View source for 2mi8


==Solution structure of lysine-free (K0) ubiquitin==
<StructureSection load='2mi8' size='340' side='right'caption='[[2mi8]]' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[2mi8]] is a 1 chain structure with sequence from [https://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens]. Full experimental information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2MI8 OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=2MI8 FirstGlance]. <br>
</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">Solution NMR</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=2mi8 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=2mi8 OCA], [https://pdbe.org/2mi8 PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=2mi8 RCSB], [https://www.ebi.ac.uk/pdbsum/2mi8 PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=2mi8 ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/UBC_HUMAN 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.<ref>PMID:16543144</ref> <ref>PMID:19754430</ref> 
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== Publication Abstract from PubMed ==
Lysine-free ubiquitin (K0-Ub) is commonly used to study the ubiquitin-signaling pathway, where it is assumed to have the same structure and function as wild-type ubiquitin (wt-Ub). However, the K0-Ub 15 N heteronuclear single quantum correlation NMR spectrum differs significantly from wt-Ub and the melting temperature is depressed by 19 degrees C, raising the question of the structural integrity and equivalence to wt-Ub. The three-dimensional structure of K0-Ub was determined by solution NMR, using chemical shift and residual dipolar coupling data. K0-Ub adopts the same backbone structure as wt-Ub, and all significant chemical shifts can be related to interactions impacted by the K to R mutations.

Solution structure of lysine-free (K0) ubiquitin.,Huang T, Li J, Byrd RA Protein Sci. 2014 Mar 3. doi: 10.1002/pro.2450. PMID:24591328<ref>PMID:24591328</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
</div>
<div class="pdbe-citations 2mi8" 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: Byrd AR]]
[[Category: Huang T]]
[[Category: Li JR]]