Mutations in the parkin gene are thought to underlie an inherited form of Parkinson's disease known as autosomal recessive juvenile parkinsonism (PARK 2). The parkin protein has been characterized as an E3 ubiquitin-ligase and, while most research has focused on its involvement in the ubiquitin proteasome system, its role in the cellular dysfunction of the nigrostriatal pathway has yet to be elucidated. Current literature focuses on the accumulation of parkin substrates as the mechanism responsible for neural degeneration in PARK2; however, pathological evaluation of neural tissue reveals the absence of intracytoplasmic inclusion bodies that typically result from excess aggregate buildup. Therefore, an alternative hypothesis needs to be investigated to address the question of neural death. One attractive hypothesis originates from parkin's association with synaptic vesicles proteins in addition to the recent finding that proteins with E3 ligase activity have been found to regulate endocytosis through the ubiquitination of proteins at the plasma membrane. We are therefore testing the hypothesis that parkin is involved in regulating the number and/or functionality of synaptic vesicles through its interaction with proteins at the presynaptic nerve terminal.
