Alpha-synuclein, a member of the synuclein family, is a protein that was first identified in 1988 whose name is derived from its localization to both the synapse and nucleus (1-3). Specifically, it is expressed primarily in the brain, including Lewy Bodies (1-6). Alpha-synuclein is encoded by the SNCA gene, located on chromosome 4p21, and is processed as a 140 amino acid (aa) protein with a theoretical molecular weight of 14 kDa (1,2,4). Structurally alpha-synuclein consists of a N-terminal binding domain (1-60 aa), a central domain core region called the non-amyloid-beta component (NAC) (61-95 aa), and a C-terminal domain (96-140 aa) (1-3). The N-terminal region contains aa repeats with a KTKEGV consensus sequence that gives the protein its alpha-helical structure that associates with lipid membranes (1-4). The hydrophobic NAC region is responsible for alpha-synuclein aggregation and fibril formation (1-4). The acidic C-terminal tail is largely unstructured but can be targeted for post-translational modifications (1-4). The function of alpha-synuclein is not entirely understood, but it is shown to have a role in suppression of apoptosis, acting as a molecular chaperone, regulating glucose, and modulating calmodulin activity (1,3).
A number of studies have revealed that alpha-synuclein aggregation is a hallmark feature in a number of neurodegenerative diseases, referred to as synucleinopathies (2-4). Alpha-synuclein protein aggregates are a large component of Lewy bodies that are present in Parkinson's disease (PD), Lewy body dementia (LBD), and multiple system atrophy (1-6). Research has shown phosphorylation of alpha-synuclein at Ser129 moves the protein from the nucleus to the cytoplasm and promotes fibril formation associated with synucleinopathies (1,2,5). Recent studies also suggest that alpha-synuclein accumulation can prevent mitochondrial import machinery causing mitochondrial dysfunction that is often observed in neurodegeneration (5). It is thought that preventing alpha-synuclein aggregation may prevent PD, thus alpha-synuclein is a target for many potential therapeutic interventions aimed at decreasing aggregate formation or increasing clearance (1,2,4-6).
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4. Lashuel, H. A., Overk, C. R., Oueslati, A., & Masliah, E. (2013). The many faces of alpha-synuclein: from structure and toxicity to therapeutic target. Nature reviews. Neuroscience. https://doi.org/10.1038/nrn3406
5. Rocha, E. M., De Miranda, B., & Sanders, L. H. (2018). Alpha-synuclein: Pathology, mitochondrial dysfunction and neuroinflammation in Parkinson's disease. Neurobiology of disease. https://doi.org/10.1016/j.nbd.2017.04.004
6. O'Leary, E. I., & Lee, J. C. (2019). Interplay between alpha-synuclein amyloid formation and membrane structure. Biochimica et biophysica acta. Proteins and proteomics. https://doi.org/10.1016/j.bbapap.2018.09.012