Parkin is a ubiquitin-protein ligase (E3) involved in the ubiquitin proteasomal pathway by participating in the removal of abnormally folded or damage protein. It is highly expressed in the brain, including the substancia nigra, and is also expressed in other tissues (heart, testis, skeletal muscle). Mutations in the parkin gene causing loss of E3 activity are responsible for autosomal recessive juvenile Parkinson's desease.