Ubiquitin carboxyl-terminal esterase-L1 (UCHL1), or gene product 9.5 (PGP9.5), belongs to a gene family that hydrolyzes small C-terminal adducts of ubiquitin to generate the monomers. The expression of UCHL1/PGP9.5 is highly specific to neurons and to cells of the diffuse neuroendocrine system as well as their tumors, and has been linked to neurodegenerative disease in humans.
