Parkin is an E3 ligase that contains a ubiquitin-like (UBL) domain in the N terminus and an R1-in-between-ring-RING2 motif in the C terminus. We showed that the UBL domain specifically interacts with the R1 domain and negatively regulates Parkin E3 ligase activity, Parkin-dependent mitophagy, and Parkin translocation to the mitochondria. The binding between the UBL domain and the R1 domain was suppressed by carbonyl cyanide m-chlorophenyl hydrazone treatment or by expression of PTEN-induced putative kinase 1 (PINK1), an upstream kinase that phosphorylates Parkin at the Ser-65 residue of the UBL domain.
