PRKN and Parkinson disease: Since inactivation of parkin’s E3 ligase activity results in the accumulation of downstream parkin substrates (aminoacyl tRNA synthetase interacting multifunctional protein 2 [AIMP2], parkin-interacting substrate [PARIS], and Parkin-associated endothelin receptor-like receptor), transgenic mice expressing these pathological parkin substrates have been developed to model PD with parkin inactivation [7–9].