Ac-ISG15prox-Rh110MP (UbiQ-127)
a new activity assay reagent for ISG15 proteases

UbiQ-127 is a quenched, fluorescent substrate for ISG15 proteases. Hereby cleavage of the amide bond between the C-terminal Gly and rhodamine110 moiety releases the highly fluorescent Rh110-morpholinecarbonyl (Rh110MP, Terentyeva et al). UbiQ-127 is based on the proximal part of mouse ISG15 (aa 77-165), in line with recent data (Basters et al) that showed that only the C-terminal ubiquitin-like domain of ISG15 is recognized and essential for USP18 activity.

Basters et al. Nat Struct Mol Biol 2017, 24, 270
Terentyeva et al. Bioconj Chem 2011, 22, 1932.