Interferon-stimulated gene 15 (ISG15) is a 17 kDa secreted protein that in humans is encoded by the ISG15 gene. ISG15 is induced by type I interferon (IFN) and serves many functions, acting both as an extracellular cytokine and an intracellular protein modifier. The precise functions are diverse and vary among species but include potentiation of Interferon gamma (IFN-II) production in lymphocytes, ubiquitin-like conjugation to newly-synthesized proteins and negative regulation of the IFN-I response.
The protein encoded by this gene is a ubiquitin-like protein that is conjugated to intracellular target proteins upon activation by interferon-alpha and interferon-beta. Several functions have been ascribed to the encoded protein, including chemotactic activity towards neutrophils, direction of ligated target proteins to intermediate filaments, cell-to-cell signaling, and antiviral activity during viral infections. While conjugates of this protein have been found to be noncovalently attached to intermediate filaments, this protein is sometimes secreted. [provided by RefSeq, Dec 2012].
via MyGene.info
Interferon-stimulated gene 15 (ISG15) is a 17 kDa secreted protein that in humans is encoded by the ISG15 gene. ISG15 is induced by type I interferon (IFN) and serves many functions, acting both as an extracellular cytokine and an intracellular protein modifier. The precise functions are diverse and vary among species but include potentiation of Interferon gamma (IFN-II) production in lymphocytes, ubiquitin-like conjugation to newly-synthesized proteins and negative regulation of the IFN-I response.
== Structure == The ISG15 gene consists of two exons and encodes for a 17 kDa polypeptide. The immature polypeptide is cleaved at its carboxy terminus, generating a mature 15 kDa product that terminates with a LRLRGG motif, as found in ubiquitin. The tertiary structure of ISG15 also resembles ubiquitin, despite only ~30% sequence identity. Specifically, this structure consists of two ubiquitin-like domains connected by a polypeptide 'hinge'. Of note, ISG15 shows substantial sequence variation among species, with homology as low as 30% between orthologs.
Discovered by embedding cosine similarity (sentence-transformers MiniLM, 384-dim).