6cp2

Structural highlights

Function

[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.^{[1] [2]} [UB2L3_HUMAN] Ubiquitin-conjugating enzyme E2 that specifically acts with HECT-type and RBR family E3 ubiquitin-protein ligases. Does not function with most RING-containing E3 ubiquitin-protein ligases because it lacks intrinsic E3-independent reactivity with lysine: in contrast, it has activity with the RBR family E3 enzymes, such as PARK2 and ARIH1, that function like function like RING-HECT hybrids. Accepts ubiquitin from the E1 complex and catalyzes its covalent attachment to other proteins. In vitro catalyzes 'Lys-11'-linked polyubiquitination. Involved in the selective degradation of short-lived and abnormal proteins. Down-regulated during the S-phase it is involved in progression through the cell cycle. Regulates nuclear hormone receptors transcriptional activity. May play a role in myelopoiesis.^{[3] [4] [5] [6] [7] [8] [9]}

See Also

• Ubiquitin
• Ubiquitin conjugating enzyme

References

1. ↑ Huang F, Kirkpatrick D, Jiang X, Gygi S, Sorkin A. Differential regulation of EGF receptor internalization and degradation by multiubiquitination within the kinase domain. Mol Cell. 2006 Mar 17;21(6):737-48. PMID:16543144 doi:S1097-2765(06)00120-1
2. ↑ Komander D. The emerging complexity of protein ubiquitination. Biochem Soc Trans. 2009 Oct;37(Pt 5):937-53. doi: 10.1042/BST0370937. PMID:19754430 doi:10.1042/BST0370937
3. ↑ Shimura H, Hattori N, Kubo S, Mizuno Y, Asakawa S, Minoshima S, Shimizu N, Iwai K, Chiba T, Tanaka K, Suzuki T. Familial Parkinson disease gene product, parkin, is a ubiquitin-protein ligase. Nat Genet. 2000 Jul;25(3):302-5. PMID:10888878 doi:10.1038/77060
4. ↑ Verma S, Ismail A, Gao X, Fu G, Li X, O'Malley BW, Nawaz Z. The ubiquitin-conjugating enzyme UBCH7 acts as a coactivator for steroid hormone receptors. Mol Cell Biol. 2004 Oct;24(19):8716-26. PMID:15367689 doi:10.1128/MCB.24.19.8716-8726.2004
5. ↑ Garside H, Waters C, Berry A, Rice L, Ardley HC, White A, Robinson PA, Ray D. UbcH7 interacts with the glucocorticoid receptor and mediates receptor autoregulation. J Endocrinol. 2006 Sep;190(3):621-9. PMID:17003263 doi:10.1677/joe.1.06799
6. ↑ Marteijn JA, van der Meer LT, Smit JJ, Noordermeer SM, Wissink W, Jansen P, Swarts HG, Hibbert RG, de Witte T, Sixma TK, Jansen JH, van der Reijden BA. The ubiquitin ligase Triad1 inhibits myelopoiesis through UbcH7 and Ubc13 interacting domains. Leukemia. 2009 Aug;23(8):1480-9. Epub 2009 Apr 2. PMID:19340006 doi:leu200957
7. ↑ Whitcomb EA, Dudek EJ, Liu Q, Taylor A. Novel control of S phase of the cell cycle by ubiquitin-conjugating enzyme H7. Mol Biol Cell. 2009 Jan;20(1):1-9. doi: 10.1091/mbc.E08-01-0036. Epub 2008 Oct, 22. PMID:18946090 doi:10.1091/mbc.E08-01-0036
8. ↑ David Y, Ziv T, Admon A, Navon A. The E2 ubiquitin conjugating enzymes direct polyubiquitination to preferred lysines. J Biol Chem. 2010 Jan 8. PMID:20061386 doi:M109.089003
9. ↑ Wenzel DM, Lissounov A, Brzovic PS, Klevit RE. UBCH7 reactivity profile reveals parkin and HHARI to be RING/HECT hybrids. Nature. 2011 Jun 2;474(7349):105-8. doi: 10.1038/nature09966. Epub 2011 May 1. PMID:21532592 doi:10.1038/nature09966
10. ↑ Wasilko DJ, Huang Q, Mao Y. Insights into the ubiquitin transfer cascade catalyzed by the Legionella effector SidC. Elife. 2018 Jul 17;7. pii: 36154. doi: 10.7554/eLife.36154. PMID:30015617 doi:http://dx.doi.org/10.7554/eLife.36154