Synphilin-1 (SNCAIP) Antibody – Mouse Monoclonal

This gene encodes a protein containing several protein-protein interaction domains, including ankyrin-like repeats, a coiled-coil domain, and an ATP/GTP-binding motif. The encoded protein interacts with alpha-synuclein in neuronal tissue and may play a role in the formation of cytoplasmic inclusions and neurodegeneration. A mutation in this gene has been associated with Parkinson's disease. Alternatively spliced transcript variants encoding different isoforms of this gene have been described, but the full-length nature of only two have been determined. [provided by RefSeq, Jul 2011]

Function: Isoform 2 inhibits the ubiquitin ligase activity of SIAH1 and inhibits proteasomal degradation of target proteins. Isoform 2 inhibits autoubiquitination and proteasomal degradation of SIAH1, and thereby increases cellular levels of SIAH. Isoform 2 modulates SNCA monoubiquitination by SIAH1. Ref.3 Ref.11

Subunit structure: Homodimer

Probable. Heterodimer of isoform 1 and isoform 2

Probable. Interacts with SIAH1, SIAH2, SNCA, RNF19A AND PARK2. Isoform 2 has a strong tendency to form aggregates and can sequester isoform 1. Ref.1 Ref.3 Ref.7 Ref.8 Ref.9 Ref.10 Ref.11 Ref.12

Subcellular location: Cytoplasm. Note: Detected in cytoplasmic inclusion bodies, together with SNCA. Ref.1 Ref.3 Ref.10 Ref.12

Tissue specificity: Detected in brain (at protein level). Widely expressed, with highest levels in brain, heart and placenta. Ref.1 Ref.3

Post-translational modification: Ubiquitinated; mediated by SIAH1, SIAH2 or RNF19A and leading to its subsequent proteasomal degradation. In the absence of proteasomal degradation, ubiquitinated SNCAIP accumulates in cytoplasmic inclusion bodies. Isoform 2 is subject to limited ubiquitination that does not lead to proteasomal degradation. Ref.7 Ref.8 Ref.9 Ref.10

Involvement in disease: 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.Note: Disease susceptibility may be associated with variations affecting the gene represented in this entry. Ref.7 Ref.13 Ref.14

Miscellaneous: Constructs encoding portions of SNCA and SNCAIP co-transfected in mammalian cells promote cytosolic inclusions resembling the Lewy bodies of Parkinson disease. Coexpression of SNCA, SNCAIP, and PARK2 result in the formation of Lewy body-like. ubiquitin-positive cytosolic inclusions. SNCAIP isoform 2 is particularly aggregation-prone. Familial mutations in PARK2 disrupt the ubiquitination of SNCAIP and the formation of the ubiquitin-positive inclusions. These results provide a molecular basis for the ubiquitination of Lewy body-associated proteins and link PARK2 and SNCA in a common pathogenic mechanism through their interaction with SNCAIP.

Sequence similarities: Contains 6 ANK repeats.