UCH-L1

UCH-L1, also known as PGP9.5 and encoded by the UCHL1 gene, is a cysteine protease of the ubiquitin C-terminal hydrolase family and one of the most abundant proteins in the brain, where it constitutes an estimated 1-2 percent of soluble neuronal protein. The enzyme hydrolyzes small C-terminal adducts of ubiquitin to generate free monoubiquitin and maintains ubiquitin homeostasis in neurons. Dimerization confers an E3 ligase-like activity reported for this protein. UCHL1 mutations, including the I93M substitution, have been linked to familial Parkinson disease, and the protein is a widely used marker for neurons, neuroendocrine cells and their tumors.