| Structural highlights
Function
[ISG15_HUMAN] Ubiquitin-like protein that is conjugated to intracellular target proteins after IFN-alpha or IFN-beta stimulation. Its enzymatic pathway is partially distinct from that of ubiquitin, differing in substrate specificity and interaction with ligating enzymes. ISG15 conjugation pathway uses a dedicated E1 enzyme, but seems to converge with the Ub conjugation pathway at the level of a specific E2 enzyme. Targets include STAT1, SERPINA3G/SPI2A, JAK1, MAPK3/ERK1, PLCG1, EIF2AK2/PKR, MX1/MxA, and RIG-1. Deconjugated by USP18/UBP43. Shows specific chemotactic activity towards neutrophils and activates them to induce release of eosinophil chemotactic factors. May serve as a trans-acting binding factor directing the association of ligated target proteins to intermediate filaments. May also be involved in autocrine, paracrine and endocrine mechanisms, as in cell-to-cell signaling, possibly partly by inducing IFN-gamma secretion by monocytes and macrophages. Seems to display antiviral activity during viral infections.[1] [2] [3] [4] [5] [6] In response to IFN-tau secreted by the conceptus, may ligate to and regulate proteins involved in the release of prostaglandin F2-alpha (PGF), and thus prevent lysis of the corpus luteum and maintain the pregnancy (By similarity).[7] [8] [9] [10] [11] [12]
Evolutionary Conservation
Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf.
Publication Abstract from PubMed
The biological effects of the ISG15 protein arise in part from its conjugation to cellular targets as a primary response to interferon-alpha/beta induction and other markers of viral or parasitic infection. Recombinant full-length ISG15 has been produced for the first time in high yield by mutating Cys78 to stabilize the protein and by cloning in a C-terminal arginine cap to protect the C terminus against proteolytic inactivation. The cap is subsequently removed with carboxypeptidase B to yield mature biologically active ISG15 capable of stoichiometric ATP-dependent thiolester formation with its human UbE1L activating enzyme. The three-dimensional structure of recombinant ISG15C78S was determined at 2.4-A resolution. The ISG15 structure comprises two beta-grasp folds having main chain root mean square deviation (r.m.s.d.) values from ubiquitin of 1.7 A (N-terminal) and 1.0 A (C-terminal). The beta-grasp domains pack across two conserved 3(10) helices to bury 627 A2 that accounts for 7% of the total solvent-accessible surface area. The distribution of ISG15 surface charge forms a ridge of negative charge extending nearly the full-length of the molecule. Additionally, the N-terminal domain contains an apolar region comprising almost half its solvent accessible surface. The C-terminal domain of ISG15 was superimposed on the structure of Nedd8 (r.m.s.d. = 0.84 A) bound to its AppBp1-Uba3 activating enzyme to model ISG15 binding to UbE1L. The docking model predicts several key side-chain interactions that presumably define the specificity between the ubiquitin and ISG15 ligation pathways to maintain functional integrity of their signaling.
Crystal structure of the interferon-induced ubiquitin-like protein ISG15.,Narasimhan J, Wang M, Fu Z, Klein JM, Haas AL, Kim JJ J Biol Chem. 2005 Jul 22;280(29):27356-65. Epub 2005 May 24. PMID:15917233[13]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
See Also
References
- ↑ Loeb KR, Haas AL. The interferon-inducible 15-kDa ubiquitin homolog conjugates to intracellular proteins. J Biol Chem. 1992 Apr 15;267(11):7806-13. PMID:1373138
- ↑ Loeb KR, Haas AL. Conjugates of ubiquitin cross-reactive protein distribute in a cytoskeletal pattern. Mol Cell Biol. 1994 Dec;14(12):8408-19. PMID:7526157
- ↑ Narasimhan J, Potter JL, Haas AL. Conjugation of the 15-kDa interferon-induced ubiquitin homolog is distinct from that of ubiquitin. J Biol Chem. 1996 Jan 5;271(1):324-30. PMID:8550581
- ↑ Knight E Jr, Cordova B. IFN-induced 15-kDa protein is released from human lymphocytes and monocytes. J Immunol. 1991 Apr 1;146(7):2280-4. PMID:2005397
- ↑ Lenschow DJ, Giannakopoulos NV, Gunn LJ, Johnston C, O'Guin AK, Schmidt RE, Levine B, Virgin HW 4th. Identification of interferon-stimulated gene 15 as an antiviral molecule during Sindbis virus infection in vivo. J Virol. 2005 Nov;79(22):13974-83. PMID:16254333 doi:79/22/13974
- ↑ Zhao C, Denison C, Huibregtse JM, Gygi S, Krug RM. Human ISG15 conjugation targets both IFN-induced and constitutively expressed proteins functioning in diverse cellular pathways. Proc Natl Acad Sci U S A. 2005 Jul 19;102(29):10200-5. Epub 2005 Jul 11. PMID:16009940 doi:0504754102
- ↑ Loeb KR, Haas AL. The interferon-inducible 15-kDa ubiquitin homolog conjugates to intracellular proteins. J Biol Chem. 1992 Apr 15;267(11):7806-13. PMID:1373138
- ↑ Loeb KR, Haas AL. Conjugates of ubiquitin cross-reactive protein distribute in a cytoskeletal pattern. Mol Cell Biol. 1994 Dec;14(12):8408-19. PMID:7526157
- ↑ Narasimhan J, Potter JL, Haas AL. Conjugation of the 15-kDa interferon-induced ubiquitin homolog is distinct from that of ubiquitin. J Biol Chem. 1996 Jan 5;271(1):324-30. PMID:8550581
- ↑ Knight E Jr, Cordova B. IFN-induced 15-kDa protein is released from human lymphocytes and monocytes. J Immunol. 1991 Apr 1;146(7):2280-4. PMID:2005397
- ↑ Lenschow DJ, Giannakopoulos NV, Gunn LJ, Johnston C, O'Guin AK, Schmidt RE, Levine B, Virgin HW 4th. Identification of interferon-stimulated gene 15 as an antiviral molecule during Sindbis virus infection in vivo. J Virol. 2005 Nov;79(22):13974-83. PMID:16254333 doi:79/22/13974
- ↑ Zhao C, Denison C, Huibregtse JM, Gygi S, Krug RM. Human ISG15 conjugation targets both IFN-induced and constitutively expressed proteins functioning in diverse cellular pathways. Proc Natl Acad Sci U S A. 2005 Jul 19;102(29):10200-5. Epub 2005 Jul 11. PMID:16009940 doi:0504754102
- ↑ Narasimhan J, Wang M, Fu Z, Klein JM, Haas AL, Kim JJ. Crystal structure of the interferon-induced ubiquitin-like protein ISG15. J Biol Chem. 2005 Jul 22;280(29):27356-65. Epub 2005 May 24. PMID:15917233 doi:10.1074/jbc.M502814200
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