirstGlance]. <br>
</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">X-ray diffraction, [[Resolution|Resolution]] 1.25&#8491;</td></tr>
<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=8ic9 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=8ic9 OCA], [https://pdbe.org/8ic9 PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=8ic9 RCSB], [https://www.ebi.ac.uk/pdbsum/8ic9 PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=8ic9 ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/UBB_HUMAN UBB_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.<ref>PMID:16543144</ref> <ref>PMID:19754430</ref> 
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
In multidomain proteins, individual domains connected by flexible linkers are dynamically rearranged upon ligand binding and sensing changes in environmental factors, such as pH and temperature. Here, we characterize dynamic domain rearrangements of Lys48-linked ubiquitin (Ub) chains as models of multidomain proteins in which molecular surfaces mediating intermolecular interactions are involved in intramolecular domain-domain interactions. Using NMR and other biophysical techniques, we characterized dynamic conformational interconversions of diUb between open and closed states regarding solvent exposure of the hydrophobic surfaces of each Ub unit, which serve as binding sites for various Ub-interacting proteins. We found that the hydrophobic Ub-Ub interaction in diUb was reinforced by cysteine substitution of Lys48 of the distal Ub unit because of interaction between the cysteinyl thiol group and the C-terminal segment of the proximal Ub unit. In contrast, the replacement of the isopeptide linker with an artificial ethylenamine linker minimally affected the conformational distributions. Furthermore, we demonstrated that the mutational modification allosterically impacted the exposure of the most distal Ub unit in triUb. Thus, the conformational interconversion of Ub chains offers a unique design framework in Ub-based protein engineering not only for developing biosensing probes but also for allowing new opportunities for the allosteric regulation of multidomain proteins.

Mutational and Environmental Effects on the Dynamic Conformational Distributions of Lys48-Linked Ubiquitin Chains.,Hiranyakorn M, Yagi-Utsumi M, Yanaka S, Ohtsuka N, Momiyama N, Satoh T, Kato K Int J Mol Sci. 2023 Mar 23;24(7):6075. doi: 10.3390/ijms24076075. PMID:37047047<ref>PMID:37047047</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
</div>
<div class="pdbe-citations 8ic9" style="background-color:#fffaf0;"></div>

==See Also==
*[[3D structures of ubiquitin|3D structures of ubiquitin]]
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Homo sapiens]]
[[Category: Large Structures]]
[[Category: Hiranyakorn M]]
[[Category: Kato K]]
[[Category: Momiyama N]]
[[Category: Ohtsuka N]]
[[Category: Satoh T]]
[[Category: Yagi-Utsumi M]]
[[Category: Yanaka S]]