6pgv

Structural highlights

Function

[JOS2_HUMAN] Cleaves 'Lys-63'-linked poly-ubiquitin chains, and with lesser efficiency 'Lys-48'-linked poly-ubiquitin chains (in vitro). May act as a deubiquitinating enzyme.^{[1] [2] [3]} [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.^{[4] [5]}

References

1. ↑ Tzvetkov N, Breuer P. Josephin domain-containing proteins from a variety of species are active de-ubiquitination enzymes. Biol Chem. 2007 Sep;388(9):973-8. PMID:17696782 doi:10.1515/BC.2007.107
2. ↑ Weeks SD, Grasty KC, Hernandez-Cuebas L, Loll PJ. Crystal Structure of a Josephin-Ubiquitin Complex: EVOLUTIONARY RESTRAINTS ON ATAXIN-3 DEUBIQUITINATING ACTIVITY. J Biol Chem. 2011 Feb 11;286(6):4555-65. Epub 2010 Nov 30. PMID:21118805 doi:10.1074/jbc.M110.177360
3. ↑ Seki T, Gong L, Williams AJ, Sakai N, Todi SV, Paulson HL. JosD1, a membrane-targeted deubiquitinating enzyme, is activated by ubiquitination and regulates membrane dynamics, cell motility, and endocytosis. J Biol Chem. 2013 Jun 14;288(24):17145-55. doi: 10.1074/jbc.M113.463406. Epub, 2013 Apr 26. PMID:23625928 doi:http://dx.doi.org/10.1074/jbc.M113.463406
4. ↑ 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
5. ↑ 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