Parkinson's Disease, the second most common neurodegenerative disease after Alzheimer's Disease, is characterized by the loss of dopaminergic neurons and the presence of Lewy bodies (comprised of alpha synuclein and parkin inclusions). Autosomal Recessive Juvenile Parkinsonism (AR-JP) is a recently described form of Parkinson's Disease that has been linked to a gene that codes for parkin. Parkin, a 52 kDa protein, has a suggested role in the ubiquitin/proteasome pathway for protein degradation. The amino terminus bears sequence homology to ubiquitin while functionally it acts as a RING type ubiquitin protein ligase (E3) that coordinates the transfer of ubiquitin to substrate proteins, thus targeting them for degradation by the proteasome.