Ubiquitin carboxyl-terminal hydrolase or Ubiquitin specific protease 11 is an enzyme that in humans is encoded by the USP11 gene. USP11 belongs to the Ubiquitin specific proteases family (USPs) which is a sub-family of the Deubiquitinating enzymes (DUBs).USPs are multiple domain proteases and belong to the C19 cysteine proteases sub‒family. Depending on their domain architecture and position there is different homology between the various members. Protein ubiquitination controls many intracellular processes, including cell cycle progression, transcriptional activation, and signal transduction. This dynamic process, involving ubiquitin conjugating enzymes and deubiquitinating enzymes, adds and removes ubiquitin. Deubiquitinating enzymes are cysteine proteases that specifically cleave ubiquitin from ubiquitin-conjugated protein substrates. This gene encodes a deubiquitinating enzyme which lies in a gene cluster on chromosome Xp11.23.