4fjv

Structural highlights

Function

[OTUB2_HUMAN] Hydrolase that can remove conjugated ubiquitin from proteins in vitro and may therefore play an important regulatory role at the level of protein turnover by preventing degradation. Mediates deubiquitination of both 'Lys-48'- and 'Lys-63'-linked polyubiquitin chains, with a preference for 'Lys-63'-linked polyubiquitin chains.^{[1] [2]} [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.^{[3] [4]}

See Also

• Thioesterase
• Ubiquitin

References

1. ↑ Balakirev MY, Tcherniuk SO, Jaquinod M, Chroboczek J. Otubains: a new family of cysteine proteases in the ubiquitin pathway. EMBO Rep. 2003 May;4(5):517-22. PMID:12704427 doi:10.1038/sj.embor.embor824
2. ↑ Edelmann MJ, Iphofer A, Akutsu M, Altun M, di Gleria K, Kramer HB, Fiebiger E, Dhe-Paganon S, Kessler BM. Structural basis and specificity of human otubain 1-mediated deubiquitination. Biochem J. 2009 Mar 1;418(2):379-90. PMID:18954305 doi:10.1042/BJ20081318
3. ↑ 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
4. ↑ 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
5. ↑ Altun M, Walter TS, Kramer HB, Herr P, Iphofer A, Bostrom J, David Y, Komsany A, Ternette N, Navon A, Stuart DI, Ren J, Kessler BM. The human otubain2-ubiquitin structure provides insights into the cleavage specificity of poly-ubiquitin-linkages. PLoS One. 2015 Jan 15;10(1):e0115344. doi: 10.1371/journal.pone.0115344., eCollection 2015. PMID:25590432 doi:http://dx.doi.org/10.1371/journal.pone.0115344