Usp14 is one of the deubiquitinating enzymes of the human 26S proteasome. Usp14 belongs to the Ub-specific proteases family. Usp14 catalyzes Ub chain trimming that shortens a polyUb chain from the distal end of the Ub chain. Usp14 was found to play an essential role in maintaining the protein levels of monomeric Ub in cells. Interestingly, Usp14 was also found to inhibit proteasomal degradation independent of its deubiquitinating activity.
