From Proteopediaproteopedia link
Structure of Parkin-S223P E3 ligase
[PRKN2_HUMAN] Defects in PARK2 are a cause of Parkinson disease (PARK) [MIM:168600]. A complex neurodegenerative disorder characterized by bradykinesia, resting tremor, muscular rigidity and postural instability. Additional features are characteristic postural abnormalities, dysautonomia, dystonic cramps, and dementia. The pathology of Parkinson disease involves the loss of dopaminergic neurons in the substantia nigra and the presence of Lewy bodies (intraneuronal accumulations of aggregated proteins), in surviving neurons in various areas of the brain. The disease is progressive and usually manifests after the age of 50 years, although early-onset cases (before 50 years) are known. The majority of the cases are sporadic suggesting a multifactorial etiology based on environmental and genetic factors. However, some patients present with a positive family history for the disease. Familial forms of the disease usually begin at earlier ages and are associated with atypical clinical features.                         Defects in PARK2 are the cause of Parkinson disease type 2 (PARK2) [MIM:600116]; also known as early-onset parkinsonism with diurnal fluctuation (EPDF) or autosomal recessive juvenile Parkinson disease (PDJ). A neurodegenerative disorder characterized by bradykinesia, rigidity, postural instability, tremor, and onset usually befor 40. It differs from classic Parkinson disease by early DOPA-induced dyskinesia, diurnal fluctuation of the symptoms, sleep benefit, dystonia and hyper-reflexia. Dementia is absent. Pathologically, patients show loss of dopaminergic neurons in the substantia nigra, similar to that seen in Parkinson disease; however, Lewy bodies (intraneuronal accumulations of aggregated proteins) are absent.          Note=Defects in PARK2 may be involved in the development and/or progression of ovarian cancer.
[PRKN2_HUMAN] Functions within a multiprotein E3 ubiquitin ligase complex, catalyzing the covalent attachment of ubiquitin moieties onto substrate proteins, such as BCL2, SYT11, CCNE1, GPR37, STUB1, a 22 kDa O-linked glycosylated isoform of SNCAIP, SEPT5, ZNF746 and AIMP2. Mediates monoubiquitination as well as 'Lys-48'-linked and 'Lys-63'-linked polyubiquitination of substrates depending on the context. Participates in the removal and/or detoxification of abnormally folded or damaged protein by mediating 'Lys-63'-linked polyubiquitination of misfolded proteins such as PARK7: 'Lys-63'-linked polyubiquitinated misfolded proteins are then recognized by HDAC6, leading to their recruitment to aggresomes, followed by degradation. Mediates 'Lys-63'-linked polyubiquitination of SNCAIP, possibly playing a role in Lewy-body formation. Mediates monoubiquitination of BCL2, thereby acting as a positive regulator of autophagy. Promotes the autophagic degradation of dysfunctional depolarized mitochondria. Mediates 'Lys-48'-linked polyubiquitination of ZNF746, followed by degradation of ZNF746 by the proteasome; possibly playing a role in role in regulation of neuron death. Limits the production of reactive oxygen species (ROS). Loss of this ubiquitin ligase activity appears to be the mechanism underlying pathogenesis of PARK2. May protect neurons against alpha synuclein toxicity, proteasomal dysfunction, GPR37 accumulation, and kainate-induced excitotoxicity. May play a role in controlling neurotransmitter trafficking at the presynaptic terminal and in calcium-dependent exocytosis. Regulates cyclin-E during neuronal apoptosis. May represent a tumor suppressor gene.             
Publication Abstract from PubMed
Parkin is a RING-between-RING E3 ligase that functions in the covalent attachment of ubiquitin to specific substrates, and mutations in Parkin are linked to Parkinson's disease, cancer and mycobacterial infection. The RING-between-RING family of E3 ligases are suggested to function with a canonical RING domain and a catalytic cysteine residue usually restricted to HECT E3 ligases, thus termed 'RING/HECT hybrid' enzymes. Here we present the 1.58 A structure of Parkin-R0RBR, revealing the fold architecture for the four RING domains, and several unpredicted interfaces. Examination of the Parkin active site suggests a catalytic network consisting of C431 and H433. In cells, mutation of C431 eliminates Parkin-catalysed degradation of mitochondria, and capture of an ubiquitin oxyester confirms C431 as Parkin's cellular active site. Our data confirm that Parkin is a RING/HECT hybrid, and provide the first crystal structure of an RING-between-RING E3 ligase at atomic resolution, providing insight into this disease-related protein.
Structure and function of Parkin E3 ubiquitin ligase reveals aspects of RING and HECT ligases.,Riley BE, Lougheed JC, Callaway K, Velasquez M, Brecht E, Nguyen L, Shaler T, Walker D, Yang Y, Regnstrom K, Diep L, Zhang Z, Chiou S, Bova M, Artis DR, Yao N, Baker J, Yednock T, Johnston JA Nat Commun. 2013 Jun 17;4:1982. doi: 10.1038/ncomms2982. PMID:23770887
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.