Positional-scanning fluorigenic substrate libraries reveal unexpected specificity determinants of DUBs (deubiquitinating enzymes)

DUBs (deubiquitinating enzymes) are a family of proteases responsible for the specific removal of ubiquitin attached to target proteins and thus control the free cellular pools of this molecule. DUB activity is usually assayed using full-length ubiquitin, and these enzymes generally show low activity towards small substrates that constitute the P4–P1 LRGG (Lys-Arg-Gly-Gly) C-terminal motif of ubiquitin. To gain insight into the C-terminal...