Parkin and its role in protein degradation. Parkin has a distinct domain structure, consisting of an amino-terminal ubiquitin-like (Ubl) domain and two carboxy-terminal RING domains separated by an in between RING (IRB) domain. Two Ubl domains interact with the proteosome whilst the very carboxyl terminal region interacts with at least one membrane protein CASK. (From Cookson 2003a) Parkin can also recruit a number of accessory proteins such as HSP70, CHIP and components of other modular E3 ligases such as hsel110.