Ubiquitinating enzymes (UBEs) catalyze protein ubiquitination, a reversible process countered by deubiquitinating enzyme (DUB) action. Five DUB subfamilies are recognized, including the USP, UCH, OTU, MJD and JAMM enzymes (1,2). USP18 (also known as UBP43) is a deubiquitinase best known for catalyzing the removal of ISG15, an interferon-regulated ubibiquitin-like protein, from conjugated proteins (3). Removal of ISG15 from target proteins by the USP18 peptidase maintains the critical cellular balance of ISG15-conjugated proteins important for normal development and brain function (4,5). Following induction by IFN or LPS (6), USP18 binds the INF receptor subunit IFNAR2 and inhibits signal transduction through the JAK-STAT pathway (7). USP18 regulation of IFN signaling inhibits IFN-mediated apoptosis and does not necessarily rely on USP18 peptidase activity (8). As the therapeutic use of recombinant IFN can lead to refractory IFN signaling and a less effective response, the combination of IFN treatment and regulation of USP18 expression may produce a more positive outcome (9).
Applications:
Suitable for use in Western Blot and Immunoprecipitation. Other applications not tested.
Recommended Dilution:
Western Blot: 1:1000
Immunoprecipitation: 1:50
Optimal dilutions to be determined by the researcher.
Storage and Stability:
May be stored at 4 degrees C for short-term only. For long-term storage and to avoid repeated freezing and thawing, aliquot and store at -20 degrees C. Aliquots are stable for at least 12 months at -20 degrees C. For maximum recovery of product, centrifuge the original vial after thawing and prior to removing the cap. Further dilutions can be made in assay buffer.