Ubiquitin Specific Peptidase 14 (USP14) is a cytoplasmic protein that belongs to the peptidase C19 family of deubiquitinating enzymes. It has a predicted molecular weight of 56.1 kDa. Human USP14 is 494 amino acids (aa) in length, contains a N-terminal ubiquitin-like (Ubl) domain (4-80 aa), and shares 97% aa sequence identity with the mouse and rat orthologs. USP14 is one of three deubiquitinating enzymes associated with the 26S Proteasome. It reversibly binds the 19S regulatory particle via its Ubl domain and mediates the disassembly of ubiquitin chains on substrates by the stepwise removal of ubiquitin molecules from the distal tip of the chain. USP14 has also been shown to deubiquitinate the chemokine receptor CXCR4, regulating both CXCL12/SDF-1-induced chemotaxis and receptor degradation. USP14 appears to be critical for the development and function of neuromuscular junctions. Additionally, USP14 is thought to serve as a physiological inhibitor of endoplasmic reticulum-associated degradation under non-stressed conditions by inhibiting the degradation of unfolded endoplasmic reticulum proteins.